Naval Education and
Training Command
NAVEDTRA 12204
May 1990
0502-LP-2 13-11 00
Training Manual
(TRAMAN)
Machinery
Repairman 3 & 2
«?
'•I
c
z
3
g
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
Nonfederal government personnel wanting a copy of this document
must use the purchasing instructions on the inside cover.
O
r—
m
S/N0502-LP-213-1100
The terms training manual (TRAMAN) and
nonresident training course (NRTC) are now the
terms used to describe Navy nonresident training
program materials. Specifically, a TRAMAN in-
cludes a rate training manual (RTM), officer text
(OT), single subject training manual (SSTM), or
modular single or multiple subject training manual
(MODULE); and an NRTC includes nonresident
career course (NRCC), officer correspondence
course (OCC), enlisted correspondence course
(ECC), or combination thereof.
Although the words "he," "him," and "his"
are used sparingly in this manual to enhance
communication, they are not intended to be
gender driven nor to affront or discriminate
against anyone reading this text.
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
this document must write to Superintendent of Documents,
t Commanding Officer, Naval Publications and Forms Center,
tention: Cash Sales, for price and availability.
MACHINERY REPAIRMAN 3 & 2
NAVEDTRA 12204
1990 Edition Prepared by
MRCM Reynaldo R. Romero
v^^^^v^reggsaxKvaNxs^^
PREFACE
This Training Manual (TRAMAN) and Nonresident Training Course
(NRTC) form a self-study package to teach the theoretical knowledge and
mental skills needed by the Machinery Repairman Third Class and Machinery
Repairman Second Class. To most effectively train Machinery Repairmen,
this package may be combined with on-the-job training to provide the necessary
elements of practical experience and observation of techniques demonstrated
by more senior Machinery Repairmen.
Completion of the NRTC provides the usual way of satisfying the
requirements for completing the TRAMAN. The set of assignments in the
NRTC includes learning objectives and supporting questions
designed to help the student learn the materials in the TRAMAN.
1990 Edition
Stock Ordering No.
0502-LP-213-1100
Published by
NAVAL EDUCATION AND TRAINING PROGRAM
MANAGEMENT SUPPORT ACTIVITY
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON, D.C.: 1990
THE UNITED STATES NAVY
GUARDIAN OF OUR COUNTRY
The United States Navy is responsible for maintaining control of the
sea and is a ready force on watch at home and overseas, capable of
strong action to preserve the peace or of instant offensive action to
win in war.
It is upon the maintenance of this control that our country's glorious
future depends; the United States Navy exists to make it so.
WE SERVE WITH HONOR
Tradition, valor, and victory are the Navy's heritage from the past. To
these may be added dedication, discipline, and vigilance as the
watchwords of the present and the future.
At home or on distant stations we serve with pride, confident in the
respect of our country, our shipmates, and our families.
Our responsibilities sober us; our adversities strengthen us.
Service to God and Country is our special privilege. We serve with
honor.
THE FUTURE OF THE NAVY
The Navy will always employ new weapons, new techniques, and
greater power to protect and defend the United States on the sea,
under the sea, and in the air.
Now and in the future, control of the sea gives the United States her
greatest advantage for the maintenance of peace and for victory in
war.
Mobility, surprise, dispersal, and offensive power are the keynotes of
the new Navy. The roots of the Navy lie in a strong belief in the
future, in continued dedication to our tasks, and in reflection on our
heritage from the past.
Never have our opportunities and our responsibilities been greater.
CONTENTS
CHAPTER Page
1. Scope of the Machinery Repairman Rating 1-1
2. Toolrooms and Tools 2-1
3. Layout and Benchwork 3-1
4. Metals and Plastics 4-1
5. Power Saws and Drilling Machines 5-1
6. Offhand Grinding of Tools 6-1
7. Lathes and Attachments 7-1
8. Basic Engine Lathe Operations 8-1
9. Advanced Engine Lathe Operations 9-1
10. Turret Lathes and Turret Lathe Operations 10-1
1 1 . Milling Machines and Milling Operations 11-1
12. Shapers, Planers, and Engravers 12-1
13. Precision Grinding Machines 13-1
14. Metal Buildup 14-1
15. The Repair Department and Repair Work 5-1
APPENDIX
I. Tabular Information of Benefit to
Machinery Repairmen AI-1
II. Formulas for Spur Gearing AIM
III. Derivation Formulas for Diametral Pitch System AIII-1
IV. Glossary AIV-1
INDEX INDEX-1
111
CREDITS
The illustrations indicated below are included in this edition of Machinery
Repairman 3 & 2, through the courtesy of the designated companies,
publishers, and associations. Permission to use these illustrations is gratefully
acknowledged. Permission to reproduce these illustrations and other materials
in this publication should be obtained from the source.
Source
Atlas Press Company, Clausing
Corporation
Brown & Sharpe Manufacturing
Company
Cincinnati Milacron Marketing
Co.
Cincinnati Inc.
Devlieg-Sundstrand
DoAlI Company
Kearney & Trecker Corporation
Lars Machine, Inc.
Monarch Tool Company
Rockford Line
SIFCO Selective Plating
South Bend Lathe Works
Warner & Swasey Co.
Figures
11-3
11-8, 11-9, 11-13, 11-14, 11-16, 11-17, 13-20
11-1, 11-2, 11-4, 11-5, 11-12, 11-13, 11-15, 11-18, 11-19, 11-20,
11-21, 11-83, 13-10, 13-11, 13-12, 13-15, 13-23, 13-24, 13-25
12-1, 12-3
10-42, 10-43
5-3, 5-5, 5-6, 5-7, 5-8, 5-9, 5-10, 5-11, 5-12, 5-13, 5-14, 5-15, 5-16,
5-17, 5-18, 5-19, 5-20, 5-21, 5-22, 5-23, 5-24
11-11
12-19, 12-20, 12-21, 12-22, 12-23, 12-24, 12-25, 12-26, 12-27,
12-28, 12-29, 12-30, 12-31, 12-32, and table 12-2
7-1
12-13
14-11, 14-12, 14-13, 14-14, 14-15, 14-16, 14-17, 14-18, 14-19,
tables 14-3, 14-4, 14-5, 14-6, 14-7, 14-8, 14-9, 14-10, 14-11, 14-12
and all inserts in Chapter 14
7-2, 7-5, 7-6, 7-8, 7-9, 7-10, 7-11, 7-12, 7-13, 7-14, 7-15, 7-16,
7-17, 7-27, 7-29, 7-32, 7-33, 7-34, 7-35, 7-36, 7-37, 7-39, 7-40,
8-2, 8-4, 8-6, 8-9, 8-10, 8-11, 8-16, 8-18, 8-19, 8-20, 8-21, 8-22,
8-23, 8-24, 8-25, 8-26, 8-27, 8-28, 8-29, 9-2, 9-3, 9-4, 9-5, 9-6,
9-7, 9-8, 9-10, 9-11, 9-13, 9-19, 9-20, 9-21, 9-23, 9-24, 9-25, 9-30
10-3, 10-4, 10-5, 10-6, 10-7, 10-8, 10-9, 10-10, 10-11, 10-12, 10-13,
10-14, 10-15, 10-16, 10-17, 10-18, 10-19, 10-21, 10-24, 10-25,
10-26, 10-30, 10-31, 10-34, 10-35, 10-36, 10-37, 10-38, 10-39,
10-40, 10-41, 13-3, 13-13
IV
CHAPTER 1
SCOPE OF THE
MACHINERY REPAIRMAN RATING
The official description of the scope of the
Machinery Repairman rating is to "perform
organizational and intermediate maintenance on
assigned equipment and in support of other ships,
requiring the skillful use of lathes, milling
machines, boring mills, grinders, power hack-
saws, drill presses, and other machine tools;
portable machinery; and handtools and measuring
instruments found in a machine shop." That is
a very general statement, not meant to define
completely the types of skills and supporting
knowledge that an MR is expected to have in the
different paygrades. The Occupational Standards
for Machinery Repairman contain the require-
ments that are essential for all aspiring Machinery
Repairmen to read and use as a guide in planning
for advancement.
The job of restoring machinery to good work-
ing order, ranging as it does from the fabrication
of a simple pin or bushing to the complete
rebuilding of an intricate gear system, requires
skill of the highest order at each task level. Often,
in the absence of dimensional drawings or other
design information, a Machinery Repairman must
depend upon ingenuity and know-how to
successfully fabricate a repair part.
One of the important characteristics you will
gain from becoming a well trained and skilled
Machinery Repairman is versatility. As you gain
knowledge and skill in the operation of the many
different types of machines found in Navy
machine shops, you will realize that even though
a particular machine is used mostly for certain
types of jobs, it may be capable of accepting many
others. Your imagination will probably be your
limiting factor and if you keep your eyes, ears,
and mind open, you will discover that there are
many things going on around you that can
broaden your base of knowledge. You will find
a certain pleasure and a source of pride in develop-
ing new and more efficient ways to do something
that has become so routine that everyone else
simply accepts the procedure currently being used
as the only one that will work.
The skill acquired by a Machinery Repairman
in the Navy is easily translated into several skills
found in the machine shops of private industry.
In fact, you would be surprised at the depth and
range of your knowledge and skill compared to
your civilian counterpart, based on a somewhat
equal length of experience. The machinist trade
in private industry tends to break job descriptions
into many different titles and skill levels. The
beginning skill level and one in which you will
surely become qualified is "Machine Tool
Operator," a job often done by semiskilled
workers. The primary requirement of the job is
to observe the operation, disengage the machine
in case of problems and possibly maintain manual
control over certain functions. Workers who do
these jobs usually have the ability to operate a
limited number of different types of machines.
Another job description found in private industry
is "Layout Man." The requirement of this job
is to layout work that is to be machined by some-
one else. An understanding of the operation and
capabilities of the different machines is required,
as well as the ability to read blueprints. As you
progress in your training in the Machinery
Repairman rating you will become proficient in
interpreting blueprints and in planning the
required machining operations. You will find that
laying out intricate parts is not so difficult with
this knowledge. A third job description is "Set-
up Man," a job which requires considerable
knowledge and skill, all within what you can
expect to gain as a Machinery Repairman. A set-
up man is responsible for placing each machine
accessory and cutting tool in the exact position
required to permit accurate production of work
by a machine tool operator. An "All Around
Machinist" in private industry is the job for which
the average Machinery Repairman would qualify
as far as knowledge and skill are concerned.
This person is able to operate all machines in the
shop and manufacture parts from blueprints.
Some Machinery Repairmen will advance their
knowledge and skills throughout their Navy career
1-1
to the point that they could move into a job as
a "Tool and Die Maker" with little trouble. They
also acquire a thorough knowledge of engineer-
ing data related to design limitations, shop math
and metallurgy. There are many other related
fields in which an experienced Machinery Repair-
man could perform — instrument maker, research
and development machinist, toolroom operator,
quality assurance inspector, and of course the
supervisory jobs such as foreman or
superintendent.
The obvious key to holding down a position
of higher skill, responsibility, and pay is the same
both in the Navy and in private industry. You
must work hard, take advantage of the skills and
knowledge of those around you, and take pride
in what you do regardless of how unimportant
it may seem to you. You have a great opportunity
ahead of you as a Machinery Repairman in the
Navy; a chance to make your future more secure
than it might have been.
TYPICAL ASSIGNMENT
AND DUTIES
As a Machinery Repairman you can be
assigned to a tour of duty aboard almost any type
of surface ship, from a small fleet tug, which has
a small 10- or 12-inch lathe, a drill press and a
grinder, to a large aircraft carrier that is almost
as well equipped in the machine shop as a tender
or repair ship. You will find that although a
ship's workspace is relatively small the machine
shop will have more equipment than you might
imagine. A lathe, drill press and grinder can
almost be assured, but in many cases a milling
machine and a second lathe are also available. A
tender or repair ship is similar to a factory in the
types of equipment that are installed. You will
find the capabilities of such a ship to be very
extensive in all areas required to maintain the
complex ships of today's Navy. A Machinery
Repairman is not destined to spend an entire
career on sea duty. There are many shore
establishments where you may be assigned. The
Navy has shore-based repair activities located at
various places throughout the United States and
overseas. Most of these have wide-ranging
capabilities for performing the required
maintenance. There are general billets or
assignments ashore that will not necessarily be
associated with the Machinery Repairman rating,
but which add to an individual's overall experience
in other ways.
It would be difficult to detail the duties that
you may perform at each of your assignments.
You will find that on small ships you may be the
only Machinery Repairman aboard. This requires
that you be self-motivated toward learning all you
can to increase your ability as a Machinery Repair-
man and that you seek advice from sources off
of your ship when you have an opportunity. You
will be surprised at how good you really are when
you make an honest effort to do your best.
Regardless of your assignment, you will have an
opportunity to work with personnel from other
ratings. This can be an experience in itself. There
are many interesting skills to be found in the
Navy. None of them are easy, but many will offer
you some amount of knowledge that will increase
your effectiveness as a Machinery Repairman.
TRAINING
Training is the method by which everyone
becomes knowledgeable of and skilled in any
activity, whether it's a job, a sport or something
as routine as eating the proper foods. Training
can take many forms and can be a conscientious
or unconscientious effort on your part. However,
you will make the most progress when you
recognize the need to increase your level of
knowledge, take the required action to obtain the
training and fully apply all your efforts and
resources to realize the maximum benefit from the
training. In the following paragraphs, we will
present a brief description of each type of train-
ing available to a Machinery Repairman. Keep in
mind that the information listed is peculiar to your
rating and that the Navy has many other programs
available which will allow you to increase your
general education. You can obtain information
concerning these programs from your career
counselor or education officer.
FORMAL SCHOOLS
The Navy has available several schools which
provide an excellent background in the Machinery
Repairman rating. You may have an opportunity
to attend one or more of them during your career
in the Navy.
The fundamentals of machine shop practice
are taught in Machinery Repairman "A" school.
Classroom instruction provides the theory of basic
operating procedures, safety precautions and
certain project procedures, while time spent in the
shop provides hands-on experience, supervised by
1-2
a trained and skilled instructor. Some of the
equipment that you can expect to work with in
this course are lathes, milling machines, drill
presses, band saws, cutoff saws, pedestal grinders
and engraving machines. The length and specific
content of the course may vary from time to time
to accommodate the needs of the fleet. You will
have no difficulty in performing the work in a
Navy machine shop if you apply yourself in MR
"A" school.
Advanced machine shop practice and the heat
treatment of metals are taught in Navy schools
also. These courses are usually attended by
personnel in their second and subsequent
enlistments at "C" school. Course content
generally covers the information and associated
equipment required for advancement to MR1 and
MRC, although the schools are not required to
establish eligibility for advancement.
You should consult with your leading petty
officer or career counselor to obtain the most
current information regarding school availability
and your eligibility to request attendance.
TRAINING MANUALS
AND NONRESIDENT
TRAINING COURSES
Navy training manuals and nonresident train-
ing courses are designed as a self-study method
to provide instruction to personnel in a variety
of subjects. You can choose your own pace in
working the courses, and you are allowed to refer
to the book when trying to decide on the best or
correct answer. If you are to learn anything, you
must work the course yourself and not take the
answers from someone else. Some training
manuals and nonresident training courses are
mandatory for you to complete to meet advance-
ment requirements. These courses are listed in the
Manual for Advancement, BUPERINST 1430.16
(series), and in the current (revised annually) issue
of the Bibliography for Advancement Study,
NAVEDTRA 10052 (series), where they are
indicated by asterisks (*). Remember that as you
advance you are responsible for the information
in the training manuals for the paygrades below
yours, in addition to the courses for the next
higher paygrade. A course offers an excellent
opportunity to become familiar with a subject
when you cannot be personally involved with the
equipment. There are many small but important
points that will be covered in a course that you
otherwise may not learn.
ON-THE-JOB TRAINING
On-the-job training is probably the most
valuable of all the training methods available to
you. This is where you put the textbook theories
and general procedures into specific job practice
in personal contact with the problem at hand. All
those unfamiliar terms that you read about in a
course now begin to fit into a plan that makes
sense to you. The one very important thing for
you to remember is that when you are unsure
about something, ask questions. An unusual job
experience is of little value to you if you have to
wing your way through it tooth and nail, guess-
ing at each new step. The people that you work
with and for had to learn what they know by
asking questions, so they won't think you any less
efficient or valuable when you ask. There will be
opportunities to tackle jobs which are difficult and
seldom done, jobs which offer a great deal of
experience and knowledge. These are the jobs that
you should be really aggressive in pursuing and
eager to accept. Regardless of the profession or
the employer, the person who gets ahead is usually
the one who is highly motivated toward increasing
personal capacity, thereby, becoming more
valuable to his or her employer. The Navy is no
different than any other employer in this sense.
OTHER TRAINING MANUALS
Some of the publications you will use are
subject to revision from time to time— some at
regular intervals, others as the need arises. When
using any publication that is subject to revision,
be sure that you have the latest edition. When
using any publication that is kept current by
means of changes, be sure you have a copy in
which all official changes have been made.
Studying canceled or obsolete information will not
help you do your work or advance; it is likely to
be a waste of time, and may even be seriously
misleading.
The training manuals you must use in conjunc-
tion with this one to attain your required
professional qualifications are:
1. Mathematics, Vol 1, NAVEDTRA 10069
and Mathematics, Vol. 2, NAVEDTRA 10071.
These two volumes provide a review of the
mathematics you will need in shop work.
2. Blueprint Reading and Sketching,
NAVEDTRA 10077, provides information on
blueprint reading and layout work.
1-3
3. Tools and Their Uses, NAVEDTRA 10085,
provides specific and practical information in the
use of almost any handtool you are likely to use.
It is important that you keep abreast of
required training manuals. To ensure that the
most current manual is available, you should
check the Bibliography for Advancement Study,
NAVEDTRA 10052 (series), and List of Train-
ing Manuals and Correspondence Courses,
NAVEDTRA 10061 (series). Both of these
references are revised annually, so be sure you
have the latest one.
In addition, there are three sources of technical
information that are ordinarily available on board
your ship: (1) NAVSHIPS' Technical Manual,
which contains the official word on all shipboard
machinery, (2) technical manuals provided by the
manufacturers of machinery and equipment used
by the Navy, and (3) machinist's handbooks. Most
of these books should be readily available.
However, if they are not, your leading petty
officer or division officer can request them
through proper channels.
SAFETY
As a Machinery Repairman, you will be
exposed to many different health and safety
hazards every day. A great many of these are
common to all personnel who work and live
aboard a Navy ship or station, and some are
peculiar only to personnel who are involved with
jobs within machinery spaces. Information
concerning these can be found in both the Fireman
and Basic Military Requirements training manuals
as well as instructions prepared by your
command. In this section we shall look at some
of the more common safety hazards you will find
in a machine shop and some of the precautions
you can take to prevent an injury to either yourself
or someone else. You will find that safety is
stressed throughout this manual as well as the
importance of an individual's responsibility to not
only be familiar with and observe all safe working
standards personally, but also to encourage others
to do so. Safety is a subject where the "learn by
doing" method does not provide the greatest
advantage.
Your eyes are one of your most priceless
possessions. When you think about this and try
to imagine how you would get along without
them, you will agree that the slight inconvenience
caused by wearing safety glasses, goggles or a face
shield is a small price to pay for eye protection.
Wear safety glasses or goggles any time you are
around machinery in operation, including hand-
tools, whether powered or nonpowered. Safety
glasses that have side guards are the most
effective for keeping out small metal chips or
particles from grinding wheels. You should wear
a face shield and safety glasses at all times
whenever you are around any grinding operation.
Another item of protection is safety-toe shoes.
Granted, the additional weight of the steel
reinforced toe does not make them the most
comfortable shoes you can wear, but they do offer
outstanding foot protection and are much more
comfortable than a cast. Look around your shop
at the dents left in the deck from objects being
dropped. Do you think your unprotected foot
would fare any better?
Some of the objects you will be handling in
the shop will have sharp or ragged edges on them
that can cut easily. You should remove as many
of these "burrs" as possible with a file. In spite
of your filing efforts, heavy objects will still cut
easily where there is a corner. A pair of leather
or heavy cotton work gloves will protect your
hands in these cases. You should NOT wear gloves
when operating machinery. The chances of their
being caught are too great.
Loose fitting clothing worn around moving
machinery will test your strength if it is caught
in the rotating equipment. You would be amazed
at the strength a shirt has when being wound up
on a machine. Rings, bracelets and other jewelry
can snag on projections of a rotating part and take
a finger or other part of your body off before you
know you have a problem.
How many times have you seen someone bend
over and pick up a heavy object by using his or
her back? Chances are this same person will
eventually injure himself or herself. The correct
way to lift any heavy object is to get as close to
the object as you can, spread your feet about a
foot apart and squat down by bending your knees.
Keep your back straight during the lift. When you
grasp the object, lift by using the muscles in your
legs and hold the object close to your body. Walk
slowly to your destination and lower the part
exactly as you lifted it. If you have to lift
something higher than your waist, seek assistance.
Of course, there is a limit to how much weight
anyone can safely pick up and this should not be
exceeded.
Good housekeeping practices may demand a
little more of your time than you are willing to
give on some occasions, but this is just as
1-4
important to a safe shop as any other measure
you can take. Small chips made during a
machining operation can become very slippery
when allowed to collect on a steel deck. Long, un-
broken chips can trip or cut someone walking past
them. Lubricating oil that has seeped from a
machine or a cutting oil thrown out by the
machine can be an extreme hazard on a steel deck.
All liquid spillage should be cleaned up right
away. If your job is causing a hazard to other
personnel by throwing chips or coolant into a
passageway, speak with your supervisor about
isolating the immediate area by stretching tape
across the area. Unused metal stock, small and
large parts of equipment being worked on,
toolboxes and countless other objects should not
be left laying around the shop where traffic can
be expected to go or where a machine operator
may have to be positioned. Most well organized
shops have a place for storing all movable objects
and this is the place for them. It will save you time
when daily cleanup or field day comes along, and
it may prevent a serious injury.
To protect yourself from injury while
operating ship machinery, there are several things
you can do. The first thing is to make sure that
you know how the machine operates, what each
control lever does, the capability of the machine
and especially where the stop button or clutch
lever is in case an emergency stop is required. All
guards that cover gears, drive belts, pulleys or
deflect chips should be in place at all times. Use
the correct tool for the job you are doing. This
means more than using a scraper to remove paint
instead of a 6-inch ruler. Every machine or hand-
tool has a safe working limit that was determined
by considering the stresses it is subjected to
during its intended use. Excessive pressures could
cause machine or tool failure followed by injury.
Whenever you are operating a machine, give
it your total concentration. Save daydreaming for
a more relaxed time. If you must talk with some-
one, shut your machine off.
Electrical safety is not the private respon-
sibility of the electricians. They can keep the
equipment operating safely if they are notified
when a problem exists. They cannot make
everyone observe safety precautions when work-
ing around electrically powered equipment. This
is a responsibility that each individual must accept
and carry out.
The electrical systems used onboard ships are
not like those found in your home, so however
efficient you may feel you are as a handyman,
do not attempt to make any repairs or adjustments
on any faulty equipment on board ship. Notify
the electric shop and let the job be done by the
trained electricians.
There are some basic safety precautions you
can observe while using electrical equipment:
• Use only authorized portable electric
equipment which has been tested by the electric
shop within the prescribed time period and which
is properly tagged to indicate such a test.
• Report all jury-rigged portable electrical
equipment to the electric shop.
• When a plastic-cased or double-insulated
electrically powered tool is available, use it in
preference to an older metal-cased tool.
• Ensure that all metal-cased electrically
powered tools have a three-conductor cable, a
three-prong grounded plug and that they are
plugged into the proper type receptacle.
• Wear rubber gloves when setting up and
using the metal-cased tools or when working
under particularly hazardous conditions and in
environments such as wet decks.
• Notify the electric shop when you feel even
a slight tingle while operating electrical equipment.
• Follow the safety precautions exactly as
prescribed by your maintenance requirement cards
when you perform maintenance on your
equipment.
Always remember that electricity strikes
without warning and, unfortunately, we cannot
always sit around and discuss what went wrong
after an accident has happened. It is to your
advantage to ask when you are not sure of
something. NEVER take unnecessary chances by
hurrying or being inattentive. ALWAYS THINK
about what your are going to do before you do it.
PURPOSES, BENEFITS,
AND LIMITATIONS
OF THE PLANNED
MAINTENANCE SYSTEM
You will soon find, if you have not done so
already, that the continued operation of
machinery depends on systematic and dedicated
maintenance. The following paragraphs contain
1-5
a brief discussion on the purposes, benefits, and
limitations of the Navy's formal maintenance
system, the Planned Maintenance System. You
will be involved in the Planned Maintenance
System, to some degree, throughout your career
in the Navy.
PURPOSES
The Planned Maintenance System (PMS) was
established for several purposes:
1. To reduce complex maintenance to
simplified procedures that are easily identified and
managed at all levels.
2. To define the minimum planned mainte-
nance required to schedule and control PMS
performance.
3. To describe the methods and tools to be
used.
4. To provide for the detection and prevention
of impending casualties.
5. To forecast and plan manpower and-
material requirements.
6. To plan and schedule maintenance tasks.
7. To estimate and evaluate material readi-
ness.
8. To detect areas that require additional or
improved personnel training and/or improved
maintenance techniques or attention.
9. To provide increased readiness of the ship.
BENEFITS
PMS is a tool of command. By using PMS,
the commanding officer can readily determine
whether his ship is being properly maintained.
Reliability is intensified. Preventive maintenance
reduces the need for major corrective
maintenance, increases economy, and saves the
cost of repairs.
PMS assures better records, containing more
data that can be useful to the shipboard
maintenance manager. The flexibility of the
system allows for programming of inevitable
changes in employment schedules, thereby help-
ing to better plan preventive maintenance.
Better leadership and management can be
realized by reducing frustrating breakdowns and
irregular hours of work. PMS offers a means
of improving morale and thus enhances the
effectiveness of both enlisted personnel and
officers.
LIMITATIONS
The Planned Maintenance System is not self-
starting; it will not automatically produce good
results. Considerable professional guidance is
required. Continuous direction at each echelon
must be maintained, and one individual must be
assigned both the authority and the responsibility
at each level of the system's operation.
Training in the maintenance steps as well as
in the system will be necessary. No system is a
substitute for the actual technical ability required
of the officers and enlisted personnel who direct
and perform the upkeep of the equipment.
SOURCES OF INFORMATION
One of the most useful things you can learn
about a subject is how to find out more about it.
No single jmblication can give you all the
information yougieed to perform the duties of
your rating. You should learn where to look for
accurate, authoritative, up-to-date information on
all subjects related to the naval requirements for
advancement and the occupational standards of
your rating.
NAVSEA PUBLICATIONS
The publications issued by the Naval Sea
Systems Command are of particular importance
to engineering department personnel. Although
you do not need to know everything in these
publications, you should have a general idea of
where to find the information they contain.
Naval Ships' Technical Manual
The Naval Ships' Technical Manual is the
basic engineering doctrine publication of the
Naval Sea Systems Command. The manual is kept
up-to-date by means of quarterly changes.
NAVSEA Deckplate
The NAVSEA Deckplate is a bimonthly
technical periodical published by the Naval
Sea Systems Command for the information of
personnel in the naval establishment on the
design, construction, conversion, operation,
maintenance, and repair of naval vessels and their
equipment, and on other technical equipment and
on programs under NAVSEA's control. This
magazine is particularly useful because it presents
1-6
information that supplements and clarifies
information contained in the Naval Ships'
Technical Manual. It is also of considerable
interest because it presents information on new
developments in naval engineering. The NAVSEA
Deckplate was formerly known as the NAVSEA
Journal.
MANUFACTURER'S TECHNICAL
MANUALS
The manufacturers' technical manuals fur-
nished with most machinery units and many items
of equipment are valuable sources of information
on construction, operation, maintenance, and
repair. The manufacturers' technical manuals that
are furnished with most shipboard engineering
equipment are given NAVSHIPS numbers.
DRAWINGS
Some of your work as a Machinery Repair-
man requires an ability to read and work from
mechanical drawings. You will find information
on how to read and interpret drawings in
Blueprint Reading and Sketching, NAVEDTRA
10077 (series).
In addition to knowing how to read drawings,
you must know how to locate applicable draw-
ings. For some purposes, the drawings included
in the manufacturers' technical manuals for
the machinery or equipment may give you the
information you need. In many cases, however,
you will need to consult the on-board drawings.
The on-board drawings, which are sometimes
referred to as ship's plans or ship's blueprints, are
listed in an index called the ship drawing index
(SDI).
The SDI lists all working drawings that
have a NAVSHIPS drawing number, all
manufacturers' drawings designated as certifica-
tion data sheets, equipment drawing lists, and
assembly drawings that list detail drawings. The
on-board drawings are identified in the SDI by
an asterisk (*).
Drawings are listed in numerical order in the
SDI. On-board drawings are filed according to
numerical sequence. A cross-reference list of
S-group numbers and consolidated index numbers
is given in Ship Work Breakdown Structure.
ENGINEERING HANDBOOKS
For certain types of information, you may
need to consult various kinds of engineering
handbooks — mechanical engineering handbooks,
marine engineering handbooks, piping hand-
books, machinery handbooks, and other hand-
books that provide detailed, specialized technical
data. Most engineering handbooks contain a great
deal of technical information, much of it arranged
in charts or tables. To make the best use of
engineering handbooks, use the table of contents
and the index to locate the information you need.
ADDENDUM
In addition to a comprehensive index that is
printed in the back of this manual, you will find
the following:
1. Appendix I contains 23 tables, such as
decimal equivalents of fractions; division of the
circumference of a circle; formulas for length,
area, and volume; tapers, and so forth. You will
find this information helpful in your everyday
shop work.
2. Appendix II contains formulas for spur
gearing.
3. Appendix III shows the derivation of
formulas for the diametral pitch system.
4. Appendix IV is a glossary of terms peculiar
to the Machinery Repairman rating.
1-7
CHAPTER 2
\
TOOLROOMS AND TOOLS
Your proficiency as a Machinery Repairman
is greatly influenced by your knowledge of tools
and your skills in using them. The information
you will need to become familiar with the correct
use and care of the many powered and non-
powered handtools, measuring instruments, and
gauges is available from various sources to which
you will have access.
This training manual will provide information
which applies to the tools and instruments used
primarily by a Machinery Repairman. You can
find additional information on tools that are
commonly used by the many different naval
ratings in Tools and Their Uses, NAVEDTRA
10085.
TOOL ISSUE ROOM
One of your responsibilities as a Machinery
Repairman is the operation of the tool crib or tool
issuing room. You should ensure that the
necessary tools are available and in good condition
and that an adequate supply of consumable items
(oil, wiping rags, bolts, nuts, and screws) is
available.
Operating and maintaining a toolroom is
simple if the correct procedures and methods are
used to set up the system. Some of the basic
considerations in operating a toolroom are (1) the
issue and custody of tools; (2) replacement of
broken, worn, or lost tools; and (3) proper storage
and maintenance of tools.
ORGANIZATION OF THE TOOLROOM
Shipboard toolrooms are limited in size by the
design characteristics of the ship. Therefore, the
space set aside for this purpose must be used as
efficiently as possible. Since the number of
tools required aboard ship is extensive, tool-
rooms usually tend to be overcrowded. Certain
peculiarities in shipboard toolrooms also require
consideration. For example: The motion of the
ship at sea requires that tools be made secure to
prevent movement. The moisture content of the
air requires that the tools be protected from
corrosion.
Permanent bins, shelves, and drawers cannot
easily be changed in the toolroom. However,
existing storage spaces can be reorganized by
dividing larger bins and relocating tools to
provide better use of space.
Hammers, wrenches, and other tools that do
not have cutting edges may normally be stored
in bins. They also may be segregated by size or
other designation. Tools with cutting edges require
more space to prevent damage to the cutting
edges. Usually these tools are stored on shelves
lined with wood, on pegboards, or on hanging
racks. Pegboards are especially adaptable for tools
such as milling cutters. Some provision must be
made to keep these tools from falling off of the
boards when the ship is rolling. Precision tools
(micrometers, dial indicators and so forth) should
be stored in felt-lined wooden boxes in a cabinet
to reduce the effects of vibration. This arrange-
ment allows a quick daily inventory. It also
prevents the instruments from being damaged by
contact with other tools. Rotating bins can be used
to store large supplies of small parts, such as nuts
and bolts. Rotating bins provide rapid selection
from a wide range of sizes. Figures 2-1, 2-2, and
2-3 show some of the common methods of tool
storage.
Frequently used tools should be located near
the issuing door so that they are readily available.
Seldom used tools should be placed in out of the
way areas such as on top of bins or in spaces that
cannot be used efficiently because of size and
shape. Heavy tools should be placed in spaces or
areas where a minimum of lifting is required.
Portable power tools should be stored in racks.
Provisions should be made for storage of electrical
extension cords and the cords of electric power
tools.
All storage areas such as bins, drawers, and
lockers should be clearly marked for ease in
2-1
Figure 2-1. — Method of tool storage.
28.333.1
Figure 2-2. — Method of tool storage.
28.334
2-2
28.335
Figure 2-3.— Method of tool storage.
2-3
You will be responsible for the condition of
all the tools and equipment in the toolroom. You
should inspect all tools as they are returned to
determine if they need repairs or adjustment. Set
aside a space for damaged tools to prevent issue
of these tools until they have been repaired.
You should wipe clean all returned tools and
give their metal surfaces a light coat of oil. Check
all precision tools upon issue and return to
determine if they are accurate. Keep all spaces
clean and free of dust to prevent foreign matter
from getting into the working parts of tools.
Plan to spend a portion of each day recondi-
tioning damaged tools. This is important in keep-
ing the tools available for issue and will prevent
an accumulation of damaged tools.
CONTROL OF TOOLS
You will issue and receive tools and maintain
custody of the tools. Be sure that a method of
identifying a borrower with the tool is established,
and that provisions are made for periodic
inventory of available tools.
There are two common methods of tool
issue control: the tool check system and the
mimeographed form or tool chit system. Some
toolrooms may use a combination of both of these
systems. For example: Tool checks may be used
for machine shop personnel, and mimeographed
forms may be used for personnel outside the shop.
Tool checks are either metal or plastic disks
stamped with numbers that identify the borrower.
In this system the borrower presents a check for
each tool, and the disk is placed on a peg near
the space from which the tool was taken. The
advantage of this system is that very little time
is spent completing the process.
If the tools are loaned to all departments in
the ship, mimeographed forms generally are used.
The form has a space for listing the tools, the
borrower's name, the division or department, and
the date. This system has the advantage of
allowing anyone in the ship's crew to borrow tools
and of keeping the toolroom keeper informed as
to who has the tools, and how long they have been
out.
You must know the location of tools and
equipment out on loan, how long tools have
been out, and the amount of equipment and
consumable supplies you have on hand. To know
this, you will have to make periodic inventories.
help you decide whether more strict control of
equipment is required and whether you need to
procure more tools and equipment for use.
Some selected items, called controlled
equipage, will require an increased level of
management and control due to their high cost,
vulnerability to pilferage, or their importance to
the ship's mission. The number of tools and
instruments in this category under the control of
a Machinery Repairman is generally small.
However, it is important that you be aware of
controlled equipage items. You can get detailed
information about the designation of controlled
equipage from the supply department of your
activity. When these tools are received from the
supply department, your department head will be
required to sign a custody card for each item,
indicating a definite responsibility for manage-
ment of the item. The department head will then
require signed custody cards from personnel
assigned to the division or shop where the item
will be stored and used. As a toolroom keeper,
you may be responsible for controlling the issue
of these tools and ensuring their good condition.
If these special tools are lost or broken beyond
repair, replacement cannot be made until the
correct survey procedures have been completed.
Formal inventories of these items are conducted
periodically as directed by your division officer
or department head.
As a toolroom keeper, you may have
additional duties as a supply representative for
your department or division. You can find
information on procurement of tools and supplies
in Military Requirements for Petty Officer 3 &
2, NAVEDTRA 10056.
SAFETY IN THE TOOLROOM
AND THE SHOP
The toolroom, because of its relatively small
size and the large quantity of different tools which
are stored in it, can become very dangerous if all
items are not kept stored in their proper places.
At sea the toolroom can be especially hazardous
if the proper precautions are not followed for
securing all drawers, bins, pegboards, and other
storage facilities. Fire hazards are sometimes
overlooked in the toolroom. When you consider
the flammable liquids and wiping rags stored in
or issued from the toolroom, there is a real danger
present.
2-4
Several of your jobs are directly connected to the
good working order and safe use of tools in the
shop. If you were to issue an improperly ground
twist drill to someone who did not have the
experience to recognize the defect, the chances of
the person being injured by the drill "digging in"
or throwing the workpiece out of the drill press
would be very real. A wrench which has been
sprung or worn oversize can become a real
"knucklebuster" to any unsuspecting user. An
outside micrometer out of calibration can cause
trouble if someone is trying to press fit two parts
together using a hydraulic press. An electric-
powered handtool that was properly inspected and
tagged last week but has had the plug crushed
since then can kill the user. The list of potential
disasters that you as an individual have some
influence in preventing is endless. The important
thing to remember is that you as a toolroom
keeper contribute more to the mission of the Navy
than first meets the eye.
SHOP MEASURING GAUGES
Practically all shop jobs require measuring or
gauging. You will most likely measure or gauge
flat or round stock; the outside diameters of rods,
shafts, or bolts; slots, grooves, and other
openings; thread pitch and angle; spaces between
surfaces; or angles and circles.
For some of these operations, you will have
a choice of which instrument to use, but in other
instances you will need a specific instrument. For
example, when precision is not important, a
simple rule or tape will be suitable, but in other
instances, when precision is of prime importance,
you will need a micrometer to obtain measure-
ment of desired accuracy.
The term "gauge," as used in this chapter
identifies any device which can be used to
determine the size or shape of an object. There
is no significant difference between gauges and
measuring instruments. They are both used to
compare the size or shape of an object against a
scale or fixed dimension. However, there is a
distinction between measuring and gauging which
is easily explained by an example. Suppose that
you are turning work in a lathe and want to know
the diameter of the work. Take a micrometer, or
perhaps an outside caliper, adjust its opening
to the exact diameter of the workpiece, and
time to measure it, set the caliper at a reading
slightly greater than the final dimension desired;
then, at intervals during turning operations,
gauge, or "size," the workpiece with the locked
instrument. After you have reduced the workpiece
dimension to the dimension set on the instrument,
you will, of course, need to measure the work
while finishing it to the exact dimension desired.
ADJUSTABLE GAUGES
You can adjust adjustable gauges by moving
the scale or by moving the gauging surface to the
dimensions of the object being measured or
gauged. For example, on the dial indicator, you
can adjust the face to align the indicating hand
with the zero point on the dial. On verniers,
however, you move the measuring surface to the
dimensions of the object being measured.
Dial Indicators
Dial indicators are used by Machinery Repair-
man in setting up work in machines and in
checking the alignment of machinery. Proficiency
in the use of the dial indicator will require a lot
of practice, and you should use the indicator as
often as possible to aid you in doing more accurate
work.
Dial indicator sets (fig. 2-4) usually have
several components that permit a wide variation
CLAMP AND
CLAMP HOLDING
INDICATOR R°D '
HOLDING ROD
HOLE
ATTACHMENT
TOOL
POST-
HOLDER
Figure 2-4.— Universal dial indicator.
2-5
nexiDiiity or setup, tne clamp and noiamg roas
permit setting the indicator to the work, the hole
attachment indicates variation or run out of
inside surfaces of holes, and the tool post holder
When you are preparing to use a dial
indicator, there are several things that you should
check. Dial indicators come in different degrees
of accuracy. Some will give readings to one
Figure 2-5 — Applications of a dial indicator.
2-6
(0.005) of an inch. Dial indicators also differ
in the total range or amount that they will
indicate. If a dial indicator has a total of one
hundred thousandths of an (0.100) inch in
graduations on its face and has a total range
of two hundred thousandths (0.200) of an
inch, the needle will only make two revolutions
before it begins to exceed its limit and jams
up. The degree of accuracy and range of a dial
indicator is usually shown on its face. Before you
use a dial indicator, carefully depress the contact
point and release it slowly; rotate the movable dial
face so the dial needle is on zero. Depress and
release the contact point again and check to
ensure that the dial pointer returns to zero; if it
does not, have the dial indicator checked for
accuracy.
A vernier caliper (fig. 2-6) can be used to
measure both inside and outside dimensions.
Position the appropriate sides of the jaws on the
surface to be measured and read the caliper from
the side marked inside or outside as required.
There is a difference in the zero marks on the two
sides that is equal to the thickness of the tips of
the two jaws, so be sure to read the correct side.
Vernier calipers are available in sizes ranging from
6 inches to 6 feet and are graduated in increments
of thousandths (0.001) of an inch. The scales on
vernier calipers made by different manufacturers
may vary slightly in length or number of divisions;
however, they are all read basically the same way.
Simplified instructions for interpreting the
readings are covered in Tools and Their Uses,
NAVEDTRA 10085.
28.314
Figure 2-6. — Vernier caliper.
2-7
out work for machining operations or to check
the dimensions on surfaces which have been
machined. Attachments for the gauge include the
offset scriber shown attached to the gauge in
figure 2-7. The offset scriber lets you measure
from the surface plate with readings taken directly
from the scale without having to make any
calculations. As you can see in figure 2-7, if you
were using a straight scriber, you would have to
calculate the actual height by taking into account
the distance between the surface plate and the zero
mark. Some models have a slot in the base for
the scriber to move down to the surface and a scale
that permits direct reading. Another attachment
is a rod that permits depth readings. Small dial
as a vernier caliper.
Dial Vernier Caliper
A dial vernier caliper (fig. 2-8) looks much like
a standard vernier caliper and is also graduated
in one-thousandths (0.001) of an inch. The main
difference is that instead of a double scale, as on
the vernier caliper, the dial vernier has the
inches marked only along the main body of the
caliper and a dial with two hands to indicate
hundredths (0.100) and thousandths (0.001) of an
inch. The range of the dial vernier caliper is
usually 6 inches.
28.4(28D)
Figure 2-7. — Vernier height gauge.
2-8
A, MEASURING THE INSIDE
B. MEASURING THE OUTSIDE
28.315
Figure 2-8.— Dial vernier caliper.
2-9
28.316
Figure 2-9.— Dial bore gauge.
\jlic ui LUC iiiusi aiA.uj.aLe luuia iui
a cylindrical bore or for checking a bore for out-
of-roundness or taper is the dial bore gauge. The
dial bore gauge (fig. 2-9) does not give a
direct measurement; it gives you the amount of
deviation from a preset size or the amount of
deviation from one part of the bore to another.
A master ring gauge, outside micrometer, or
vernier caliper can be used to preset the gauge.
A dial bore gauge has two stationary spring-
loaded points and an adjustable point to permit
a variation in range. These three points are evenly
spaced to allow accurate centering of the tool in
the bore. A fourth point, the tip of the dial
indicator, is located between the two stationary
points. By simply rocking the tool in the bore,
you can observe the amount of variation on the
dial. Accuracy to one ten-thousandth (0.0001) of
an inch is possible with some models of the dial
bore gauge.
Internal Groove Gauge
The internal groove gauge is very useful for
measuring the depth of an O-ring groove or other
recesses inside a bore. This tool lets you measure
a deeper recess and one located farther back in
the bore than if you were to use an inside caliper.
As with the dial bore gauge, this tool must be set
with gauge blocks, a vernier caliper, or an out-
side micrometer. The reading taken from the dial
indicator on the groove gauge represents the dif-
ference between the desired recess or groove depth
and the measured depth.
Universal Vernier Bevel Protractor
The universal vernier bevel protractor (fig.
2-10) is the tool you will use to lay out or measure
angles on work to very close tolerances. The
vernier scale on the tool permits measuring an
angle to within 1/12° (5 minutes) and can be used
completely through 360°. Interpreting the reading
on the protractor is similar to the method used
on the vernier caliper.
Universal Bevel
The universal bevel (fig. 2-11), because of the
offset in the blade, is very useful for bevel gear
work and for checking angles on lathe workpieces
which cannot be reached with an ordinary bevel.
The universal bevel must be set and checked with
2-10
Figure 2-10. — Universal vernier bevel protractor.
28.317
28.5
Figure 2-11.— Universal bevel.
2-11
Gear Tooth Vernier
Cutter Clearance Gauge
''' '' """• '""•'-
Adjustable Parallel
Figure 2-12._Gear tooth vernier.
28.318
2-12
28.7
Figure 2-13. — Cutter clearance gauge.
minimum iimus. i ms msirumem, constructed to
about the same accuracy of dimensions as parallel
blocks, is very useful in leveling and positioning
setups in a milling machine or in a shaper vise.
An outside micrometer is usually used to set the
adjustable parallel for height.
Surface Gauge
A surface gauge (fig. 2-15 is useful in gauging
or measuring operations. It is used primarily in
layout and alignment work. The surface gauge
is commonly used with a scriber to transfer
dimensions and layout lines. In some cases a dial
indicator is used with the surface gauge to check
trueness or alignment.
FIXED GAUGES
Fixed gauges cannot be adjusted. They can
generally be divided into two categories,
graduated and nongraduated. The accuracy of
your work, when you use fixed gauges, will
depend on your ability to determine the difference
between the work and the gauge. For example,
a skilled machinist can take a dimension
accurately to within 0.005 of an inch or less when
Figure 2-14. — Adjustable parallel.
28.6
2-13
SURFACE
PLATE
28.9
Figure 2-15. — Setting a dimension on a surface gauge.
using a common rule. Practical experience in the
use of these gauges will increase your ability to
take accurate measurements.
Graduated Gauges
Graduated gauges are direct reading gauges in
that they have scales inscribed on them enabling
you to take a reading while using the gauge. The
gauges in this group are rules, scales, thread
gauges, and feeler gauges.
RULES.— The steel rule with holder set (fig.
2-16A) is convenient for measuring recesses. It has
a long tubular handle with a split chuck for
holding the ruled blade. The chuck can be
adjusted by a knurled nut at the top of the holder,
allowing the rule to be set at various angles. The
set has rules ranging from 1/4 to 1 inch in length.
The angle rule (fig. 2-16B) is useful in
measuring small work mounted between centers
on a lathe. The long side of the rule (ungraduated)
is placed even with one shoulder of the work. The
graduated angle side of the rule can then be
positioned easily over the work.
Another useful device is the keyset rule (fig.
2-16C). It has a straightedge and a 6-inch
machinist 's-type rule arranged to form a right
angle square. This rule and straightedge combina-
tion, when applied to the surface of a cylindrical
workpiece, makes an excellent guide for drawing
or scribing layout lines parallel to the axis of the
work. You will find this device very convenient
when making keyseat layouts on shafts.
You must take care of your rules if you
expect them to give accurate measurements. Do
not allow them to become battered, covered with
rust, or otherwise damaged so that the markings
cannot be read easily. Do not use them for
scrapers, for once rules lose their sharp edges and
square corners their general usefulness is
decreased.
SCALES. — A scale is similar in appearance
to a rule, since its surface is graduated into regular
spaces. The graduations on a scale, however,
differ from those on a rule because they are either
larger or smaller than the measurements indicated.
For example, a half-size scale is graduated so that
2-14
ANGLE RULE
RULE WITH HOLDER
CENTER
LINE OF WORK
KEYSEAT
CLAMPS
Figure 2-16. — Special rules for shop use.
28.10
1 inch on the scale is equivalent to an actual
measurement of 2 inches; a 12-inch long scale of
this type is equivalent to 24 inches. A scale,
therefore, gives proportional measurements
instead of the actual measurements obtained with
a rule. Like rules, scales are made of wood,
plastic, or metal, and they generally range from
6 to 24 inches.
ACME THREAD TOOL GAUGE.— This
gauge (fig. 2-17) is used to both grind the tool used
to machine Acme threads and to set the tool up
in the lathe. The sides of the Acme thread have
an included angle of 29° (14 1/2° to each side),
and this is the angle made into the gauge. The
width of the flat on the point of the tool varies
according to the number of threads per inch. The
gauge provides different slots for you to use as
a guide when you grind the tool. Setting the tool
up in the lathe is simple. First, ensure that the tool
is centered on the work as far as height is
5.16.1
Figure 2-17.— Acme thread gauges.
2-15
Til 1 1 II 1 1 II I A
5.16.2
Figure 2-18. — Center gauge.
Figure 2-19. — Feeler (thickness) gauge.
4.19
concerned. Then, with the gauge edge laid parallel
to the centerline of the work, adjust the side of
your tool until it fits the angle on the gauge very
closely.
CENTER GAUGE.— The center gauge (fig.
2-18) is used like the Acme thread gauge. Each
notch and the point of the gauge has an included
angle of 60°. The gauge is used primarily to check
and to set the angle of the V-sharp and other 60 °
standard threading tools. The center gauge is also
used to check the lathe centers. The edges are
graduated into 1/4, 1/24, 1/32, and 1/64 inch for
ease in determining the pitch of threads on screws.
FEELER GAUGE.— A feeler (thickness)
gauge, like the one shown in figure 2-19, is used
to determine distances between two closely mating
surfaces. This gauge is made like a jackknife with
blades of various thicknesses. When you use a
combination of blades to get a desired gauge
thickness, try to place the thinner blades between
the heavier ones to protect the thinner blades and
to prevent their kinking. Do not force blades into
openings which are too small; the blades may bend
and kink. A good way to get the "feel" of using
a feeler gauge correctly is to practice with the
gauge on openings of known dimensions.
28.338
Figure 2-20. — Fillet or radius gauges.
28.11
Figure 2-21. — Straightedge.
28.12
Figure 2-22. — Machinist's square.
RADIUS GAUGE.— The radius gauge (fig.
2-20) is often underrated in its usefulness to the
machinist. Whenever possible, the design of most
parts includes a radius located at the shoulder
formed when a change is made in the diameter.
This gives the part an added margin of strength at
2-16
iwu euiuws, uuc uccu
cnu, wmwu
28.339
Figure 2-23.— Sine bars.
that particular place. When a square shoulder is
machined in a place where a radius should have
been, the possibility that the part will fail by bend-
ing or cracking is increased. The blades of most
radius gauges have both concave (inside curve) and
convex (outside curve) radii in the common sizes.
Nongraduated Gauges
Nongraduated gauges are used primarily as
standards, or to determine the accuracy of form
or shape.
STRAIGHTEDGES.— Straightedges look very
much like rules, except that they are not graduated.
They are used primarily for checking surfaces for
straightness; however, they can also be used as
guides for drawing or scribing straight lines. Two
types of straightedges are shown in figure 2-21.
Part A shows a straightedge made of steel which
is hardened on the edges to prevent wear; it is the
one you will probably use most often. The
straightedge shown in Part B has a knife edge and
is used for work requiring extreme accuracy.
balance points. When a box is not provided, place
resting pads on a flat surface in a storage area
where no damage to the straightedge will occur
from other tools. Then, place the straightedge so
the two balance points sit on the resting pads.
MACHINIST'S SQUARE.— The most com-
mon type of machinist's square has a hardened
steel blade securely attached to a beam. The steel
blade is NOT graduated. (See fig. 2-22.) This
instrument is very useful in checking right angles
and in setting up work on shapers, milling
machines, and drilling machines. The size of
machinist's squares ranges from 1 1/2 to 36 inches
in blade length. You should take the same care
of machinist's squares, in storage and use, as you
do with a micrometer.
SINE BAR.— A sine bar (fig. 2-23) is a
precision tool used to establish angles which
required extremely close accuracy. When used in
conjunction with a surface plate and gauge blocks,
angles are accurate to 1 minute (1/60°). The sine
bar may be used to measure angles on work and
to lay out an angle on work to be machined, or
work may be mounted directly to the sine bar for
machining. The cylindrical rolls and the parallel
bar, which make up the sine bar, are all precision
ground and accurately positioned to permit such
close measurements. Be sure to repair any
scratches, nicks, or other damage before you use
the sine bar, and take care in using and storing
the sine bar. Instructions on using the sine bar
are included in chapter 3.
PARALLEL BLOCKS.— Parallel blocks (fig.
2-24) are hardened, ground steel bars that are used
in laying out work or setting up work for machin-
ing. The surfaces of the parallel block are all either
.
28.319
Figure 2-24. — Parallel blocks.
2-17
pairs and in standard fractional dimensions. Use
care in storing and handling them to prevent
damage. If it becomes necessary to regrind the
parallel blocks, be sure to change the size stamped
on the ends of the blocks.
GAUGE BLOCKS.— Gauge blocks are used
as master gauges to set and check other gauges
and instruments. Their accuracy is from eight
millionths (0.000008) of an inch to two millionths
(0.000002) of an inch, depending on the grade of
the set. To visualize this minute amount, consider
that the thickness of a human hair divided 1 ,500
times equals 0.000002 inch. This degree of accu-
racy applies to the thickness of the gauge block,
the parallelism of the sides, and the flatness of the
surfaces. To attain this accuracy, a fine grade of
hardenable alloy steel is ground and then lapped
until the gauge blocks are so smooth and flat that
when they are "wrung" or placed one atop the
other in the proper manner, you cannot separate
them by pulling straight out. A set of gauge blocks
has enough different size blocks that you can estab-
lish any measurement within the accuracy and
range of the set. As you might expect, anything
so accurate requires exceptional care to prevent
damage and to ensure continued accuracy. A dust-
free temperature-controlled atmosphere is pre-
ferred. After use, wipe each block clean of all
marks and fingerprints and coat it with a thin
layer of white petrolatum to prevent rust.
MICROMETER STANDARDS.— Microm-
eter standards are either disk- or tubular-shaped
gauges that are used to check outside micrometers
for accuracy. Standards are made in sizes so that
any size micrometer can be checked. They should
be used on a micrometer on a regular basis to
ensure continued accuracy. Additional informa-
tion for the use of the standards are given later
in this chapter.
RING AND PLUG GAUGES.— A ring gauge
(fig. 2-25) is a cylindrically-shaped disk that has
a precisely ground bore. Ring gauges are used to
check machined diameters by sliding the gauge
over the surface. Straight, tapered, and threaded
diameters can be checked by using the appropriate
gauge. The ring gauge is also used to set other
measuring instruments to the basic dimension
required for their operation. Normally, ring
gauges are available with a "GO" and a "NO
GO" size that represents the tolerance allowed for
the particular size or job.
A. PLAIN CYLINDRICAL PLUG GAUGE
GAUGE LINE
TAPER PLUG GAUGE
c. PLAIN CYLINDRICAL RING GAUGE
•GAUGE LINE
0. TAPER RING GAUGE
28.340
Figure 2-25. — Ring gauge and plug gauge.
A plug gauge (fig. 2-25) is used for the same
types of jobs as a ring gauge except that it is a
solid shaft-shaped bar that has a precisely ground
diameter for checking inside diameters or bores.
THREAD MEASURING WIRES.— The
most accurate method of measuring the fit or
pitch diameter of threads, without going into
the expensive and sophisticated optical and
comparator equipment, is thread measuring wires.
The wires are accurately sized, depending on the
number of threads per inch, so that when they
are laid over the threads in a position that allows
an outside micrometer to measure the distance
between them, the pitch diameter of the threads
can be determined. Sets are available that
contain all the more common sizes. Detailed
information on computing and using the wire
method for measuring is covered in chapter 9.
MICROMETERS
Micrometers are probably the most often used
precision measuring instruments in a machine
shop. There are many different types, each
designed to permit measurement of surfaces for
various applications and configurations of
workpieces. The degree of accuracy obtainable
from a micrometer also varies, with the most
common graduations being from one thousandth
of an inch (0.001) to one ten-thousandth of an
inch (0.0001). Information on the correct
2-18
_- ... -- . . - . .
the more common types of micrometers is often called a micrometer caliper, or mike, is used
provided in the following paragraphs. to measure the thickness or the outside diameter
28.320
Figure 2-26. — Common types of micrometers.
2-19
U. "OLtltVt
Figure 2-27. — Nomenclature of an outside micrometer calipcr.
28.321
of parts. They are available in sizes ranging from
1 inch to about 96 inches in steps of 1 inch. The
larger sizes normally come as a set with inter-
changeable anvils which provide a range of several
inches. The anvils have an adjusting nut and a
locking nut to permit setting the micrometer with
a micrometer standard. Regardless of the degree
of accuracy designed into the micrometer, the skill
applied by each individual is the primary factor
in determining accuracy and reliability in
measurements. Training and practice will result
in a proficiency in using this tool that will benefit
you greatly.
Inside Micrometer
An inside micrometer (fig. 2-26) is used to
measure inside diameters or between parallel
surfaces. They are available in sizes ranging from
0.200 inch to about 107 inches. The individual
interchangeable extension rods that are assembled
to the micrometer head vary in size by 1 inch. A
small sleeve or bushing, which is 0.500 inch long,
is used with these rods in most inside micrometer
sets to provide the complete range of sizes.
Using the inside micrometer is slightly more
difficult than using the outside micrometer,
primarily because there is more chance of your
not getting the same "feel" or measurement each
time you check the same surface.
The correct way to measure an inside diameter
is to hold the micrometer in place with one hand
as you "feel" for the maximum possible setting
of the micrometer by rocking the extension rod
from left to right and in and out of the hole.
Adjust the micrometer to a slightly larger
measurement after each series of rocking
movements until no rocking from left to right is
possible and you feel a very slight drag on the in
and out movement. There are no specific
guidelines on the number of positions within a
hole that should be measured. If you are check-
ing for taper, you should take measurements as
far apart as possible within the hole. If you are
checking for roundness or concentricity of a hole,
you should take several measurements at different
angular positions in the same area of the hole.
You may take the reading directly from the
inside micrometer head, or you may use an out-
side micrometer to measure the inside micrometer.
Depth Micrometer
A depth micrometer (fig. 2-26) is used to
measure the depth of holes, slots, counterbores,
recesses, and the distance from a surface to some
2-20
the closed end of the thimble. The measurement
is read in reverse and increases in amount (depth)
as the thimble moves toward the base of the
instrument. The extension rods come either round
or flat (blade-like) to permit measuring a narrow,
deep recess or groove.
Thread Micrometer
The thread micrometer (fig. 2-26) is used to
measure the depth of threads that have an
included angle of 60°. The measurement obtained
represents the pitch diameter of the thread. They
are available in sizes that measure pitch diameters
up to 2 inches. Each micrometer has a given range
of number of threads per inch that can be
measured correctly. Additional information on
using this micrometer can be found in chapter 9.
Miscellaneous Micrometers
The machine tool industry has been very
responsive to the needs of the machinist by design-
ing and manufacturing measuring instruments for
practically every imaginable application. If you
find that you are devising measuring techniques
for a particularly odd application with the
resulting measurements being of questionable
value and that you do it on a routine basis, maybe
a special micrometer will make your work easier
and more reliable. Some of the special
micrometers that you may have a need for are
described below.
BALL MICROMETER.— This type microm-
eter has a rounded anvil and a flat spindle. It can
be used to check the wall thickness of cylinders,
sleeves, rings, and other parts that have a hole
bored in a piece of material. The rounded anvil
is placed inside the hole and the spindle is bought
into contact with the outside diameter. Ball
attachments that fit over the anvil of regular out-
side micrometers are also available. When using
the attachments, you must compensate for the
diameter of the ball as you read the micrometer.
BLADE MICROMETER.— A blade microm-
eter has an anvil and a spindle that are thin and
flat. The spindle does not rotate. This micrometer
is especially useful in measuring the depth of
narrow grooves such as an O-ring seat on an out-
side diameter.
IWU liai UJ31S.3. 1 11C UlMiUJUC UCIWCCII LUC
increases as you turn the micrometer. It is used
to measure the width of grooves or recesses on
either the outside or the inside diameter. The
width of an internal O-ring groove is an excellent
example of a groove micrometer measurement.
CARE AND MAINTENANCE
OF GAUGES
The proper care and maintenance of precision
instruments is very important to a conscientious
Machinery Repairman. To help you maintain
your instruments in the most accurate and reliable
condition possible, the Navy has established a
calibration program that provides calibration
technicians, the required standards and pro-
cedures, and a schedule of how often an
instrument must be calibrated to be reliable. When
an instrument is calibrated, a sticker is affixed to
it showing the date the calibration was done and
the date the next calibration is due. Whenever
possible, you should use the Navy calibration
program to verify the accuracy of your instru-
ments. Some repair jobs, due to their sensitive
nature, demand the reliability provided by the
program. Information concerning the procedures
that you can use in the shop to check the accuracy
of an instrument is contained in the upcoming
paragraphs.
Micrometers
The micrometer is one of the most used, and
often one of the most abused, precision measuring
instruments in the shop. Careful observation of
the do's and don'ts listed below will enable you
to take proper care of the micrometer you use.
1. Always stop the work before taking a
measurement. Do NOT measure moving parts
because the micrometer may get caught in the
rotating work and be severely damaged.
2. Always open a micrometer by holding the
frame with one hand and turning the knurled
sleeve with the other hand. Never open a
micrometer by twirling the frame, because such
practice will put unnecessary strain on the instru-
ment and cause excessive wear of the threads.
3. Apply only moderate force to the knurled
thimble when you take a measurement. Always
use the friction slip ratchet if there is one on the
instrument. Too much pressure on the knurled
2-21
4. When a micrometer is not in actual use,
place it where it is not likely to be dropped.
Dropping a micrometer can cause the frame to
spring; if dropped, the instrument should be
checked for accuracy before any further readings
are taken.
5. Before a micrometer is returned to stowage,
back the spindle away from the anvil, wipe all
exterior surfaces with a clean, soft cloth, and coat
the surfaces with a light oil. Do not reset the
measuring surfaces to close contact because the
protecting film of oil in these surfaces will be
squeezed out.
MAINTENANCE OF MICROMETERS.—
A micrometer caliper should be checked for zero
setting (and adjusted when necessary) as a matter
of routine to ensure that reliable readings are
being obtained. To do this, proceed as follows:
1 . Wipe the measuring faces, making sure that
they are perfectly clean, and then bring the spindle
into contact with the anvil. Use the same moderate
force that you ordinarily use when taking a
measurement. The reading should be zero; if it
is not, the micrometer needs further checking.
2. If the reading is more than zero, examine
the edges of the measuring faces for burrs. Should
burrs be present, remove them with a small slip
of oilstone; clean the measuring surfaces again,
and then recheck the micrometer for zero setting.
3. If the reading is less than zero, or if you
do not obtain a zero reading after making the
correction described above, you will need to
adjust the spindle-thimble relationship. The
method for setting zero differs considerably
between makes of micrometers. Some makes have
a thimble cap which locks the thimble to the
spindle; some have a special rotatable sleeve on
the barrel that can be unlocked; and some have
an adjustable anvil.
Methods for Setting Zero. — To adjust the
THIMBLE-CAP TYPE, back the spindle away
from the anvil, release the thimble cap with the
small spanner wrench provided for that purpose,
and bring the spindle into contact with the anvil.
Hold the spindle firmly with one hand and rotate
the thimble to zero with the other; after zero
relation has been established, rotate the spindle
counterclockwise to open the micrometer, and
then tighten the thimble cap. After tightening the
To adjust the ROTATABLE SLEEVE TYPE,
unlock the barrel sleeve with the small spanner
wrench provided for that purpose, bring the
spindle into contact with the anvil, and rotate the
sleeve into alignment with the zero mark on the
thimble. After completing the alignment, back the
spindle away from the anvil, and retighten the
barrel sleeve locking nut. Recheck for zero setting,
to be sure you did not disturb the thimble-sleeve
relationship while tightening the lock nut.
To set zero on the ADJUSTABLE ANVIL
TYPE, bring the thimble to zero reading, lock the
spindle if a spindle lock is provided, and loosen
the anvil lock screw. After you have loosened the
lock screw, bring the anvil into contact with the
spindle, making sure that the thimble is still set
on zero. Tighten the anvil setscrew lock nut
slightly, unlock the spindle, and back the spindle
away from the anvil; then lock the anvil setscrew
firmly. After locking the setscrew, check the
micrometer for zero setting to make sure you did
not move the anvil out of position while you
tightened the setscrew.
The zero check and methods of adjustment of
course apply directly to micrometers that will
measure to zero; the PROCEDURE FOR
LARGER MICROMETERS is essentially the
same except that a standard must be placed
between the anvil and the spindle in order to get
a zero measuring reference. For example, a 2-inch
micrometer is furnished with a 1-inch standard.
To check for zero setting, place the standard
between the spindle and the anvil and measure the
standard. If zero is not indicated, the micrometer
needs adjusting.
Testing for and Correcting Errors By the Use
Of Standards. — A micrometer must be tested
from time to time for uneven wear of measuring
threads and for concave wear of the measuring
faces because these defects are not detectable by
zero-setting checks. The test for uneven internal
wear can be made by measuring a flat-surfaced
standard; the test for concavity of measuring
faces, by measuring a cylindrical disk-shaped
standard.
The procedure for making these tests and
correcting the defects which are found is as
follows: First, check the micrometer for zero
setting and adjust as necessary. Then take
measurements of several different size gauge
blocks or other accurate standards. If the
2-22
is muiuaieu, anu me nuuiuiiieiei
be adjusted. Adjustment is made with the thread
wear compensating nut, located inside the thimble
assembly. After you complete the gauge block
test, measure several cylindrical standards of
different sizes. Discrepancies between micrometer
readings and the marked (actual) sizes of the
standards indicate that the measuring surfaces are
concave. You can correct this condition by
lapping the measuring faces on a true flat surface.
After lapping the faces of the micrometer, reset
the instrument for zero reading and measure the
cylindrical standards again.
Inside Micrometers.— These instruments can
be checked for zero setting adjusted in about the
same way as a micrometer caliper; the main
difference in the method of testing is that an
accurate micrometer caliper is required for
transferring readings to and from the standard
when an inside micrometer is being checked.
Micrometers of all types should be dis-
assembled periodically for cleaning and lubrica-
tion of internal parts. When this is done, each part
should be cleaned in noncorrosive solvent,
completely dried, and then given a lubricating coat
of watchmaker's oil or a similar light oil.
Vernier Gauges
Vernier gauges also require careful handling
and proper maintenance if they are to remain
accurate. The following instructions apply to
vernier gauges in general:
1. Always loosen a gauge into position.
Forcing, besides causing an inaccurate reading,
is likely to force the arms out of alignment.
neavy pressure win lorce me two scales oui 01
parallel.
3. Prior to putting a vernier gauge away, wipe
it clean and give it a light coating of oil. (Perspira-
tion from hands will cause the instrument to cor-
rode rapidly.)
Dials
Dial indicators and other instruments that
have a mechanically operated dial as part of their
measurement features are easily damaged by
misuse and lack of proper maintenance. The
following instructions apply to dials in general:
1 . As previously mentioned, be sure that the
dial you have selected to use has the range
capability required. When a dial is extended
beyond its design limit, some lever, small gear or
rack must give to the pressure. The dial will be
rendered useless if this happens.
2. Never leave a dial in contact with any
surface that is being subjected to a shock (such
as hammering a part when dialing it in) or an
erratic and uncontrolled movement that could
cause the dial to be overtraveled.
3. Protect the dial when it is not being used.
Provide a storage area where the dial will not
receive accidental blows and where dust, oil, and
chips will not contact it.
4. When a dial becomes sticky or sluggish in
operating, it may be either damaged or dirty. You
may find that the pointer is rubbing the dial crystal
or that it is bent and rubbing the dial face. Never
oil a sluggish dial. Oil will compound the
problems. Use a suitable cleaning solvent to
remove all dirt and residue.
2-23
CHAPTER 3
LAYOUT AND BENCHWORK
As an MR 3 or MR 2 you will repair or assist
in repairing a great many types of equipment used
on ships. In addition to making replacement parts,
you will disassemble and assemble equipment,
make layouts of parts to be machined, and do
precision work in fitting mating parts of equip-
ment. This is known as benchwork and includes
practically all repair work other than actual
machining.
This chapter contains information that you
should know to enable you to make effective
repairs to equipment. A brief discussion on
blueprints and mechanical drawings is included
because in many repair jobs you must rely heavily
on information acquired from these sources.
Other sources of information that you should
study for details on specific equipment include the
NA VSHIPS' Technical Manual, manufacturers'
technical manuals, and training manuals that have
information related to the equipment on which
you are working.
MECHANICAL DRAWINGS
AND BLUEPRINTS
A mechanical drawing, made with special
instruments and tools, gives a true representation
of an object to be made, including its shape, size,
description, specifications of material to be used,
and method of manufacture. A blueprint is an
exact duplicate of a mechanical drawing. For
reference purposes, every ship is furnished
blueprint copies of all important mechanical
drawings used in the construction of its hull and
machinery. These blueprints are usually stowed
in an indexed file in the log room, damage control
office, technical library, or other central location,
where they will be readily available for reference.
The following paragraphs cover briefly some
important points concerning working from
sketches and blueprints. They do not contain
definitions of all drafting terms, or information
regarding the mechanics of blueprint reading,
both of which are covered in detail in the training
manual, Blueprint Reading and Sketching,
NAVEDTRA 10077.
Of the many types of blueprints you will use
aboard ship, the simplest is the PLAN VIEW.
This blueprint shows the position, location, and
use of the various parts of the ship. You will use
plan views to find your duty and battle stations,
the sickbay, the barber shop, and other parts of
the ship.
In addition to plan views, you will find aboard
ship other blueprints called assembly prints, unit
or subassembly prints, and detail prints. These
prints show various kinds of machinery and
mechanical equipment.
ASSEMBLY PRINTS show the various parts
of a mechanism and how the parts fit together.
Individual mechanisms, such as motors and
pumps, will be shown on SUBASSEMBLY
PRINTS. These show location, shape, size, and
relationships of the parts of the subassembly unit.
Assembly and subassembly prints are used to learn
operation and maintenance of machines and
equipment.
Machinery Repairmen are most interested in
DETAIL PRINTS; these will give you the
information required to make a new part. They
show size, shape, kind of material, and method
of finishing. You will find them indispensable in
your work.
WORKING FROM DRAWINGS
Detail prints usually show only the individual
part that you must produce. They show two or
more orthographic views of the object, and
3-1
8.
lO
N.
I O
: O
O
10
^ M
l; §81
i «
*l
&
i S'
• y
s »
: «'
i i
i *.
c o
a o
eo
2
TJ
Bf>
3-2
projection shows how the part will look when it
is made.
to figure 3-1 to see how each is used in blueprints.
Each drawing or blueprint has a number in
the title box in the lower right-hand corner of the
print. The title box also shows the part name, scale
used, pattern number, material required, assembly
or subassembly print number to which the part
belongs, and name or initials of the persons who
drew, checked, and approved the drawings. (See
fig. 3-1.)
Accurate and satisfactory fabrication of a part
described on a drawing depends upon how well
the MR does the following:
• Correctly reads the drawing and closely
observes all of its data.
• Selects the correct material.
• Selects the correct tools and instruments
for laying out the job.
• Uses the baseline or reference line method
of locating the dimensional points during layout,
thereby avoiding cumulative errors (described
later in this chapter).
• Strictly observes tolerances and
allowances.
• Accurately gauges and measures the work
throughout the fabricating process.
• Gives due consideration, when measuring,
for expansion of the workpiece by heat generated
by the cutting operations. This is especially
important in checking dimensions during finishing
operations, if work is being machined to close
tolerance.
COMMON BLUEPRINT SYMBOLS
In learning to read machine drawings you
must first become familiar with the common
terms, symbols and conventions (general practice)
that are normally used. The information in figures
3-2, 3-3, and 3-4 will provide the basic data that
Surface Texture
Control over the finished dimensions of a part
is no longer the only factor you must consider
when deciding how you will do a job. The degree
of smoothness, or surface roughness, has become
very important in the efficiency and life of a
machine part.
A finished surface may appear to be perfectly
flat; however, upon close examination with
surface finish measuring instruments, the surface
is found to be formed of irregular waves. On top
of the waves are other smaller waves which we
shall refer to as peaks and valleys. These peaks
and valleys are used to determine the surface
roughness measurements of height and width. The
larger waves are measured to give the waviness
height and width measurements. Figure 3-5
illustrates the general location of the various areas
for surface finish measurements and the relation
of the symbols to the surface characteristics.
Surface roughness is the measurement of the
finely spaced surface irregularities, the height,
width, direction, and shape of which establish the
predominant surface pattern. The irregularities
are caused by the cutting or abrading action of
the machine tools that have been used to obtain
the surface. One method of measuring the
irregularities is by using special measuring
instruments equipped with a tracer arm. The
tracer arm has either a diamond or a sapphire
contact point with a 0.0005-inch radius. As the
tracer arm travels across the surface the contact
point moves up and down the peaks and valleys.
The movement of the contact point is amplified
electrically and recorded graphically on a
graduated tape. From this tape the various
measurements are determined.
The basic roughness symbol is a check mark.
This symbol is supplemented with a horizontal
extension line above it when requirements such
as waviness width, or contact area must be
specified in the symbol. A drawing that shows
only the basic symbol indicates that the surface
finish requirements are detailed in the Notes
block. The roughness height rating is placed
at the top of the short leg of the check
3-3
VISIBLE
LINES
HEAVY UNBROKEN LINES
USED TO INDICATE VISIBLE
EDGES OF AN OBJECT
;
MEDIUM LINES WITH SHORT
EVENLY SPACED DASHES
1
1
i
i
i
HIDDEN
LINES
USED TO INDICATE CONCEALED
EDGES
r^
1_
CENTER
LIMES
THIN LINES MADE UP OF LONG
AND SHORT DASHES ALTERNATELY
SPACED AND CONSISTENT IN
LENGTH
USED TO INDICATE SYMMETRY
ABOUT AN AXIS AND LOCATION
OF CENTERS
^k
—
3
3
DIMENSION
LINES
1
I
THIN L INES TERMIMATED WITH
ARROW HEADS AT EACH END
USED TO INDICATE DISTANCE
MEASURED
~~1
r^
••— ••— •
-*•
-»•
THIN UNBROKEN LINES
-
-»
LINES
USED TO INDICATE EXTENT
OF DIMENSIONS
LEADER
dl
THIN LINE TERMINATED WITH ARROW.
HEAD OR DOT ATONE END
USED TO INDICATE A PART,
DIMENSION OR OTHER REFERENCE
r '. X 20 THD.
y
PHANTOM
OR
DATUM LINE
MEDIUM SERIES OF ONE LONG DASH AND
TWO SHORT DASHES EVENLY SPACED
ENDING Wl TH L ONG DASH
USED TO INDICAT E ALTERNATE POSITION
OF PARTS, REPEAT ED DETAIL OR TO
INDICATE A DATUM PLANE
r
BREAK
(LONG)
-V-
-vy-
THIN SOLID RUL ED LINES WITH
FREEHAND ZIG-ZAGS
USED TO REDUCE SIZE OF DRAWING
REQUIRED TO DELINEATE OBJECT AND
REDUCE DETAIL
i — \ — i
1 v 1
BREAK
(SHORT)
1
THICK SOL ID FREE HAND LINES
USED TO INDICATE A SHORT BREAK
~u
CUTTINGOR
VIEWING
PLANE
r i
1 1
THICK SOLID LINES WITH ARROWHEAD
TO INDICATE DIRECTION IN WHICH
SECTION OR PLANE IS VIEWED OR
TAKEN
EflTWTEl
VIEWING
PLANE
OPTIONAL
CUTTING
PLANE FOR
COMPLEX OR
OFFSET
VIEWS
*-i
i
(%
%vi
i
.4-j
THICK SHORT DASHES
USED TO SHOW OFFSET WITH ARROW.
HEADS TO SHOW DIRECTION VIEWED
-4",
S^*~^fc*. P"/^
Ni./ \nm
•+•
Figure 3-2. — Line characteristics and conventions for MIL-STD drawing.
3-4
-^
ANGULARITY
1
PERPENDICULARITY
II
PARALLELISM
©
CONCENTRICITY
^
TRUE POSITION
0
ROUNDNESS
•=-
SYMMETRY
(M)
(MMO MAXIMUM MATERIAL
CONDITION
®(RFS) REGARDLESS OF
FEATURE SIZE
B3
DATUM IDENTIFYING
SYMBOL
Figure 3-3.— Geometric characteristic symbols.
\
-SYMBOL
(THIS FEATURE
SHALL BE
PERPENDICULAR)
A [ B
MR
DATUM
REFERENCE
(TO DATUM
A)
REFERENCE
TO TWO
TOLERANCE D*™*'
(WITHIN .001 '
REGARDLESS OF
FEATURE SIZE)
J. A .001
-B-
Figure 3-4. — Feature control symbol incorporating datum
reference.
rROUGHNESS HEIGHT
TYPICAL FLAW
(SCRATCH)
WAV I NESS
HEIGHT
(INCHES)
•LAY (DIRECTION OF
DOMINANT PATTERN)
WAVINESS WIDTH
(INCHES)
SURFACE ROUGHNESS
WIDTH
ROUGHNESS -WIDTH
CUTOFF (INCHES)
WAVINESS
HEIGHT (INCHES)'
ROUGHNESS
HEIGHT RATING
WAVJNESS WIDTH (INCHES)
ROUGH NESS -WIDTH CUTOFF
(INCHES)
LAY
SURFACE ROUGHNESS WIDTH
(INCHES)
Figure 3-5. — Relation of symbols to surface characteristics.
3-5
63
63
63
Figure 3-6.— Symbols used to indicate surface roughness,
waviness, and lay.
mium pciuussiuic luugmiess iicigiu ictimg;
if two are shown, the top number is the
maximum (part B, fig. 3-6). A point to
remember is that the smaller the number
in the roughness height rating, the smoother
the surface.
Waviness height values are shown directly
above the extension line at the top of the
long leg of the basic check (part C, fig.
3-6). Waviness width values are placed just
to the right of the waviness height values
(part D, fig. 3-6). Where minimum requirements
LAY SYMBOL
DESIGNATION
EXAMPLE
LAY PARALLEL TO THE BOUNDARY LINE REPRESENT-
ING THE SURFACE TO WHICH THE SYMBOL APPLIES.
DIRECTION
OF TOOL
MARKS
_L
LAY PERPENDICULAR TO THE BOUNDARY LINE REPRE-
SENTING THE SURFACE TO WHICH THE SYMBOL
APPLIES.
DIRECTION
OF TOOL
MARKS
X
LAY ANGULAR IN BOTH DIRECTIONS TO BOUNDARY
LINE REPRESENTING THE SURFACE TO WHICH SYMBOL
APPLIES.
DIRECTION
OF TOOL
MARKS
M
LAY MULTIDIRECTIONAL
C
LAY APPROXIMATELY CIRCULAR RELATIVE TO THE
CENTER OF THE SURFACE TO WHICH THE SYMBOL
APPLIES.
R
LAY APPROXIMATELY RADIAL RELATIVE TO THE
CENTER OF THE SURFACE TO WHICH THE SYMBOL
APPLIES.
P
LAY PARTICULATE, NON-DIRECTIONAL,
OR PROTUBERANT
3 The "P" symbol is not currently shown in ISO Standards. American
National Standards Committee B46 (Surface Texture) has proposed its
inclusion in ISO 1302-"Methods of indicating surface texture on drawings."
Figure 3-7.— Symbols indicating the direction of lay.
3-6
\JJL Lilt
E, fig. 3-6). Any further surface finish
requirements that would have been shown
in that location, such as waviness width
or height, will be shown in the Notes block
of the drawing.
Lay is the direction of the predominant
surface pattern produced by the tool marks.
The symbol indicating lay is placed to the
right and slightly above the point of the
surface roughness symbol as shown in part
F of figure 3-6. (Figure 3-7 shows the
seven symbols that indicate the direction of
lay.)
The roughness width value is shown just to
the right of and parallel to the lay symbol. The
roughness width cutoff is placed immediately
below the extension line and to the right of the
In the past, an alpha-numeric symbol was used
to indicate the degree of smoothness required on
a part. This system was not very effective
because no specific or measurable value was
assigned to each classification of finish. A
fine tool finish can mean different things
to different people. Some of the more common
symbols that may be found on older blueprints
are shown in table 3-1.
Your shop may not have the delicate and
expensive instruments used to measure the
irregularities of a surface although some of
the larger and more fully equipped repair facilities
will have them. There are roughness comparison
specimens available today that will serve all
but the most critical applications. These can be
small plastic or metal samples, representing
various roughness heights in several lay patterns.
Table 3-1.— Former Finish Designations
Preferred
Symbols
Meaning
Alternate Symbols
F,
Rough Tool Finish
V,
Fr.
FIN.
TF.
F2
Fine Tool Finish
V2
F.
Fs.
SF.
F3
Grind Finish
V3
Fg.
Gr.
F4
Polish
V4
Bf.
Buff
Fs
Drill
vs
Dr.
F6
Ream
V6
Rm.
F7
File Finish
V7
ff.
Ff.
F8
Scrape
V8
scr.
F9
Spot Face
V9
Finish All
Over
F.A.O.
f.a.o.
3-7
Figure 3-8 gives a sampling of some roughness
height values that can be obtained by the different
machine operations that you will encounter. Use
it as an estimating tool only, as it has the same
shortcomings as the "F" values in table 3-1.
UNITS OF MEASUREMENTS
Accuracy is the trademark of the Machinery
Repairman, and it is to your advantage to always
strive for the greatest amount of accuracy. You
can work many hours on a project and if it is not
accurate, you will oftentimes have to start over.
With this thought in mind, study carefully the
following information about both the English and
the metric systems of measurement.
English System
The inch is the basic (or smallest whole) unit
of measurement in the English system. Parts of
the inch must be expressed as either common
fractions or decimal fractions. Examples of
common fractions are 1/2, 1/4, 1/8, 1/16, 1/32,
and 1/64. Decimal fractions can be expressed with
a numerator and denominator (1/10, 1/100,
1/1000, etc.,) but in most machine shop work and
on blueprints or drawings they are expressed in
decimal form such as 0.1, 0.01, and 0.001.
Decimal fractions are expressed in the following
manner:
One-tenth inch = 0.1 in.
One-hundredth inch = 0.01 in.
One-thousandth inch = 0.001 in.
One ten-thousandth inch = 0.0001 in.
You will occasionally need to convert a
common fraction to a decimal. This is easily
done by dividing the denominator of the fraction
into the numerator. As an example, the
decimal equivalent of the fraction 1/16 inch
is: 1 -r 16 = 0.0625 inch. A chart giving the
decimal equivalents of the most common fractions
is shown in Appendix I.
MACHINE
OPERATION
ROUGHNESS HEIGHT (MICROINCHES)
2000 1000 500 250 125 63 32 16 8 4
FLAME CUTTING
SAWING
PLANING
DRILLING
MILLING
BROACHING
REAMING
BORING, TURNING
ROLLER BURNISHING
GRINDING
HONING
POLISHING
LAPPING
SAND CASTING
Figure 3-8. — Roughness height values for machine operations.
J. •/ *••*» Q -V
this system of measurement. The basic unit of
linear measurement for the metric system is the
meter.
In the metric system the meter can be sub-
divided into the following parts:
10 decimeters (dm)
or
100 centimeters (cm)
or
1000 millimeters (mm)
Therefore, 1 decimeter is 1/10 of a meter, 1
centimeter is 1/100 meter, and 1 millimeter is
1/1000 meter. The metric unit of measurement
most often used in the machinist trade is the
millimeter (mm).
If you understand the relationship of the
two systems, you can convert easily from
one system to the other. For example, 1 meter
is equal to 39.37 inches; 1 inch is equal to 2.54
centimeters (or 25.4 millimeters). To convert
from the English system to the metric system,
multiply the number of inches by 2.54 (for
centimeters) or 25.40 (for millimeters). As an
example: 1.375 inches converted to centi-
meters is 1.375 inch x 2.540 = 3.4925 cm.
Further, 0.0008 inch converted to millimeters
is 0.0008 inch x 25.40 = 0.0203 mm.
To convert from the metric system to the
English system, divide the metric units of measure
by either 2.54 (for centimeters) or 25.4 (for
millimeters). As an example: 0.215 mm converted
to inches is 0.215 mm -f 25.4 = 0.0084 inch.
LIMITS OF ACCURACY
You must work within the limits of accuracy
specified on the drawing. A clear understanding
of TOLERANCE and ALLOWANCE will help
you to avoid making small, but potentially
dangerous errors. These terms may seem closely
related but each has a very precise meaning and
application. In the following paragraphs we will
point out the meanings of these terms and the
importance of observing the distinction between
them.
addition to the basic dimensions, an allowable
variation. The amount of variation, or limit of
error permissible is indicated on the drawing as
plus or minus (±) a given amount, such as
±0.005; ±1/64. The difference between
allowable minimum and the allowance maximum
dimension is tolerance. For example, in figure 3-9:
Basic dimension = 4
Long limit = 4 1/64
Short limit = 3 63/64
Tolerance = 1/32
When tolerances are not actually specified on
a drawing, fairly concrete assumptions can be
made concerning the accuracy expected, by using
the following principles. For dimensions that end
in a fraction of an inch, such as 1/8, 1/16, 1/32,
1/64, consider the expected accuracy to be to the
nearest 1/64 inch. When the dimension is given
in decimal form, the following applies:
If a dimension is given as 3.000 inches, the
accuracy expected is ±0.0005 inch; or if the
dimension is given as 3.00 inches, the accuracy
expected is ±0.005 inch. The ±0.0005 is called
in shop terms, "plus or minus five ten-
thousandths of an inch." The ±0.005 is called
"plus or minus five thousandths of an inch."
Allowance
Allowance is an intentional difference in
dimensions of mating parts to provide the desired
fit. A CLEARANCE ALLOWANCE permits
movement between mating parts when they are
assembled. For example, when a hole with a
0.250-inch diameter is fitted with a shaft that has
a 0.245-inch diameter, the clearance allowance is
0.005 inch. An INTERFERENCE ALLOW-
ANCE is the opposite of a clearance allowance.
_
64
Figure 3-9.— Basic dimension and tolerance.
3-9
nidi nave ail miciiciciiLC auuwaucc. IL
Si 0.251-inch diameter is fitted into the hole
identified in the preceding example, the difference
between the dimensions will give an interference
allowance of 0.001 inch. As the shaft is larger than
the hole, force is necessary to assemble the parts.
What is the relationship between tolerance and
allowance? In the manufacture of mating parts,
the tolerance of each part must be controlled so
that the parts will have the proper allowance when
they are assembled. For example, if a hole 0.250
inch in diameter with a tolerance of 0.005 inch
(±0.0025) is prescribed for a job, and a shaft to
be fitted in the hole is to have a clearance
allowance of 0.001 inch, the hole must first be
finished within the limits and the required size of
the shaft determined exactly, before the shaft can
be made. If the hole is finished to the upper limit
of the basic dimension (0.2525 inch), the shaft
would be machined to 0.2515 inch or 0.001 inch
smaller than the hole. If the dimension of the shaft
were given with the same tolerance as the hole,
there would be no control over the allowance
between the parts. As much as 0.005-inch
allowance (either clearance or interference) could
result.
To provide a method of retaining the required
allowance while permitting some tolerance in the
dimensions of the mating parts, the tolerance is
limited to one direction on each part. This single
direction (unilateral) tolerance stems from the
basic hole system. If a clearance allowance is
required between mating parts, the hole may be
larger but not smaller than the basic dimension;
the part that fits into the opening may be smaller,
but not larger than the basic dimension. Thus,
shafts and other parts that fit into a mating
opening have a minus tolerance only, while the
openings have a plus tolerance only. If an
interference allowance between the mating parts
is required, the situation is reversed; the opening
can be smaller but not larger than the basic
dimension, while the shaft can be larger, but not
smaller than the basic dimension. Therefore you
can expect to see a tolerance such as +0.005, - 0,
or +0, -0.005, but with the required value not
necessarily 0.005. One way to get a better
understanding of a clearance allowance, or an
interference allowance, is to make a rough sketch
of the piece and add dimensions to the sketch
where they apply.
metal surfaces to provide an outline for
machining. A layout is comparable to a single
view (end, top, or side) of a part which is sketched
directly on the workpiece. Any difficulty in
making layouts depends on the intricacies of the
part to be laid out and the number of operations
required to make the part. A flange layout, for
example, is relatively simple as the entire layout
can be made on one surface of the blank flange.
However, an intricate casting may require layout
lines on more than one surface. This requires
careful study and concentration to ensure that the
layout will have the same relationships as those
shown on the drawing (or sample) that you are
using.
When a part must be laid out on two or more
surfaces, you may need to lay out one or two
surfaces and machine them to size before using
further layout lines. This prevents removal of
layout lines on one surface while you are
machining another. In other words, it would be
useless to lay out the top surface of a part and
machine off the layout lines while cutting the part
to the layout lines of an end surface.
Through the process of computing and
transferring dimensions, you will become familiar
with the relationship of the surfaces. Under-
standing this relationship will benefit you in
planning the sequence of machining operations.
You should be able to hold the dimensions of
a layout to within a tolerance of 1/64 inch.
Sometimes you must work to a tolerance of even
less than that.
A layout of a part is made when the directional
movement or location of the part is controlled by
hand or aligned visually without the use of
precision instruments (such as when work is done
on bandsaws or drill presses.) In cutting irregular
shapes on shapers, planers, lathes, or milling
machines, layout lines are made, and the tool or
work is guided by hand. In making a part with
hand cutting tools, layout is essential.
Mechanical drawing and layout are closely
related subjects; knowledge of one will help you
to understand the other. A knowledge of general
mathematics, trigonometry, and geometry, as well
as the selection and use of the required tools is
necessary in doing jobs related to layout and
mechanical drawing. Study Mathematics, Volume
7, NAVEDTRA 10069; Mathematics, Volume II,
NAVEDTRA 10071; Tools and Their Uses,
NAVEDTRA 10085, and Blueprint Reading and
3-10
MATERIALS AND EQUIPMENT
A scribed line on the surface of metal is usually
hard to see; therefore, a layout liquid is used to
provide a contrasting background. Commercially
prepared layout dyes or inks are available through
the Navy supply system. Chalk can be used, but
it does not stick to a finished surface as well as
layout dye. The commonly used layout dyes color
the metal surface with a blue or copper tint. A
line scribed on this colored surface reveals the
color of the metal through the background.
The tools generally used for making layout
lines are the combination square set, machinist's
square, surface gauge, scribe, straightedge, rule,
divider, and caliper. Tools and equipment used
in setting up the part to be laid out are surface
plates, parallel blocks, angle plates, V-blocks, and
sine bar. Surface plates have very accurately
scraped flat surfaces. They provide a mounting
table for the work to be laid out so that all lines
in the layout can be made to one reference
surface. Angle plates are used to mount the work
at an angle to the surface plate. Angle plates are
commonly used when the lines in the layout are
at an angle to the reference surface. These plates
may be fixed or adjustable; fixed angle plates are
more accurate because one surface is machined
to a specific angle in relation to the base.
Adjustable angle plates are convenient to use
because the angular mounting surface can be
adjusted to meet the requirements of the job. V-
blocks are used for mounting round stock on the
surface plate. Parallel blocks are placed under the
work to locate the work at a convenient height.
The sine bar is a precision tool used for
determining angles which require accuracy within
5 minutes of arc. The sine bar may be used to
check angles or to establish angles for layout and
inspection work. The sine bar must be used in
conjunction with a surface plate and gauge blocks
if accuracy is to be maintained. Use of the sine
bar will be covered later in this chapter.
Toolmaker's buttons (figure 3-10) are hard-
ened and ground cylindrical pieces of steel, used
to locate the centers of holes with extreme
accuracy. You may use as many buttons as
necessary on the same layout by spacing them the
proper distance from each other with gauge
blocks.
Many other special tools, which you may
make, will be useful in obtaining layouts that are
CAP SCREW
BUTTON
WORK
Figure 3-10. — Toolmaker's buttons and their application.
accurate and easily done. Transfer screws and
punches for laying out from a sample are two that
you can use on many jobs and save time in doing
the job.
LAYOUT METHODS
To ensure complete accuracy when making
layouts, establish a reference point or line on the
work. This line, called the baseline, is located so
you can use it as a base from which to measure
dimensions, angles, and lines of the layout. You
can use a machined edge or centerline as a
reference line. Circular layouts, such as flanges,
are usually laid out from a center point and a
diameter line.
You can hold inaccuracy in layouts to a
minimum by using the reference method because
errors can be made only between the reference line
and one specific line or point. Making a layout
by referencing each line or point to the preceding
one can cause you to compound any error, thus
creating an inaccurate layout.
Making a layout on stock that has one or more
machine finished surfaces usually is easy. Laying
out a casting, however, presents special problems
because the surfaces are too rough and not true
enough to permit the use of squares, surface
plates, or other mounting methods with any
degree of accuracy. A casting usually must be
machined on all surfaces. Sufficient material must
be left outside the layout line for truing up the
surface by machining. For example, a casting
might have only 1/8-inch machining allowance on
each surface (or be a total of 1/4-inch oversize).
It is obvious in this example that taking more than
1/8 inch off any surface would mean the loss of
the casting. The layout procedure is especially
3-11
must be within the machining allowance on all
surfaces.
Making Layout Lines
The following information applies to practi-
cally all layouts. Layout lines are formed by
using a reference edge or point on the stock or
by using the surface plate as a base. Study care-
fully the section on geometric construction as this
will aid you in making layouts when a reference
edge of the stock or a surface plate mounting of
the stock cannot be used.
LINES SQUARE OR PARALLEL TO
EDGES. — When scribing layout lines on sheet
metal, hold the scratch awl, or scribe, as shown
in figure 3-11, leaning it toward the direction in
which it will be moved and away from the
straightedge. This will help scribe a smooth line
which will follow the edge of the straightedge,
template, or pattern at its point of contact with
the surface of the metal.
To scribe a line on stock with a combination
square, place the squaring head on the edge of
square with the edge of the stock against
which the squaring head is held; that is, the
angle between the line and the edge will be
90°.
To draw lines parallel to an edge using a
combination square, extend the blade from the
squaring head the required distance, such as the
2-inch setting shown in figure 3-13. Secure the
blade at this position. Scribe a line parallel to the
edge of the stock by holding the scratch awl, 01
scribe, at the end of the blade as you move the
square along the edge. All lines so scribed, with
different blade settings, will be parallel to the edge
of the stock and parallel to each other.
Figure 3-13.— Laying out parallel lines with a combinatioi
square.
Figure 3-11. — Using a scribe.
Figure 3-12. — Using the combination square.
Figure 3-14. — Laying out a parallel line with a hermaphrodil
caliper.
3-12
in figure 3-14, so the curved leg maintains
contact with the edge while the other leg scribes
the line. Hold the caliper so that the line will be
scribed at the desired distance from the edge of
the stock.
FORMING ANGULAR LINES.— To lay out
a 45 ° angle on stock, using a combination square,
place the squaring head on the edge of the stock,
as shown in figure 3-15, and draw the line along
either edge of the blade. The line will form a 45 °
angle with the edge of the stock against which the
squaring head is held.
To draw angular lines with the protractor head
of a combination square, loosen the adjusting
screw and rotate the blade so the desired angle
Figure 3-15. — Laying out a 45° angle.
PARALLEL
UNES
SCRIBER
TRUE
EDGE
is 60°. Tighten the screw to hold the setting.
Hold the body of the protractor head in
contact with the true edge of the work with the
blade resting on the surface. Scribe the lines along
the edge of the blade on the surface of the work.
The angle set on the scale determines the angle
laid out on the work. All lines drawn with the
same setting, and from the same true edge of the
work, will be parallel lines.
Use the center head and rule as illustrated in
figure 3-17 to locate the center of round stock.
To find the center of square and rectangular
shapes, scribe straight lines from opposite corners
of the workpiece. The intersection of the lines
locates the center.
LAYING OUT CIRCLES AND IRREG-
ULAR LINES.— Circles or segments of circles are
laid out from a center point. To ensure accuracy,
prick-punch the center point to keep the point of
the dividers from slipping out of position.
To lay out a circle with a divider, take the
setting of the desired radius from the rule, as
shown in figure 3-18. Note that the 3-inch setting
Figure 3-17. — Locating the center of round stock.
Figure 3-16. — Laying out angular lines.
Figure 3-18.— Setting a divider to a dimension.
3-13
is being taken AWAY from the end of the rule.
This reduces the chance of error as each point of
the dividers can be set on a graduation. Place one
leg of the divider at the center of the proposed
circle, lean the tool in the direction it will be
rotated, and rotate it by rolling the knurled
handle between your thumb and index finger. (A
of fig. 3-19.)
Figure 3-21.— Angle plate.
Figure 3-19. — Laying out circles.
BULKHEAD
SURFACE
PLATE
Figure 3-20. — Laying out an irregular line from a surface.
Figure 3-22.— Setting and using a surface gauge.
trammel points.
To lay out a circle with trammel points, hold
one point at the center, lean the tool in the
direction you plan to move the other point, and
swing the arc, or circle, as shown in B of figure
3-19.
To transfer a distance measurement with
trammel points, hold one point as you would for
laying out a circle and swing a small arc with the
other point opened to the desired distance.
Scribing an irregular line to a surface is a skill
used in fitting a piece of stock, as shown in figure
3-20, to a curved surface. In A of figure 3-20 you
see the complete fit. In B of figure 3-20 the divider
has scribed a line from left to right. When scribing
horizontal lines, keep legs of the divider plumb
(one above the other). When scribing vertical
lines, keep the legs level. To scribe a line to an
irregular surface, set the divider so that one leg
will follow the irregular surface and the other leg
will scribe a line on the material that is being fitted
to the irregular surface. (See B of fig. 3-20.)
USING THE SURFACE PLATE.— The
surface plate is used with such tools as parallels,
squares, V-blocks, surface gauges, angle plates,
and sine bar in making layout lines. Angle plates
similar to the one shown in figure 3-21 are used
to mount work at an angle on the surface plate.
To set the angle of the angle plate, use a protractor
and rule of the combination square set or use a
vernier protractor.
Part A of figure 3-22 shows a surface gauge
V-block combination used in laying out a piece
of stock. To set a surface gauge for height, first
aa MIUWU ill Jj Ul llgluc
3-22. Secure the scale so the end is in contact with
the surface of the plate. Move the surface gauge
into position.
USING THE SINE BAR.— A sine bar is a
precisely machined tool steel bar used in
conjunction with two steel cylinders. In the type
shown in figure 3-23, the cylinders establish a
precise distance of either 5 inches or 10 inches
from the center of one to the center of the other,
depending upon the model used. The bar itself
has accurately machined parallel sides, and the
axes of the two cylinders are parallel to the
adjacent sides of the bar within a close tolerance.
Equally close tolerances control the cylinder
roundness and freedom from taper. The slots or
holes in the bar are for convenience in clamping
workpieces to the bar. Although the illustrated
bars are typical, there is a wide variety of
specialized shapes, widths, and thicknesses.
The sine bar itself is very easy to set up and
use. You do need to have a basic knowledge of
trigonometry to understand how it works. When
a sine bar is set up, it always forms a right triangle.
A right triangle has one 90° angle. The base of
the triangle, formed by the sine bar, is the surface
plate, as shown in figure 3-23. The side opposite
is made up of the gauge blocks that raise one end
of the sine bar. The hypotenuse is always formed
by the sine bar, as shown in figure 3-23. The
height of the gauge block setting may be found
in two ways. The first method is to multiply the
sine of the angle needed by the length of the sine
bar. The sine of the angle may be found in any
table of natural trigonometric functions. For
HYPOTENUSE
SINE BAR
(HYPOTENUSE)
GAGE BLOCKS
(SIDE OPPOSITE)
GIVEN ANGLE
SIDE ADJACENT
SURFACE PLATE
(SIDE ADJACENT)
Figure 3-23.— Setup of the sine bar.
3-15
LU a. LO.UIC ui iia.iuLd.1 LugunuuicuUr
find the sine of 30 °5'. Then multiply the sine value
by 10 inches: 0.50126 x 10 = 5.0126, to find the
height of the gauge blocks. The second method
is to use a table of sine bar constants. These tables
give the height setting for any given angle (to the
nearest minute) for a 5-inch sine bar. Tables are
not normally available for 10-inch bars because
it is just as easy to use the sine of the angle and
move the decimal point one place to the right.
Although sine bars have the appearance of
being rugged, they should receive the same care
as gauge blocks. Because of the nature of their
use in conjunction with other tools or parts that
are heavy, they are subject to rough usage.
Scratches, nicks, and burrs should be removed or
repaired. They should be kept clean from abrasive
dirt and sweat and other corrosive agents. Regular
inspection of the sine bar will locate such defects
before they are able to affect the accuracy of the
bar. When sine bars are stored for extended
periods, all bare metal surfaces should be cleaned
and then covered with a light film of oil. Placing
a cover over the sine bar will further prevent
accidental damage and discourage corrosion.
GEOMETRIC CONSTRUCTION OF LAY-
OUT LINES. — Sometimes you will need to scribe
a layout that cannot be made using conventional
layout methods. For example, you cannot readily
make straight and angular layout lines on sheet
metal with irregular edges by using a combination
square set; neither can you mount sheet metal on
angle plates in a manner that permits scribing
angular lines. Geometric construction is the
answer to this problem.
Use a divider to lay out a perpendicular
FROM a point TO a line, as shown in figure 3-24.
Lightly prick-punch point C, then swing any arc
auu jc/ as
uwu cues
at a point such as F. Place a straightedge on points
C and F. The line drawn along this straightedge
from point C to line AB will be perpendicular
(90°) to line AB.
Use a divider to lay out a perpendicular
FROM a point ON a line, as shown in figure 3-25.
Lightly prick-punch the point identified in the
figure as C on line AB. Then set the divider to
any distance to scribe arcs which intersect AB at
D and E with C as the center. Punch C and E
lightly. With D and E used as centers and with
the setting of the divider increased somewhat,
scribe arcs which cross at points such as F and
G. The line drawn through F and G will pass
through point C and be perpendicular to line AB.
To lay out parallel lines with a divider, set the
divider to the selected dimension. Then referring
to figure 3-26, from any points (prick-punched)
such as C and D on line AB, swing arcs EF and
GH. Then draw line IJ tangent to these two arcs
and it will be parallel to line AB and at the selected
distance from it.
Bisecting an angle is another geometric
construction with which you should be familiar.
Angle ABC (fig. 3-27) is given. With B as a center,
draw an arc cutting the sides of the angle at D
and E. With D and E as centers, and with a radius
greater than half of arc DE, draw arcs intersecting
at F. A line drawn from B through point F bisects
the angle ABC.
Figure 3-25.— Layout of a perpendicular from a point
on a line.
Figure 3-24. — Layout of a perpendicular from a point
to a line.
AC D B
Figure 3-26. — Layout of a parallel line.
3-16
Figure 3-27.— Bisecting an angle.
Laying Out Valve Flange
Bolt Holes
Before describing the procedure for making
valve flange layouts, we need to clarify the
terminology used in the description. Figure 3-28
shows a valve flange with the bolt holes marked
on the bolt circle. The straight-line distance
between the centers of two adjacent holes is called
the PITCH CHORD. The bolt hole circle itself
is called the PITCH CIRCLE. The vertical line
across the face of the flange is the VERTICAL
BISECTOR, and the horizontal line across the
face of the flange is the HORIZONTAL
BISECTOR.
PITCH CIRCLE
HORIZONTAL-
BISECTOR
VERTICAL
BISECTOR
PITCH CHORD
SNUGLY FITTING
WOOD PLUG
Figure 3-28. — Flange layout terminology.
LIIC same as me
chord between any other two adjacent holes. Note
that the two top holes and the two bottom holes
straddle the vertical bisector; the vertical bisector
cuts the pitch chord for each pair exactly in half.
This is the standard method of placing the holes
for a 6-hole flange. In the 4-, 8-, or 12-hole flange,
the bolt holes straddle both the vertical and
horizontal bisectors. This system of hole place-
ment permits a valve to be installed in a true
vertical or horizontal position, provided, of
course, that the pipe flange holes are also in
standard location on the pitch circle. Before
proceeding with a valve flange layout job, find
out definitely whether the holes are to be placed
in the standard position. If you are working on
a "per sample" job, follow the layout of the
sample.
Assuming that you have been given informa-
tion concerning the size and number of holes and
the radius of the pitch circle, the procedure for
setting up the layout for straight globe or gate
valve flanges is as follows:
1. Fit a fine grain wood plug into the
opening in each flange. (See fig. 3-28.) The plug
should fit snugly and be flush with the face of the
flange.
2. Apply layout dye to the flange faces,
or, if dye is not available, rub chalk on
the flange faces to make the drawn lines clearly
visible.
3. Locate the center of each flange with a
surface gauge, or with a center head and rule
combination, if the flange diameter is relatively
small. (See part A fig. 3-22 and fig. 3-17.)
After you have the exact center point located
on each flange, mark the center with a sharp
prick-punch.
4. Scribe the pitch or bolt circle, using
a pair of dividers. Check to see that the
pitch circle and the outside edge of the flange are
concentric.
5. Draw the vertical bisector. This line
must pass through the center point of the
flange and must be visually located directly
in line with the axis of the valve stem.
(see fig. 3-28.)
3-17
6. Draw the horizontal bisector. This
line must also pass through the center point
of the flange and must be laid out at a
right angle to the vertical bisector. (See fig. 3-28
and fig. 3-25.)
Up to this point, the layout is the same for
all flanges regardless of the number of holes.
Beyond this point, however, the layout differs
with the number of holes. The layout for a 6-hole
flange is the simplest one and will be described
first.
SIX-HOLE FLANGE.— Set your dividers
exactly to the dimension of the pitch circle radius.
Place one leg of the dividers on the point where
the horizontal bisector crosses the pitch circle on
the right-hand side of the flange, point (1) in part
A of figure 3-29, and draw a small arc across the
pitch circle at points (2) and (6). Next, place one
leg of the dividers at the intersection of the pitch
circle and horizontal bisector on the left-hand side
of the flange point (4), and draw a small arc across
the pitch circle line at points (3) and (5). These
points, (1 to 6), are the centers for the holes.
Check the accuracy of the pitch chords. To do
this, leave the dividers set exactly as you had them
set for drawing the arcs. Starting from the located
center of any hole, step around the circle with the
dividers. Each pitch chord must be equal to the
setting of the dividers; if it is not, you have an
error in hole mark placement that you must
correct before you center punch the marks
for the holes. After you are sure the lay-
out is accurate, center punch the hole marks
and draw a circle of appropriate size around
each center-punched mark and prick-punch
"witness marks" around the circumference
as shown in part B of figure 3-29. These
witness marks will be cut exactly in half
by the drill to verify a correctly located
hole.
FOUR-HOLE FLANGE.— Figure 3-30 shows
the development for a 4-hole flange layout.
Set your dividers for slightly more than
half the distance of arc AB, and then scribe
an intersecting arc across the pitch circle
line from points A, B, C, and D, as shown
in part A of figure 3-30. Next, draw a
short radial line through the point of inter-
section of each pair of arcs as shown in
part B. The points where these lines cross
the pitch circle, (1), (2), (3), and (4), are
the centers for the holes. To check the
layout for accuracy, set your divider for
the pitch between any two adjacent holes
and step around the pitch circle. If the
holes are not evenly spaced, find your error
and correct it. When the layout is correct, follow
the center-punching and witness-marking
procedure described for the 6-hole flange layout.
"WITNESS MARKS"
Figure 3-29. — Development of a 6-hole flange.
me same memo a as aescnoea lor locaung poim
(1) in the 4-hole layout. Then divide arc AE in
half by the same method. The midpoint of arc
AE is the location for the center of hole (1). (see
part A of fig. 3-31.) Next, set your dividers for
distance A (1), and draw an arc across the pitch
circle line from A at point (8); from B at points
(2) and (3); from C at (4) and (5); and from D
at (6) and (7). (see part B of fig. 3-31.)
Now set your calipers for distance AE and
MATHEMATICAL DETERMINATION OF
PITCH CHORD LENGTH.— In addition to the
geometric solutions given in the preceding
paragraphs, the spacing of valve flange bolt hole
centers can be determined by simple multiplica-
tion, provided a constant value for the desired
number of bolt holes is known. The diameter
of the pitch circle multiplied by the constant
equals the length of the pitch chord. The
Figure 3-30.— Four-hole flange development.
Figure 3-31. — Eight-hole flange development.
3-19
Here is an example of the use of the table.
Suppose a flange is to have 9 bolt holes laid out
on a pitch circle with a diameter of 10 inches.
From the table, select the constant for a 9-hole
flange. The pitch diameter (10 inches) multiplied
by the appropriate constant (.342) equals the
length of the pitch chord (3.420 inches). Set a pair
of dividers to measure 3.420 inches, from point
to point, and step off around the circumference
of the pitch circle to locate the centers of the
flange bolt holes. Note, however, that the actual
placement of the holes in relation to the vertical
and horizontal bisectors is determined separately.
(This is of no concern if the layout is for an
unattached pipe flange rather than for a valve
flange.)
BENCHWORK
In this chapter, we will consider benchwork
related to repair work, other than machining, in
restoring equipment to an operational status. In
repairing equipment, benchwork progresses in
several distinct steps: obtaining information,
disassembly of the equipment, inspection for
defects, repair of defects, reassembly, and testing.
Table 3-2. — Constants for Locating Centers of Flange
bolt Holes
No. bolt holes
9
10
11
12
13
14
15
16
17
18
19
20
Constant
0.866
.7071
.5879
.3827
.342
,2588
,2079
.195
.184
possible sources for this information. Job orders
generally give brief descriptions of the equipment
and the required repair. Manufacturers' technical
manuals and blueprints give detailed information
on operational characteristics and physical
descriptions of the equipment. Operators can
provide information on specific techniques of
operation and may furnish clues as to why the
equipment failed. The leading petty officer of
your shop can provide valuable information on
repair techniques, and can help you interpret the
information. Use these sources of information to
become familiar with the equipment before
attempting the actual repair work. If you
are thoroughly acquainted with the equipment,
you will not have to rely on trial and error
methods which are time consuming and some-
times questionable in effectiveness.
There are specific techniques that can be used
in assembly and disassembly of equipment which
will improve the effectiveness of a repair job.
Whenever you repair equipment, you should note
such things as fastening devices, fits between
mating parts, and the uses of gaskets and packing.
Noting the positions of parts in relation to mating
parts or the unit as a whole is extremely helpful
in ensuring that the parts are in correct locations
and positions when the unit is reassembled.
Inspecting the equipment before and during
the repair procedure is necessary to determine
causes of defects or damage. The renewal or
replacement of a broken or worn part of a unit
may give the equipment an operational status.
Eliminating the cause of damage prevents
recurrence.
Repairs are made by replacement of parts, by
machining the parts to new dimensions, or by
using handtools to overhaul and recondition the
equipment. Handtools are used in the repair
procedure in jobs such as filing and scraping to
true surfaces and in removing burrs, nicks, and
sharp edges.
It is often said that a repair job is incomplete
until the repaired equipment has been tested for
satisfactory operation. How equipment is tested
depends on the characteristics of the equipment.
In some cases testing facilities are available in the
shop. When these facilities are not available, the
unit may be placed back in operation and tested
by normal use.
3-20
mucn ot me equipment tnat you are required to
disassemble, repair, and reassemble. You must,
therefore, use techniques that will aid you in
remembering the position and location of parts
in relatively intricate mechanisms. The following
information applies in general to assembly and
disassembly of any equipment.
Equipment should be disassembled in a clean,
well-lighted work area. With plenty of light, small
parts are less likely to be misplaced or lost, and
small but important details are more easily noted.
Cleanliness of the work area, as well as the proper
cleaning of the parts as they are removed,
decreases the possibility of damage due to foreign
matter when the parts are reassembled.
Before starting any disassembly job, select the
tools and parts you think you will need and take
them to the work area. This will permit you to
concentrate on the work without unnecessary
interruptions during the disassembly and re-
assembly processes.
Have a container at hand for holding small
parts to prevent their loss. Use tags or other
methods of marking the parts to identify the unit
from which they are taken. Doing this prevents
mixing parts of one piece of equipment with parts
belonging to another similar unit, especially if
several pieces of equipment are being repaired in
the same area. Use a scribe or prick-punch to
mark the relative positions of mating parts that
are required to mate in a certain position. (See
fig. 3-32.) Pay close attention to details of the
equipment you are taking apart and fix in your
mind how the parts fit together. When you
PUNCH
MARKS
JOINTS
PUNCH
MARKS
Figure 3-32. — Mating parts location marks.
heavy pressure is required to separate parts. An
overlooked pin, key, or setscrew that locks parts
in place can cause extensive damage if pressure
is applied to the parts. If hammers are required
to disassemble parts, use a mallet or hammer with
a soft face (lead, plastic, or rawhide) to prevent
distortion of surfaces. If bolts or nuts or other
parts are stuck together due to corrosion, use
penetrating oil to free the parts.
PRECISION WORK
The majority of repair work that you perform
will involve some amount of precision hand work
of parts. Broadly defined, precision hand work
to the Machinery Repairman can range from using
a file to remove a burr or rough, sharp edge on
a hatch dog to reaming a hole for accurately
locating very close fitting parts. To accomplish
these jobs, you must be proficient in the use of
files, scrapers, precision portable grinders, thread
cutting tools, reamers, broaches, presses and
oxyacetylene torches.
Scraping
Scraping produces a surface that is more
accurate in fit and smoother in finish than a
surface obtained in a machining operation. It is
a skill that requires a great deal of practice before
you become proficient at it. Patience, sharp tools
and a light "feel" are required to scrape a surface
that is smooth and uniform in fit.
Some of the tools you will use for scraping
will be similar to files without the serrated
edges. They are available either straight or
with various radii or curves for scraping an
internal surface at selected points. Other scraper
tools may look like a paint scraper, possibly
with a carbide tip attached. You may find that
a scraper that you make from material in your
shop will best suit the requirements of the job at
hand.
A surface plate and nondrying prussian blue
are required for scraping a flat surface. Lightly
coat the surface plate with blue and move the
workpiece over this surface. The blue will stick
to the high spots on the workpiece, revealing the
3-21
areas to be scraped. (See fig. 3-33.) Scrape the
areas of the workpiece surface that are blue and
check again. Continue this process until the blue
coloring shows on the entire surface of the
workpiece. To reduce frictional "drag" between
mating finished scraped surfaces, rotate the solid
surfaces so that each series of scraper cuts is made
at an angle of 90° to the preceding series. This
action gives the finished scraped surface a
crosshatched or basket weave appearance. The
crosshatched method also enables you to more
easily see where you have scraped the part.
A shell-type, babbitt-lined, split bearing or a
bushing often requires hand scraping to ensure
a proper fit to the surface that it supports or runs
on. To do this, very lightly coat the shaft (or a
mandrel the same size as the shaft) with nondrying
Prussian blue. Turning the bearing on the shaft
(or the mandrel in the bearing) just a short
distance will leave thin deposits of the bluing on
the high spots in the bearing babbitt. Then lightly
scrape the high spots with a scraper shaped to
permit selective scraping of the high spots without
dragging along the other areas. Be very careful
when doing this to prevent tapering the bearing
excessively in either the longitudinal or radial
direction. When you have worked out all the high
spots, smooth out (or replace if necessary) the
bluing on the shaft or mandrel and repeat the
process until you have produced an acceptable
seating pattern. This job cannot be rushed and
done properly at the same time. A poor seating
pattern on a bearing could lead to an early failure
when the bearing is placed into service.
Removal of Burrs and Sharp Edges
One of the most common injuries that occurs
in machine shops is a cut or scratch caused by a
Figure 3-33.— Checking a surface.
sharp edge on a part. When a pump or other piece
of machinery that has been overhauled binds or
wipes with little or no operating time, an investiga-
tion will often reveal a sharp edge that has peeled
or broken off and jammed into an area that has
very little clearance. In spite of this and
other instances that cause either discomfort or
additional work, the removal of burrs and sharp
edges is often overlooked by the machinist. Close
examination of the old part or the blueprint will
sometimes indicate that a machined radius is
required. Regardless of the design or use of a part,
a few seconds in removing these sharp edges with
a file is time well spent.
Hand Reaming
When you need a round hole that is accurate
in size and smooth in finish, reaming is the process
that you will probably select. There are two types
of reaming processes — machine reaming and hand
reaming. Machine reaming requires a drill press,
lathe, milling machining or other power tool to
hold and drive either the reamer or the part.
Machine reaming will be covered in chapter 8.
Hand reaming is more accurate and is the method
you will probably use most in precision
bench work.
A hand reamer has a straight shank and a
square machined on its end. It is driven by hand
with a tap wrench placed on the square end.
Several different types of hand reamers are
available, as shown in figure 3-34. Each of the
different types has an application for which it is
best suited and a limiting range or capability. The
solid hand reamer in part A of figure 3-34 is used
for general purpose reaming operations where a
standard or common fractional size is required.
It is made with straight, helical, or spiral flutes.
A helical fluted reamer is used when an
interrupted cut, such as a part with a key way
through it, must be made. The helical flutes ensure
a greater contact area of the cutting edges than
the straight fluted reamer, preventing the reamer
from hanging up on the keyway and causing
chatter, oversizing and poor finishes.
The expansion reamer in B of figure 3-34 is
available as either straight or helical fluted. These
reamers are used when a reamed hole slightly
larger than the standard size is required.
Expansion reamers can be adjusted from about
0.006 inch larger for a 1/4-inch reamer to about
0.012 inch larger for a 1 1/2-inch reamer. The
adjustment is made by turning the screw on the
cutting end of the reamer.
SOLID HAND REAMER
D
B
TAPER PIN REAMER
EXPANSION REAMER SOLID
TAPER PIPE REAMER
EXPANSION REAMER INSERTED TOOTH
Figure 3-34. — Hand reamers.
The expansion reamer in C of figure 3-34 has
a much greater range for varying its size. Each
reamer is adjustable to allow it to overlap the
smallest diameter of the next larger reamer. The
cutting blades are the insert type and can be
removed and replaced when they become dull.
Adjustment is made by loosening and tightening
the two nuts on each side of the blades.
The taper pin reamer in D of figure 3-34 has
a taper of 1/4 inch per foot and is used to ream
a hole to accept a standard size taper pin. This
reamer is used most often when two parts require
a definite alignment position. When drilling the
hole for this reamer, it is often necessary to step
drill through the part with several drills of
different sizes to help reduce the cutting pressure
put on the reamer. Charts which give the
recommended drill sizes are available in several
machinist reference books. In any case, the
smallest drill used cannot be larger than the small
diameter of the taper pin.
The taper pipe reamer in E of figure 3-34 has
a taper of 3/4 inch per foot and is used to prepare
a hole that is to be threaded with a tapered pipe
thread.
The size of the rough drilled or bored hole to
be hand reamed should be between 0.002 inch and
about 0.015 inch (1/64) smaller than the reamer
size. A smoother and more accurately reamed hole
can be produced by keeping to a minimum the
amount of material that a reamer is to remove.
You must be careful to keep the rough hole from
being oversized or out-of-round. This is a very
common problem in drilling holes, and you can
prevent it only by using a correctly sharpened drill
under the most closely controlled conditions
possible. Information on drilling can be found in
chapter 5.
Alignment of the reamer to the rough hole is
a critical factor in preventing oversized, out-of-
round or bell-mouthed holes. If possible, perform
the reaming operation while the part is still set
up for the drilling or boring operation. Insert a
center in the spindle of the machine and place it
in the center hole in the shank of the reamer to
guide the reamer.
Another method of alignment is to fabricate
a fixture with guide bushings made from bronze
or a hardened steel to keep the reamer straight.
When a rough casting or a part that has the
reamed hole at an angle to its surface must be
reamed, it is best to spot face or machine the area
next to the hole so that the hole and the surface
are perpendicular. This will prevent an uneven
start and possibly reamer breakage. In most
reaming operations, you will find that the use of
a lubricant will give a better reamed hole. The
lubricant or cutting fluid helps to reduce heat and
friction and washes away the ships that build up
on the reamer. Soluble oil will normally serve very
3-23
well; however, in some cases, a lard or sulfurized
cutting oil may be required. When the reaming
operation is complete, remove the reamer from
the part by continuing to turn the reamer
in the same direction (clockwise) and putting
a slight upward pressure on it with your hand
until it has cleared the hole completely. Reversing
the direction of the reamer will probably
result in damage to both the cutting edges and the
hole.
A straight hand reamer is generally tapered on
the beginning of the cutting edges for a distance
approximately equal to the diameter of the
reamer. You will have to consider this when you
ream a hole that does not go all the way through
a part.
Broaching
Broaching is a machining process that cuts or
shears the material by forcing a broach through
the part in a single stroke. A broach is a tapered,
hardened bar, into which have been cut teeth that
are small at the beginning of the tool and get
progressively larger toward the end of the tool.
The last several teeth will usually be the correct
size of the desired shape. Broaches are available
to cut round, square, triangular and hexagonal
holes. Internal splines and gears and key ways can
also be cut using a broach. A key way broach
requires a bushing that will fit snugly in the hole
of the part and has a rectangular slot in it to slide
the broach through. Shims of different thicknesses
are placed behind the broach to adjust the depth
of the key way cut (fig. 3-35).
A broach is a relatively expensive cutting tool
and is easily rendered useless if not used and
handled properly. Like all other cutting tools, it
should be stored so that no cutting edge is in
contact with any object that could chip or dull
it. Preparation of the part to be broached is as
important as the broaching operation itself. The
size of the hole should be such that the beginning
pilot section enters freely but does not allow the
broach to freely fall past the first cutting edge or
tooth. If the hole to be broached has flat sides
opposite each other, you need only to measure
across them and allow for some error from drill-
ing. The broach will sometimes have the drill size
printed on it. Be sure the area around the hole
to be broached is perpendicular on both the
entry and exit sides.
Most Navy machine shop applications involve
the use of either a mechanical or a hydraulic press
to force the broach through the part. A
considerable amount of pressure is required to
broach, so be sure that the setup is rigid and that
all applicable safety precautions are strictly
observed. A slow even pressure in pushing the
broach through the part will produce the most
accurate results with the least damage to the
broach and in the safest manner. Do not bring
the broach back up through the hole, push it on
through and catch it with a soft cushion of some
type. A lubricant is required for broaching most
metals. A special broaching oil is best; however,
lard oil or soluble oil will help to cool the tool,
wash away chips and prevent particles from gall-
ing or sticking to the teeth.
Hand Taps and Dies
Many of the benchwork projects that you do
will probably have either an internally or an
externally threaded part in the design specifica-
tions. The majority of the threads cut on a bench-
work project are made with either hand taps, for
internally threaded parts, or hand dies for
externally threaded parts. The use of these two
cutting tools has come to be considered as a simple
skill requiring little or no knowledge of the tools
and no preplanning of the operation to be
performed. It is true that the operations are
simple, but only after several factors concerning
the correct selection and use of the tools have been
studied and practiced. Taps and dies are fast and
accurate cutting tools that can make a job much
easier and will produce an excellent end product.
The information given in the following
paragraphs will provide the general knowledge
and operational factors to start you in the
correct use of taps and dies.
TAPS.— Hand taps (fig. 3-36) are precision
cutting tools which usually have three or four
flutes and a square on the end for placing a tap
wrench to turn the tap. Taps are made from either
hardened carbon steel or high-speed steel and are
very hard and brittle. They are easily broken or
damaged when treated roughly or forced too
quickly through a hole.
Taps for most of the different thread forms,
described later in this manual, are available either
as a standard stock item or catalog special ordered
from a tap manufacturer. The information in this
section concerns only the most commonly used
thread forms, the Unified thread and the
American National thread. Both of these thread
systems have a 60-degree included angle or V
form.
28.33
Figure 3-35. — Broaching a keyway on a gear.
V8-I6 NC
G H4
TAPER
__D V'6NC C • •„........-
6 H4 IHUlllUni
PLUG
_-^^vw^AA^^^^^^^v^A^vvvi^
BOTTOMING
Figure 3-36.— Set of taps.
Taps usually come in a set of three for each
different diameter and number of threads per
inch. A taper, or starting tap (fig. 3-36), has 8 to
10 of the beginning teeth that are tapered. The
taper allows each cutting edge or tooth to cut
slightly deeper than the one before it. This permits
an easier starting for the tap and exerts a
minimum amount of pressure against the tool.
The next several teeth after the taper ends are at
the full designed size of the tap. They remove only
a small amount of material and help to leave a
fine finish on the threads. The last few teeth have
a very slight back taper that allows the tap to clear
the final threads cut without rubbing or binding.
The plug tap has 3 to 5 of the beginning teeth
tapered and the remaining length has basically the
same design as the taper tap. The bottoming tap
3-25
by the tapered teeth, it is always advisable to begin
the tapping operation with the taper, or starting
tap. If the hole being tapped goes all the way
through the material, the taper tap is usually the
only one required. If the hole is a blind one, or
does not go all the way through the material, all
three taps will be required. The taper tap will be
used first, followed by the plug tap, and the final
pass will be made with the bottoming tap.
Standard Sizes and Designations. — The size
of a tap is marked on the shank or the smooth
area between the teeth and the square on the end.
The numbers and letters always follow the same
pattern and are simple to understand. As an
example, the marking 3/8 - 16 NC (fig. 3-36)
means that the diameter of the tap is 3/8 inch and
that it has 16 threads per inch. The NC is a sym-
bol indicating the thread series. In this case, the
NC stands for the American National Coarse
Thread Series.
Some additional common thread series
symbols are NF, American National Fine; NS,
American National Special; NEF, American
National Extra Fine; and NPT, American
National Standard Tapered pipe. A "U" placed
in front of one of these symbols indicates the
UNIFIED THREAD SYSTEM, a system that has
the same basic form as the American National and
is interchangeable with it, differing mainly in
tolerance or clearance. These thread systems will
be covered in more detail in chapter 9. If an LH
appears on the marking after the thread series
symbols, the tap is left-handed.
The next group of markings usually found on
taps refers to the method of producing the threads
on the tap and the tolerance of the tap. As an
example, in the marking G H4 (fig. 3-36) the G
indicates that the threads were ground on the tap.
The greatest majority of the taps manufactured
today are ground. The next symbol, H4, refers
to the tolerance of the tap. The H means that the
tap has a pitch diameter that is above (HIGH) the
basic pitch diameter for that size tap. An L means
that the pitch diameter is under (LOW) the basic
pitch diameter for that size tap. The number
following the H or L indicates the amount of
tolerance in increments of 0.0005 inch. In the
example H4, the pitch diameter is a maximum of
0.002 inch (4 x 0.0005) above the basic pitch
diameter. In the case of an L, the amount is under
the basic pitch diameter. A number of 1 through
10 can be found on taps. This tolerance limit
classes will be covered later in this manual.
The only difference in the size and designation
markings for taps that will probably be found in
Navy machine shops is in machine screw diameter
taps, or numbered taps, as they are often called
in the shop. Instead of the diameter being
represented by a fraction, a number of 0 through
14 is used. You can easily convert these numbers
to a decimal equivalent by remembering that the
number 0 tap has a diameter of 0.060 inch and
each tap number after that increases in diameter
by 0.013 inch. As an example:
Size 0 = 0.060 inch dia.
Size 3 = 0.099 inch dia. [0.060 + 3 x 0.013]
Size 14 = 0.242 inch dia. [0.060 + 14 x 0.0131
A typical marking on a tap might be 10.24 UNC,
indicating a diameter of 0.190 inch, 24 threads
per inch, and a Unified National Coarse thread
series.
Tapping Operations.— The first step in any
successful tapping operation is the selection of the
correct size tap with sharp, unbroken cutting edges
on the teeth. A dull tap will require excessive force
to produce the threads and increases greatly the
chance of the tap breaking and damaging the part
being tapped. A dull tap can also produce ragged,
torn and undersize threads, leading to a damaged
part.
The tap drill or the size of the hole that is made
for the tap is very important if the correct fit is
to be obtained. If a hole were to be drilled equal
in size to the minor, or smallest, diameter of the
tap, a 100% thread height would result. To tap
a hole this size would require excessive pressure
and breakage could occur, especially with a small
tap or a material that is hard. Unless a blueprint
or other design references indicate differently, a
15% thread height is usually considered adequate
and is actually only about 5% less in terms of
strength or holding power than a 100% thread
height. In some of the less critical jobs, it is
possible to have a 60% thread height without a
significant loss in strength.
There are two simple formulas that you may
use to calculate the tap drill size for any size tap.
The simplest and the one most often used will
produce a thread height of approximately 75%.
3-26
(DS = TD - ). As an example, the drill
size for a 1/4 - 20 NC tap is required as follows:
Step 1: DS= 1/4 - 1/20
Step 2: DS = 0.250 - 0.050
Step 3: DS = 0.200 in.
The nearest standard size drill would then be
selected to make the hole. In this case, a number
8 drill has a diameter of 0. 199 inch and a number
7 drill has a diameter of 0.201 inch. Unless the
size differences are very great, it is more effective
to select the larger drill size or the number 7 drill
for this tap.
The second formula, although slightly more
difficult, allows for a selection of the desired
percentage of thread height. To use it, you must
know the straight depth of the thread. You can
obtain this data from various charts in handbooks
for machinists or by using the formulas in chapter
9 of this manual. It is as follows: DRILL
SIZE = TAP DIAMETER MINUS THE
DESIRED PERCENTAGE OF THREAD
HEIGHT TIMES TWICE THE STRAIGHT
DEPTH. As an example, if 60% thread height
is desired for a 1/4 - 20 NC tap, the drill size is
figured as follows:
Step 1: DS = 1/4 - .60 x 2(0.032)
Step 2: DS = 0.250 - .60 x 0.064
Step 3: DS = 0.250 - 0.038
Step 4: DS = 0.212 in.
The nearest standard size drill to 0.212 inch is a
number 3 drill which has a diameter of 0.213 inch.
A word of caution about drilling holes for tapping
is important at this point. Even if the drill is
ground perfectly, the part is rigidly clamped and
the drilling machine has no looseness, the drilled
hole can be expected to be oversized. In the case
of the number 7 and the number 3 drills selected
in the two examples given, the drilled holes will
probably be approximately 0.003 to 0.004 inch
oversize. You should consider this in planning the
operation. Additional information on drilling
holes is in chapter 5.
and shape. You MUST be sure that the part can-
not vibrate loose and be thrown out of the vise
or off of the drill press table. When a twist drill
driven by a geared motor digs in or binds in a part,
a great amount of force is exerted against the part.
You could lose a finger or hand, break a leg, or
worse if this happens. It is best to start the drilling
operation with a small drill or a center drill
(described later in this manual) by aligning the
drill point as close as possible to the center punch
mark you made to locate the center of the hole.
When you have done this, insert the tap drill
into the drilling machine or drill press and drill
the hole. If the hole is very large, use a drill several
sizes below the tap drill size to prevent an out-
of-round or excessively oversized hole. Do NOT
move the part when you make the various tool
changes.
The hole is now ready to be tapped. Some taps
have a center hole in the shank that will fit over
the point of a center. If this is the case and the
setup will allow it, place a center in the drill press
without moving the part; place a tap wrench over
the square shank, turn the center into the center
hole on the tap wrench over the square shank, (fig.
3-37) and slowly turn the tap while applying a
CHUCK
CENTER
WORK
TAPPING WORK IN
A DRILL PRESS
TAP
SQUARE
WORK
CHECKING TAP
WITH A SQUARE
Figure 3-37.— Starting a tap.
3-27
slight downward pressure on the center to help
guide the tap. If a center cannot be used, align
the tap as close as possible by eye and make 2 or
3 turns with the tap handle. Remove the tap
handle and place a good square on the surface
of the part (if the part is machined flat) and bring
the square into contact with one set of teeth. Do
the same check on the next set of teeth in either
direction around the tap (fig. 3-37). If the tap is
not perpendicular or square with the surface at
both points, back it out and start over. When the
tap is square, begin turning the tap wrench slowly.
After making two or three turns, turn the tap
backwards to break the chips and help clear them
from the path of the tap. Proceed with this until
the tap bottoms out; then place the next tap in
the set in the hole and repeat the tapping
procedure. If the hole is blind, remove the taps
often to clear the chips from the bottom.
It is often necessary to remove burrs from
around a hole that has been tapped. Do this with
a file, by slowly hand-spinning a larger twist drill
in the hole, or by using a countersink.
A cutting oil should be used in most tapping
operations. There are several commercial products
available that greatly enhance the quality of thread
produced. A heavy cutting oil with either a sulfur,
mineral oil or lard oil base is available in the
supply system. If no other cutting oil is available,
a heavy mixture of soluble oil is acceptable.
DIES. — Hand threading dies come in various
styles, including unadjustable solid square and
round shaped dies and adjustable single and two-
piece dies. The most common die used in Navy
machine shops is the adjustable single piece or
round split die (fig. 3-38). The adjustable round
split die is a round disk-shaped tool which has
internal threads and usually four holes or flutes
that interrupt the threads and present four sets
of cutting edges. The die has a groove cut
completely through one side and a setscrew to
allow for a small amount of expansion and
contraction of the die. This feature permits an
adjustment for taking a rough and a finish cut
on particularly hard or tough metals and also
allows for slight adjustments to obtain a close fit
with a mated nut or other internally threaded part.
There is a difference in the two sides of the die —
the starting side has about 3 full threads tapered
and the trailing side has about 1 thread tapered.
To prevent damage to the die and the threads
being cut, the die should always be started with
the greatest taper leading. The die is held in a
diestock (fig. 3-38), a tool which has a circular
ADJUSTING
SCREW
ROUND SPLIT DIE
A
LOCKING
HOLE
THREE SCREW DIESTOCK
B
Figure 3-38.— Die and diestock.
recess to hold the die and three setscrews that fit
into small indentations in the outside diameter of
the die.
The size of a die is usually marked on the trail-
ing face (the side that is up during threading) and
follows the same format as a tap. A die marked
5/8-11 NC will cut a thread that has a
5/8-inch diameter and 11 American National
Coarse threads per inch. The G, H, L, and
associated numbers found on a tap are not
normally marked on a die because they represent
a fixed tolerance and the die is adjustable.
The steps involved in threading a part with a
die are similar to those for a tap. The part to be
threaded should have a chamfer ground or cut on
the end to help in starting the die squarely with
the part. Select the correct die and insert it in the
diestock with the longest tapered side opposite the
square shoulder. Apply cutting oil and place the
die over the part by grasping the diestock in the
middle with one hand. Turn the die several turns,
then look carefully at the die and the part to
ensure that they are square to one another.
Threads that are deeper on one side than the other
indicate a misaligned die. Turn the die about three
3-28
LIUI/CIUO, J. 1>1JUI_F V
it from the part and check the fit with the part
that will mate with it. Make any adjustments
necessary at this time. Replace the die on the part
and continue threading until you reach the desired
thread length. If you are cutting the threads to
a shoulder, you may turn the die over and cut the
last 2 or 3 threads with the short tapered side.
Removing Broken Taps
Removing a broken tap is usually a difficult
operation and requires slow, deliberate actions to
remove it successfully without damaging the part
involved. There is no single method that you can
use in all the different circumstances you may
experience. The following information describes
briefly some of the methods that have proven to
be effective. You will need to evaluate the
particular problem and attempt removal with the
method that will work best.
A tap that has broken and has at least 1/4 inch
left protruding above the part can sometimes be
grasped by locking pliers and removed. Use a
scribe first to remove as many as of the chips as
possible from the hole and the flutes of the tap.
Do not use compressed air to remove the chips
because there is always a chance that a small chip
will be blown into either your eyes or someone's
nearby. Apply penetrating oil around the threads
if possible. Use a small hand grinder to shape the
end of the tap to provide a good grip for the
locking pliers. If they are permitted to slip on the
tap, additional fragments will probably break
away, giving you less surface to grasp. Apply a
slow, even force. Excessive force or jerky
movements will cause more damage. You may
need to carefully rock or reverse the direction in
which you are turning the tap in order to free it.
This is especially true in beginning the removal.
Use a lubricant once you have loosened the tap
in the hole. When you have removed the tap,
examine the hole and threads closely to ensure that
no fragments of the tap or jagged threads remain
to cause problems when you use another tap to
finish or clean up the threads.
Another method is to use a punch and apply
sharp blows to the broken tap. You will probably
use this method when the tap is broken below the
surface of the part. Always wear safety goggles
and a face shield to protect your face and eyes
from flying fragments. Do not allow anyone to
stand near you while you do this type of
\Ji LJ.ll' U«.j-/« ^ 1.J JTV/U Wi WtlJV U. 1 J. tig, All Will' V/i LJ.1V bU£/
away, remove it from the hole. This method will
probably cause serious damage to the threaded
hole when the punch strikes the threads, or an
oversized condition can result from forcing the
tap around in the hole. You should be sure that
there is an approved method of repair or
modification of the threaded hole before under-
taking this method of removal.
It is sometimes possible to weld a stud to the
top of a tap that is broken off below the surface.
The tap diameter must be large enough for inser-
tion of both the stud and the welding rod into the
hole without running the risk of having the
welding rod touch or splatter the threads. There
are materials that can be used to help protect the
threads. Unless you are an accomplished welder,
do not attempt this job. Request the assistance
of a Hull Maintenance Technician (HT). After the
stud is welded to the tap, you can apply a more
even pressure in removing the tap if you grind a
square on the top of the stud so that you can use
a tap wrench. The heat generated by the welding
process could have expanded the tap slightly so
that when it cooled and contracted, it may have
loosened slightly. On the other hand, the tap may
bind even more and the structure and condition
of the surrounding metal may have changed.
If the tap is broken off below the surface of
the part, you can use a tool called a tap extractor
(fig. 3-39) to remove it. You should try this
method first as it does no damage to the threads.
Tap extractors are available for each of the
standard diameter taps over about 3/16 inch. As
you see in figure 3-38, the tap extractor has a
square end for using a tap wrench and sliding
prongs or fingers that fit into each of the flutes
on the tap. The upper collar is secured in place
by setscrews while the bottom collar is free to
move. Position the bottom collar as close as
BROKEN
/TAP
SLIDING
PRONG
UPPER
COLLAR
SQUARE
SHANK
Figure 3-39.— Tap extractor.
3-29
possible to the top of the hole to prevent the
sliding prongs from twisting. The best results are
obtained from this tool when the sliding prongs
have a minimum amount of unsupported length
exposed. Apply a slow, even pressure to the tap
wench in removing the tap.
In all of the methods listed, remove all chips
prior to beginning the removal process. There are
several methods for helping to free the tap that
you can use with any of the removal methods if
the particular situation lends itself to their use.
As previously mentioned, you can apply
penetrating oil around the threads. You can also
apply a controlled heat to the area surrounding
the tap to cause expansion. Be very careful to limit
the heat so the tap does not begin to expand also.
Since most taps are made from high-speed steel,
this probably will not occur, but do not overlook
the possibility. You must also consider damage
to the part from heat. If the part is very big and
has a large mass of metal in the immediate area,
the heat will carry to the surrounding area rapidly,
preventing adequate heat and expansion where it
is needed.
Another method, one that you must conduct
under strict safety conditions, is to apply a
solution of 1 part nitric acid and 5 parts water
to the threaded hole. The nitric acid solution will
gradually eat away some of the surface metal and
loosen the tap. After the acid solution has worked
for a little while, pour it out and rinse the part
thoroughly. This method is effective primarily on
steel parts. When you mix the acid solution add
the acid to the premeasured amount of water. The
procedure of adding the acid to the water is a
safety measure because some acids react violently
when water is added to them. You should wear
chemically resistant goggles, a face shield, rubber
or plastic gloves, and an apron. Nitric acid can
damage your eyes, burn your skin, and eat holes
in your clothes. If any acid gets on your skin,
immediately flush the skin with water for at least
15 minutes and seek medical attention. You will
use nitric acid often in identifying metals. You
should treat each occasion as seriously as the first,
strictly observing every safety precaution.
There is one other method for removing
broken taps that is used primarily on tenders,
repair ships, and shore based repair activities. It
involves the use of a special machine (metal
disintegrator), electrodes, and a coolant. Any
metal that will conduct electricity can be worked
with this machine. The action of the electrode and
the coolant combined create a hole through the
part that is equal in size to the diameter of the
electrode. There are portable models available;
however, most models either have their own
cabinet or they are used in a drill press. Detailed
information on this method can be found later
in this manual.
Classes of Fit
The following information concerns plain
cylindrical parts such as sleeves, bearings, pump
wearing rings and other nonthreaded round parts
that fit together. Fit is defined as the amount of
tightness or looseness between two mating parts
when certain allowances are designed into them.
As defined earlier in this chapter, an allowance
is the total difference between the size of a shaft
and the hole in the part that fits over it. The
resulting fit can be a clearance (loose) fit or
interference (tight) fit, or a transitional
(somewhere between loose and tight) fit. These
three general types of fit are further divided into
classes of fit, with each class having a different
allowance based on the intended use or function
of the parts involved. A brief description of each
type fit will be given in the following paragraphs.
Any good handbook for machinists has complete
charts with detailed information on each class of
fit. The majority of equipment repaired in Navy
machine shops will have the dimensional sizes and
allowances already specified in either the
manufacturer's technical manual, NAVSHIPS*
Technical Manual, or the appropriate Preventive
Maintenance System Maintenance Requirement
Card, which is the priority reference on
maintenance matters.
CLEARANCE FITS.— Clearance fits, or
running and sliding fits as they are often called,
provide a varying degree of clearance (looseness)
depending on which one of the nine classes is
selected. The classes of fit range from class 1 (close
sliding fit), which permits a clearance allowance
of from +0.0004 to +0.0012 inch on mating parts
with a 2.500 inch basic diameter, to class 9 (loose
running fit), which permits a clearance allowance
of from +0.009 to +0.0205 inch on the same parts.
Even for a basic diameter, the small (2.500 inch)
clearance allowance from a class 1 minimum to
a class 9 maximum differs by +0.0201 inch. As
the basic diameter increases, the allowance
increases. Although the class of fit may not be
specified on a blueprint, the dimensions given for
the mating parts are based on the service
performed by the parts and the specific conditions
under which they operate. Some parts that fall
ing rings (loose removal).
other part.
TRANSITIONAL FITS.— Transitional fits
are subdivided into three types known as loca-
tional clearances, locational transition and loca-
tional interference fits. Each of these three
subdivisions contains different classes of fit which
provide either a clearance or an interference
allowance, depending on the intended use and
class. All of the classes of fit in the transitional
category are primarily intended for the assembly
and disassembly of stationary parts. Stationary
in this sense means that the parts will not rotate
against each other although they may rotate
together as part of a larger assembly. The
allowances used as examples in the following
descriptions of the various fits represent the sum
of the tolerances of the external and internal parts.
To achieve maximum standardization and to
permit common size reamers and other fixed sized
boring tools to be used as much as possible, it is
best to use the unilateral tolerance method
previously explained and consult one of the class
of fit charts in a handbook for machinists.
Locational clearance fits are broken down into
1 1 different classes of fit. The same basic diameter
with a class 1 fit ranges from a zero allowance
to a clearance allowance of +0.0012 inch, while
a class 1 1 fit ranges from a clearance allowance
of +0.014 to +0.050 inch. The nearer a part is to
a class 1 fit, the more accurately it can be installed
without the use of force.
Locational transition fits have six different
classes providing either a small amount of clear-
ance or an interference allowance, depending on
the class of fit selected. The 2.500-inch basic
diameter in a class 1 fit ranges from an interference
allowance of -0.0003 inch to a clearance
allowance of +0.0015 inch while a class 6 fit
ranges from an interference allowance of — 0.002
inch to a clearance allowance of +0.0004 inch. The
interference allowance fits may require a very light
pressure to assemble or disassemble the parts.
Locational interference fits are divided into
five different classes of fit, all of which provide
an interference allowance of varying amounts. A
class 1 fit for a 2.500-inch basic diameter ranges
from an interference allowance of -0.0001 to
-0.0013 inch, while a class 5 fit ranges from an
interference allowance of from -0.0004 to
- 0.00023 inch. These classes of fits are used when
parts must be located very accurately while main-
taining alignment and rigidity. They are not
INTERFERENCE FITS.— There are five
classes of fit within the interference type. They
are all fits that require force to assemble or
disassemble parts. These fits are often called force
fits and in certain classes of fit they are referred
to as shrink fits. Using the same basic diameter
as an example, the class 1 fit ranges from an
interference allowance of -0.0006 to -0.0018
inch and a class 5 fit ranges from an interference
allowance of - 0.0032 to - 0.0062 inch. The class
5 fit is normally considered to be a shrink fit class
because of the large amounts of interference
allowance required.
A shrink fit requires that the part with the
external diameter be chilled or that the part with
the internal diameter be heated. You can chill a
part by placing it in a freezer, packing it in dry
ice, spraying it with CO2 (do not use a CO2 bottle
from a fire station) or by submerging it in liquid
nitrogen. All of these methods except the freezer
are potentially dangerous, especially the liquid
nitrogen, and should NOT be used until all
applicable safety precautions have been reviewed
and implemented. When a part is chilled, it
actually shrinks a certain amount depending on
the type of material, design, chilling medium, and
length of time of exposure to the chilling medium.
You can heat a part by using an oxyacetylene
torch, a heat-treating oven, electrical strip heaters
or by submerging it in a heated liquid. As with
chilling, all applicable safety precautions must be
observed. When a part is heated, it expands,
allowing easier assembly. All materials expand a
different amount per degree of temperature
increased. This is called the coefficient of
expansion of a metal. Most handbooks for
machinists include a chart of the factors and
explain their use. It is important that you calculate
this information to determine the maximum
temperature increase required to expand the part
the amount of the shrinkage allowance plus
enough clearance to allow assembly. Overheating
a part can cause permanent damage and produce
so much expansion that assembly becomes
difficult.
A general rule of thumb for determining the
amount of interference allowance on parts requir-
ing a force or shrink fit is to allow approximately
0.0015 inch per inch of diameter of the internally
bored part. There are many variables that will
prohibit the use of this general rule. The amount
3-31
of interference allowance recommended decreases
as the diameter of the part increases. The
dimensional difference between the inside and
outside diameter (wall thickness) also has an
effect on the interference allowance. A part that
has large inside and outside diameters and a
relatively thin wall thickness will split if installed
with an excessive interference allowance. You
must consider all of these variables before you
select a fit when there are no blueprints or other
dimensional references available.
Hydraulic and Arbor Presses
Hydraulic and arbor presses are used in many
Navy machine shops. They are used to force
broaches through parts, assemble and disassemble
equipment with force fitted parts, and many other
shop projects.
Arbor presses are usually bench mounted with
a gear and gear rack arrangement. They are used
for light pressing jobs, such as pressing arbors or
mandrels into a part for machining or forcing a
small broach through a part.
Hydraulic presses can be either vertical or
horizontal, although the vertical design is
probably more common and versatile. The
pressure that a hydraulic press can generate ranges
from about 10 to 100 tons in most of the Navy
machine shops. The pressure can be exerted
by either a manually operated pump or an electro-
hydraulic pump.
Regardless of the type of press equipment you
use, be sure to operate it correctly. The only way
you can determine the amount of pressure a
hydraulic press exerts is by watching the pressure
gauge. A part being pressed can reach the break-
ing point without any visible indication that too
much pressure is being applied. When using the
press, you must consider the interference
allowance between mating parts; corrosion and
marred edges; and overlooked fastening devices,
such as pins, setscrews, and retainer rings.
To prevent damage to the work, observe the
following precautions whenever you use a
hydraulic press:
• Ensure that the work is adequately
supported.
• Place the ram in contact with the work by
hand, so that the work is positioned accurately
in alignment with the ram.
• Use a piece of brass or other material
(preferably slightly softer than the workpiece)
between the face of the ram and the work to
prevent mutilation of the "surface of the
workpiece.
• Watch the pressure gauge. You cannot
determine the pressure exerted by "feel." If you
begin to apply excessive pressure, release the
pressure and double check the work to find the
cause.
• When pressing parts together, use a
lubricant between the mating parts to prevent
seizing.
Information concerning the pressure required
to force fit two mating parts together is available
in most handbooks for machinists. The distance
the parts must be pressed directly affects the
required pressure, and increased interference
allowance requires greater pressure. As a guideline
for force-fitting a cylindrical shaft, the maximum
pressure, in tons, should not exceed 7 to 10 times
the shaft's diameter in inches.
Oxyacetylene Equipment
As a Machinery Repairman, you may have to
use an oxyacetylene torch to heat parts to expand
them enough to permit assembly or disassembly.
Do this with great care, and only with proper
supervision. The operation of the oxyacetylene
torch, as used in heating parts only, is explained
in this chapter along with safety precautions which
you must observe when you use the torch and
related equipment.
Oxyacetylene equipment consists of a cylinder
of acetylene, a cylinder of oxygen, two regulators,
two lengths of hose with fittings, a welding torch
with tips, and either a cutting attachment or a
separate cutting torch. Accessories include a spark
lighter to light the torch; an apparatus wrench to
fit the various connections, regulators, cylinders,
and torches; goggles with filter lenses for eye
protection; and gloves for protection of the hands.
Flame-resistant clothing is worn when necessary.
Acetylene (chemical formula C2H2) is a fuel
gas made up of carbon and hydrogen. When
burned with oxygen, acetylene produces a very hot
flame having a temperature between 5700 ° and
6300 °F. Acetylene gas is colorless, but has a
distinct, easily recognized odor. The acetylene
used on board ship is usually taken from
compressed gas cylinders.
3-32
burn by itself, but it will support combustion
when combined with other gases. You must be
extremely careful to ensure that compressed
oxygen does not become contaminated with
hydrogen or hydrocarbon gases or liquids, unless
the oxygen is controlled by such means as the
mixing chamber of a torch. A highly explosive
mixture will be formed if uncontrolled compressed
oxygen becomes contaminated. Oxygen should
NEVER come in contact with oil or grease.
The gas pressure in a cylinder must be reduced
to a suitable working pressure before it can be
used. This pressure reduction is accomplished by
an LC REGULATOR or reducing valve.
Regulators that control the flow of gas from the
cylinder are either the single-stage or the double-
stage type. Single-stage regulators reduce the
pressure of the gas in one step; two-stage
regulators do the same job in two steps, or stages.
Less adjustment is generally necessary when two-
stage regulators are used.
The hose connected between the torch and the
regulators is strong, nonporous, and sufficiently
flexible and light to make torch movements easy.
The hose is made to withstand high, internal
pressures, and the rubber from which it is made
is specially treated to remove sulfur to avoid the
danger of spontaneous combustion. Welding hose
is available in various sizes, depending upon the
size of work for which it is intended. Hose used
for light work has a 3/16- or 1/4-inch inside
diameter, and contains one or two plies of
fabric. For heavy duty welding and handcutting
operations, hose with an inside diameter of 1/4
or 5/16 inch and three to five plies of fabric is
used. Single hose comes in lengths of 12 1/2 feet
to 25 feet. Some manufacturers make a double
hose which conforms to the same general
specifications. The hoses used for acetylene and
oxygen have the same grade but differ in color
and have different types of threads on the hose
fittings. The oxygen hose is GREEN and the
acetylene hose is RED. The oxygen hose has right-
hand threads and the acetylene hose has left-hand
threads for added protection against switching the
hoses during connection.
The oxyacetylene torch is used to mix oxygen
and acetylene gas in the proper proportions and
to control the volume of these gases burned at the
torch tip. Torches have two needle valves, one for
adjusting the flow of oxygen and the other for
adjusting the flow of acetylene. In addition, they
have a handle (body), two tubes (one for oxygen
which dissipates heat (less than 60% copper) and
are available in different sizes to handle a wide
range of plate thicknesses.
Torch tips and mixers made by different
manufacturers differ in design. Some makes of
torches have an individual mixing head or mixer
for each size of tip. Other makes have only one
mixer for several tip sizes. Tips come in various
types. Some are one-piece, hard copper tips.
Others are two-piece tips that include an extension
tube to make connection between the tip and the
mixing head. When used with an extension tube,
removable tips are made of hard copper, brass,
or bronze. Tip sizes are designated by numbers,
and each manufacturer has its own arrangement
for classifying them. Tips have different hole
diameters.
No matter what type or size tip you select, you
must keep the tip clean. Quite often the orifice
becomes clogged. When this happens, the flame
will not burn properly. Inspect the tip before you
use it. If the passage is obstructed, you can clear
it with wire tip cleaners of the proper diameter,
or with soft copper wire. Do not clean tips with
machinist's drills or other sharp instruments.
Each different type of torch and tip size
requires a specific working pressure to operate
properly and safely. These pressures are set by
adjusting the regular gauges to the setting
prescribed by charts provided by the manufac-
turer.
PROCEDURE FOR SETTING UP OX-
YACETYLENE EQUIPMENT.— Take the
following steps in setting up oxyacetylene
equipment:
1. Secure the cylinders so they cannot be
upset. Remove the protective caps.
2. Crack (open) the cylinder valves slightly to
blow out any dirt that may be in the valves. Close
the valves and wipe the connections with a clean
cloth.
3. Connect the acetylene pressure regulator to
the acetylene cylinder and the oxygen pressure
regulator to the oxygen cylinder. Using the
appropriate wrench provided with the equipment
tighten the connecting nuts.
4. Connect the red hose to the acetylene
regulator and the green hose to the oxygen
regulator. Tighten the connecting nuts enough to
prevent leakage.
3-33
5. Turn the regulator screws out until you
feel little or no resistance then open the cylinder
valves slowly. Then open the acetylene valve 1/4
to 1/2 turn. This will allow an adequate flow of
acetylene and the valve can be turned off quickly
in an emergency. (NEVER open the acetylene
cylinder valve more than 11/2 turns.) Open the
oxygen cylinder valve all the way to eliminate
leakage around the stem. (Oxygen valves are
double seated or have diaphragms to prevent
leakage when open.) Read the high-pressure gauge
to check the pressure of each cylinder.
6. Blow out the oxygen hose by turning the
regulator screw in and then back out again. If you
need to blow out the acetylene hose, do it ONLY
in a well-ventilated place that is free from sparks,
flames, or other possible sources of ignition.
7. Connect the hoses to the torch. Connect
the red acetylene hose to the connection gland that
has the needle valve marked AC or ACET.
Connect the green oxygen hose to the connection
gland that has the needle valve marked OX. Test
all hose connections for leaks by turning both
regulator screws IN, while the needle valves are
closed. Then turn the regulator screws OUT, and
drain the hose by opening the needle valves.
8. Adjust the tip— Screw the tip into the
mixing head and screw the mixing head onto the
torch body. Tighten the mixing head/tip assembly
by hand and adjust the tip to the proper angle.
Secure this adjustment by tightening the assembly
with the wrench provided with the torch.
9. Adjust the working pressures — Adjust the
acetylene pressure by turning the acetylene gauge
screw to the right. Adjust the acetylene regulator
to the required working pressure for the particular
tip size. (Acetylene pressure should NEVER
exceed 15 psig.)
10. Light and adjust the flame — Open the
acetylene needle valve on the torch and light the
acetylene with a spark lighter. Keep your hand
out of the way. Adjust the acetylene valve until
the flame just leaves the tip face. Open and
adjust the oxygen valve until you get the proper
neutral flame. Notice that the pure acetylene flame
which just leaves the tip face is drawn back to the
tip face when the oxygen is turned on.
PROCEDURE FOR ADJUSTING THE
FLAME. — A pure acetylene flame is long and
bushy and has a yellowish color. It is burned by
the oxygen in the air, which is not sufficient to
burn the acetylene completely; therefore, the
flame is smoky, producing a soot of fine,
unburned carbon. The pure acetylene flame is
unsuitable lor use. When the oxygen valve is
opened, the mixed gases burn in contact with the
tip face. The flame changes to a bluish- white color
and forms a bright inner cone surrounded by an
outer flame envelope. The inner cone develops the
high temperature required.
The type of flame commonly used for heating
parts is a neutral flame. The neutral flame is
produced by burning one part of oxygen with one
part of acetylene. The bottled oxygen, together
with the oxygen in the air, produces complete
combustion of the acetylene. The luminous white
cone is well-defined and there is no greenish tinge
of acetylene at its tip, nor is there an excess of
oxygen. A neutral flame is obtained by gradually
opening the oxygen valve to shorten the acetylene
flame until a clearly defined inner luminous cone
is visible. This is the correct flame to use for many
metals. The temperature at the tip of the inner
cone is about 5900 °F, while at the extreme end
of the outer cone it is only about 2300 °F. This
gives you a chance to exercise some temperature
control by moving the torch closer to or farther
from the work.
EXTINGUISHING THE OXYACETYLENE
FLAME.— To extinguish the oxy acetylene flame
and to secure equipment after completing a job,
or when work is to be interrupted temporarily,
you should take the following steps:
1. Close the acetylene needle valve first; this
extinguishes the flame and prevents flashback.
(Flashback is discussed later.) Then close the
oxygen needle valve.
2. Close both the oxygen and acetylene
cylinder valves. Leave the oxygen and acetylene
regulators open temporarily.
3. Open the acetylene needle valve on the
torch and allow gas in the hose to escape for 5
to 15 seconds. Do NOT allow gas to escape into
a small or closed compartment. Close the
acetylene needle valve.
4. Open the oxygen needle valve on the torch.
Allow gas in the hose to escape for 5 to 15
seconds. Close the valve.
5. Close both oxygen and acetylene cylinder
regulators by backing out the adjusting screws
until they are loose.
Follow the above procedure whenever your
work will be interrupted for an indefinite period.
If your work is to stop for only a few minutes,
securing the cylinder valves and draining the hoses
is not necessary. However, for any indefinite work
in areas other than the shop, it is a good idea to
remove the pressure regulators and the torch from
the system and to double check the cylinder valves
to make sure that they are closed securely.
SAFETY: OXYACETYLENE
EQUIPMENT
When you are heating with oxyacetylene
equipment, you must observe certain safety
precautions to protect personnel and equipment
from injury by fire or explosion. The precautions
which follow apply specifically to oxyacetylene
work.
• Use only approved apparatus that has been
examined and tested for safety.
• When you use cylinders, keep them far
enough away from the actual heating area so they
will not be reached by the flame or sparks from
the object being heated.
• NEVER interchange hoses, regulators, or
other apparatus intended for oxygen with those
intended for acetylene.
• Keep valves closed on empty cylinders.
• Do NOT stand in front of cylinder valves
while opening them.
• When a special wrench is required to open
a cylinder valve, leave the wrench in position on
the valve stem while you use the cylinder so the
valve can be closed rapidly in an emergency.
• Always open cylinder valves slowly. (Do
NOT open the acetylene cylinder valve more than
1 1/2 turns.)
• Close the cylinder valves before moving the
cylinders.
• NEVER attempt to force unmatching or
crossed threads on valve outlets, hose couplings,
or torch valve inlets. The threads on oxygen
regulator outlets, hose couplings, and torch valve
inlets are right-handed; for acetylene, these
threads are left-handed. The threads on acetylene
cylinder valve outlets are right-handed, but have
a pitch that is different from the pitch of the
threads on the oxygen cylinder valve outlets. If
the threads do not match, the connections are
mixed.
involved. This information should be taken from
tables or worksheets supplied with the equipment.
• Do NOT allow acetylene and oxygen to ac-
cumulate in confined spaces. Such a mixture is
highly explosive.
• Keep a clear space between the cylinder
and the work so the cylinder valves may be
reached quickly and easily if necessary.
• When lighting the torch, use friction
lighters, stationary pilot flames, or some other
suitable source of ignition. The use of matches
may cause serious hand burns. Do NOT light a
torch from hot metal. When lighting the torch,
open the acetylene valve first and ignite the gas
with the oxygen valve closed. Do NOT allow
unburned acetylene to escape into a small or
closed compartment.
• When extinguishing the torch, close the
acetylene valve first and then close the oxygen
valve.
• Do NOT use lubricants that contain oil or
grease on oxyacetylene equipment. OIL OR
GREASE IN THE PRESENCE OF OXY-
GEN UNDER PRESSURE WILL IGNITE
VIOLENTLY. Consequently, oxygen must not be
permitted to come in contact with these materials
in any way. Do NOT handle cylinders, valves,
regulators, hose, or any other apparatus which
uses oxygen under pressure with oily hands or
gloves. Do NOT permit a jet of oxygen to strike
an oily surface or oily clothes. NOTE: A suitable
lubricant for oxyacetylene equipment is glycerin.
• NEVER use acetylene from cylinders
without reducing the pressure through a suitable
pressure reducing regulator. Avoid acetylene
working pressures in excess of 15 pounds per
square inch. Oxygen cylinder pressure must
likewise be reduced to a suitable low working
pressure; high pressure may burst the hose.
• Stow all cylinders carefully according to
prescribed procedures. Store cylinders in dry, well-
ventilated, well-protected places away from heat
and combustible materials. Do NOT stow oxygen
cylinders in the same compartment with acetylene
cylinders. Stow all cylinders in an upright
position. If they are not stowed in an upright
position, do not use them until they have been
allowed to stand upright for at least 2 hours.
3-35
cylinder, or on any flammable materials. Be sure
a fire watch is posted as required to prevent
accidental fires.
Be sure you and anyone nearby wear flame-
proof protective clothing and shaded goggles to
prevent serious burns to the skin or the eyes. A
number 5 or 6 shaded lens should be sufficient
for your heating operations.
These precautions are by no means all the
safety precautions that pertain to oxyacetylene
equipment, and they only supplement those
specified by the manufacturer. Always read the
manufacturer's manual and adhere to all pre-
cautions and procedures for the specific equip-
ment you are going to be using.
Flashback and Backfire
A backfire and a flashback are two common
problems encountered in using an oxyacetylene
torch.
Unless the system is thoroughly purged of air
and all connections in the system are tight before
the torch is ignited, the flame is likely to burn in-
side the torch instead of outside the tip. The
difference between the two terms backfire and
flashback is this: in a backfire, there is a
momentary burning back of the flame into the
torch tip; in a flashback, the flame burns in or
beyond the torch mixing chamber. A backfire is
characteristized by a loud snap or pop as the flame
goes out. A flashback is usually accompanied by
a hissing or squealing sound. At the same time,
the flame at the tip becomes smoky and sharp-
pointed. When a flashback occurs, immediately
shut off the torch oxygen valve, then close the
acetylene valve.
A flashback indicates that something is
radically wrong either with the torch or with the
manner of handling it. A backfire is less serious.
Usually the flame can be relighted without
difficulty. If backfiring continues whenever the
torch is relighted, check for these causes;
overheated tip, gas working pressures greater than
that recommended for the tip size being used,
loose tip, or dirt on the torch tip seat. These same
difficulties may be the cause of a flashback,
except that the difficulty is present to a greater
degree. For example, the torch head may be
distorted or cracked.
In most instances, backfires and flash-
backs result from carelessness. To avoid these
closed) when the equipment is stowed, (3) the
oxygen and acetylene working pressures used are
those recommended for the torch, and (4) you
have purged the system of air before using it.
Purging the system of air is especially necessary
when the hose and torch have been newly
connected or when a new cylinder is put into the
system.
PURGING THE OXYACETYLENE
TORCH.—
1 . Close the torch valves tightly, then slowly
open the cylinder valves.
2. Open the acetylene regulator slightly.
3. Open the torch acetylene valve and allow
acetylene to escape for 5 to 15 seconds,
depending on the length of the hose.
4. Close the acetylene valve.
5. Repeat the procedure on the oxygen side
of the system.
After purging air from the system, light the
torch as described previously.
FASTENING DEVICES
Parts of machinery and equipment are held
together by several types of fastening devices. The
fastening devices commonly used by the
Machinery Repairman are classified into three
general groups: threads, keys, and pins.
The selection of the correct fastener (specified
in blueprints, list of material blocks, and technical
manuals) and the use of an approved installation
method are important factors in the efficiency and
reliability of a piece of equipment. Improper use
of fasteners will lead to equipment failures and
possible personnel injuries.
Threaded Fastening Devices
Bolts, studs, nuts, capscrews, machine screws
and setscrews are all threaded devices used to
clamp or secure mating parts together. Each of
the different types has a specific range of applica-
tions and is available in various sizes, designs and
material specifications. The most common sizes
evolve from the established diameters, threads per
inch, and classes of fit described in the Unified
(UNC, UNF) and the American National (NC,
NF) thread systems explained in chapter 9. The
3-36
j. uii£,v \jt. £,viivi u.j. cippjuvcii..ivji.io iv^i any givtii
fastener. However, some equipment requires such
specialized fasteners that the fasteners can only
be used for that specific purpose. The material
specification for a certain application of a fastener
is based on the function of the mating parts,
stresses, and temperatures applied to the
fasteners and on the elements to which the equip-
ment is exposed, such as steam, saltwater and oil.
Table 3-3 is a general guide for material usage and
the different identifying markings found on
fasteners.
BOLTS.— A bolt is an externally threaded
fastener, with a threaded diameter of 1/4 inch or
larger, and either a squarely or hexagonally
shaped head. Bolts are designed to be inserted into
holes slightly larger than their diameter. A nut is
attached to the threaded end to draw the mating
parts together. As a general rule, the width of the
thread ranges from 2 times the thread diameter
plus 1/4 inch to a point just below the head,
depending on the intended use. The length of the
bolt is measured from the under side of the head
to the tip of the threaded portion. It is best to use
a bolt that has an unthreaded length slightly less
than the combined thickness of the parts being
mated. The overall length should allow a
minimum of 1 full thread and a maximum of 10
threads (space permitting) to protrude above the
nut after the assembly is completely torqued
down. The class of fit normally found on the
threads of bolts and the nuts used with them is
class 2A for the bolt and class 2B for the nut.
This fit permits an allowance so that the bolt
and nut can be assembled without seizing or
galling. Detailed information on the different
classes of fit for threads is covered later in this
manual.
Table 3-3. — Specifications and Uses of Fasteners
MATERIAL
MATERIAL SPECS.
GRADE
CONDITION
MARKING ON
FASTENER
INTENDED USE
CARBON STEEL
SAE 10XX SERIES
STEEL WITH A MAX
IMUM OF 0.55%
5
HEAT
TREATED
3 EQUALLY
SPACED RADIAL
LINES
GENERAL USE
CARBON STEEL
CARBON
8
HEAT
TREATED
6 EQUALLY
SPACED RADIAL
LINES
GENERAL USE
ALLOY STEEL
SAE 4140 TO
SAE 4145
B7
HEAT
TREATED
B7
FOR USE UP TO 775°F WITH GRADE 2H AND
GRADE 4 NUTS
ALLOY STEEL
ASTM A 193
B16
HEAT
TREATED
B16
FOR USE UP TO 1000°F WITH GRADE 4 NUT
CORROSION
RESISTANT STEEL
FED. STD. 66
303
ANNEALED
303
FOR USE WHERE LOW MAGNETIC AND
CORROSION RESISTANT PROPERTIES ARE
REQUIRED
CORROSION
RESISTANT STEEL
FED. STD. 66
41 OT
HEAT
TREATED
410
FOR USE WHERE LOW MAGNETIC AND
CORROSION RESISTANT PROPERTIES ARE
REQUIRED
NAVAL BRASS
QQ-B-637
482
—
482
FOR CONNECTING NON-FERROUS MATERIALS
IN CONTACT WITH SALT WATER
SILICON BRONZE
QQ-C-591
651
—
651
FOR CONNECTING NON-FERROUS MATERIALS
IN CONTACT WITH SALT WATER
NICKLE COPPER
QQ-N-281 CL. A&B
400
400
FOR CONNECTING FERROUS AND
NON-FERROUS MATERIALS (EXCEPT
ALUMINUM) IN CONTACT WITH SALT WATER
NICKLE COPPER
ALUMINUM
QQ-N-286 CL.A
500
—
500
FOR CONNECTING FERROUS AND
NON-FERROUS MATERIALS (EXCEPT
ALUMINUM) IN CONTACT WITH SALTWATER
CARBON STEEL
SAE 10XX SERIES
STEEL WITH A
MAX. OF 0.55%
CARBON
2H
HEAT
TREATED
2H (NUTS ONLY)
FOR USE UP TO 775°F WITH GRADE B7 STUD OR
BOLT
ALLOY STEEL
SAE 4140 to
SAE 4145
4
HEAT
TREATED
4 (NUTS ONLY)
FOR USE UP TO 1000°F WITH GRADE B16 AND
B7 STUD OR BOLT
3-37
fastener with threads on both ends. It can either
be inserted through a clearance hole and secured
by a nut on each end, or it can be used in an
assembly where one part has a tapped hole and
the second part has a clearance hole. In the latter
case, the stud is screwed into the tapped hole and
a nut is screwed onto the other end of the stud.
One type of stud is continuously threaded, with
threads beginning at one end and running the
entire length of the stud. Another type of stud
has threads beginning at each end and an un-
threaded portion in the center of the stud. The
unthreaded portion may have the same diameter
as the major diameter of the threads, or it may
be recessed to provide clearance. A continuously
threaded stud generally has a class 2A or 3A fit
to allow relative ease in assembly. A stud with the
center portion unthreaded may have a different
class of fit on each end. One end will have a class
2A or 3A fit. This is the end on which the nut
is screwed. The end of the stud that screws into
the tapped hole will have an interference fit that
will require a torque wrench to install it. The
interference fit is a class 5 fit and is divided into
several subdivisions to provide the correct fit for
different materials and lengths of engagement. A
stud of this type is screwed into the tapped hole
the maximum distance possible without jamming
either the end of the stud against the bottom of
the hole or the shoulder of the unthreaded part
of the stud against the top of the tapped hole. A
small amount of lubricant approved for use in the
temperature range in which the equipment is
exposed should be applied to the threads. You will
find the correct tolerances and torque required for
each application in charts in most handbooks for
machinists.
NUTS. — A nut is an internally threaded
fastener with the same size threads as the
externally threaded part to which it will be
attached. Nuts come in either square or a hexagon
shapes and have standard widths and thicknesses
based on the basic thread size. Any application
of threaded fasteners that are subjected to
working conditions which could cause the nut to
loosen through heat or vibration usually has some
method of locking the mating parts securely.
Several methods are available to you. You may
use different styles of lock washers, deform the
area around the threads by staking or peening with
a center punch, install setscrews, or use locknuts.
Locknuts in common use are of two types.
One type applies pressure to the bolt or stud
and is used when the nut must be removed
frequently. Included in this type are jam nuts, a
thin nut that goes under the regular nut; plastic
angular ring and nylon plug insert nuts that use
the resiliency of the plastic and nylon to create
large frictional pressures on the bolt or stud;
spring nuts that use springs of different types to
apply pressure between the nut and the working
surface; and spring beam nuts that have a slight
taper in the upper portion of the nut with slots
cut to form segments which permit expansion
when the nut is screwed onto a bolt or stud. The
other type of locknut deforms the threads on the
bolt or stud and should be used only when
removal is seldom required. This type includes (1)
a distorted collar nut that has an oval shaped
opening at the top and applies pressure when
forced over the bolt or stud and (2) a distorted
thread nut that has depressions in the face or
threads of the nut.
MACHINE SCREWS AND CAP-
SCREWS. — Machine screws and capscrews are
similar except for size range. Machine screws have
diameters up to 3/4 inch (including size numbers
from 0 to 12), while capscrews come in sizes above
1/4-inch diameter. Both machine screws and
capscrews are available in several head shapes,
such as flat, fillister, and hexagonal. These
screwheads are slotted so they can be tightened
with a screwdriver.
SETSCREWS.— Setscrews are available in
several different styles of heads including square,
hexagon, slotted and the most common type, the
recessed hexagon socket. The points on setscrews
differ from the points on other threaded fasteners
to permit a positive engagement with a prepared
recess in the external surface on one of the mating
parts. Available point shapes are a cone (90°
point), a cup (recessed point), an oval, a flat, and
a half -dog (a short, reduced diameter). The point
selection depends on whether the setscrew is in-
tended to prevent slippage of a pulley or gear on
a shaft or to hold nonrotating parts in place.
There is a definite relationship between the
holding power and the diameter of a setscrew and
between the number of setscrews required to
transmit rotational movement of equipment
rotating at any given revolutions per minute and
horsepower. If the equipment specifications do
not provide this information, you may obtain it
from most handbooks for machinists. Setscrews
are normally made of hardened steel, although
3-38
corrosive liquids are involved.
Screw Thread Inserts
A screw thread insert (fig. 3-40) is a helically
wound coil designed to screw into an internally
threaded hole and receive a standard sized
externally threaded fastener. A screw thread
insert can be used to repair a threaded hole when
the threads have been corroded or stripped away
and to provide an increased level of thread
strength when the base metal of the part is
aluminum, zinc, or other soft materials. Before
using screw thread inserts for a repair job, care-
fully evaluate the feasibility of using this method.
When you have no specific guidance, ask your
supervisor for advice.
Screw thread inserts come in sizes up to
1 1/2-inch in diameter in both American National
and Unified, coarse and fine thread series. The
overall length of an insert is based on a fractional
multiple of its major diameter. A 1/2-inch screw
thread insert is available in lengths of 1/2, 3/4,
1 inch, and so on. Screw thread inserts are
normally made from stainless steel; however
phosphor bronze and nickel alloy inserts are
available by special order. A stainless steel insert
should NOT be used in any application where the
temperature exceeds 775 °F or where a corrosive
material such as acid or saltwater is involved.
There are several tools associated with the
installation and removal of screw thread inserts
that are essential if the job is to be done correctly.
The most important tool is the tap used to thread
the hole that the insert will be screwed into. These
taps are oversized by specific amounts according
to the size of the insert, so that after installation
pitch diameter tolerance, as previously explained
in the section on hand taps, are marked on the
taps. As an example of the amount of oversize
involved, a tap required for a 1/2-13 UNC
insert has a maximum major diameter of 0.604
inch. Because of the increase in the size of the hole
required, it is important to ensure that there is
sufficient material around the hole on the part to
provide strength. A rule of thumb is that the
minimum amount of material around the hole
should equal the thread size of the insert,
measured from the center of the hole. Using this
rule, a 1/2 - 13 UNC insert will require a 1/2-inch
distance from the center of the hole to the nearest
edge of the part. The tap drill size for each of the
taps is marked on the shank of the tap. The
diameter of this drill will sometimes vary
according to the material being tapped.
The next tool that you will use is an inserting
tool (fig. 3-41). There are several styles of
inserting tools that are designed to be used for
a specific range of insert sizes and within each of
these styles are tools for each individual size of
insert. All of the inserting tools have similar
operating charactistics. Either slip the insert over
or screw it onto the shank of the tool until the
tang (the horizontal strip of metal shown at the
top of the insert in figure 3-40) solidly engages
the shoulder or recess on the end of the tool. Then
install the insert by turning the tool until the
correct depth is reached. Remove the tool by
reversing the direction of rotation.
After you have the insert properly installed,
break off the tang to prevent any interference with
the fastener that will be screwed into the hole. A
tang break-off tool is available for all insert sizes
INSERTING TOOL
EXTRACTOR
Figure 3-40. — Screw thread insert.
Figure 3-41. — Screw thread insert tools.
3-39
of 1/2 inch and below. The tang has a slight notch
ground into it that will give way and break when
struck with the force of the punch-type, tang
break-off tool. On insert sizes over 1/2 inch use
a long-nosed pair of pliers to move the tang back
and forth until it breaks off.
When it is necessary to remove a previously
installed screw thread insert, use an extracting tool
(fig. 3-41). There are several different sized tools
that cover a given range of insert sizes; be sure
you select the correctly sized tool. Insert the tool
into the hole so the blade contacts the top coil of
the insert approximately 90 ° from the beginning
of the insert coil. Then, lightly hit the tool to cause
the blade to cut into the coil. Turn the tool
counterclockwise until the insert is clear.
The steps involved in repairing a damaged
threaded hole with a screw thread insert are as
follows:
1. Determine the original threaded hole size.
Select the correct standard sized screw thread
insert with the length that best fits the applica-
tion. Be sure the metal from which the insert is
made is recommended for the particular
application.
2. Select the correct tap for the insert to be
installed. Some taps come in sets of a roughing
and a finishing tap.
3 . Select the correct size of drill based on the
information on the shank of the tap or from
charts normally supplied with the insert kits.
Measure the part with a rule to determine if the
previously referenced minimum distance from the
hole to the edge of the part exists. With all
involved tools and parts secured rigidly in place,
drill the hole to a minimum depth that will permit
full threads to be tapped a distance equaling or
exceeding the length of the insert, not counting
any spot-faced or countersunk area at the top of
the hole. Remove all chips from the hole.
4. Tap the hole. Use standard tapping
procedures in this step. If the tapping procedure
calls for both roughing and finishing taps, be sure
to use both taps prior to attempting to install the
insert. Use lubricants to improve the quality of
the threads. When you have completed the
tapping, inspect the threads to ensure that full
threads have been cut to the required depth of the
hole. Remove all chips.
5. Next, install the insert. If the hole being
repaired is corroded badly, apply a small amount
of preservative, such as zinc chromate, to the
'T
H
D
FLAT BOTTOM
OPTIONAL
V V
A. SQUARE
B. RECTANGULAR
C. WOODRUFF
Figure 3-42. — Types of keys and keyseats.
required by the particular style being used. Turn
the tool clockwise to install the insert. Continue
to turn the tool until the insert is approximately
1/2 turn below the surface of the part. Remove
the tool by turning it counterclockwise.
6. Use an approved antiseize compound when
screwing the threaded bolt or stud into the insert.
Avoid using similar metals such as a stainless
insert and a stainless bolt to prevent galling and
seizing of the threads.
Keyseats and Keys
Keyseats are grooves cut along the axis of the
cylindrical surface of a shaft and the bored hole
in a hub. Metal keys of various shapes are fitted
into these grooves to transfer torque between the
shaft and the hub. There are basically three types
of keys: taper, parallel and Woodruff. The
standard taper keys have a taper of 1/8 inch per
foot and are either a plain taper or a gib head
taper style key. Taper keys are not often found
on marine equipment and will not be covered in
this text. Parallel keys consist mainly of square
and rectangular shaped keys. These are probably
the most common types of keys that you will work
with. A Woodruff key is a semicircular shaped
key designed primarily to permit easy removal of
pulleys from shafts. Keys are made from several
different types of metal including medium carbon
steel, nickel steel, nickel-copper alloy, stainless
steel and several bronze alloys. Each different key
style and material has a particular use for which
it is best suited, depending on the forces and
when replacing a key to prevent selecting one that
will not perform as required.
Square keys (fig. 3-42A) are recommended for
applications where the shaft diameter is 6 1/2
inches and below, while rectangular keys (fig.
3-42B) are recommended for shaft diameters over
6 1/2 inches. Some applications may require that
two keys be installed to drive equipment under
high torque conditions. The width and height of
a key depend on the diameter of the shaft that
it will be used on, while the length of the key is
based on the key's width. A chart giving some
of the more common sizes of shafts and
recommended key size combinations is provided
in table 3-4.
Parallel keys (square and rectangular) and the
keyseats machined to accept them are designed
to provide assembly fits of three different classes.
Each of the classes gives the recommended
tolerance on both the key and the keyseat for the
fit on the sides and the top and bottom of the
keyed assembly. The top and bottom tolerances
for the key and keyseat assemblies generally
provide a range of fit from metal-to-metal up to
approximately 0.040-inch clearance (depending on
the width of the key) for all three classes of fits.
The side fit for a class 1 fit allows for a metal to
metal 0.017-inch clearance fit. The amount of
clearance increases as the width of the key
increases. A class 2 fit allows for a side fit
ranging from a 0.002-inch clearance to an
interference fit of up to 0.003 inch. A class 3 fit
allows only an interference fit for the sides of the
key with individual applications determining the
Table 3-4.— Key Size Versus Shaft Diameter.
SHAFT DIAMETER
KEY SIZE KEY LENGTH "L"
WIDTH "W"
HEIGHT "H"
MIN.
MAX.
FROM
TO
SQUARE
RECTANGULAR
4XW
16XW
7/8"
1 1/4"
1/4"
1/4"
3/16"
1"
4'
1 1/4"
1 3/8"
5/16"
5/16"
1/4"
1 1/4"
5'
1 3/8"
1 3/4"
3/8"
3/8"
1/4"
1 1/2"
6'
1 3/4"
2 1/4"
1/2"
1/2"
3/8"
2"
8'
4 1/2"
5 1/2"
1 1/4"
1 1/4"
7/8"
5"
20'
6 1/2"
7 1/2"
1 3/4"
1 3/4"
1 1/2"
7"
28'
Selective excerts extracted from "American
Society of Mechanical Engineers" USAS
B 17. 1-1 967 Page 2, table 1
3-41
shaft diameters and the allowable tolerance for
each of the classes of fit are available in most
handbooks for machinists.
The ends of square or rectangular keys are
often prepared with a radius equal to one-half of
the width as shown in the top illustration of figure
3-42B. This design permits a snug assembly fit
when the machining on the keyseat was done with
a conventional milling machine and an end mill
cutter.
Woodruff keys (fig. 3-42C) are manufactured
in various diameters and thicknesses. The circular
side of the key is seated in a keyseat milled in the
shaft with a cutter having the same radius and
thickness as the key.
The size of a Woodruff key is designated by
a system of numbers which represent the nominal
key dimensions. The last two digits of the number
indicate the diameter of the key in eighths of an
inch, while the digit or digits preceding them
indicate the width of the key in thirty-seconds of
an inch. Thus, a number 404 key would be 4/8
or 1/2 inch in diameter and 4/32 or 1/8 inch wide,
while a number 1012 key would be 12/8 or 1 1/2
inches in diameter and 10/32 or 5/16 inch wide.
For proper assembly of keyed members,
clearance is required between the top surface of
the key and the key seat. This clearance is
normally approximately 0.006 inch.
Positive fitting of the key in the keyseat is
provided by making the key 0.0005 to 0.001 inch
wider than the seat.
Information on the machining of keyseats for
parallel and Woodruff keys is included in chapter
11.
Pins
The three pins commonly used in the machine
shop are the dowel pin, the taper pin, and the
cotter pin. The DOWEL PIN, which is made of
machine-finished round stock, is used for aligning
parts. It is used in applications such as pump
housings. A hole in the housing matches with a
hole in the end casing and a dowel pin is inserted
to provide exact alignment. As this is an aligning
pin, the dowel must have a light drive fit. The
TAPER PIN which has a 1/4-inch per foot taper
is used to hold slow-speed, low-torque, rotor-shaft
applications, such as hand-operated wheels and
levers on machine tools. When taper pins are
used, the hole must be drilled and then reamed
with a taper pin reamer to obtain the correct
1 \J L4.lJ.vl XXJ.V L>dJ. J L v v*l\. W 11J.W11 CtJL W L-ltJ V'H L/A J.HJlW-1 JLJL V LU
lock nuts in place on bolts. All pins come in a
variety of standard sizes and lengths. Most
machinist's handbooks give information on hole
sizes and numbers for specific dimensions of pins.
Gaskets, Packing and Seals
Many of the repair jobs that you do will
require the installation of gaskets, packing, or
seals to prevent leakage. Gaskets are used mainly
for sealing fixed type joints such as flanged pipe
and valve joints and pump casings, while packing
and seals are used for sealing joints where one part
moves in relation to the other. All of these seal-
ing devices are available in a wide range of
diameters, thicknesses and classifications (grades)
to provide suitable sealing of any system or
equipment. A general knowledge of the different
sealing materials is important; however, the
proper selection of a gasket, packing or other seal
must never be based on general application
guidelines or memory. The modern ships of to-
day have systems that reach 1000°F in
temperature and 2050 psi in pressure under nor-
mal operating conditions. A wrong selection can
cause serious injury to personnel and major
damage to equipment. The equipment's technical
manual, allowance parts list, snip's plan on the
appropriate PMS Maintenance Requirement Card
are sources that can provide the exact specifica-
tions required for the sealing device.
A brief description of some of the more
common types of gaskets, packing, and seals used
in shipboard equipment and their general applica-
tion is provided in the following paragraphs.
Gaskets
Spiral wound, metallic-asbestos gaskets are
composed of alternate layers of dovetailed
stainless steel ribbon and strips of asbestos spirally
wound, ply upon ply, to the desired diameter. The
gasket is then placed in a solid steel retainer ring
to keep the gasket material intact, to assist in
centering the gasket on the flange, and to act as
a reinforcement to prevent blowouts. This type
gasket is used on steam, boiler feedwater, fuel and
lubricating oil systems. System pressures of 100
to 2050 psi and normal operating temperatures
of 1 50 ° of 1000 °F are within the range that these
gaskets can effectively seal. Each application
requires a specific gasket and substitutions should
not be considered. When installing this gasket,
3-42
thickness required for the particular application.
Synthetic rubber and cloth inserted rubber
gaskets are used on freshwater and seawater
systems with pressures of 50 to 400 psi and
temperatures of 150° to 250 °F.
Gasoline and JP-5 systems require a gasket
made from Buna-N and cork. The use of the
wrong gasket material in these systems will result
in a deterioration of the gasket resulting in
contamination of the system and a hazardous
situation if a leak should develop.
Prior to installing any gasket, carefully inspect
the surfaces of the mating parts for cuts or
scratches that will prevent the proper sealing of
the gasket. When any doubt exists, refinish the
surface. You will find additional information on
flange refinishing later in this manual.
Packing
The packing used to seal against leakage
around equipment, such as valve stems on pump
shafts, is available in many different material
types, shapes, and sizes. Specific recommenda-
tions on packing selection is best left to the
appropriate technical document; however, there
are some common errors made in packing
selection and installation that are important to
note. Packing that has a metallic or semimetallic
base should not be used on a brass or bronze part.
Parts that are softer than 250 BRINELL hard-
ness should not be packed with a copper bearing
packing. The surface condition of the valve stem
or shaft and the stuffing box into which the pack-
ing is placed are important also. A surface that
has pits and scratches which could provide a path
for leakage should be repaired. An out-of-round
condition will cause excessive clearance between
the packing and the rotating part. A type of pack-
ing called corrugated ribbon packing, which is
intended for steam valves, requires very close
control over the finishes, dimensions, and
concentricity of the parts that contact it. Each part
must be measured and checked carefully before
this type packing can be used.
Seals
The types of seals you will work with most
often are oil seals, mechanical seals, and O-rings.
Each type requires careful attention to the
contact area and the installation procedures to
ensure a good seal against leakage.
cup or flange retainer, which press fits into a
cylindrical bore, and a spring-loaded rubber or
neoprene lip, which make contact with the shaft.
The spring will cause the seal to maintain a firm
contact with the shaft even if there is a small
amount of shaft runout. The seal contact area on
the shaft must be free of pits, scratches and old
wear patterns to operate as designed. When
replacing a seal of this type, be particularly careful
in selecting the proper seal as indicated by the
equipment manufacturer. The type of fluid
being sealed and the operating temperature are
as important in correct seal selection as the
dimensions of the seal.
Mechanical seals are considerably more
difficult to install correctly. The majority of
mechanical seals consist of one part that is sealed
against the housing or seal retainer with a gasket
or O-ring, while another part of the seal is
attached to the shaft and is sealed by a rubber or
neoprene bellows. Each of these two parts has a
flat-faced seal that makes a rubbing contact when
the shaft is turning. One of the flat-faced seals
is spring-loaded to maintain a constant contact
pressure when end play occurs in the equipment
during operation. The flat-faced seals may be
made from carbon, alloy steel, ceramic, or several
other materials. Regardless of the material used
for these parts, they should be handled very
carefully to avoid damage. The installation
instructions provided by the seal or equipment
manufacturer should be followed very closely to
ensure the correct loading and proper function-
ing of the seal. Shaft runout, alignment, and end
play (thrust) must be within the limitations
prescribed for the equipment.
O-rings may be used as a static seal where no
motion exists between the mating parts or as a
dynamic seal where a reciprocating, oscillating,
or rotary motion exists between the mating parts.
O-rings are made from either synthetic or natural
materials which have the capability of returning
to their original shape and size after being
deformed. The substance being sealed and the
operating pressures and temperatures are very
important factors in determining the exact O-ring
to use in any given application. Preparation of
the O-ring groove requires special care to ensure
that the specified finish and dimensions are
obtained. The annular or circular finish pattern
(lay) produced by a lathe provides a surface that
allows a more effective seal than one produced
by an end mill cutter in a milling machine.
3-43
A roughness value of 32 microinches for a static
seal and 15 microinches for a dynamic seal is
generally acceptable for the O-ring groove. To
achieve maximum effectiveness, an O-ring should
not be stretched more than 5% beyond the
designed dimension of the inside diameter after
the O-ring is in position in the groove. This can
be controlled only by accurate machining and
measuring of the depth of the O-ring groove.
Excessive width of the groove will allow the
O-ring to roll or twist during installation and
operation. Many applications require the use of
backup rings which are placed on one or
both sides of the O-ring to provide additional
protection against O-ring distortion under
pressure. The equipment specifications should
be reviewed carefully to determine if a backup
ring is required. An approved O-ring lubricant
is essential during installation to prevent
damage to the O-ring and to enhance the
sealing effectiveness. The lubricant selected
should be one that will not affect the O-ring
material or contaminate the substance being
sealed.
civ •*
METALS AND PLASTICS
A Machinery Repairman is expected to repair
broken parts and to manufacture replacements
according to samples and blueprints. To choose
the metals and plastics best suited for fabrication
of replacement parts, you must have a knowledge
of the physical and mechanical properties of
materials and know the methods of identifying
materials that are not clearly marked. For
instance, stainless steel and nickel-copper are quite
similar in appearance, but completely different
in their mechanical properties and cannot be
used interchangeably. A thermosetting plastic
may look like a thermoplastic but the former
is heat resistant, whereas the latter is highly
flammable. Some of the properties of materials
that an MRS and MR2 must know are presented
in this chapter.
PROPERTIES OF METALS
The physical properties of a metal determine
its behavior under stress, heat, and exposure
to chemically active substances. In practical
application, the behavior of a metal under
these conditions determines its mechanical
properties; indentation and rusting. The
mechanical properties of a metal, therefore, are
important considerations in selecting material for
a specific job.
STRESS
Stress in a metal is its internal resistance to
a change in shape (deformation) when an external
load or force is applied to it. There are three
different forms of stress to which a metal may
be subjected. Tensile stress is a force that pulls
a metal apart. Compression stress is a force that
squeezes the metal. Shear stress is forces from
opposite directions that work to separate the
metal. When a piece of metal is bent, both tensile
and compression stresses are applied. The side of
the metal on the outside of the bend undergoes
tensile stress as it is stretched, while the
metal on the inside of the bend is squeezed under
compression stress. When a metal is subjected to
a torsional load such as a sump shaft driven by
an electric motor, all three forms of stress are
applied to a certain degree.
STRAIN
Strain is the deformation or change in shape
of a metal that results when a stress or load is
applied. When the load is removed, the metal is
no longer under a strain. The type of deforma-
tions which result when a metal is subjected to
a stress will be similar to the form of stress
applied.
STRENGTH
Strength is the property of a metal which
enables it to resist strain (deformation) when a
stress (load) is applied. The strength of a metal
may be expressed by several different terms. The
most commonly used term is tensile strength.
Tensile strength is the maximum force required
to pull metal apart. To find the tensile strength
of a metal, divide the force required to pull the
metal apart by the area in square inches of a
prepared specimen.
Another term used often to describe the
strength of a metal is yield strength. The yield
strength is determined during the same test that
establishes the tensile strength. The yield strength
is established when the metal specimen first begins
to elongate (stretch) while pressure is gradually
applied. A relationship between the tensile
strength and the hardness of metals is often
present. As the hardness of a metal is increased,
the tensile strength is also increased and vice versa.
4-1
LUC muic cuuuj.nju.iy uacu
Some other terms that may be used to describe
a metal's strength are compression strength, shear
strength, and torsional strength. You will not see
these terms often. However, in certain design
applications, where stress would result in strains
of one of these types being applied to a part, you
would need to establish and use specific values
in safety computations.
PLASTICITY
Plasticity is the ability of a metal to withstand
extensive permanent deformation without break-
ing or rupturing. Modeling clay is an example of
a highly plastic material, since it can be deformed
extensively and permanently without rupturing.
Metals with a high plasticity value will produce
long, continuous chips when machined on a lathe.
ELASTICITY
Elasticity is the ability of a metal to return to
its original size and shape after an applied force
has been removed. Steel used to make springs is
an example of applying this property.
DUCTILITY
Ductility is the ability of a metal to be
permanently deformed by bending or by being
stretched into wire form without breaking. To
find the ductility of a metal, measure the
percentage of elongation which results when the
metal is stretched during the tensile strength test.
Copper is an example of a very ductile metal.
MALLEABILITY
Malleability is the ability of a metal to be
permanently deformed by a compression stress
produced by hammering, stamping, or rolling the
metal into thin sheets. Lead is a highly malleable
metal.
BRITTLENESS
Brittleness is the tendency of a metal to break
or crack with no prior deformation. Generally,
brittle metals.
TOUGHNESS
Toughness is the quality that enables a
material to withstand shock, to endure stresses
and to be deformed without breaking. A tough
material is not easily separated or cut and can be
bent first in one direction and then in the opposite
without fracturing.
HARDNESS
Hardness of a metal is generally defined as its
ability to resist indentation, abrasion or wear, and
cutting. The degree of hardness of many metals
may be either increased or decreased by being
subjected to one or more heat treatment processes.
In most cases, as the hardness of a steel is
decreased, its toughness is increased.
HARDENABILITY
Hardenability is a measure of the depth
(from the metal's surface toward its center)
that a metal can be hardened by heat treatment.
A metal that achieves a shallow depth of hard-
ness and retains a relatively soft and tough core
has a low hardenability value. The hardenability
of some metals can be changed by the addition
of certain alloys during the manufacturing
process.
FATIGUE
Fatigue is the action which takes place in a
metal after a repetition of stress. When a sample
is broken in a tensile machine, a definite load is
required to cause that fracture; however, the same
material will fail under a much smaller load if the
load is applied and removed many times. In this
way, a shaft may break after months of use even
though the load has not been changed. The pieces
of such a part will not show any sign of
deformation; but the mating areas of the section
that fractured last will usually be quite coarse
grained, while the mating areas of other sections
of the break will show signs of having rubbed
together for quite some time.
4-2
highly resistant to practically all types of corrosive
agents, others to some types of corrosive agents,
and still others to only a very few types of
corrosive substances. Some metals, however, can
be made less susceptible to corrosive agents by
either coating or alloying them with other metals
that are corrosion resistant.
HEAT RESISTANCE
Heat resistance is the property of a steel
or alloy that permits the steel or alloy to
retain its properties at elevated temperatures.
For example; red hardness in tungsten steel; high
strength for chromium molybdenum steel;
nondeforming qualities for austenitic stainless
steel; malleability for forging steels. Tungsten steel
(which even when red hot can be used to cut other
metals) and chromium molybdenum steel (which
is used for piping and valves in high temperature,
high-pressure steam systems) are examples of heat
resistant metals.
WELDABILITY
Weldability refers to the relative ease with
which a metal can be welded. The weldability of
a metal part depends on many different factors.
The basic factor is the chemical composition of
the elements that were added during the metal's
manufacture. A steel with a low carbon content
will be much easier to weld than a metal with a
high carbon content. A low alloy steel that has
a low hardenability value will lend itself more
readily to welding than one with a high
hardenability value. The welding procedure,
such as gas or arc welding, also must be
considered. The design of the part, its thickness,
surface condition, prior heat treatments, and
the method of fabrication of the metal also
affect the weldability. Charts are available
that provide guidelines concerning the weldability
of a metal and the recommended welding
procedure. The weldability of a metal should be
considered an integral part of planning a job that
requires the manufacture or repair of equipment
components if any metal buildup or weld joint
is involved.
IU.I.IA V/J.
used in machine shops. The machinability of each
metal is given as a percentage of 100, with Bl 1 12,
a resulphurized, free-machining steel, used as a
basis for comparison. The higher rated metals can
be cut using a higher cutting speed or surface feet
per minute than those with lower ratings.
There are several factors that affect the
machinability of a metal: a variation in the
amount or type of alloying element, the method
used by the manufacturer to form the metal bar
(physical condition), any heat treatment which has
changed the hardness, the type of cutting tool used
(high-speed steel or carbide) and whether or not
a cutting fluid is used. Information concerning
some of these factors will be discussed later in this
chapter and in chapter 8. Details of the AISI and
SAE designations used in the chart are explained
later in this chapter.
METALS
Metals are divided into two general types —
ferrous and nonferrous. Ferrous metals are those
whose major element is iron. Iron is the basis for
all steels. Nonferrous metals are those whose
major element is not iron, but they may contain
a small amount of iron as an impurity.
FERROUS METALS
Iron ore, the basis of all ferrous metals, is
converted to metal (pig iron) in a blast furnace.
Alloying elements can be added later to the pig
iron to obtain a wide variety of metals with
different characteristics. The characteristics of
metal can be further changed and improved by
heat treatment and by hot or cold working.
Pig Iron
The product of the blast furnace is called pig
iron. In early smelting practice, the arrangement
of the sand molds into which the molten crude
iron was drawn resembled groups of nursing pigs,
hence the name.
4-3
Table 4-1.— Machinability Rating
SAE-AISI BHN Machinability
Numbers %
Plain Carbon Steels
SAE-AISI
Numbers
BHN
B-1006 147
78
B-1010 147
78
C-1008 175
66
C-1010 172
65
C-1015 160
72
C-1016 148
78
C-1017 163
72
C-1019 146
78
C-1020 162
72
C-1022 147
78
C-1023 154
75
C-1025 162
72
C-1030 164
70
C-1035 162
70
C-1040 179
64
C-1043 178
64
C-1045 199
60
C-1046 203
57
C-1050 210
55
C-1054 217
53
C-1055 221
52
C-1059 222
52
C-1060 223
51
C-1064 224
50
C-1065 229
50
C-1069 231
48
C-1070 230
49
C-1075 238
48
C-1080 271
42
C-1085 269
42
C-1090 273
42
C-1095 274
42
Resulphurlzed Carbon Steels
Bessemer FCC
C-1106 150
79
C-1108 149
80
C-1109 152
81
C-1110 148
83
B-llll 131
94
B-1112 122
100
B-1113 101
132
C-1113 120
100
C-1115 150
81
C-1116 139
94
C-1118 139
91
C-1119 120
100
C-1125 152
81
C-1126 150
81
C-1137 169
72
C-1138 164
75
C-1140 171
72
C-1146 167
76
C-1151 180
70
Manganese Steels
Mn 1.75%
1320 210
57
1321 212
59
NE 1330 210
60
1335 211
60
NE 1340 216
57
Nickel Steels
NI 3.50%
2317 185
66
2330 220
55
2335 242
51
2340 210
57
2345 231
51
Nickel Steels
NI 5. 00*
2512 210
2515 212
NE 2517 215
Machinability
%
SAE-AISI BHN Machinability
Numbers %
Nickel -Chrome Steels
NI 1.25*
Cr 0.655! or 0.80*
3115
3120
3130
3135
3140
3145
3150
191
190
213
225
282
192
201
66
66
57
53
44
64
60
Nickel -Chrome Steels
NI 3. SOX Cr 1.55%
E 3310
E 3316
241
250
Molybdenum Steels
Mo 0.25%
4017
4023
4024
4027
4028
4032
4037
4042
4047
4053
4063
185
182
182
212
191
184
189
198
204
261
153
Chrome-Moly Steels
Cr 0.95% Mo 0.20%
4130
E 4132
4135
4137
E 4137
4140
4142
4145
4147
4150
181
190
189
209
205
212
227
221
219
242
78
78
78
66
72
76
73
70
65
53
52
72
72
70
65
67
62
59
60
60
59
Nickel -Chrome-Moly Steels
NI 1.80% Cr 0.50% Mo 0.25%
4317
215
60
4320
201
63
E 4337
243
54
4340
240
57
E 4340
239
57
Nickel -Moly
Steels
NI 1.80% Mo
0.25%
4608
242
58
E 4617
201
66
4615
192
66
4620
198
64
X 4620
193
66
E 4620
202
64
4621
199
66
4640
198
66
E 4640
245
51
Nickel -Moly Steels
NI '3.50% Mo 0.25%
4812 249
4815 256
4817 251
4820 248
51
51
51
53
Chrome Steels
Cr 0.30% or 0.60%
5045 188
5046 186
70
70
Chrome Steels
Cr 0.80%, 0.95% or 1.05%
5120
5130
5132
5135
5140
5145
5147
5150
5152
187
241
189
188
192
210
211
215
216
75
57
72
72
70
65
66
64
64
Carbon-Chrome Steels
C 1.00%
Cr 0.50%, 1.00% or 1.45%
E 50100 211
E 51100 221
E 52100 220
45
40
40
Chrome-Vanadium Steels
Cr 0.85% or 0.95%
V 0.10% or 0.15%
6102
6145
6150
6152
202
182
192
195
57
66
60
60
Nickel -Chrome-Moly Steels
N1 0.55% Cr 0.50% Mo 0.20%
8617
182
66
8620
183
66
8622
185
65
8625
189
62
8627
188
64
8630
161
72
8635
165
70
8637
164
70
8640
172
66
8642
177
65
8645
182
64
8647
194
60
8650
195
60
8653
203
56
8655
205
57
8660
215
54
Nickel -Chrome-Moly Steels
NI 0.55% Cr 0.50% Mo 0.259%
8719
8720
8735
8740
8742
8747
8750
175
178
171
183
185
192
194
67
66
70
66
64
60
60
Manganese-Silicon Steels
Mn 0.55% SI 2.00%
9255
9260
9262
122
238
235
54
51
49
SAE-AISI BHN Machinability
Numbers %
Nickel -Chrome-Moly Steels
N1 3.25% Cr 1.20* Mo 0.12*
E 9310
E 9315
E9317
243
238
239
48
50
49
Manganese-Nickel -Chrome-Moly
Steels
Mn 1.00* N1 0.45*
Cr 0.40% Mo 0.12*
9437
9440
9442
9445
182
183
179
181
66
66
66
64
Nickel -Chrome-Moly Steels
N1 0.55* Cr 0.17% Mo 0.20*
9747
9763
187
215
64
54
Nickel -Chrome-Moly Steels
N1 1.00* Cr 0.80% Mo 0.25*
9840
9845
9850
232
238
242
Stainless Steels
302
303*
304
308+
309+
314+
317+
321
330*
347
403
410
416*
420
420 F*
430
430 F**
440
440 A
440 B
440 C
440 F*
50
49
45
45
60
45
27
28
32
29
36
27
36
39
54
72
57
79
54
91
37
45
42
40
59
+ Poorest Machining Properties.
* Fairly Good Machlnlng-Contaln
Sulfur and Selenium.'
** Best Machining Properties.
Cast Iron
Soft 130
Medium 168
Hard 243
81
64
47
Malleable Iron
Malleable
Iron 115
Malleable
Iron 135
106
80
Cast Steel
Cast Steel 121
Cast Steel 219
Cast Steel 245
85
50
44
amounts of impurities, is seldom used directly as
an industrial manufacturing material. It is,
however, used as the basic ingredient in making
cast iron, wrought iron, and steel.
Cast Iron
Cast iron is produced by resmelting a charge
of pig iron and scrap iron in a furnace and
removing some of the impurities from the molten
metal by using various fluxing agents. There are
many grades of cast iron, based on strength and
hardness. The quality depends upon the extent of
refining, the amount of scrap iron used, and the
method of casting and cooling the molten metal
when it is drawn from the furnace. The higher
the proportion of scrap iron, the lower the grade
of cast iron. Cast iron has some degree of
corrosion resistance and great compressive
strength, but at best is brittle and has a
comparatively low tensile strength. Therefore, it
has very limited use in marine service.
Wrought Iron
Wrought iron is a highly refined pure iron
which has uniformly distributed particles of slag
in its composition. Wrought iron is considerably
softer than cast iron and has a fibrous internal
structure, created by the rolling and squeezing
given to it when it is being made. Like cast iron,
wrought iron is fairly resistant to corrosion and
fatigue. Wrought iron, because of these
characteristics, is used extensively for low-pressure
pipe, rivets, and nails.
Plain Carbon Steels
Pig iron is converted into steel by a process
which separates and removes impurities from the
molten iron by use of various catalytic agents and
extremely high temperatures. During the refining
process, practically all of the carbon originally
present in the pig iron is burned out. In the final
stages when higher carbon alloys are desired,
measured amounts of carbon are added to the
relatively pure liquid iron to produce carbon steel
of a desired grade. The amount of carbon added
controls the mechanical properties of the finished
steel to a large extent, as will be pointed out in
succeeding paragraphs. After the steel has been
drawn from the furnace and allowed to solidify,
it may be sent either to the stockpile or to shaping
Plain steels that have small additions of sulfur
(and sometimes phosphorous) are called free
cutting steels. These steels have good machining
characteristics and are used in applications similar
to carbon steels. The addition of sulfur and
phosphorous limits their ability to be formed hot.
LOW CARBON STEEL (0.05% TO 0.30%
carbon), usually referred to as mild steel, can be
easily cut and bent and does not have great tensile
strength, as compared with other steels. Low
carbon steels which have less than 0.15% carbon
are usually more difficult to machine than steel
with a higher carbon content.
MEDIUM CARBON STEEL (0.30% TO
0.60% carbon) is considerably stronger than low
carbon steel. Heat treated machinery parts are
made of this steel.
HIGH CARBON STEEL (0.60% to 1.50%
carbon) is used for many machine parts, hand-
tools, and cutting tools, and is usually referred
to as carbon tool steel. Cutting tools of high
carbon steel should not be used when the cutting
temperature will exceed 400 °F.
Alloy Steels
The steels discussed thus far are true alloys of
iron and carbon. When other elements are added
to iron during the refining process, the resulting
metal is called alloy steel. There are many types,
classes, and grades of alloy steel.
Alloy steels usually contain several different
alloying elements, with each one contributing a
different characteristic to the metal. Alloying
elements can change the machinability, har den-
ability, weldability, corrosion resistance and the
surface appearance of the metal. Knowledge of
how each of the alloying elements affects a metal
will allow you to more readily select the best metal
for a given application and then to determine
which, if any, heat treatment process should be
used to achieve the best mechanical properties.
A few of the more common alloy steels and the
effects of certain alloying elements upon the
mechanical properties of steel are discussed briefly
in the following paragraphs.
CHROMIUM.— Chromium is added to steel
to increase hardenability, corrosion resistance,
toughness, and wear resistance. The most
4-5
is often used to manufacture parts which will
be subjected to acids and saltwater and for
such parts as ball bearings, shafts and valve stems
in applications involving high-pressure and high
temperature.
VANADIUM.— Vanadium is added in small
quantities to steel to increase tensile strength,
toughness, and wear resistance. It is most
often combined with chromium and is used for
crankshafts, axles, piston rods, springs, and other
parts where high strength and fatigue resistance
are required. Greater amounts of vanadium are
added to high-speed steel cutting tools to
prevent tempering of their cutting edges when
high temperatures are generated by the cutting
action.
NICKEL. — Nickel is added to steel to increase
corrosion resistance, strength, toughness, and
wear resistance. Nickel is used in small amounts
in the steel for armor plating of a ship due to its
resistance to cracking when penetrated. Greater
amounts of nickel are added to chromium to
produce a metal which withstands severe work-
ing conditions. Crankshafts, rear axles, and other
parts subjected to repeated shock are made from
nickel chrome steel.
MOLYBDENUM.— Molybdenum is added to
steel to increase toughness, hardenability, shock
resistance and resistance to softening at high
temperatures. Molybdenum steel is used for
transmission gears, heavy duty shafts, and
springs. Carbon molybdenum (CMo) and chrome
molybdenum (CrMo) are two alloy steels with
molybdenum added that are widely used in high
temperature piping systems in Navy ships.
Relatively large amounts of molybdenum are used
to form some of the cutting tools used in the
machine shop.
TUNGSTEN. — Tungsten is used primarily in
high-speed steel or cemented carbide cutting tools.
It is this alloy that gives the cutting tools
their hard, wear resistant and heat resistant
characteristics. Tungsten has the additional
property of being air-hardening and allows tools
to be hardened without using oil or water to cool
the tool after heating.
are included among me nonierrous metals. You
will find that these metals, and their alloys such
as brass, bronze, copper-nickel, and so on, are
used in large amounts in the construction and
maintenance of Navy ships.
Copper Alloys
Copper is a metal which lends itself to a variety
of uses. You will see it aboard ship in the form
of wire, rod, bar, sheet, plate, and pipe. As a
conductor of both heat and electricity, copper
ranks next to silver; it also offers a high resistance
to saltwater corrosion.
Copper becomes hard when worked but can
be softened easily by being heated to a cherry red
and then cooled. Its strength, however, decreases
rapidly at temperatures above 400 °F.
Pure copper is normally used in molded or
shaped forms when machining is not required.
Copper for normal shipboard use generally is
alloyed with an element that provides good
machinability characteristics.
BRASS. — Brass is an alloy of copper and zinc.
Complex brasses contain additional alloying
agents, such as aluminum, lead, iron, manganese,
or phosphorus. Naval brass is a true brass
containing about 60% copper, 39% zinc, and 1%
tin added for corrosion resistance. It is used for
propeller shafts, valve stems, and marine
hardware.
Brass used by the Navy is classified as either
leaded or unleaded, meaning that small amounts
of lead may or may not be used in the copper-
zinc mixture. The addition of lead improves the
machinability of brass.
BRONZE.— Bronze is primarily an alloy of
copper and tin, although several other alloying
elements are added to produce special bronze
alloys. Aluminum, nickel, phosphorous, silicon
and manganese are the most widely used alloy-
ing metals. Some of the more common alloys,
their chemical analyses and some general uses are
listed in the following paragraphs to give you an
idea of how basic bronze is changed.
GUN METAL.— Gun metal, a copper-tin
alloy, contains approximately 86%-89% copper
(Cu), 7 l/2%-9% tin (Sn), 3%-5% zinc Zn),
0.3% lead (Pb), 0.15% iron (Fe), 0.05%
4-6
alloy, the term "copper-tin" is used only to
designate the major alloying elements. Gun metal
bronze is used for bearings, bushings, pump
bodies, valves, impellers, and gears.
ALUMINUM BRONZE.— Aluminum bronze
is actually a copper-aluminum alloy that does not
contain any tin. It is made of 86% copper,
8 l/2%-9% aluminum (Al), 2 l/2%-4% iron
and 1% of miscellaneous alloys. It is used for
valve seats and stems, bearings, gears, propellers,
and marine hardware.
COPPER-NICKEL.— Copper-nickel alloy is
used extensively aboard ship because of its high
resistance to the corrosive effects of saltwater. It
is used in piping and tubing. In sheet form it is
used to construct small storage tanks and hot
water reservoirs. Copper-nickel alloy may contain
either 70% copper and 30% nickel or 90%
copper and 10% nickel. It has the general working
characteristics of copper but must be worked cold.
These and the many other copper alloys
commonly used by the Navy have certain physical
and mechanical properties (imparted by the
various alloying elements) which cause one alloy
to be more effective than another for a given
application. Remember this if you go to the metal
storage rack and select a bronze-looking metal
without regard to the specific type. The part you
make may fail prematurely in spite of the skill and
attention to detail that you use to machine it.
Nickel Alloys
Nickel is a hard, malleable, and ductile metal.
It is resistant to corrosion and therefore often is
used as a coating on other metals. Combined with
other metals, it makes a tough strong alloy.
NICKEL-COPPER, —Nickel-copper alloys
are stronger and harder than either nickel or
copper. They have high resistance to corrosion
and are strong enough to be substituted for
steel when corrosion resistance is of primary
importance. Probably the best known nickel-
copper alloy is Monel (the trademark for a
product of the International Nickel Company).
Monel contains approximately 65% nickel, 30%
copper, and a small percentage of iron,
manganese, silicon, and cobalt. Monel is used for
pump shafts and internal parts, valve seats and
K-MONEL.— K-Monel, also a trademark, is
essentially the same as Monel except that it con-
tains about 3% aluminum and is harder and
stronger than other grades of Monel. K-Monel
stock is very difficult to machine; however, you
can improve the metal's machinability con-
siderably by annealing it immediately before
machining. K-Monel is used for the shaft sleeves
on many pumps because of its resistance to the
heating and rubbing action of the packing.
There are several other nickel alloys that you
may find used in Navy equipment. INCONEL,
INCONEL-X; H, S, R, and KR MONEL are a
few of the more common alloys.
Aluminum Alloys
Aluminum is being used more and more in
ship construction because of light weight, easy
workability, good appearance, and other desirable
properties. Pure aluminum is soft and not very
strong. When alloying elements such as
magnesium, copper, nickel, and silicon are added,
however, a much stronger metal is produced.
Each of the aluminum alloys has properties
developed specifically for a certain type of
application. The hard aluminum alloys are easier
to machine than the soft alloys and often are equal
to low carbon steel in strength.
Zinc Alloys
Zinc is a comparatively soft, yet somewhat
brittle metal. Its tensile strength is only slightly
greater than that of aluminum. Because of its
resistance to corrosion, zinc is used as a
protective coating for less corrosion resistant
metals, principally iron and steel. There are
three methods of applying a zinc coating:
(1) electroplating in a zinc-acid solution; (2) hot
dipping, in which the metal is dipped into a bath
of molten zinc; (3) sherardizing, in which zinc is
reduced to a gaseous state and deposited on the
base metal.
Pure zinc, having a strong anodic potential,
is used to protect the hulls of steel ships against
electrolysis between dissimilar metals caused by
electric currents set up by saltwater. Zinc plates
bolted on the hull, especially near the propellers,
decompose quite rapidly, but in doing so, greatly
reduce localized pitting of the hull steel.
4-7
parts used in electrical appliances. This alloy is
often mistakenly referred to as the copper and
lead alloy called "pot-metal."
Tin Alloys
Pure tin is seldom used except as a coating for
food containers, sheet steel and in some applica-
tions involving electroplating to build up the metal
surfaces of some equipment (motor end bell bear-
ing housings). Several different grades of tin
solder are made by adding either lead or
antimony. One of the primary uses of tin by the
Navy is to make bearing babbitt. About 5%
copper and 10% antimony are added to 85% tin
to make this alloy. There are various grades of
babbitt used in bearings and each grade may have
additional alloying elements added to give the
babbitt the properties required.
Lead Alloys
Lead is probably the heaviest metal with
which you will work. A cubic foot of it weighs
approximately 700 pounds. It has a grayish color
and is amazingly pliable. It is obtainable in sheets
and pigs. The sheets normally are wound around
a rod and pieces can be cut off quite easily. One
of the most common uses of lead is as an alloying
element in soft solder.
DESIGNATIONS AND MARKINGS
OF METALS
You must have knowledge of the standard
designations of metals and the systems of marking
metals used by the Navy and industry so you can
select the proper material for a specific job. There
are several different numbering systems currently
in use by different trade associations, societies,
and producers of metals and alloys that you may
find on blueprints and specifications of equipment
that you will be required to repair. You may find
several different designations which refer to a
metal with the same chemical composition, or
several identical designations which refer to metals
with different chemical compositions. A book
published by the Society of Automotive
Engineers, Inc. (SAE), entitled Unified Number-
ing System of Metals and Alloys and Cross Index
of Chemically Similar Specifications, provides a
of the numbering systems that you may need to
identify are:
Aluminum Association (AA)
American Iron and Steel Institute (AISI)
Society of Automotive Engineers (SAE)
Aerospace Materials Specifications (AMS)
American National Standards Institute (ANSI)
American Society of Mechanical Engineers
(ASME)
American Society for Testing and Materials
(ASTM)
Copper Development Association (CD A)
Military Specification (MIL-S-XXXX, MIL-
N-XXXX)
Federal Specification (QQ-N-XX, QQ-S-
XXX)
The Unified Numbering System, which is
presented in the book, lists all the different
designations for a metal and assigns one number
that identifies the metal. This system of number-
ing covers only the composition of the metal and
not the condition, quality or form of the metal.
Use of the Unified Numbering System by the
various metal producers is voluntary and it could
be some time before any widespread uses is
evident. (Another publication that will be useful
is NAVSEA 0900-LP-038-8010, Ship Metallic
Material Comparison and Use Guide.)
The two major systems used for iron and steel
are those of the Society of Automotive Engineers
(SAE) and the American Iron and Steel Institute
(AISI). The Aluminum Association method is
used for aluminum; other nonferrous metals are
designated by the percentage and types of
elements in their composition. The Navy uses
these methods of designation as a basis for
marking metals so they can be identified readily.
FERROUS METAL DESIGNATIONS
You should be familiar with the SAE and AISI
systems of steel classifications. These systems,
4-8
the steel. The major difference between the two
systems is that the AISI system normally uses a
letter before the numbers to show the process used
in making the steel. The letters used are as follows:
B — Acid Bessemer carbon steel; C — Basic open-
hearth or basic electric furnace carbon steel; and
E — Electric furnace alloy steel. Example:
SAE
AISI
10
10
20
20
1 t t
Basic Open
Hearth Carbon
Steel
Plain Carbon
Steel
Carbon
Content
A description of these numbering systems is
provided in the following paragraphs.
The first digit normally indicates the basic type
of steel. The different groups are designated as
follows:
1 — Carbon steel
2 — Nickel steel
3 — Nickel-chromium steel
4 — Molybdenum steel
5 — Chromium steel
6 — Chromium-vanadium steel
8 — Nickel-chrome-molybdenum steel
9 — Silicon-manganese steel
The second digit normally indicates a series
within the group. The term "series" usually refers
to the percentage of the major alloying element.
Sometimes the second digit gives the actual
percentage of the chief alloying element; in other
cases, the second digit may indicate the relative
position of the series in a group without reference
to the actual percentage.
The third, fourth, and fifth digits indicate the
average carbon content of the steel. The carbon
content is expressed in points; for example:
2 points = 0.02%, 20 points = 0.20%, and
100 points = 1.00%. To make the various steels
fit into this classification, it is sometimes necessary
to vary the system slightly. However, you can
(1) SAE 1035: The first digit is 1, so this is
a carbon steel. The second digit, 0, indicates that
there is no other important alloying element;
hence, this is a PLAIN carbon steel. The next
two digits, 35, indicate that the AVERAGE
percentage of carbon in steels of this series is
0.35%. There are also small amounts of other
elements in this steel, such as manganese,
phosphorus, and sulfur.
(2) SAE 1146: This is a resulfurized carbon
steel (often called free cutting steel). The first digit
indicates a carbon steel with an average
manganese content of 1.00% and an average
carbon content of 0.46%. The amount of sulfur
added to this steel ranges from 0.08% to 0.13%.
These two elements, (manganese and sulfur) in
this great a quantity make this series of steel one
of the most easily machined steels available.
(3) SAE 4017: The first digit, 4, indicates that
this is a molybdenum steel. The second digit, 0,
indicates that there is no other equally important
alloying element; hence, this is a plain
molybdenum steel. The last two digits, 17, indicate
that the average carbon content is 0.17%.
Other series within the molybdenum steel
group are indicated by the second digit. If the
second digit is 1, the steel is chromium-
molybdenum steel; if the second digit is 3, the steel
is a nickel-chromium-molybdenum steel; if the
second digit is 6, the steel is a nickel-molybdenum
steel. In such cases, the second digit does not
indicate the actual percentage of the alloying
elements, other than molybdenum.
(4) SAE 51100: This number indicates a
chromium steel (first digit) with approximately
1.0% chromium (second digit) and an average
carbon content of 1.00% (last three digits). The
actual chromium content of SAE 51 100 steels may
vary from 0.95% to 1.10%.
(5) SAE 52100: This number indicates a
chromium steel (first digit) of a higher alloy series
(second digit) than the SAE 51100 steel just
described. Note, however, that in this case the
second digit, 2, merely identifies the series but
does NOT indicate the percentage of chromium.
A 52100 steel will actually have from 1.30% to
1.60% chromium with an average carbon content
of 1.00% (last three digits).
4-9
The current commonly used tool steels are
classified by the American Iron and Steel Institute
into seven major groups and each commonly
accepted group or subgroup is assigned an
alphabetical letter. Methods of quenching,
applications, special characteristics, and steels for
particular industries are considered in this type
classification of tool steels as follows:
Group Symbol and type
Water hardening ---- W
Shock resisting ...... S
!O— Oil hardening
A— Medium alloy
D — High carbon-high-chromium
Hot work .......... H— (HI to H19 incl. chromium
base, H20 to H39 incl.
tungsten base, H40 to H59
incl. Molybdenum base)
High-speed
( Jr-
[ M—
base
Molybdenum base
Special purpose ..... (L-Low alloy
I F
Carbon tungsten
Mold steels ......... P
Navy blueprints and the drawings of equip-
ment furnished in the manufacturers' technical
manuals usually specify materials by Federal or
Military specification numbers. For example, the
coupling on a particular oil burner is identified
as "cast steel, class B, MIL-S-15083." This
particular cast steel does not have any other
designation under the various other metal
identification systems as there are no chemically
similar castings. On the other hand, a valve stem
which has a designated material of "MIL-S-862
class 410" (a chromium stainless steel) may be
cross referenced to several other systems. Some
of the chemically similar designations for "MIL-
S-862 class 410" are as follows:
SAE = J405 (51410)
Federal Spec. = QQ-S-763(410)
AISI = 410
ASTM = A176(410)
ASM = 5504
ASME = SA194
NONFERROUS METAL
DESIGNATIONS
Nonferrous metals are generally grouped
according to the alloying elements. Examples of
these groups are brass, bronze, copper-nickel, and
nickel-copper. Specific designations of an alloy
are described by the amounts and chemical
symbols of the alloying elements. For example,
a copper-nickel alloy might be described as
copper-nickel, 70 Cu-30 Ni. The 70 Cu represents
the percentage of copper, and the 30 Ni represents
the percentage of nickel.
Common alloying elements and their symbols
are:
Aluminum Al
Carbon C
Chromium Cr
Cobalt Co
Copper Cu
Iron Fe
Lead Pb
Manganese Mn
Molybdenum Mo
Nickel Ni
Phosphorus P
Silicon Si
Sulphur S
Tin Sn
Titanium Ti
Tungsten W
Vanadium V
Zinc Zn
In addition to the type of designations
previously described, a trade name (such as Monel
or Inconel) is sometimes used to designate certain
alloys.
system described for steels. The numerals
assigned, with their meaning for the first digits
of this system, are:
Aluminum (99.00% minimum Ixxx
and greater)
Major Alloying Element
Copper 2xxx
Manganese 3xxx
Silicon 4xxx
Magnesium 5xxx
Magnesium and silicon 6xxx
Zinc 7xxx
Other element 8xxx
The first digit indicates the major alloying element
and the second digit indicates alloy modifications
or impurity limits. The last two digits identify the
particular alloy or indicate the aluminum purity.
In the Ixxx group for 99.00% minimum
aluminum, the last two digits indicate the
minimum aluminum percentage to the right of the
decimal point. The second digit indicates
modifications in impurity limits. If the second
digit in the designation is zero, there is no
special control on individual impurities. Digits
1 through 9, indicate some special control of one
or more individual impurities. As an example,
1030 indicates a 99.30% minimum aluminum
without special control on individual impurities,
and 1 130, 1230, 1330, and so on indicate the same
purity with special control of one or more
individual impurities.
Designations 2 through 8 are aluminum alloys.
In the 2xxx through 8xxx alloy groups, the second
digit in the designation indicates any alloy
modification. The last two of the four digits in
the designation have no special significance but
serve only to identify the different alloys in the
group.
In addition to the four-digit alloy designation,
a letter or letter/number is included as a temper
designation. The temper designation follows the
four-digit alloy number and is separated from it
solution neat treated,
then artificially aged; T6 is the temper designa-
tion. The aluminum alloy temper designations and
their meanings are:
W Fabricated
O Annealed recrystallized (wrought only)
H Strain hardened (wrought only)
HI, plus one or more digits, strain
hardened only
H2, plus one or more digits, strain
hardened then partially annealed
H3, plus one or more digits, strain
hardened then stabilized
W Solution heat treated— unstable temper
T Treated to produce stable tempers other
than F, O, or H
T2 Annealed (cast only)
T3 Solution heat treated, then cold
worked
T4 Solution heat treated and naturally
aged to a substantially stable condi-
tion
T5 Artificially aged only
T6 Solution heat treated, then artifi-
cially aged
T7 Solution heat treated, then stabilized
T8 Solution heat treated, cold worked,
then artificially aged
T9 Solution heat treated, artificially
aged, then cold worked
T10 Artificially aged, then cold worked
Note that some temper designations apply only
to wrought products, others to cast products, but
most apply to both. A second digit may appear
to the right of the mechanical treatment. This
second digit indicates the degree of hardening;
2 is 1/4 hard, 4 is 1/2 hard, 6 is 3/4 hard, and
8 is full hard. For example, the alloy 5456-H32
is an aluminum/magnesium alloy, strain hardened
then stabilized, and 1/4 hard.
STANDARD MARKING OF METALS
Metals used by the Navy are usually marked
with the continuous identification marking
4-11
system. This system will be explained in the
following paragraphs. Do not depend only on the
markings to ensure that you are using the correct
metal. Often, the markings provided by the metal
producer will be worn off or cut off and you are
left with a piece of metal that you are not sure
about. Additional systems, such as separate
storage areas or racks for different types of metal
or etching on the metal with an electric etcher
could save you time later on.
CONTINUOUS IDENTIFICATION
MARKING
The continuous identification marking system,
which is described in Federal Standards is a means
for positive identification of metal products even
after some portions have been used. In the
continuous identification marking system, the
markings appear at intervals of not more than 3
feet. Thus, if you cut off a piece of bar stock,
the remaining portions will still carry the proper
identification. Some metals, such as small tubing,
coils of wire, and small bar stock cannot be
marked readily by this method. On these items,
tags with the required marking information are
fastened to the metal.
The continuous identification marking is
actually "printed" on the metals with a heavy ink
that is almost like a paint.
The manufacturer is required to make these
markings on materials before delivery. The mark-
ing intervals for various shapes and forms, are
specified in the Federal Standard previously
mentioned. Figure 4-1 shows the normal spacing
and layout.
For metal products, the continuous identifica-
tion marking must include (1) the producer's name
or registered trademark and (2) the commercial
designation of the material. In nonferrous metals
the government specification for the material is
often used. The producer's name or trademark
shown is that of the producer who performs the
final processing or finishing operation before the
material is marketed. The commercial designation
includes (1) a material designation such as an SAE
BARS
PRODUCERS NAME
OR TRADEMARK 1035 AQ NORM HT 69321
HEAT OR PROCESSING NUMBER
(NORMALLY USED BY MANUFACTURER)
PHYSICAL CONDITION
COMMERCIAL DESIGNATION
SHEET
— 8' —
PRODUCER S NAME
OR TRADEMARK MIL-S-7809 HT6875
PRODUCERS NAME
OR TRADEMARK MIL-S-7809 HT6875
PRODUCER S NAME
OR TRADEMARK MIL-S-7809 HT6875
IN SOME CASES, COMMERCIAL DESIGNATIONS
ARE USED INSTEAD OF SPECIFICATIONS
designation — that is, the designation of temper
or other physical condition approved by a
nationally recognized technical society or
industrial association such as the American
Iron and Steel Institute. Some of the physical
conditions and quality designations for various
metal products are listed below:
CR cold rolled
CD cold drawn
HR hot rolled
AQ aircraft quality
CQ commercial quality
1/4H quarter hard
1/2H half hard
H hard
HTQ high tensile quality
AR as rolled
HT heat treated
G ground
lead, zinc, and aluminum have certain identifying
characteristics— surface appearance and weight-
by which persons who work with or handle these
materials readily distinguish one from another.
There are, however, a number of related alloys
which resemble each other and their base metal
so closely that they defy accurate identification
by simple means.
There are other means of rapid identification
of metals. These methods, however, do not
provide positive identification and should not be
used in critical situations where a specific metal
is required. Some of the methods that will be
discussed here are magnet tests, chip tests, file
tests, acid reaction tests, and spark tests. The latter
two are the most commonly used by the Navy.
Table 4-2 contains information related to surface
appearance, magnetic reaction, lathe chip test,
and file test. The acid test and the spark test are
discussed in more detail in the next sections. When
you perform these tests, you should have a known
sample of the desired material and make a
Table 4-2.— Rapid Identification of Metals
Metal
Surface Appearance
or markings
Reaction to a
Magnet
Lathe Chip test
Color of freshly
filed surface
White cast Iron
Dull gray
Strong
Short, crumbly chips
Silvery white
Gray cast Iron
Dull gray
Strong
Short, crumbly chips
Light silvery gray
Aluminum
L/lght gray to white
dull or brilliant
None
Easily cut, smooth
ong chips
White
Brass
Yellow to green or
brown
None
Smooth long chips
slightly brittle
Reddish yellow to
yellowish white
Bronze
Red to brown
•tone
Short crumbly
chips
Reddish yellow to
yellowish white
Copper
Smooth; red brown
to green (oxides)
None
Smooth long pliable
chips
Bright copper
color
Copper-nickel
Smooth; gray to
yellow or yellowish
green
Mono
Smooth, continuous
chips
Bright silvery
white
Lead
White to gray;
smooth, velvety-
None
Cut by knife, any
shape chip
White
Nickel
Dark gray; smooth;
sometimes green
(oxides)
Medium
Cuts easily, smooth
continuous chip
Bright silvery
white
Nickel-copper
Dark gray, smooth
Very slight
Continuous chip;
tough to cut
Light gray
Plain carbon steel
Dark gray; may be
rusty
Strong
Varies depending
upon carbon content
Bright silvery
gray
Stainless steel (18-8)
(25-20) "Note 1 below"
Dark gray, dull to
brilliant; usually
clean
None (faint If
severely cold
worked)
Varies depending
upon heat treatment
Bright silvery
gray
Zinc
Whitish blue, may
be mottled
None
Easily cut; long
stringy chips
White
l' Stainless steels that have less than 26 percent alloying elements react to magnet.
4-13
comparison. You will also need good lighting, a
strong permanent magnet, and access to a lathe.
A word of caution: when you perform these tests,
DO NOT be satisfied with the results of only one
test. Use as many tests as possible so you can
increase the chances of making an accurate
identification.
SPARK TEST
Spark testing is the identification of a metal
by observing the color, size, and shape of the
spark stream given off when the metal is held
against a grinding wheel. This method of
identification is adequate for most machine shop
purposes. When the exact composition of a metal
must be known, a chemical analysis must be
made. Identification of metals by the spark test
method requires considerable experience. To gain
this experience, you will need to practice by
comparing the spark stream of unknown
specimens with that of sample specimens of
known composition. Many shops maintain
specimens of known composition for comparison
with unknown samples.
Proper lighting conditions are essential for
good spark testing practice. You should perform
the test in an area where there is enough light, but
should avoid harsh or glaring light. In many ships
you may find that a spark test cabinet has been
erected. Generally, these cabinets consist of a box
mounted on the top of a workbench and have a
dark painted interior. A bench grinder is mounted
inside the cabinet. Test specimens of known
composition are contained in shelves at the end
of the cabinet. Where possible, the testing area
should be away from heavy drafts of air, because
air drafts can change the tail of the spark stream
and may result in improper identification of the
sample.
The speed of the grinding wheel and the
pressure you exert on the samples greatly affect
the spark test. The faster the speed of the wheel,
the larger and longer the spark stream will be.
(Generally speaking, a suitable grinding wheel for
spark testing is an 8-inch wheel turning at 3600
rpm. This provides a surface speed of 7,537 feet
per minute.) The pressure of the piece against the
wheel has a similar effect: the more pressure
applied to the test piece, the larger and longer the
spark stream will be. Hold the test piece lightly
but firmly against the wheel with just enough
pressure to prevent the piece from bouncing.
Remember, you must apply the same amount of
pressure to the test specimen as to the sample
are testing.
The grain size of the grinding wheel sh<
be from 30 to 60 grains. Be sure to keep the \\
clean at all times. A wheel loaded with part
of metal will give off a spark stream of the
of metal in the wheel mixed with the spark sti
of the metal being tested. This will ten<
confuse you and prevent you from proi
identifying the metal. Dress the wheel before
begin spark testing and before each new tei
a different metal.
The spark test is made by holding a sai
of the material against a grinding wheel.
sparks given off, or the lack of sparks, assi
identifying the metal. The length of the s;
stream, its color, and the type of sparks an
features for which you should look. Then
four fundamental spark forms produced wh
sample of metal is held against a power grir
(See fig. 4-2.) Part A shows shafts, b
breaks, and arrows. The arrow or spearhe;
characteristic of molybdenum, a metallic elei
of the chromium group which resembles iron
is used for forming steel-like alloys with car
Figure 4-2.— Fundamental spark forms.
shows shafts and sprigs or sparklers which indicate
a high carbon content. Part C shows shafts, forks,
and sprigs which indicate a medium carbon
content. Part D shows shafts and forks which
indicate a low carbon content.
The greater the amount of carbon present in
a steel, the greater the intensity of bursting that
will take place in the spark stream. To under-
stand the cause of the bursts, remember that while
the spark is glowing and in contact with the
oxygen of the air, the carbon present in the
particle is burned to carbon dioxide (CO2). As the
solid carbon combines with oxygen to form COa
in the gaseous state, the increase in volume builds
up a pressure that is relieved by an explosion of
the particles. If you examine the small steel
particles under a microscope when they are cold,
you will see that they are hollow spheres with one
end completely blown away.
Steels having the same carbon content but
different alloying elements are not always easily
identified because alloying elements affect the
carrier lines, the bursts, or the forms of
characteristic bursts in the spark picture. The
effect of the alloying element may retard or
accelerate the carbon spark or make the carrier
line lighter or darker in color. Molybdenum, for
example, appears as a detached, orange-colored,
spearhead on the end of the carrier line. Nickel
seems to suppress the effect of the carbon burst.
But the nickel spark can be identified by tiny
blocks of brilliant white light. Silicon suppresses
the carbon burst even more than nickel. When
silicon is present, the carrier line usually ends
abruptly in a flash of white light.
To make the spark test, hold the piece of metal
on the wheel so that you throw the spark stream
about 12 inches at a right angle to your line of
vision. You will need to spend a little time to
discover at just what pressure you must hold the
sample to get a stream of this length without
reducing the speed of the grinder. Do not press
too hard because the pressure will increase the
temperature of the spark stream and the burst.
It will also give the appearance of a higher carbon
content than that of the metal actually being
tested. After practicing to get the feel of correct
pressure on the wheel until you are sure you have
it, select a couple of samples of metal with widely
varying characteristics; for example, low-carbon
careful to strike the same portion of the wheel
with each piece. With your eyes focused at a point
about one-third the distance from the tail end of
the stream of sparks, watching only those sparks
which cross the line of vision, you will find that
after a little while you will form a mental image
of the individual spark. After you can fix the
spark image in mind, you are ready to examine
the whole spark picture.
Notice that the spark stream is long (about 70
inches normally) and that the volume is
moderately large in low-carbon steel, while in high
carbon steel the stream is shorter (about 55 inches)
and large in volume. The few sparklers which may
occur at any place in low carbon steel are forked,
while in high carbon steel the sparklers are small
and repeating and some of the shafts may be
forked. Both will produce a white spark stream.
White cast iron produces a spark stream
approximately 20 inches long (see fig. 4-3). The
volume of sparks is small with many small,
repeating sparklers. The color of the spark stream
close to the wheel is red, while the outer end of
the stream is straw-colored.
Gray cast iron produces a stream of sparks
about 25 inches long. It is small in volume with
fewer sparklers than in the stream from white cast
iron. The sparklers are small and repeating. Part
of the stream near the grinding wheel is red, and
the outer end of the stream is straw-colored.
The malleable iron spark test will produce a
spark stream about 30 inches long. It is of
moderate volume with many small, repeating
sparklers toward the end of the stream. The
entire stream is straw-colored.
The wrought iron spark test produces a spark
stream about 65 inches long. The stream has a
large volume with few sparklers. The sparklers
show up toward the end of the stream and are
forked. The stream next to the grinding wheel is
straw-colored, while the outer end of the stream
is a bright red.
Stainless steel produces a spark stream
approximately 50 inches long, of moderate
volume, and with few sparklers. The sparklers are
forked. The stream next to the wheel is straw-
colored, while at the end it is white.
4-15
LOW CARBON AND CAST STEEL
MALLEABLE IRON
GRAY CAST IRON
WROUGHT IRON
HIGH CARBON STEEL
STAINLESS STEEL
WHITE CAST IRON NICKEL
Figure 4-3.— Spark pictures formed by common metals.
11.37
Nickel produces a spark stream only about 10
inches long. It is small in volume and orange in
color. The sparks form wavy streaks with no
sparklers.
Monel forms a spark stream almost identical
to that of nickel and must be identified by other
means. Copper, brass, bronze, and lead form no
sparks on the grinding wheel, but they are easily
identified by other means, such as color,
appearance, and chip tests.
You will find the spark tests easy and
convenient to make. They require no special
equipment and are adaptable to most any
situation. Here again, experience is the best
teacher.
ACID TEST
The nitric acid test is the most commonly used
test for metal identification in the Navy today;
it is used only in noncritical situations. For rapid
identification of metal, the nitric acid test is one
of the easiest tests to use and requires no special
training in chemistry to perform. It is most helpful
in distinguishing between stainless steel, Monel,
copper-nickel, and carbon steels. Whenever you
perform an acid test, be sure to observe the
following safety precautions.
• NEVER open more than one container of
acid at one time.
• In mixing, always pour acid slowly into
water. NEVER pour water into acid because an
explosion is likely to occur.
• If you spill any acid, dilute it with plenty
of water to weaken it so it can be safely swabbed
up and disposed of.
4-16
Then wash with a solution of borax and water.
• Wear CLEAR-LENS safety goggles to
ensure the detection of the reaction of metal to
an acid test which may be evidenced by a color
change, the formation of a deposit, or the
development of a spot.
• Conduct tests in a well-ventilated area.
To perform the nitric acid test, place one or
two drops of concentrated (full strength) nitric
acid on a metal surface that has been cleaned by
grinding or filing. Observe the resulting reaction
(if any) for about 2 minutes. Then, add three or
four drops of water, one drop at a time, and
continue observing the reaction. If there is no
reaction at all, the test material may be one of
the stainless steels. A reaction that results in a
brown-colored liquid indicates a plain carbon
steel. A reaction producing a brown to black color
indicates a gray cast iron or one of the alloy steels
containing as its principal element either
chromium, molybdenum, or vanadium. Nickel
steel reacts to the nitric acid test by forming a
brown to greenish-black liquid, while a steel
containing tungsten reacts slowly to form a
brown-colored liquid with a yellow sediment.
When nonferrous metals and alloys are sub-
jected to the nitric acid test, instead of the brown-
black colors that usually appear when ferrous
metals are tested, various shades of green and blue
appear as the material dissolves. Except for
nickel and Monel, the reaction is vigorous. The
reaction of nitric acid on nickel proceeds slowly,
developing a pale green color. On Monel, the
reaction takes place at about the same rate as on
ferrous metals, but the characteristic color of the
liquid is greenish-blue. Brass reacts vigorously,
with the test material changing to a green color.
Tin bronze, aluminum bronze, and copper all
react vigorously in the nitric acid test, with the
liquid changing to a blue-green color. Aluminum
and magnesium alloys, lead, lead-silver, and lead-
tin alloys are soluble in nitric acid, but the blue
or green color is lacking.
From the information given thus far, it is easy
to see that you will need considerable visual skill
to identify the many different reactions of metals
to nitric acid. There are acid test kits available
containing several different solutions to identify
the different metals. Some of the kits can
identify between the different series of stainless
quickly with these tests. A chemical laboratory
is available in most large repair ships and shore
repair facilities. The personnel assigned are also
available to identify various metals in more critical
situations or when a greater degree of accuracy
is required on a repair job.
HEAT TREATMENT
Heat treatment is the operations, including
heating and cooling of a metal in its solid state,
that develop or enhance a particular desirable
mechanical property, such as hardness, toughness,
machinability, or uniformity of strength. The
theory of heat treatment is based upon the effect
that the rate of heating, degree of heat, and the
rate of cooling have on the molecular structure
of a metal.
There are several forms of heat treating. The
forms commonly used for ferrous metals are:
annealing, normalizing, hardening, tempering,
and case-hardening. Detailed procedures for the
various heat treatments of metals and the theories
behind them are beyond the scope of this manual.
However, since you will run across the terms from
time to time and will probably perform some of
the heat treatment processes under the supervision
of an MR1 or MRC, we will discuss some of the
general terminology.
ANNEALING
The chief purposes of annealing are (1) to
relieve internal strains and (2) to make a metal
soft enough for machining. Annealing is the
process of heating a metal to and holding it at a
suitable temperature and then cooling it at a
suitable rate, for such purposes as reducing hard-
ness, improving machinability, facilitating cold
working, producing a desired microstructure or
obtaining desired mechanical, physical or other
properties.
Besides rendering metal more workable,
annealing can also be used to alter other physical
properties, such as magnetism and electrical
conductivity. Annealing is often used for
softening nonferrous alloys and pure metals after
they have been hardened by cold work. Some of
these alloys require annealing operations which
are different from those for steel.
For ferrous metals, the annealing method most
commonly used, if a controlled atmosphere
4-17
furnace is not available, is to place the metal in
a cast iron box and cover it with sand or fire clay.
Packing this material around the metal prevents
oxidation. The box is then placed in the furnace,
heated to the proper temperature, held there for
a sufficient period, and then allowed to cool
slowly in the sealed furnace.
Instructions for annealing the more common
metals:
CAST IRON: Heat slowly to between 1400°
and 1800°F, depending on composition. Hold at
the specific temperature for 30 minutes, and then
allow the metal to cool slowly in the furnace or
annealing box.
COPPER: Heat to 925 °F. Quench in water.
A temperature as low as 500 °F will relieve most
of the stresses and strains.
ZINC: Heat TO 400 °F. Cool in open, still air.
ALUMINUM: Heat to 750 °F. Cool in open
air. This reduces hardness and strength but
increases electrical conductivity.
NICKEL-COPPER ALLOYS INCLUDING
MONEL: Heat to between 1400° and 1450 °F.
Cool by quenching in water or oil.
NICKEL-MOLYBDENUM-IRON and
NICKEL-MOLYBDENUM-CHROMIUM AL-
LOYS (Stellate): Heat to between 2100° and
21 SOT. Hold at this temperature for a suitable
time, depending on thickness. Follow by rapid
cooling in a quenching medium.
BRASS: Annealing to relieve stress may be
done at a temperature as low as 600 °F. Fuller
anneals may be done with increased temperatures.
Larger grain size and loss of strength will result
from too high temperatures. Do NOT anneal at
temperatures exceeding 1300 °F. Slowly cool the
brass to room temperature. Either wrap the part
with heat retarding cloth or bury it in slaked lime
or other heat retarding material.
BRONZE: Heat to HOOT. Cool in an open
furnace to SOOT or place in a pan to avoid uneven
cooling caused by air drafts.
NORMALIZING
Normalizing is the process of heating a
ferrous alloy to a suitable temperature above the
critical temperature or transformation range (see
section on hardening) and then cooling in still
air. Normalizing relieves stresses and strains
caused by welding, forging and uneven cooling.
Normalizing also removes the effects of previous
heat treatments.
HARDENING
Cutting tools, chisels, twist drills, and many
other pieces of equipment and tools must be
hardened to enable them to retain their cutting
edges. Surfaces of roller bearings, parallel blocks,
and armor plate must be hardened to prevent wear
or penetration. Metals and alloys can be hardened
in several ways; a brief general description of one
method of hardening follows:
Each steel has a critical temperature at which
a marked change will occur in its grain structure
and physical properties. This critical temperature
varies according to the carbon content of the steel.
To be hardened, steel must be heated to a little
more than this critical temperature — to ensure that
every point in it will have reached critical
temperature and to allow for some slight loss of
heat when the metal is transferred from the
furnace to the cooling medium. The steel must
then be cooled rapidly by being quenched in oil,
freshwater, or brine. Quenching firmly fixes the
structural changes which occurred during heating
and thus causes the metal to remain hard.
If allowed to cool too slowly, the metal will
lose its hardness. On the other hand, to prevent
too rapid quenching which would result in
warping and cracking, it is sometimes necessary
to use oil instead of freshwater or saltwater for
high carbon and alloy steels. Saltwater, as
opposed to freshwater, produces greater hardness.
To prevent hard and soft spots when quench-
ing, hold the part with a set of tongs made with
long handles and grips or jaws that will hold the
part firmly but with a minimum amount of
surface contact. When you submerge the part in
the cooling medium, rapidly move it up and down
while moving it around the cooling medium
container in a clockwise or counterclockwise
direction.
TEMPERING
The tempering process relieves strains that are
brought about in steel during the hardening
hardened steel to a temperature below the critical
range, holding this temperature for a sufficient
time to penetrate the whole piece, and then
cooling the piece. In this process, ductility and
toughness are improved, but tensile strength and
hardness are reduced.
CASE HARDENING
Case hardening is a process of heat treating
by which a hard skin is formed on a metal, while
the inner part remains relatively soft and tough.
A metal that is originally low in carbon is packed
in a substance high in carbon content and heated
above the critical range. The case hardening
furnace must give a uniform heat. The length of
time the piece is left in the oven at this high heat
determines the depth to which carbon is absorbed.
A commonly used method of case hardening is
to (1) carburize the material (an addition of
carbon during the treatment), (2) allow it to cool
slowly, (3) reheat, and (4) harden in water. Small
pieces such as bolts, nuts, and screws, however,
can be dumped into water as soon as they are
taken out of the carburizing furnace.
HARDNESS TEST
A number of tests are used to measure the
physical properties of metals and to determine
whether a metal meets specification requirements.
Some of the more common tests are hardness
tests, tensile strength tests, shear strength tests,
bend tests, fatigue tests, and compression tests.
Of primary importance to a Machinery Repair-
man is the hardness test.
Most metals possess some degree of hard-
ness— that is, the ability to resist penetration by
another material. Many tests for hardness are
used; the simplest is the file hardness test. While
fair estimates of hardness can be made by an
experienced workman, more consistent quan-
titative measurements are obtained with standard
hardness testing equipment. Such equipment
eliminates the variables of size, shape, and hard-
ness of the file selected, and of the speed, pressure,
and angles of the file used by the person
conducting the test. Before discussing the hard-
ness test equipment, let us consider hardness itself,
and the value of such information to a Machinery
Repairman.
resistance to machine tool cutting, and resistance
to bending (stiffness) by wrought products.
Except for resistance to penetration, these
characteristics of hardness are not readily
measurable. Consequently, most hardness tests
are based on the principle that a hard material
will penetrate a softer one. In a scientific sense,
then, hardness is a measure of the resistance of
a material to penetration or indentation by an
indenter of fixed size and geometrical shape,
under a specific load.
The information obtained from a hardness test
has many uses. It may be used to compare alloys
and the effects of various heat treatments on
them. Hardness tests are useful as a rapid,
nondestructive method for inspecting and
controlling certain materials and processes and to
ensure that heat-treated objects have developed
the hardness desired or specified. The results of
hardness tests are useful not only for comparative
purposes, but also for estimating other properties.
For example, the tensile strength of carbon and
low-alloy steels can be estimated from the hard-
ness test number. There is also a relationship
between hardness and endurance or fatigue
characteristics of certain steels.
Hardness may be measured by many types of
instruments. The most common are the Rockwell
and Brinell hardness testers. Other hardness tests
include the Vickers, Eberbach, Monotron, Tukon,
and Scleroscope. Since there are many tests and
the hardness numbers derived are not equivalent,
the hardness numbers must be designated
according to the test and the scale used in the test.
Since you are more likely to have access to a
Rockwell tester than any other, this method is
discussed in detail. The essential differences
between the Rockwell and Brinell tests will also
be discussed in the sections which follow. In
addition, the Scleroscope and Vickers hardness
tests will be covered briefly.
ROCKWELL HARDNESS TEST
Of all the hardness tests, the Rockwell is the
one most frequently used. The basic principle of
the Rockwell test (like that of the Brinell, Vickers,
Eberbach, Tukron, and Monotron tests) is that
a hard material will penetrate a softer one. This
test operates on the principle of measuring the
indentation, in a test piece of metal, made by a
ball or cone of a specified size which is being
forced against the test piece of metal with specified
4-19
pressure. In the Rockwell tester shown in
figure 4-4, the hardness number is obtained by
measuring the depression made by a hardened
steel ball (indenter) or a spheroconical diamond
penetrator of a given size under a given pressure.
With the normal Rockwell tester shown, the
120° spheroconnical penetrator is used in conjunc-
tion with a 150-kilogram (kg) weight to make
impressions in hard metals. The hardness number
obtained is designated Rockwell C (Re). For softer
metals, the penetrator is a 1/16-inch steel ball used
in conjunction with a 100-kg weight. A hardness
number obtained under these conditions is
designated Rockwell B (Rb).
Figure 4-5 illustrates the principle of indenter
hardness tests. Although the conical penetrator
is shown, the principle is the same for a ball
penetrator. (The geometry of the indentations
will, of course, differ slightly.)
With the Rockwell tester, a deadweight, acting
through a series of levers, is used to press the ball
or cone into the surface of the metal to be tested.
Then the depth of penetration is measured. The
softer the metal being tested, the deeper the
SMALL
POINTER
HARDNESS
DIAL-
LING
NEEDLE
INDENTER
ANVIL
ELEVATING
WHEEL
KNURLED
ZERO
ADJUSTER
DEPRESSOR
BAR
WEIGHTS
102.90
Figure 4-4.— Standard Rockwell hardness testing machine.
penetration will be under a given load. The
average depth of penetration on samples of very
soft steel is only about 0.008 inch. The hardness
is indicated on a dial, calibrated in the Rockwell
B and the Rockwell C hardness scales. The harder
the metal, the higher the Rockwell number will
be. Ferrous metals are usually tested with the
spheroconical penetrator, with hardness numbers
being read from the Rockwell C scale. The steel
ball is used for nonferrous metals and the results
are read on the B scale.
With most indenter-type hardness tests, the
metal being tested must be sufficiently thick to
avoid bulging or marking the opposite side. The
specimen thickness should be at least 10 times the
depth of penetration. It is also essential that the
surface of the specimen be flat and clean. When
hardness tests are necessary on thin material, a
superficial Rockwell tester should be used.
The Rockwell superficial tester differs from
the normal Rockwell tester in the amount of load
applied to perform the test and in the kind of scale
used to interpret the results. When the major loads
on the normal tester are 100 and 150 kg, the major
loads on the superficial tester are 15, 30, and 45
kg. One division on the dial gauge of the normal
tester represents a vertical displacement of the
indenter of 0.002 millimeter (mm). One division
of the dial gauge of the superficial tester represents
a vertical displacement of the indenter of 0.001
mm. Hardness scales for the Rockwell superficial
tester are the N and T scales. The N scale is used
for materials that, if they were thicker, would
usually be tested with the normal tester using the
C scale. The T scale is comparable to the B scale
used with the normal tester'. In other respects the
normal and superficial Rockwell testers are much
alike.
If you have properly prepared a sample and
have selected the appropriate penetrator and
weights, you can use the following step-by-step
procedure to operate a Rockwell tester:
1 . Place the piece to be tested on the testing
table, or anvil.
2. Turn the wheel that elevates the testing
table until the piece to be tested comes in contact
with the testing cone or ball. Continue to turn the
elevating wheel until the small pointer on the
indicating gauge is nearly vertical and slightly to
the right of the dot.
3. Watch the long pointer on the gauge;
continue raising the work with the elevating wheel
until the long pointer is nearly upright — within
approximately five divisions, plus or minus, on
CONE -SHAPED
PENETRATOR
THIS INCREASE IN DEPTH OF PENTRATION, CAUSED BY APPLICATION OF MAJOR LOAD,
FORMS THE BASIS FOR THE ROCKWELL HARDNESS TESTER READINGS.
Figure 4-5. — Principle of Rockwell hardness test.
126.87
the scale. This step of the procedure sets the minor
load.
4. Turn the zero adjuster, located below the
elevating wheel, to set the dial zero behind the
pointer.
5. Tap the depressor bar downward to release
the weights and apply the major load. Watch the
pointer until it comes to rest.
6. Turn the crank handle upward and for-
ward, thereby removing the major but not the
minor load. This will leave the penetrator in
contact with the specimen but not under pressure.
7. Observe where the pointer now comes to
rest and read the Rockwell hardness number on
the dial. If you have made the test with the
1/16-inch ball and a 100-kilogram weight, take
the reading from the red, or B, scale. If you have
made the test with the spheroconical penetrator
and a weight of 150 kilograms, take the reading
from the black, or C scale. (In the first example
prefix the number by Rb, and in the latter instance
by Re.)
8. Turn the hand wheel to lower the anvil.
Then remove the test specimen.
BRINELL HARDNESS TEST
The Brinell hardness testing machine provides
a convenient and reliable hardness test. The
machine is not suitable, however, for thin or small
pieces. This machine has a vertical hydraulic press
design and is generally hand operated. A lever
is used to apply the load which forces a
10-millimeter diameter hardened steel or tungsten-
carbide ball into the test specimen. For ferrous
metals, a 3,000-kilogram load is applied. For
nonferrous metals, the load is 500 kilograms. In
general, pressure is applied to ferrous metals for
10 seconds, while 30 seconds is required for
nonferrous metals. After the pressure has been
applied for the appropriate time, the diameter of
the depression produced is measured with a
microscope having an ocular scale.
The Brinell hardness number (Bhn) is the ratio
of the load in kilograms to the impressed surface
area in square millimeters. This number is found
by measuring the distance the ball is forced, under
a specified pressure, into the test piece. The
greater the distance, the softer the metal, and the
4-21
lower the Brinell hardness number will be.
The width of the indentation is measured
with a microscope, and the hardness number
corresponding to this width is found by consulting
a chart or table.
The Brinell hardness machine is of greatest
value in testing soft and medium-hard metals and
in testing large pieces. On hard steel the imprint
of the ball is so small that it is difficult to read.
SCLEROSCOPE HARDNESS TEST
If you place a mattress on the deck and drop
two rubber balls from the same height, one on
the mattress and one on the deck, the one dropped
on the deck will bounce higher. The reason is that
the deck is the harder of the two surfaces; this
is the principle upon which the Scleroscope works.
When using the Scleroscope hardness test, drop
a diamond-pointed hammer through a guiding
glass tube onto the test piece and check the
rebound (bounce) height on a scale. The harder
the metal being tested, the higher the hammer will
rebound, and the higher will be the number on
the scale. The Scleroscope is portable and can be
used to test the hardness of pieces too large to be
placed on the anvil or tables of other machines.
Since the Scleroscope is portable and can be held
in the hand, it can be used to test the hardness
of large guns and marine and other f orgings that
cannot be mounted on stationary machines.
Another advantage of the Scleroscope is that it
can be used without damaging finished surfaces.
The chief disadvantage, however, of this machine,
is its inaccuracy. The accuracy of the Scleroscope
is affected by the following factors:
1. Small pieces do not have the necessary
backing and cannot be held rigidly enough to give
accurate readings.
2. If large sections are not rigid, if they are
oddly shaped, if they have overhanging sections,
or if they are hollow, the readings may be in error.
3. If oil-hardened parts are tested, oil may
creep up the glass tube and interfere with the
drop of the diamond-pointed hammer in the
instrument, thus causing an error.
VICKERS HARDNESS TEST
The Vickers test measures hardness by a
method similar to that of the Brinell test. The
indenter, however, is not a ball, but a square-
based diamond pyramid, which makes it accurate
for testing thin sheets as well as the hardest steels.
Up to an approximate hardness number of
300, the results of the Vickers and the Brinell tests
are about the same. Above 300, Brinell accuracy
becomes progressively lower. This divergence
represents a weakness in the Brinell method — a
weakness that is the result of the tendency of the
Brinell indenter ball to flatten under heavy loads.
For this reason, Brinell numbers over 600 are
considered to be of doubtful reliability.
If a ship has one type of hardness tester and
the specifications indicated by the blueprint are
for another type, a conversion table, such as
table 4-3, may be used to convert the reading.
File Hardness Test
Hardness tests are commonly used to
determine the ability of a material to resist
abrasion or penetration by another material.
Many methods have evolved for measuring the
hardness of metal. The simplest method is the file
hardness test. This test cannot be used to make
positive identification of metals but can be used
to get a general idea of the type of metal being
tested and to compare the hardness of various
metals on hand. Thus, when identification of
metals by other means is not possible, you can
use a file to determine the relative hardness of
various metals. The results of such a test may
enable you to select a metal suitable for the job
being performed.
The file hardness test is simple to perform.
You may hold the metal being tested in your hand
and rested on a bench, or put it in a vise. Grasp
the file with your index finger extended along the
file and apply the file slowly but firmly to the
surface being tested.
If the material is cut by the file with extreme
ease and tends to clog the spaces between the file
teeth, it is VERY SOFT. If the material offers
some resistance to the cutting action of the file
and tends to clog the file teeth, it is SOFT. If the
material offers considerable resistance to the file
but can be filed by repeated effort, it is HARD
and may or may not have been treated. If the
material can be removed only by extreme effort
and in small quantities by the file teeth, it is VERY
HARD and has probably been heat treated. If the
file slides over the material and the file teeth are
dulled, the material is EXTREMELY HARD and
has been heat treated.
The file test is not a scientific method. It
should not be used when positive identification
of metal is necessary or when an accurate
measurement of hardness is required. Tests
4-22
Hardness
No. 3,000 kg
Hardness
No. C Scale
Approximate
Xl,000psi
Hardness
No. 3,000 kg
Hardness
No. C Scale
Approximati
Xl,000psi
70C
477
50.3C
234
69C
461
48.8C
226
68C
444
47.2C
218
67C
429
45.7C
210
767
66.4C
376
415
44.5C
203
757
65.9C
371
401
43. 1C
196
745
65.3C
365
388
41.8C
190
733
64.7C
359
375
40.4C
184
722
64.0C
354
363
39.1C
178
710
63.3C
348
352
37.9C
172
698
62.5C
342
341
36.6C
167
682
61.7C
334
331
35.5C
162
670
61.0C
328
321
34.3C
157
653
60.0C
320
311
33. 1C
152
638
59.2C
313
302
32.1C
148
627
58.7C
307
293
30.9C
144
601
57.3C
294
285
29.9C
140
578
56.0C
283
277
28.8C
136
555
54.7C
272
269
27.6C
132
534
53.5C
262
262
26.6C
128
524
52.1C
257
255
25.3C
125
495
51.0C
243
4-23
Table 4-3.— Hardness Conversion Chart (Ferrous Metals)— Continued
Brinell
Hardness
No. 500 kg
Rockwell
Hardness
No. B Scale
Brinell
Hardness
No. 500 kg
Rockwell
Hardness
No. B Scale
201
99.0B
143
85.0B
195
98.2B
140
82.9B
189
97.3B
135
80. 8B
184
96.4B
130
80.0B
179
95.5B
120
75.B
175
94.6B
110
70.0B
171
93. 8B
100
63. 5B
167
92.8B
95
60.0B
164
91. 9B
90
56. OB
161
90.7B
85
52.0B
158
90.0B
80
47. OB
156
89.0B
75
41. OB
153
87.8B
70
34.0B
149
86. 8B
65
26.0B
146
86.0B
already described should be used for positive
identification of metals. Special machines, such
as the Rockwell and Brinell testers, should be used
when it is necessary to determine accurately the
hardness of the material.
PLASTICS
Plastic materials are being increasingly used
aboard ship. In some respects, they tend to
surpass structural metals; plastic has proven to
be shock resistant, not susceptible to saltwater
corrosion, and in casting it lends itself to mass
production and uniformity of end product.
CHARACTERISTICS
Plastics are formed from organic materials,
generally with some form of carbon as their
basic element. Plastics are referred to as
synthetic material, but this does not necessarily
mean that they are inferior to natural material.
On the contrary, they have been designed
to perform particular functions that no natural
material can perform. Plastics can be obtained
in a variety of colors, shapes, and forms —
some are as tough, but not as hard, as steel;
some are as pliable as rubber; some are more
transparent than glass; and some are lighter than
aluminum.
4-24
MOPLASTICS — and it is necessary, if you are
going to perform any kind of shopwork on
plastics, to know which of these two you are
using.
Thermosettings are tough, brittle, and heat
hardened. When placed in a flame, they will not
burn readily, if at all. Thermosettings are so hard
that they resist the penetration of a knife blade;
any such attempt will dull the blade. If the plastic
is immersed in hot water and allowed to remain,
it will neither absorb moisture nor soften.
Thermoplastics, on the other hand, when
exposed to heat, become soft and pliable, or even
melt. When cooled, they retain the shape that they
took under the application of heat. Some ther-
moplastics will even absorb a small amount of
moisture, if placed in hot water. A knife blade
will cut easily into thermoplastics.
When testing a plastic by inserting it into a
fire, you should exercise caution, because ther-
moplastics will burst into sudden intense flame,
and give off obnoxious gases. If you use the fire
test, be sure to hold the plastic piece a considerable
distance from you.
MAJOR GROUPS
While it is not necessary for you to know the
exact chemical composition of the many plastics
in existence, it will be helpful to have a general
idea of the composition of the plastics you are
most likely to use. Table 4-4 provides informa-
tion on some groups of plastics which are of
primary concern to a Machinery Repairman.
Laminated plastics are made by dipping,
spraying, or brushing flat sheets or continuous
rolls of paper, fabric, or wood veneer with resins,
and then pressing several layers together to get
hard, rigid, structural material. The number of
layers pressed together into one sheet of laminated
plastic will depend upon the thickness desired. The
choice of paper, canvas, wood veneer, or glass
fabric will depend upon the end use of the
product. Paper-based material is thin and quite
brittle, breaking if bent sharply, but canvas-based
material is difficult to break. As layers are added
to paper-based material, it gains in strength, but
it is never as tough and strong in a laminated part
as layers of glass fabric or canvas.
Laminated materials are widely used aboard
ship. For example, laminated gears are used on
internal-combustion engines, usually as timing or
idler gears; on laundry equipment; and on
heat when friction is generated, and wear longer.
Plastics are identified by several commercial
designations, trade names, and by Military and
Federal specifications. There is such a large
number of types, grades, and classes of plastics
within each major group that to rely on the
recognition of a trade name only would result in
the wrong material being used. The appropriate
Federal Supply Catalog should be used to cross
reference the Military (MIL-P-XXXX) or Federal
(FED-L-P-XXXX) designations to the correct
procuring data for the Federal Supply System.
MACHINING OPERATIONS
Machining operations that you may perform
on plastics include cutting parts from sheet or rod
stock, using various metal cutting saws; removing
stock from parts by rotating tools as in a drill press
or a milling machine; cutting moving parts by
stationary tools, as on a lathe; and finishing
operations.
Sawing
You can use several types of saws — bandsaw,
jigsaw, circular saw — to cut blanks from plastic
stock. Watch the saw speed carefully. Since
almost none of the heat generated will be carried
away by the plastic, there is always danger that
the tool will be overheated to the point that it will
burn the work.
Drilling
In drilling plastics, back the drill out
frequently to remove the chips and cool the tool.
A liberal application of kerosene will help keep
the drill cool. To obtain a smooth, clean hole, use
paraffin wax on the drill; for the softer plastics,
you may prefer a special coolant.
Lathe Operations
Lathe operations are substantially the same for
plastics as for metals, except for the type of tool,
and the manner in which contact is made with the
work. For plastics, set the tool slightly below
center. Use cutting tools with zero or slightly
negative back rake.
For both thermo settings and thermoplastics,
recommended cutting speeds are: 200 to 500 fpm
4-25
Table 4-4.— Major Groups of Plastics
Plastic
Trade Names in ( )
Advantages and Examples of Uses
Disadvantages
Acrylic
(Lucite, Plexiglass)
Cellulose nitrate
(Celluloid)
Polyamide
(Nylon)
Polyethylene
(Polythene)
THERMOPLASTICS
Formability; good impact strength; good aging
and weathering resistance; high transpar-
ency, shatter -resistance, rigidity. Used
for lenses, dials, etc.
Ease of fabrication; relatively high impact
strength and toughness; good dimensional
stability and resilience; low moisture
absorption. Used for tool handles, mallet
heads, clock dials, etc.
High resistance to distortion under load at
temperatures up to 300° F; high tensile
strength, excellent impact strength at
normal temperatures; does not become
brittle at temperatures as low as minus
70°F; excellent resistance to gasoline and
oil; low coefficient of friction on metals.
Used for synthetic textiles, special types
of bearings, etc.
Inert to many solvents and corrosive chemi-
cals; flexible and tough over wide tempera-
ture range, remains so at temperatures as
low as minus 100 °F; unusually low moisture
absorption and permeability; high electrical
resistance; dlmensionally stable at normal
temperatures; ease of molding; low cost.
Used for wire and cable insulation, and
acid resistant clothing.
Softening point of 170°
to 220° F; low
scratch resistance.
Extreme flammabil-
ity; poor electrical
insulating prop-
erties; harder with
age; low heat dis-
tortion point.
Absorption of water;
large coefficient of
expansion; relatively
high cost; weather-
ing resistance poor.
Low tensile, co De-
pressive, flexural
strength; very high
elongation at nor-
mal temperatures;
subject to spontan-
eous cracking when
stored in contact
with alcohols,
toluene, and sili-
cone grease, etc.;
softens at tem-
peratures above
200 °F; poor
abrasion'and cut
resistance; cannot
be bonded unless
given special
surface treatment.
Trade Names in ( )
Advantages and Examples of Uses
Disadvantages
Polytetrafluoroethylene
(Teflon)
THERMOPLASTICS
Extreme chemical inertness; high heat re-
sistance; nonadhesive; tough; low coefficient
of friction. Used for preformed packing and
gaskets.
Not easily cemented;
cannot be molded by
usual methods; gen-
erates toxic fumes
at high tempera-
tures; high cost.
Phenolformaldehyde
(Bakelite, Durez,
Resinox)
Urea-formaldehyde
(Beetle, Bakelite
Urea, Plaskon)
THERMOSETTING PLASTICS
Better permanence characteristics than
most plastics; may be used at temperatures
from 250° to 475°F; good aging resistance;
good electrical insulating properties; not
readily flammable, does not support com-
bustion; inserts can be firmly embedded;
strong, light; low water absorption; low
thermal conductivity; good chemical re-
sistance; economical in production of com-
plex shapes; free from cold flow; relatively
insensitive to temperature; low coefficient
of thermal expansion; no change in dimen-
sions under a load for a long time; does not
soften at high temperatures or become
brittle down to minus 60° F; inexpensive.
Used for handles, telephone equipment,
electrical insulators, etc.
High degree of translucency and light finish;
hard surface finish; outstanding electrical
properties when used within temperature
range of minus 70° to plus 170° F; com-
plete resistance to organic solvents;
dimensionally stable under moderate load-
ings and exposure conditions. Used for
instrument dials, electric parts, etc.
Difficult to mold when
filled for greatest
impact strength, or
when in sections less
than 3/32-inch thick;
can be expanded or
contracted by un-
usually wet or dry
atmosphere.
Low impact strength;
slight warping with
age; poor water
resistance.
4-27
with high-speed steel tools and 500 to 1500 fpm
with carbide-tipped tools.
Finishing Operations
Plastics must be finished to remove tool marks
and produce a clean, smooth surface. Usually,
sanding and buffing are sufficient for this
purpose.
You can remove surface scratches and pits by
hand sandpapering with dry sandpaper of fine
grit. You can also wet sand by hand, with water
and abrasive paper of fine grade. If you need to
remove a large amount of material, use sanding
wheels or disks.
After you have removed the pits and scratches,
buff the plastic. You can do this on a wheel made
of loose muslin buffs. Use tripoli and rouge
buffing compounds, depositing a layer of the
compound on the outside of the buffing wheel.
Renew the compound frequently.
When you buff large flat sheets, be careful not
to use too much pressure, nor to hold the work
too long in one position. In buffing small plastic
parts, be careful that the wheel does not seize the
piece and pull it out of your grasp.
4-28
POWER SAWS AND DRILLING MACHINES
Machine shop work is generally understood
to include all cold metal work in which a portion
of the metal is removed by either power driven
tools or handtools. In your previous studies
you have become familiar with common hand-
tools. This chapter and the following chapters
contain information on power driven, or machine,
tools.
The term MACHINE TOOL refers to
any piece of power driven equipment that
drills, cuts, or grinds metals and other materials.
Through the use of attachments, some machine
tools will perform two or more of these
operations. Machine tools actually hold and
work the material. The operator guides the
mechanical movements by properly setting up
the work and by adjusting the gearing or
linkage controls. In this chapter we will
deal primarily with power saws and drilling
machines.
• NEVER make adjustments to the saw or
relocate the stock to be sawed while the
saw is in operation.
• Keep your hands as far away as possible
from the saw blade while the saw is in
operation.
• NEVER attempt to move a large heavy
piece of stock to or from the saw -without
help.
• Always support protruding ends of long
pieces of stock so they will not fall and
cause injury to either the machine or
personnel.
• NEVER use bare hands to clean the saw
cuttings from the machine.
POWER SAW
SAFETY PRECAUTIONS
Before we discuss the operation of power
saws, you must realize the importance of
observing safety precautions. Carelessness is one
of the prime causes of accidents in the machine
shop. Moving machinery is always a potential
danger. When this machinery is associated with
sharp cutting tools, the hazard is greatly increased.
Some of the more important safety precautions
are listed here:
• Be alert for sharp burrs on the sawed end
of stock and remove such burrs with a file
to prevent injury to personnel.
• Inspect the blade at frequent intervals and
NEVER use a saw with a dull, pinched,
or burned blade.
• In all sawing jobs, the golden rule of safety
is SAFETY FIRST, ACCURACY SEC-
OND, and SPEED LAST.
• DO NOT operate a power saw that you are
not fully qualified and authorized to
operate.
• Wear goggles or a face shield at all times
when you are operating a power saw.
POWER HACKSAWS
The power hacksaw is found in many Navy
machine shops. It is used for cutting bar stock,
pipe, tubing, or other metal stock. The power
hacksaw consists of a base, a saw frame, and a
5-1
work-holding device. Figure 5-1 is an illustration
of a standard power hacksaw.
The base consists of a reservoir to hold the
coolant, a coolant pump, the drive motor and a
transmission for speed selection. Some models
may have the feed mechanism attached to the
base.
The saw frame consists of linkage and a
circular disk with an eccentric (off center)
pin designed to convert circular motion into
reciprocating motion. The blade is inserted
between the two blade holders and securely
attached by either hardened pins or socket
head screws. The inside blade holder is
adjustable. This adjustable blade holder allows
the correct tension to be put on the blade
to ensure that it is held rigidly enough to
prevent it from wandering and causing a
slanted cut. The feed control mechanism
is also attached to the saw frame on many
models.
The work holding device is normally a vise
with one stationary jaw and one movable jaw. The
movable jaw is mounted over a toothed rack to
permit a rapid and easy initial adjustment
close to the material to be cut. Final tightening
is made by turning the vise screw until
the material is held securely. An adjustable
stop permits pieces of the same length to
be cut without measuring each piece separately.
A stock support stand (available for both sides
of the saw) keeps long stock from falling when
being cut.
The capacity designation of the power
hacksaw illustrated is 4 inches x 4 inches. This
means that it can handle material up to 4 inches
wide and 4 inches thick.
BLADE SELECTION
The blade shown in figure 5-2 is especially
designed for use with the power hacksaw. It is
made with a tough alloy steel back and high-speed
steel teeth, a combination which gives a strong
blade, and at the same time, a cutting edge
suitable for high-speed sawing.
These blades differ by the pitch of the
teeth (number of teeth per inch). The correct
pitch of teeth for a particular job is determined
by the size and material composition of
the section to be cut. Use coarse pitch teeth
for wide, heavy sections to provide ample
chip clearance. For thinner sections, use a
blade with a pitch that keeps two or more
teeth in contact with the work so that the teeth
do not straddle the work. Straddling strips the
teeth from the blade. In general, select blades
according to the following information:
1 . Coarse (4 teeth per inch), for soft steel, cast
iron, and bronze.
TOUGH ALLOY
STEEL BACK
HIGH SPEED
STEEL TEETH
ELECTRIC WELD
11.18
Figure 5-1. — Standard power hacksaw.
11.19
Figure 5-2. — Hacksaw blade.
3. Medium (10 teeth per inch), for solid brass
stock, iron pipe, and heavy tubing.
4. Fine (14 teeth per inch), for thin tubing and
sheet metals.
COOLANT
The use of a coolant is recommended for most
power hacksawing operations. (Cast iron can be
sawed dry.) The coolant keeps the kerf (narrow
slot created by the cutting action of the blade)
clear of chips so that the blade does not bind up
and start cutting crooked. The teeth of the blade
are protected from overheating by the coolant,
permitting the rate of cutting to be increased
beyond the speed possible when sawing without
coolant. A soluble oil solution with a mixture of
the oil and water, made so that no rust problems
will occur, should be suitable for most sawing
operations. The normal mixture for soluble oil is
40 parts water to 1 part oil.
FEEDS AND SPEEDS
A power hacksaw will have one of three types
of feed mechanisms:
1 . Mechanical feed, which ranges from 0.001
to 0.025 inch per stroke, depending upon
the class and type of material being cut.
2. Hydraulic feed, which normally exerts a
constant pressure but is designed so that
when hard spots are encountered the feed
is automatically stopped or shortened to
decrease the pressure on the saw until the
hard spot has been cut through.
3. Gravity feed, in which weights are placed
on the saw frame and shifted to give more
or less pressure of the saw blade against the
material being cut.
To prevent unnecessary wear on the back sides
of the saw blade teeth, the saw frame and blade
are automatically raised clear of the surface being
cut on each return stroke. The rate of feed or the
pressure exerted by the blade on the cutting stroke
of a hollow pipe, the wall thickness. A hard, large
diameter piece of stock must be cut with a slower
or lighter feed rate than a soft, small diameter
piece of stock. Pipe with thin walls should be cut
with a relatively light feed rate to prevent stripping
the teeth from the saw blade or collapsing the
walls of the pipe. A feed rate that is too heavy
or fast will often cause the saw blade to wander,
producing an angled cut.
The speed of hacksaws is stated in strokes per
minute, counting only those strokes on which the
blade comes in contact with the stock. Speed is
changed by a gear shift lever. There may be a chart
attached to or near the saw, giving recommended
speeds for cutting various metals. The following
speeds, however, can be used:
1. Medium and low carbon steel, brass, and
soft metals — 136.
2. Alloy steel, annealed tool steel, and cast
iron— 90.
3. Unannealed tool steel, and stainless
steel— 60.
POWER HACKSAW OPERATION
A power hacksaw is relatively simple to
operate. There are, however, a few checks you
should make to ensure good cuts. Support
overhanging ends of long pieces to prevent
sudden breaks at the cut before the work is
completely cut through. Block up irregular shapes
so that the vise holds firmly. Check the blade to
ensure that it is sharp and that it is secured at the
proper tension.
Place the workpiece in the clamping device,
adjusting it so the cutting off mark is in line with
the blade. Turn the vise lever to clamp the material
in place. Be sure the material is held firmly.
See that the blade is not touching the
workpiece when you start the machine. Blades are
often broken when this rule is not followed. Feed
the blade slowly into the work, and adjust the
coolant nozzle so that it directs the fluid over the
saw blade.
5-3
CONTINUOUS FEED CUTOFF SAW
Figure 5-3 illustrates a type of cutoff saw that
is now being used throughout the Navy. There are
different models of this saw, but the basic design
and operating principles remain the same.
BAND SELECTION
AND INSTALLATION
The bands for the continuous feed cutoff saw
are nothing more than an endless hacksaw blade.
With this thought in mind, you can see that all
the factors that were discussed for power hacksaw
blade selection can be applied to this saw. This
saw is also equipped with a band selection chart
(fig. 5-3) to help you make the proper selection.
The bands come in two different forms; ready
made loops of the proper length and coils of
continuous lengths of 100 feet or more. Nothing
must be done to the presized band, but the coils
of saw bands must be cut to the proper length and
then butt welded. (Butt welding is covered later
in this chapter.)
Once you have selected the saw band, install
it in the following manner:
1 . Lift the cover on the saw head to expose
the band wheels.
2. Place the band on the wheels with the teeth
down, or toward the deck, and pointing in
the direction of the band rotation.
BAND
SELECTION
CHART
BAND
TENSION
HANDWHEEL
VISE
LOCK
HANDWHEEL
28.297X
This action applies enough tension to hold
the band on the wheels. When the machine
is operating, the hydraulic system main-
tains the proper band tension.
5. Adjust the saw guides according to the
manufacturer's manual. Do not set the
distance between the two guide arms more
than necessary or the blade will wander.
6. Select the proper surface speed (feet-per-
minute), and adjust the V-belt for that
speed. (See fig. 5-4.)
-90 F.P.M.
-125 F.P.M.
-ISO F.P.M.
-250 F.P.M.
DRIVEN
"PULLEY
Figure 5-4.— Speed change pulley.
be sawed is held securely in the machine. The
movement of the saw head is controlled from the
control panel (fig. 5-5). You can raise, stop, and
feed the machine with the main control handle.
The FEED portion of the control is divided into
vernier and rapid. The RAPID area is used to
bring the saw band down close to the work; the
VERNIER controls the feed pressure. Figure 5-5
shows the vernier control knob with graduations
from 0 to 9. By using this vernier, you can get
the maximum cutting efficiency for the type of
material being cut. When the cut is complete, the
machine will automatically stop. To raise the head
above the workpiece for the next cut, push the
start button and place the control lever in the
RAISE position. You may have to hold the start
button down for a second or two until the saw
head starts to rise.
METAL CUTTING HANDSAWS
Metal cutting bandsaws are standard equip-
ment in repair ships and tenders. These machines
can be used for nonprecision cutting similar to
that performed by power hacksaws. Some types
can be used for precision cutting, filing, and
O
o
O
o
o
o
28.296X
Figure 5-5. — Control panel (Do AH saw).
5-5
polishing. A handsaw has a greater degree of
flexibility for straight cutting than a power
hacksaw in that it can cut objects of any
reasonable size and of regular and irregular
shapes. A bandsaw also cuts faster than a power
hacksaw because the cutting action of the blade
is continuous.
Figure 5-6 illustrates a metal cutting bandsaw
with a tillable table. On the type shown, work is
fed either manually or by power to the blade
which runs in a fixed position.
The tillable band type saw is particularly suited
to taking straight and angle cuts on large, long,
or heavy pieces.
The tiltable table type is convenient for
contour cutting because the angle at which work
is fed to the blade can be changed readily. This
machine usually has special attachments and
accessories for precision inside or outside
cutting of contours and disks and for mitering
and has special bands for filing and polishing
work.
BANDSAW TERMINOLOGY
As was previously mentioned, the metal
cutting bandsaws installed in machine shops in
tenders and repair ships generally are the tiltable
table type which can cut, file, or polish work when
appropriate bands are mounted on the band
wheels. The saw bands, file bands, and polishing
bands used on these machines are called BAND
TOOLS, and the machine itself is often referred
to as a BAND TOOL MACHINE. Definitions
which will be helpful in understanding band tool
terminology are given below for saws, files, and
polishing bands, in that order.
SET
SIDE CLEARANCE
28.39X
11.21X
Figure 5-6.— Tiltable (contour) metal-cutting bandsaw.
Figure 5-8. — Set and side clearance.
GAGE
L^~
L—T—
T 1
RAKER SET PATTERN
,-™_.,./ ,j ™_r- — _
I L.
_ 1^ L 1
"
- r i
WAVE SET PATTERN
STRAIGHT SET PATTERN
29.15X
28.43X
PITCH: The number of teeth per linear
inch.
WIDTH: The distance across the flat face of
the band. The width measurement is always
expressed in inches, or fractions of an inch.
GAUGE: The thickness of the band back.
This measurement is expressed in thousandths of
an inch.
SET: The bend or spread given to the teeth
to provide clearance for the body or band back
when a cut is being made.
SIDE CLEARANCE: The difference between
the dimension of the band back (gauge) and the
set of the teeth. Side clearance provides running
room for the band back in the kerf or cut.
Without side clearance, a band will bind in the
kerf.
used for cutting hollow materials, such as pipe
and tubing, and for other work where there is a
great deal of variation in thickness. Straight set
bands are not used to any great extent for metal
cutting work.
TEMPER: The degree of hardness of
the teeth, indicated by the letters A and
B, temper A being the harder. Temper A bands
are used for practically all bandsaw metal cutting
work.
File Bands
A file band consists of a long steel strip upon
which are mounted a number of file segments that
can be flexed around the band wheels and still
present a straight line at the point of work.
Figure 5-10 illustrates the file band flexing
principle and shows the construction of a file
A -FILE SEGMENT
B-BACK BAND
C- TAIL GATE
D- SPACER
SEGMENTS
LOCKED IN
ALIGNMENT
o t — > o
GATE CLIP
<=o
o o
TAIL GATE
ENDS
OF
BAND
BACK
.XBAND
28.41X
Figure 5-10. — File band flexing principle and construction.
5-7
band. The parts ot a rue band and tneir functions
are described below:
FILE SEGMENT: A section of the cutting
face of a file band. The individual segments are
attached to the file band with rivets.
BACK BAND: The long steel strip or loop on
which the file segments are mounted. Do not
confuse this term with BAND BACK, which
refers to a part of a saw band.
GATE CLIP: A steel strip at the leading end
of the back band — a part of an adapter for joining
the back band ends to form the file band loop.
TAIL GATE: A steel strip at the other end
of the back band. This is the other half of the
adapter for joining the back band ends to form
the file band loop.
SPACER: A small steel strip inserted between
the file segment and the surface of the back band.
There are as many spacers as there are file
segments in each file band.
Polishing Bands
Abrasive coated fabric bands are used for
grinding and polishing operations in a band tool
machine. They are mounted in the same way as
saw and file bands. Figure 5-1 1 shows a polishing
band. Figure 5-12 shows a backup support strip
28.43X
Figure 5-12. — Installing a backup support strip for polishing
band.
being installed, before the polishing band is
installed.
28.42X
Figure 5-11. — Polishing band.
Band Tool Guides
SAW BAND GUIDES: The upper and lower
guides keep the saw band in its normal track when
work pressure is applied to the saw. The lower
guide is in a fixed position under the work table,
and the upper guide is attached to a vertically
adjustable arm above the table which permits
raising or lowering the guide to suit the height of
work. To obtain adequate support for the band
and yet not interfere with the sawing operation,
place the upper guide so that it will clear the top
of the workpiece by 1/8 to 3/8 of an inch.
Figure 5-13 shows the two principal types of saw
band guides: the insert type and the roller type.
Note in both types the antifriction bearing
surface for the band's relatively thin back edge.
This feature allows the necessary work pressure
to be placed on the saw without causing serious
rubbing and wear. Be sure to lubricate the
5-8
A. INSERT
TYPE
B. ROLLER
TYPE
28.44X
Figure 5-13.— Saw band guides.
bearings of the guide rollers according to the
manufacturer's recommendations.
FILE BAND AND POLISHING BAND
GUIDES: For band filing operations, the regular
saw band guide is replaced with a flat, smooth-
surface metal backup support strip, as shown in
figure 5-14, which prevents sagging of the file
band at the point of work. A similar support is
used for a polishing band. This support has a
graphite-impregnated fabric face that prevents
undue wear on the back of the polishing band,
which also is fabric.
28.45X
Figure 5-14.— File band guide.
SELECTION OF SAW BANDS,
SPEEDS AND FEEDS
Saw bands are available in widths ranging
from 1/16 to 1 inch; in various even-numbered
pitches from 6 to 32; and in three gauges— 0.025,
0.032, and 0.035 inch. The gauge of saw band that
can be used in any particular machine depends
on the size of the band wheels. A thick saw band
cannot be successfully used on a machine that has
small diameter bandwheels; therefore, only one
or two gauges of blades may be available for some
machines. Generally, only temper A, raker set,
and wave set bands are used for metal cutting
work. Another variable feature of saw bands is
that they are furnished in ready made loops of
the correct length for some machines, while for
others they come in coils of 100 feet or more from
which a length must be cut and formed into a
band loop by butt welding the ends together in
a special machine. The process of joining the ends
and installing bands will be described later in this
chapter.
Band tool machines have a multitude of band
speeds, ranging from about 50 feet per minute to
about 1500 feet per minute. Most of these
machines are equipped with a hydraulic feed
which provides three feeding pressures: low,
medium, and heavy.
Success in your precision sawing with a metal
cutting bandsaw depends to a large extent on your
selecting the correct saw blade or band, running
5-9
the saw band at the correct speed, and feeding
the work to the saw at the correct rate. Many band
tool machines have a JOB SELECTOR similar
to the one shown in figure 5-15, which indicates
the kind of saw band you should use, the speed
at which to operate the machine, and the power
feed pressure to use to cut various materials.
Not all bandsaws have a job selector. You
must know something about selecting the correct
saw bands, speeds, and feeds to operate a band-
saw successfully. Table 5-1 gives you some of
that information. Although this table does not
cover all types and thicknesses of metals nor
recommended feed pressure, it provides a basis
on which you can build, using your own
experience.
Tooth Pitch
Tooth pitch is the primary consideration in
selecting a saw band for any cutting job. For
cutting thin materials, the pitch should be fine
enough so that at least two teeth are in contact
with the work; fewer than two will tend to cause
the teeth to snag and tear loose from the band.
For cutting thick material, you should not have
too many teeth in contact with the work, because
as you increase the number of teeth in contact,
you must increase the feed pressure in order to
force the teeth into the material.
Excessive feed pressure puts severe strain on
the band and the band guides. It also causes the
band to wander sideways which results in off-line
cutting. Other points to consider in selecting a saw
band of proper pitch for a particular cutting job
are the composition of the material to be cut, its
hardness, and its toughness. Table 5-1 is a saw
band pitch and velocity selection chart showing
the pitch of saw band to use for cutting many
commonly used metals.
Band Width and Gauge
The general rule is to use the widest and
thickest saw band that can do the job successfully.
For example, you should use a band of maximum
width and thickness (if bands of different
thickness are available) when the job calls for only
straight cuts. On the other hand, when a layout
requires radius cuts (curved cuts), the band you
select must be capable of following the sharpest
curve involved. Thus for curved work, select the
widest band that will negotiate the smallest radius
required. The saw band width selection guides,
shown in figure 5-16, give the radius of the
WIDTH OF
SAW BAND
MINIMUM
RADII CUT
1/16'
SQ.
3/'--1
1/16"
1/8«
1/8"
3/le"
S/16"
1/4"
s/a"
3/8"
1-7/16'
1/2'
2-1/Z"
5/8-
3-3/4"
3/4"
5-7/16"
1*
7-1/4"
>/.• '/i- vf 'A' w v>'W w
28.46X
Figure 5-15. — Job selector.
28.47X
Figure 5-16. — Saw band width selection guides.
5-10
MATERIAL
SAW PITCH
Work Thickness
Over
2"
SAW VELOCITY
Work Thickness
Over
FERROUS METALS
Carbon Steel #1010-tl095*. 14
Free Machining #X1112-#1340*. . . 14
Nickel Chromium #2115-#3415* . . 14
Molybdenum #4023 -#4820.*. 14
Chromium #5120-#52100 * 14
Tungsten #7620-#71360 * 14
Silicon Manganese #9255-#9260 14
* (SAE numbers)
Armor Plate 14
Graphitic Steel 14
High Speed Steel 14
Stainless Steel 12
Angle Iron 14
Pipe 14
I Beams & Channels 14
Tubing (Thinwall) 14
Cast Steels 14
Cast Iron 12
NON-FERROUS METALS
Aluminum (All Types) 8
Brass 8
Bronze (Cast) 10
Bronze (Rolled) 12
Beryllium Copper 10
Copper 10
Magnesium 8
Kirksite 10
Monel Metal 10
Zinc 8
NON-METALS
Bakelite 10
Carbon 10
Plastics (All Types) 12
Wood 8
10
8
10
10
10
10
10
12
12
10
10
14
12
14
14
12
10
6
8
8
10
8
8
8
8
8
8
8
8
8
8
6-8
6-8
6-8
6-8
8
6-8
6-8
6-8
6-8
8
8
10
8
10
14
8
8
6-8
8
8
6-8
6-8
6-8
6-8
6-8
6-8
6-8
6-8
6-8
8
6-8
175
250
100
125
100
85
100
100
150
100
60
190
250
250
250
150
200
250
250
175
175
175
250
250
200
100
250
250
250
250
250
150
200
85
100
75
60
75
75
125
75
50
175
225
200
200
75
185
250
250
125
125
150
225
250
175
75
225
250
250
250
250
125
150
60
75
50
50
50
50
75
50
40
150
185
175
200
50
160
250
250
50
75
125
225
250
150
50
200
250
250
250
250
5-11
sharpest curve that can be cut with a particular
width saw band. Note that the job selector
illustrated in figure 5-15 contains a saw band radii
cutting diagram similar to the one shown in figure
5-16.
Band Speeds
The rate at which the saw band travels in feet
per minute from wheel to wheel is the saw band
velocity. Saw band velocity has considerable
effect upon both the smoothness of the cut
surfaces and the life of the band. The higher the
band velocity, the smoother the cut; however, heat
generated at the cutting point increases as band
velocity increases. Too high a band velocity causes
overheating and failure of the saw teeth. The band
velocities given in Table 5-1 are based on
manufacturers' recommendations, which in turn
are based on data obtained from saw life tests and
cutting experiments under various conditions. If
you follow the recommendations given, you will
be assured of the best band performance and
maximum band life.
Adjustment of the machine to obtain the
proper band velocity cannot be covered in detail
here because speed change is done by different
methods on different models of machines.
Consult the manufacturer's technical manual for
your particular machine and learn how to set up
the various speeds available.
Feeds
Though manual feeding of the work to the saw
is satisfactory for cutting metals up to 1 inch thick,
power feeding generally provides better results and
will be much safer for the operator. Regardless
of whether power or manual feed is used, it is
important not to crowd the saw because the band
will tend to bend and twist. However, feed
pressure must not be so light that the teeth slip
across the material instead of cutting through
because this rapidly dulls the teeth. The job
selector, shown in figure 5-15, shows the correct
feed pressures for cutting any of the materials
listed on the outer ring of the dial. In the absence
of a job selector, you can use table 5-2 as a guide
for selecting feed pressures for hard, medium
hard, and soft metals.
The power feed controls vary with different
makes of handsaws and even with different
models of the same make; therefore, no
description of the physical arrangement of the
power feed controls will be given here. Consult
the manufacturer's technical manual and study
the particular machine to learn its power feed
arrangement and control.
SIZING, SPLICING,
AND INSTALLING BANDS
Most contour cutting type handsaws are
provided with a buttwelder-grinder combination
Table 5-2.— Feed Pressures* for Hard, Medium Hard, and Soft Metal
Material
Work thickness
0-1/4"
1/4-1/2"
1/2-1"
1-3"
Over 3"
Tool Steel
M
M
L
L
L
L
L
M
M
M
M
L
L
L
H
M
H
H
M
M
M
H
H
H
H
H
M
M
H
H
H
H
H
M
M
Cast iron
Mild steel
Nickel-copper ....
Copper-nickel ....
Zinc
Lead
L-light, M-medium, H-heavy.
5-12
makes inside cutting possible, since the saw
band loop can be parted and rejoined after
having been threaded through a starting hole in
the work.
The following sections describe how to
determine the length of the band, how to join the
ends in the butt welder, and how to install a band
tool in the machine.
Band Length
You can quickly determine the correct saw
band length for any two-wheeled bandsaw by
measuring the distance from the center of
one wheel to the center of the other wheel,
multiplying by 2, and adding the circumference
of one wheel.
Figure 5-17. — Butt welder-grinder unit.
adjust the upper wheel so that it is approximately
halfway between the upper and lower limits of its
vertical travel. This allows for taking up any band
stretch resulting from operation.
Band Splicing
Figure 5-17 shows band ends being joined by
using a butt welder. The procedure for joining is
as follows:
1 . Grind both ends of the band until they are
square with the band back edge. If you do
not do this carefully, the weld may not go
completely across the ends of the band and,
as a result, the weld will not withstand the
pressure of the cut when it is used. One easy
method to ensure that the ends of the band
will go together perfectly is to twist one end
180 degrees and then place the band ends
on top of each other. This will provide a
set of teeth and a band back edge on both
sides of the stacked ends. Ensure that the
band back edge and the teeth are in a
straight line on both sides. Carefully touch
the tips of the ends of the band to the face
of the grinding wheel and lightly grind until
both ends have been ground completely
across. Release the ends of the band so that
they assume their normal position. Lay the
back edge of the band on a flat surface and
bring the ends together. If you did the
grinding correctly, the ends will meet
perfectly.
2. Set the controls of the butt welder to the
weld position and adjust the adjusting lever
according to the width of band to be
welded. The various models of butt welders
that are found in many machine shops
differ in the number of controls that must
be set and the method of setting them.
Most models have a lever that must be
placed in the weld position so that the
stationary and the movable clamping jaws
28.4SX are separated the correct distance. Some
models have a resistance setting control
5-13
which is set according to the width of the
band, while other models have a jaw
pressure control knob that is also set
according to band width. Read the
manufacturer's instruction manual care-
fully before attempting welding.
3 . Place the ends of the band in the jaws with
the teeth of the band facing away from the
welder. Push the back edge of the band
firmly back toward the flat surfaces behind
the clamping jaws to ensure proper align-
ment. Position the ends of the band so that
they touch each other and are located in
the center of the jaw opening. Some models
of butt welders have interchangeable inserts
for the clamping jaws to permit welding
bands of different widths. This is done so
that the teeth of the band are not damaged
when the jaws are clamped tight.
4. You are now ready to weld the band. Some
welders require that the weld button be
fully depressed and held until the welding
is complete, while other welders required
only that the button be fully depressed and
then quickly released. There will be a
shower of sparks from the welding action.
Be sure you are wearing either safety glasses
or a face shield before welding and then
stand back from the welder when you push
the button.
5. When the welding is complete, release
the jaw clamps and remove the band from
the welder. Inspect the band to be sure it
is straight and welded completely across.
Do not bend or flex the band at this- time
to test the weld. The welding process
has made the weld and the area near it hard
and brittle and breakage will probably
occur.
6. Place the lever that controls movement
of the jaws in the anneal position. This
should separate the jaws again. Set the
control that regulates the anneal tempera-
ture to the setting for the width of the
band.
7. Place the band in the clamping jaws with
the teeth toward the welder and the welded
section in the center of the jaw opening.
Close the jaws.
8. The band is ready to be annealed. Push
and then quickly release the anneal button
repeatedly until the welded area becomes
a dull cherry red. (Do NOT push and hold
the anneal button. This will overheat and
damage the band.) After the proper
temperature is reached, push the anneal
button and release it with increasingly
longer intervals between the push cycle to
allow the band to cool slowly.
9. The metal buildup resulting from the weld
must be ground off. Using the attached
grinding wheel, remove the weld buildup
from both sides and the back of the band
until the band fits snugly into the correct
slot on the saw band thickness gauge
mounted on the welder. Do this grinding
carefully to prevent looseness or binding
between the saw guides and the band. Be
careful not to grind on the teeth of the
band.
10. Repeat the procedure for annealing in step
8 after grinding the blade.
11. The welding process is complete. To test
your weld, hold the band with both hands
and form a radius in the band slightly
smaller than the smallest wheel on the
bandsaw by bringing your hands together.
Move your hands up and down in
opposite directions and observe the
welded area as it rolls around the radius
that you formed.
Installing Bands
Insert saw band or tool guides of the correct
size for the band you are going to install. Adjust
the upper band wheel for a height that will allow
you to easily loop the band around the wheels.
Then place one end of the loop over the upper
band wheel and the other end of the loop around
the lower band wheel, being sure that the teeth
are pointing downward on the cutting side of the
band loop and that the band is properly located
in the guides. Place a slight tension on the band
by turning the upper wheel takeup hand wheel
and revolve the upper band wheel by hand until
the band has found its tracking position. If
the band does not track on the center of the
crowns of the wheels, use the upper wheel tilt
. . ,
band guide rollers or inserts so that you have a
total clearance of 0.001 to 0.002 inch between the
sides of the band back and the guide rollers or
inserts, and a slight contact between the back edge
of the band back and the backup bearings of the
guides. When you have set the band guide
clearance, increase the band tension. The amount
of tension to put on the band depends on the
width and gauge of the band. A narrow, thin band
will not stand as much tension as a wider or
thicker band. Too much tension will cause the
saw to break; insufficient tension will cause
the saw to run off the cutting line. The best
way to obtain the proper tension is to start
with a moderate tension; if the saw tends to
run off the line when cutting, increase the
tension slightly.
SAWING OPERATIONS
As previously mentioned, the types of sawing
operations possible with a band tool machine are
straight, angular, contour, inside, and disk
cutting. The procedures for each of these cutting
operations are described in the following
paragraphs; but first, let us consider the general
rules applicable to all sawing operations.
28.49X
Figure 5-18. — Upper wheel tilt adjustment.
adjust me table, it necessary, to suit the
angle of the cut.
• Use the proper blade and speed for each
cutting operation. This ensures not only
the fastest and most accurate work but also
longer saw life.
• Always be sure the band guide inserts are
the correct size for the width of the band
installed and that they are properly
adjusted.
• Before starting the machine, adjust the
height of the upper band guide so that it
will clear the work from 1/8 to 3/8 inch.
The closer the guide is to the work, the
greater the accuracy.
• When starting a cut, feed the work to the
saw gradually. After the saw has started
the kerf, increase the feed slowly to the
recommended pressure. Do not make a
sudden change in feed pressure because
such a change may cause the band to
break.
Be sure the saw band and guides are
properly lubricated.
Use lubricants and cutting coolants as
recommended by the manufacturer of your
machine.
Straight Cuts with Power Feed
1. Change band guides as necessary. Select
and install the proper band for the job and
adjust the band guides.
2. Place the workpiece on the table of the
machine and center the work in the work
jaw.
3. Loop the feed chain around the work
jaw, the chain roller guides, and the
5-15
left-right guide sprocket, as shown in
figure 5-19.
4. Determine the proper band speed and set
the machine speed accordingly.
5. Start the machine and feed the work to the
saw in the manner described in the general
rules of operation given in the preceding
section. Use the left-right control for
guiding the work along the layout line.
Angular Cutting
Angular or bevel cuts on flat pieces are made
in the same way as straight cuts except that the
table is tilted to the desired angle of the cut as
shown in figure 5-20.
Contour Cutting
Contour cutting, that is, following straight,
angle, and curved layout lines, can be done
28.51X
Figure 5-20.— Angular cutting.
LEFT-RIGHT GUIDE SPROCKET
LEFT-RIGHT CONTROL KNOB
28. SOX
Figure 5-19. — Work jaw and feed chain adjustment.
for guiding the work along the layout line when
power feed is used. A fingertip control for
actuating the sprocket is located at the edge of
the work table. If there are square corners in the
layout, drill a hole adjacent to each corner; this
will permit the use of a wider band, greater feed
pressure, and faster cutting. Figure 5-21 shows the
placement of corner holes on a contour cutting
layout.
28.52X
Figure 5-21. — Sharp radii cutting eliminated by drilling
corner holes.
To make an inside cut, drill a starting hole
slightly larger in diameter than the width of the
band you are going to use. Remove the band from
the machine. Shear the band; slip one end through
the hole, and then splice the band. When the band
has been spliced and reinstalled, the machine is
ready for making the inside cut as illustrated in
figure 5-22.
Disk Cutting
Disk cutting can be done either offhand by
laying out the circle on the workpiece and follow-
ing the layout circle or by using a disk cutting
attachment which automatically guides the work
so that a perfect circle is cut. Figure 5-23 shows
a disk cutting attachment in use. The device
consists of a radius arm, a movable pivot point,
and a suitable clamp for attaching the assembly
to the saw guidepost. To cut a disk using this
device, lay out the circle and punch a center point.
Clamp the radius arm to the guidepost. Position
the workpiece (fig. 5-23) so that the saw teeth are
tangent to the scribed circle. Adjust the pivot
point radially and vertically so that it seats in the
center-punch mark; then clamp the pivot point
securely. Then rotate the work around the pivot
point to cut the disk.
Filing and Polishing
In filing and polish finishing, the work is
manually fed and guided to the band. Proper
28.53X
Figure 5-22.— Inside cutting.
28.54X
Figure 5-23. — Disk-cutting attachment.
5-17
installation of the guides and backup support
strips is very important if good results are to be
obtained. A guide fence similar to the one shown
in figure 5-24 is very helpful when working to
close tolerances. Be sure to wear goggles or an
eye protection shield when filing and polishing,
and above all, be careful of your fingers. For
proper band speeds and work pressures, consult
the manufacturer's technical manual for the
machine you are using.
DRILLING MACHINES
AND DRILLS
Although drilling machines or drill presses are
commonly used by untrained personnel, you
cannot assume that operating these machines
proficiently is simply a matter of inserting the
proper size drill and starting the machine. As a
Machinery Repairman, you will be required to
perform drilling operations with a great degree
of accuracy. It is therefore necessary for you to
be well acquainted with the types of machines and
the methods and techniques of operation of drill
presses and drills found in Navy machine shops.
DRILLING MACHINE
SAFETY PRECAUTIONS
Because of the widespread use of the drill press
by such a diverse group of people with different
training and experience backgrounds, some
28.55X
Figure 5-24.— Polish finishing.
unsafe operating practices have become rather
routine in spite of the possibility of serious injury.
The basic safety precautions for the use of a drill
press are listed below:
• Always wear safety glasses or a face shield
when you operate a drill press.
• Keep loose clothing clear of rotating parts.
• NEVER attempt to hold a piece being
drilled in your hand. Use a vise, hold-down
bolts or other suitable clamping device.
• Check the twist drill to ensure that it is
properly ground and is not damaged or
bent.
• Make sure that the cutting tool is held
tightly in the drill press spindle.
• Use the correct feeds and speeds.
• When feeding by hand, take care to
prevent the drill from digging in and taking
an uncontrolled depth of cut.
• Do NOT remove chips by hand. Use a
brush.
TYPES OF MACHINES
The two types of drilling machines or drill
presses common to the Navy machine shop are
the upright drill press and the radial drill
press. These machines have similar operating
characteristics but differ in that the radial drill
provides for positioning the drilling head rather
than the workpiece.
Upright drill presses discussed in this section
will be the general purpose, the heavy duty, and
the sensitive drill presses. One or more of these
types will be found on practically all ships. They
are classified primarily by the size of drill that can
be used, and by the size of the work that can be
set up.
The GENERAL PURPOSE DRILL PRESS
(ROUND COLUMN), shown in figure 5-25, is
perhaps the most common upright type of
machine and has flexibility in operational
characteristics. The basic components of this
machine are shown in the illustration.
SPEED
CHANGE
GEARS
DRIVE
MECHANISM
ARM,
SPINDLE
HEAD
SPINDLE
WORKTABLE
BASE
Figure 5-25.— General purpose drill press.
11.9
The BASE has a machined surface with T-slots
for heavy or bulky work.
The COLUMN supports the work table, the
drive mechanism and the spindle head.
The WORK TABLE and ARM can be
swiveled around the column and can be moved
up or down to adjust for height. In addition, the
work table may be rotated 360 ° about its own
center.
The SPINDLE HEAD guides and supports
the spindle and can be adjusted vertically to
provide maximum support near the spindle
socket.
The SPINDLE is a splined shaft with a Morse
taper socket for holding the drill. The spline
permits vertical movement of the spindle while it
is rotating.
HEAVY DUTY DRILL PRESSES (BOX
COLUMNS) are normally used in drilling large
holes. They differ from the general purpose drill
presses in that the work table moves only
vertically. The work table is firmly gibbed to
vertical ways or tracks on the front of the column
and is further supported by a heavy adjusting
screw from the base to the bottom of the table.
As the table can be moved only vertically, it is
necessary to position the work for each hole.
The SENSITIVE DRILL PRESS shown in
figure 5-26 is used for drilling small holes in work
under conditions which make it necessary for the
operator to "feel" what the cutting tool is doing.
The tool is fed into the work by a very simple
device — a lever, a pinion and shaft, and a rack
which engages the pinion. These drills are nearly
always belt-driven because the vibration caused
FEED LEVER
11.10
Figure 5-26.— Sensitive drill press.
5-19
by gearing would be undesirable. Sensitive drill
presses are used in drilling holes less than one-
half inch in diameter. The high-speed range of
these machines and the holding devices used make
them unsuitable for heavy work.
The RADIAL DRILL PRESS, shown in
figure 5-27, has a spindle head on an arm that can
be rotated axially on the column. The spindle head
may be traversed horizontally along the ways of
the arm, and the arm may be moved vertically on
the column. This machine is especially useful
when the workpiece is bulky or heavy or when
many holes can be drilled with one setup. The arm
and spindle are designed so that the drill can be
positioned easily over the layout of the workpiece.
Some operational features that are common
to most drilling machines are: (1) high- and low-
speed ranges provided from either a two-speed
drive motor or a low-speed drive gear; (2) a
reversing mechanism for changing the direction
of rotation of the spindle by either a reversible
motor or a reversing gear in the drive gear train;
(3) automatic feed mechanisms which are driven
from the spindle and feed the cutting tool at a
selected rate per revolution of the spindle; (4)
depth setting devices which permit the operator
to preset the required depth of penetration o
cutting tool; and (5) coolant systems to prc
lubrication and coolant to the cutting tool
On other machines the control levers m*
placed in different positions; however, they i
the same purposes as those shown. In usini
locking clamps to lock or "dog down" the i
or head of a drill after it is positioned ove
work, make sure that the locking action doe
cause the drill or work to move slightly o\
position.
TWIST DRILL
The twist drill is the tool generally usec
drilling holes in metal. This drill is formed e
by forging and twisting grooves in a flat str:
steel or by milling a cylindrical piece of st
In figure 5-28 you see the principal par
a twist drill: the BODY, the SHANK, anc
POINT. The portion of the LAND behinc
MARGIN is relieved to provide BC
CLEARANCE. The body clearance assisi
reducing friction during drilling. The LIP i;
cutting edge, and on the CONE of the drill i
COLUMN
ARM ELEVATING SCREW
COMBINATION ARM ELEVATING
AND LOCKING LEVER
COLUMN LOCKING
LEVER
SPINDLE HEAD
FEED CHANGE LEVER
SPINDLE SOCKET
Figure 5-27.— Radial drill press.
CUTTING EDGE
FLUTE
SHANK <
TANG
Figure 5-28.— The parts of a twist drill.
44.20
area called the LIP CLEARANCE. DEAD
CENTER is the sharp edge located at the tip end
of the drill. It is formed by the intersection of the
cone-shaped surfaces of the point and should
always be in the exact center of the axis of the
drill. Do not confuse the point of the drill with
the dead center. The point is the entire cone-
shaped surface at the cutting end of the drill. The
WEB of the drill is the metal column which
separates the flutes. It runs the entire length of
the body between the flutes and gradually
increases in thickness toward the shank, giving
additional rigidity to the drill.
The TANG is found only on tapered-shank
tools. It fits into a slot in the socket or spindle
remove the drill from the socket with the aid of
a drill drift. (NEVER use a file or screwdriver to
do this job.)
The SHANK is the part of the drill which
fits into the socket, spindle, or chuck of the
drill press. The types of shanks that are most
often found in Navy machine shops are the
Morse taper shank, shown in figures 5-28 and
5-29A and the straight shank, shown in figures
5-29B and 5-29C.
Twist drills are made from several different
materials. Drills made from high-carbon steel
are available; however, the low cutting speed
required to keep this type of drill from becoming
permanently dull limits their use considerably.
Most of the twist drills that you will use are made
from high-speed steel and will have two flutes (fig.
5-28).
Core drills (fig. 5-29 A) have three or more
flutes and are used to enlarge a cast or previously
drilled hole. Core drills are more efficient and
more accurate when used to enlarge a hole than
Figure 5-29.— Twist drills: A. Three-fluted core drill;
B. Carbide tipped drill with two helical flutes;
C. Carbide tipped die drill with two flutes parallel to the
drill axis.
5-21
the standard two-fluted drill. Core drills are made
from high-speed steel.
A carbide-tipped drill (fig. 5-29B), which is
similar in appearance to a standard two-fluted
drill with carbide inserts mounted along the lip
or cutting edge, is used for drilling nonferrous
metals, cast iron, and cast steel at high speeds.
These drills are not designed for drilling steel and
alloy metals.
A carbide-tipped die drill, or spade drill as it
is often called (fig. 5-29C), has two flutes that run
parallel to the axis of the drill as opposed to the
helical flutes of the standard two-fluted drill. This
drill can be used to drill holes in hardened steel.
A standard two-fluted drill made from cobalt
high-speed steel is superior in cutting efficiency
and wear resistance to the high-speed steel drill
and is used at a cutting speed between the speed
recommended for a high-speed steel drill and a
carbide-tipped drill.
A solid carbide drill with two helical flutes is
also available and can be used to drill holes in hard
and abrasive metal where no sudden impact will
be applied to the drill.
Drill sizes are indicated in three ways: by
measurement, letter, and number. The nominal
measurements range from 1/16 to 4 inches or
larger, in 1/64-inch steps. The letter sizes run from
"A" to "Z" (0.234 to 0.413 inch). The number
sizes run from No. 80 to No. 1 (0.0135 to 0.228
inch).
Before putting a drill away, wipe it clean and
then give it a light coating of oil. Do not leave
drills in a place where they may be dropped or
where heavy objects may fall on them. Do not
place drills where they will rub against each other.
DRILLING OPERATIONS
Using the drill press is one of the first skills
you will learn as a Machinery Repairman.
Although a drill press is relatively simpler to
operate and understand than other machine tools
in the shop, the requirements for accuracy and
efficiency in its use are no less strict. To achieve
skill in drilling operations, you must have a
knowledge of feeds and speeds, how the work is
held, and how to ensure accuracy.
Speeds, Feeds, and Coolants
The cutting speed of a drill is expressed in feet
per minute (fpm). This speed is computed by
multiplying the circumference of the drill (in
inches) by the revolutions per minute (rpm) of
the drill. The result is then divided by 12.
For example, a 1/2-inch drill, which has a
circumference of approximately 11/2 inches,
turned at 100 rpm has a surface speed of
150 inches per minute. To obtain fpm, divide this
figure by 12 which results in a cutting speed of
approximately 12 1/2 feet per minute.
The correct cutting speed for a job depends
on many variable factors. The machinability of
a metal, any heat treatment process such as
hardening, tempering, or normalizing, the type
of drill used, the type and size of the drilling
machine, the rigidity of the setup, the finish and
accuracy required, and whether or not a cutting
fluid is used are the main factors that you must
consider when selecting a cutting speed for
drilling. The following cutting speeds are
recommended for high-speed steel twist drills.
Carbon steel drills should be run at one-half these
speeds, while carbide may be run at two to three
times these speeds. As you gain experience in
using twist drills, you will be able to vary the
speeds to suit the job you are doing.
Low carbon steel 80-1 10 fpm
Medium carbon steel 70- 80 fpm
Alloy steel 50-70 fpm
Corrosion-resistant
steel (stainless) 30-40 fpm
Brass 200-300 fpm
Bronze 200-300 fpm
Monel 40-50 fpm
Aluminum 200-300 fpm
Cast iron 70-150 fpm
The speed of the drill press is given in rpm.
Tables giving the proper rpm at which to run a
drill press for a particular metal are usually
available in the machine shop, or they may be
found in machinists' handbooks. A formula may
be used to determine the rpm required to give a
specific rate of speed in fpm for a specific size
drill. For example, if you wish to drill a
5-22
TI X D
50 x 12
3. 1416 x 1
600
3.1416
= 190
where
fpm = required speed in feet per minute
7r = 3.1416
12 = constant
D = diameter of drill in inches
The feed of a drill is the rate of penetration
into the work for each revolution. Feed is
expressed in thousandths of an inch per
revolution. In general, the larger the drill, the
heavier the feed that may be used. Always
decrease feed pressure as the drill breaks through
the bottom of the work to prevent drill breakage
and rough edges. The rate of feed depends on the
size of the drill, the material being drilled, and
the rigidity of the setup.
Use the following feed rates, given in
thousandths of an inch per revolution (ipr), as a
general guide until your experience allows you to
determine the most efficient feed rate for each
different job.
Drill Diameter
No. 80 to 1/8 inch
1/8 inch to 1/4 inch
1/4 inch to 1/2 inch
1/2 inch to 1 inch
Greater than 1 inch
IPR
0.001-0.002
0.002-0.004
0.004-0.007
0.007-0.015
0.015-0.025
Use the lower feed rate given for each range of
drill sizes for the harder materials such as tool
steel, corrosion-resistant steel and alloy steel. Use
the higher feed rate for brass, bronze, aluminum,
and other soft metals.
corrosion-resistant steel and certain nonferrous
metals such as Monel. For most drilling opera-
tions, you can use soluble oil. You may drill
aluminum, brass, cast iron, bronze and similarly
soft metals dry unless you use a high drilling
speed and feed. Use mineral-lard oil for the
exceptionally hard metals.
Holding the Work
Before drilling, be sure your work is well
clamped down. On a sensitive drill press you will
probably have to use a drill vise and center the
work by hand. Because the work done on this drill
press is comparatively light, the weight of the vise
is sufficient to hold the work in place.
The larger drill presses have slotted tables to
which work of considerable weight can be bolted
or clamped. T-bolts, which fit into the T-slots on
the table, are used for securing the work. Various
types of clamping straps, shown in figure 5-30,
also can be used. (Clamping straps are also
identified as clamps or dogs.) The U-strap is the
most convenient for many setups because it has
a larger range of adjustment.
It is often necessary to use tools such as
steel parallels, V-blocks, and angle plates for
supporting and holding the work. Steel parallels
GOOSENECK STRAP
U-STRAP
11.15
Figure 5-30.— Common types of clamping straps.
5-23
are used to elevate the work above the table so
you can better see the progress of the drill.
V-blocks are used for supporting round stock, and
angle plates are used to support work where a hole
is to be drilled at an angle to another surface.
Some examples of setups are shown in figure 5-31.
Drilling Hints
To ensure accuracy in drilling, position the
work accurately under the drill, and use the proper
techniques to prevent the drill from starting off
center or from moving out of alignment during
the cut. Here are some hints that will aid you in
correctly starting and completing a drilling job.
1. Before setting up the machine, wipe all
foreign matter from the spindle and the
table of the machine. A chip in the spindle
socket will cause the drill to have a
wobbling effect which tends to make the
hole larger than the drill. Foreign matter
on the work holding device under the
workpiece tilts it in relation to the spindle,
causing the hole to be out of alignment.
2. Center punch the work at the point to be
drilled. Position the center-punched
workpiece under the drill. Use a dead
center inserted in the spindle socket to
align the center-punch mark on the
workpiece directly under the axis of the
spindle.
ANGLE PLATE
DRILL PRESS
TABLE
3 . Bring the spindle with the inserted center
down to the center-punch mark and hold
it in place lightly while fastening the locking
clamps or dogs. This will prevent slight
movement of the workpiece, table, or both
when they are clamped in position.
4. Insert a center drill (fig. 5-32) in the spindle
and make a center hole to aid in starting
the drill. This is not necessary on small
drills on which the dead center of the drill
is smaller than the center-punch mark, but
on large drills it will prevent the drill
from "walking" away from the center-
punch mark. This operation is especially
important in drilling holes on curved
surfaces.
5 . Using a drill smaller than the required size
to make a pilot hole will increase accuracy
by eliminating the need for the dead center
oif the finishing drill to do any cutting,
decreasing the pressure required for feeding
the finishing drill and decreasing the width
of cut taken by each drill. In drilling holes
over 1 inch in diameter, you may need to
use more than one size of pilot drill to
increase the size of the hole by steps until
the finished size is reached.
6. If the outer corners of the drill (margin)
appear to be wearing too fast or have a
burnt look, the drill is going too fast.
7. If the cutting edges (lips) chip during
drilling, too much lip clearance has been
ground into the drill, or you are using too
heavy a feed rate.
8. A very small drill will break easily if the
drill is not going fast enough.
9. When a hole being drilled is more than
three or four times the drill diameter in
depth, back out the drill frequently to clear
the chips from the flutes.
Figure 5-31.— Work mounted on the table.
11.16 Figure 5-32.-
-Combined drill and countersink (center
drill).
10. If the drill becomes hot quickly, is difficult
to feed, squeals when being fed and
produces a rough finish in the hole, it has
become dull and requires resharpening.
11. If the drill has cutting edges of different
angles or unequal length, the drill will cut
with only one lip and will wobble in
operation, resulting in an excessively over-
sized hole.
12. If the drill will not penetrate the work,
insufficient or no lip clearance has been
ground into the drill.
13. The majority of drilled holes will be over-
sized regardless of the care taken to ensure
a good setup. Generally, you can expect
the oversize to average an amount equal
to 0.004 inch times the drill diameter
plus 0.003 inch. For example, you
can expect a 1/2-inch drill to produce
a hole approximately 0.505 in diameter
([0.004 x 0.500] + 0.003). This amount
can vary up or down depending on the
condition of the drilling machine and the
twist drill.
Correcting Offcenter Starts
A drill may start off center because of
improper center drilling, careless starting of the
drill, improper grinding of the drill point, or hard
spots in the metal. To correct this condition, take
a half-round chisel and cut a groove on the side
of the hole toward which the center is to be drawn.
(See fig. 5-33.) The depth of this groove depends
upon the eccentricity (deviation from center) of
the partially drilled hole with the hole to be drilled.
When the groove is drilled out, lift the drill from
the work and check the hole for concentricity with
the layout line. Repeat the operation until the edge
of the hole and the layout line are concentric.
When you use this method to correct an off
center condition, be very careful that the cutting
edge or lip of the drill does not grab in the chisel
groove. Generally, you should use very light feeds
until you establish the new center point. (Heavy
feeds cause a sudden bite in the groove which may
result in the work being pulled out of the holding
device, or the drill being broken.)
Counterboring, Countersinking,
and Spotfacing
A counterbore is a drilling tool used in the drill
press to enlarge portions of previously drilled
holes to allow the heads of fastening devices to
be flush with or below the surface of the
workpiece. The parts of a counterbore that
distinguish it from a regular drill are a pilot, which
aligns the tool in the hole to be counterbored, and
the cutting edge of the counterbore, which is flat
so that a flat surface is left at the bottom of the
cut, enabling fastening devices to seat flat against
the bottom of the counterbored hole.
Figure 5-34 shows two types of counterbores
and an example of a counterbored hole. The basic
difference between the counterbores illustrated is
that one has a removable pilot and the other does
not. A conterbore with provisions for a removable
pilot can be used in counterboring a range of hole
sizes by simply using the appropriate size pilot.
The use of the counterbore with a fixed pilot is
limited to holes of the same dimensions as the
pilot.
11.17
Figure 5-33.— Using a half-round chisel to guide a drill to
J*|
piL<5r
TANG TAPER SHANK SETSCREW
COUNTERBORE
Countersinks are used for seating flathead
screws flush with the surface. The basic difference
between countersinking and counterboring is that
a countersink makes an angular sided recess, while
the counterbore forms straight sides. The angular
point of the countersink acts as a guide to center
the tool in the hole being countersunk. Figure 5-35
shows two common types of countersinks.
Spotfacing is an operation that cleans up the
surface around a hole so that a fastening device
can be seated flat on the surface. This operation
is commonly required on rough surfaces that have
not been machined and on the circumference of
concave or convex workpieces. Figure 5-36 shows
an example of spotfacing and the application of
spotfacing in using fastening devices. This opera-
tion is commonly done by using a counterbore.
Reaming
In addition to drilling holes, the drill press may
be used for reaming. For example, when specifica-
tions call for close tolerances, the hole must be
drilled slightly undersize and then reamed to the
exact dimension. Reaming is also done to remove
burrs in a drilled hole or to enlarge a previously
used hole for new applications.
Machine reamers have tapered shanks that fit
the drilling machine spindle. Be sure not to
confuse them with hand reamers, which have
straight shanks. Hand reamers will be ruined if
they are used in a machine.
There are many types of reamers, but the ones
used most extensively are the straight-fluted,
the taper, and the expansion types. They are
illustrated in figure 5-37.
m
28.59
Figure 5-35. — Countersinks.
•5-X2 HEX. HEAD
CAP SCREW
SPOT
FACE
COUNTERBORE
PILOT
BODY.
HOLE
A B
Figure 5-36. — Examples of spotfacing.
STRAIGHT FLUTED REAMER
TAPER REAMER
EXPANSION REAMER
Figure 5-37. — Reamers.
5.10
The STRAIGHT-FLUTED REAMER is
made to remove small portions of metal and to
cut along the edges to bring a hole to close
tolerance. Each tooth has a rake angle which is
comparable to that on a lathe tool.
The TAPER PIN REAMER has a tapered
body and is used to smooth and true tapered holes
and recesses. The taper pin reamer is tapered at
1/4 inch per foot.
The EXPANSION REAMER is especially
useful in enlarging reamed holes by a few
thousandths of an inch. It has a threaded plug
in the lower end which expands the reamer to
various sizes.
To ream a hole, follow the steps outlined
below:
1 . Drill the hole about 1/64 inch less than the
reamer size.
2. Substitute the reamer in the drill press
without removing the work or changing the
position of the work.
3. Adjust the machine for the proper spindle
speed. (Reamers should turn at about one-
half the speed of the twist drill.)
4. Use a cutting oil to ream. Use just enough
pressure to keep the reamer feeding into the
work; excessive feed may cause the reamer
to dig in and break.
5. The starting end of a reamer is slightly
tapered; always run it all the way through
the hole. NEVER RUN A REAMER
BACKWARD because the edges are likely
to break.
Tapping
Special attachments that permit cutting
internal screw threads with a tap driven by the
drilling machine spindle can save considerable
time when a number of identically sized holes
must be threaded. The attachment is equipped
5-26
with a reversing device that automatically changes
the direction of rotation of the tap when either
the tap strikes the bottom of the hole or a slight
upward pressure is applied to the spindle down-
feed lever. The reversing action takes place
rapidly, permitting accurate control over the depth
of the threads being cut. A spiral-fluted tap should
be used to tap a through hole while a standard
straight-fluted plug tap can be used in a blind hole.
A good cutting oil should always be used in
tapping with a machine.
DRILLING ANGULAR HOLES
An angular hole is a hole having a series of
straight sides of equal length. A square (4-sided),
a hexagon (6-sided), a pentagon (5 -sided), and an
octagon (8-sided) are examples of angular holes.
An angular hole that goes all the way through a
part can be made easily by using a broach;
however, a blind hole, one in which the angular
hole does not go all the way through the part, can-
not be made with a broach. There are two
methods available to you for machining a blind
angular hole. One method, the shaper, will be
covered later in Chapter 12. The second method,
drilling the angular hole in a drill press or on a
lathe, is described briefly in the following
paragraphs.
EQUIPMENT
The equipment required to drill angular holes
is specialized and is designed to do only this
particular operation. The machining process,
known as the WATTS METHOD, was developed
by the Watts Bros. Tool Works, Incorporated
and the required equipment is patented and
manufactured exclusively by that company. A
brief description of the equipment is included in
the following paragraphs. A complete description
of the equipment and its use is available from the
manufacturer when the equipment is ordered.
Chuck
The chuck (fig. 5-3 8 A) used in drilling angular
holes is of an unusual design in that while it holds
the drill in a position parallel to the spindle of the
lathe or drill press and prevents it from revolving,
FLOATING CHUCK
B
GUIDE PLATES
GUIDE HOLDER
D
SLIP BUSHINGS
SQUARE DRILL
HEXAGON
DRILL
Figure 5-38.— Equipment for drilling angular holes. A. Chuck; B. Guide plate; C. Guide holder; D. Slip bushing; E. Angular
drill.
it allows the drill to float freely so that the flutes
can follow the sides of the angular hole in the
guide plate. The chuck is available with a Morse
taper shank to fit most lathes and drill presses.
There are several different sizes of chucks, each
capable of accepting drills for a given range of
hole sizes.
Guide Plates
The guide plate (fig. 5-3 8B) is the device that
causes the drill to make an angular hole. The free-
floating action of the chuck allows the drill to
randomly follow the straight sides and corners of
the guide plate as it is fed into the work. Attach
the guide plate to a guide holder when you use
a lathe and directly to the work when you use a
drill press. A separate guide plate is required for
each different shape and size hole.
Guide Holder
The guide holder (fig. 5-38C), as previously
stated, holds the guide plate and is placed over
the outside diameter of the work and locked in
place with a setscrew. The guide holder is used
when the work is being done in a lathe and is not
required for drill press operations.
Slip Bushings
Prior to actually drilling with the angular hole
drill, you must drill a normal round hole in the
center of the location where the angular hole will
be located. This pilot hole reduces the pressure
that would otherwise be required to feed the
angular drill and ensures that the angular drill will
accurately follow the guide plate. In a lathe, you
need only drill a hole using the tailstock since it
and the chuck will automatically center the pilot
hole. In a drill press, you must devise a method
to assist you in aligning the pilot hole. A slip
bushing will do the job quickly and accurately.
The slip bushing (fig. 5-38D) fits into the guide
plate and has a center hole which is the correct
size for the pilot hole of the particular size angular
hole being drilled. After you have installed the
bushing, position the correct drill so that it enters
the hole in the slip bushing and drill the pilot hole.
Angular Drill
The angular drills (fig. 5-38E) are straight
fluted and have one less flute or cutting lip than
the number of sides in the angular hole they are
designed to drill. The drills have straight shanks
with flats machined on them to permit securing
Figure 5-39. — Lathe setup for drilling an angular hole.
5-28
them in the floating chuck with setscrews. The
cutting action of the drill is made by the cutting
lips or edges on the front of the drill.
OPERATION
The procedure for drilling an angular hole is
similar to that for drilling a normal hole, differing
only in the preliminary steps required in setting
the job up. The feeds and speeds for drilling
angular holes should be slower than those
recommended for drilling a round hole of the
same size. Obtain specific recommendations
concerning feeds and speeds from the informa-
tion provided by the manufacturer. Use a coolant
to keep the drill cool and help flush away the
chips. The following procedures apply when the
work is being done on a lathe. See figure 5-39 for
an example of a lathe setup.
1 . Place the work to be drilled in the lathe
chuck. The work must have a cylindrical
outside diameter and the intended location
of the angular hole must be in the center
of the work.
2. Place the guide holder over the outside
diameter of the work and tighten the
setscrew. If the bore in the back of the
guide holder is larger than the diameter of
the work, make a sleeve to adapt the two
together. If the part to be drilled is short,
place it in the guide holder and place the
guide holder in the chuck.
3. Drill the pilot hole at this time. The size
of the pilot hole should be slightly smaller
than the distance across the flats of the
angular hole. The manufacturer makes
specific recommendations on pilot hole
sizes.
4. Attach the guide plate to the guide
holder.
5. Mount the floating chuck in the lathe
tailstock spindle and place the drill in the
chuck. Tighten the setscrews to hold the
drill securely.
6. You are now ready to drill the angular
hole. Do not force the drill into the
work too rapidly, and use plenty of
coolant.
The setup for drilling an angular hole using
a drill press differs in that instead of using a guide
holder, clamp the guide plate directly to the work
and drill the pilot hole by using a slip bushing
placed in the guide plate to ensure alignment.
Once you have positioned the work under the drill
press spindle and have drilled the pilot hole, do
not move the setup. Any movement will result in
misalignment between the work and the angular
drill.
METAL DISINTEGRATORS
There are occasions when a broken tap or a
broken hardened stud cannot be removed by the
usual removal methods previously covered. To
remove such a piece without damaging the
part, use a metal disintegrator. This machine
disintegrates a hole through the broken tap
or stud by the use of an electrically charged
electrode that vibrates as it is fed into the
work. The part to be disintegrated and the
mating part that it is screwed into must be
made from a material that will conduct electricity.
Figure 5-40 shows a disintegrator removing a
broken stud.
You can obtain the specific operating
procedure for the metal disintegrator from the
reference material furnished by the manufacturer;
however, there are several steps involved in
setting up for a disintegrating job that are
common to most of the models of disintegrators
found aboard Navy ships.
Setting up the part to be disintegrated is the
first step that you must do. Some disintegrator
models have a built-in table with the disintegrating
head mounted above it in a fashion similar to a
drill press. On a machine such as this, you need
only bolt the part securely to the table, ensuring
that the part makes good contact so that an
electrical ground is provided. Align the tap or
stud to be removed square with the table so the
electrode will follow the center of the hole
correctly. Misalignment could result in the
electrode leaving the tap or stud and damaging
the part. Use either a machinist's square laid on
the table or a dial indicator mounted on the
disintegrating head to help align the part. If the
part will not make an electrical ground to the table
or if the model of machine being used is designed
as an attachment to be mounted in a drill press
Figure 5-40. — Metal disintegrator removing a broken stud.
spindle, attach the disintegrator's auxiliary ground
cable to the part.
Selection of the correct electrode depends on
the diameter and length of the part to be removed.
As a general rule, the electrode should be large
enough in diameter to equal the smallest diameter
of a tap (the distance between the bottom of
opposite flutes). To remove a stud, the electrode
must not be so large that it could burn or damage
the part if a slight misalignment is present. Use
a scribe and a small magnet to remove any of the
stud material not disintegrated.
The coolant is pumped from a sump to the
disintegrating head and then through the
electrode, which is hollow, to the exact point of
the disintegrating action.
The specific controls which must be set may
vary among the different machines; however,
most have a control to start the disintegrating head
vibrating and a selector switch for the heat or
used. Some models have an automatic feed
control that regulates the speed that the electrode
penetrates the part to be removed. Regardless of
whether the feed is automatic or manual, it must
NOT be advanced so fast that it stops the
disintegrating head and the electrode from
vibrating. If this happens, the disintegrating
action will stop and the electrode could be bent
or broken.
5-31
OFFHAND GRINDING OF TOOLS
One requirement for advancement in the MR
rating is to demonstrate the ability to grind and
sharpen some of the tools used in the machine
shop. Equipment used for this purpose includes
bench, pedestal, carbide, and chip breaker
grinders and precision grinding machines. This
chapter contains information on the use of these
grinders and how to grind small tools by using
the offhand grinding technique. (Precision
grinding machines will be discussed in a later
chapter.)
Grinding is the removal of metal by the
cutting action of an abrasive. In offhand grinding
you hold the workpiece in your hand and position
it as needed while grinding. To grind accurately
and safely, using the offhand method, you must
have experience and practice. In addition, you
must know how to install grinding wheels on
pedestal and bench grinders and how to sharpen
or dress them. You must also know the safety
precautions concerning grinding.
To properly grind small handtools, single-
edged cutting tools, and twist drills, you must
know the terms used to describe the angles and
surfaces of the tools. You must also know the
composition of the material from which each tool
is made and the operations for which the to6l is
used.
GRINDING SAFETY
The grinding wheel is a fragile cutting tool
which operates at high speeds. Therefore, the safe
operation of bench and pedestal grinders is as
important to you as are proper grinding
techniques. Observance of safety precautions,
posted on or near all grinders used by the Navy,
is mandatory for your safety and the safety of
personnel nearby.
What are some the injuries that result from
grinding operations? Eye injuries caused by grit
generated during the grinding process are the most
common and the most serious. Abrasions caused
by bodily contact with the wheel are quite painful
and can be serious. Cuts and bruises caused by
segments of an exploding wheel, or a tool
"kicked" away from the wheel are other sources
of injury. Additionally, prior cuts and abrasions
can become infected if they are not protected from
grit and dust produced during grinding.
Safety in using bench and pedestal grinders is
primarily a matter of using common sense and
concentrating on the job at hand. Each time you
start to grind a tool, stop briefly to consider how
the observance of safety precautions and the use
of safeguards protect you from injury. Consider
the complications that could be caused by loss of
your sight, or loss or mutilation of an arm or
hand.
Some guidelines for safe grinding practices
are:
• Secure all loose clothing and remove rings
or other jewelry.
• Inspect the grinding wheel, wheel guards,
toolrest, and other safety devices to ensure
that they are in good condition and
positioned properly. Set the toolrest so that
it is within 1/8 inch of the wheel face and
level with the center of the wheel.
• Clean and adjust transparent shields
properly, if they are installed. Transparent
shields do not protect against dust and grit
that may get around a shield. You must
ALWAYS wear goggles while grinding.
Goggles with side shield give the best eye
protection.
• Stand aside when starting the grinder
motor until it has run for 1 minute. This
prevents injury in case the wheel explodes
from a defect that you did not notice.
• Use light pressure when you begin
grinding; too much pressure on a cold
wheel may cause the wheel to fail.
6-1
• On bench and pedestal grinders, grind only
on the face or periphery of a grinding
wheel unless the grinding wheel is
specifically designed for side grinding.
• Use a coolant to prevent the work from
overheating.
BENCH AND
PEDESTAL GRINDERS
Bench grinders (fig. 6-1) are small, self-
contained grinders which are usually mounted on
a workbench. They are used for grinding and
sharpening small tools such as lathe, planer, and
shaper cutting tools; twist drills; and handtools
such as chisels and center punches. These grinders
do not have installed coolant systems; however,
a container of water is usually mounted on the
front of the grinder.
Grinding wheels up to 8 inches in diameter and
1 inch in thickness are normally used on bench
grinders. A wheel guard encircles the grinding
wheel except for the work area. An adjustable
toolrest steadies the workpiece and can be moved
in or out or swiveled to adjust to grinding wheels
of different diameters. An adjustable eye shield
made of safety glass should be installed on the
upper part of the wheel guard. Position this shield
to deflect the grinding wheel particles away from
you.
Pedestal grinders are usually heavy duty bench
grinders which are mounted on a pedestal fastened
to the deck. In addition to the features of the
bench grinder, pedestal grinders normally have
a coolant system which includes a pump, storage
sump, and a hose and fittings to regulate and carry
the coolant to the wheel surface. Pedestal grinders
are particularly useful for rough grinding such as
"snagging" castings. Figure 6-2 shows a pedestal
grinder in use.
GRINDING WHEELS
A grinding wheel is composed of two basic
elements: (1) the abrasive grains, and (2) the
bonding agent. The abrasive grains may be
compared to many single point tools embedded
in a toolholder or bonding agent. Each of these
grains removes a very small chip from the
workpiece as it makes contact on each revolution
of the grinding wheel.
An ideal cutting tool is one that will sharpen
itself when it becomes dull. This, in effect, is what
happens to the abrasive grains. As the individual
grains become dull, the pressure that is generated
on them causes them to fracture and present new
sharp cutting edges to the work. When the grains
can fracture no more, the pressure becomes too
great and they are released from the bond, allow-
ing new sharp grains to contact the work.
SIZES AND SHAPES
Grinding wheels come in various sizes and
shapes. The size of a grinding wheel is determined
Figure 6-1.— Bench grinder.
28.61
Figure 6-2. — Grinding on a pedestal grinder.
spindle hole, and the width of its face. All the
shapes of grinding wheels are too numerous to
list in this manual, but figure 6-3 shows most of
the frequently used wheel shapes. The type
TYPEl
STRAIGHT
TYPE 2
CYLINDER
TYPE i
CUT-OFF
TYPE 6 STRAIGHT CUP
TYPE 5 RECESSED ONE SIDE
TYPE 7 RECESSED TWO SIDE
TYPE 12
DISH
TYPE il
TYPE 13
FLARING CUP
SAUCER
Figure 6-3. — Grinding wheel shapes.
manufacturers. The shapes are shown in cross-
sectional views. The specific job will dictate the
shape of the wheel to be used.
WHEEL MARKINGS AND
COMPOSITION
Grinding wheel markings are composed of six
stations. Figure 6-4 illustrates the standard
marking. The following information breaks down
the marking and explains each station — type of
abrasive, grain size, bond grade, structure, type
of bond, and the manufacturer's record symbol.
Study this information carefully, as it will be
invaluable to you in making the proper wheel
selection for each grinding job you attempt.
Type of Abrasive
The first station of the wheel marking is the
abrasive type. There are two types of abrasives:
natural and manufactured. Natural abrasives,
such as emery, corundum, and diamond, are used
only in honing stones and in special types of
grinding wheels. The common manufactured
abrasives are aluminum oxide and silicon carbide.
They have superior qualities and are more
economical than natural abrasives. Aluminum
oxide (designated by the letter A) is used for
C 60 I 8
ABRASIVE
GRAIN
TYPE
SIZE
A- ALUMINUM
10
OXIDE
12
-»>
•C-SILICON
14
CARBIDE
16
18
20
24
"-»»
60
1
600
\
BOND
GRADE
STRUCTURE
A-SOFT
1 - DENSE
8
2
C
3
D
4
E
5
F
6
G
7
H-TO
h
J3 TO
— "fc
I
P
9
"j
10
K
11
L
12
M
13
N
14 \
)
t
15- OPEN
Z-HARD
BOND
TYPE
V-VITRIFIED
S SILICATE
R-RU88ER
B-RESINOID
E-SHELLAC
0-OXYCHLOR-
IDE
Figure 6-4.— Standard marking system for grinding wheels (except diamond).
6-3
work such as cleaning up steel castings. Silicon
carbide (designated by the letter C), which is
harder but not as tough as aluminum oxide, is
used mostly for grinding nonferrous metals and
carbide tools. The abrasive in a grinding wheel
comprises about 40% of the wheel.
Grain Size
The second station of the grinding wheel
marking is the grain size. Grain sizes range from
10 to 500. The size is determined by the size of
mesh of a sieve through which the grains can pass.
Grain size is rated as follows: Coarse: 10, 12, 14,
16, 18, 20, 24; Medium: 30, 36, 46, 54, 60; Fine:
70, 80, 90, 100, 120, 150, 180; and Very Fine: 220,
240, 280, 320, 400, 500, 600. Grain sizes finer than
240 are generally considered to be flour. Fine grain
wheels are preferred for grinding hard materials,
as they have more cutting edges and will cut faster
than coarse grain wheels. Coarse grain wheels are
generally preferred for rapid metal removal on
softer materials.
Bond Grade (Hardness)
Station three of the wheel marking is the grade
or hardness of the wheel. As shown in figure 6-4,
the grade is designated by a letter of the alphabet;
grades run from A to Z, or soft to hard.
The grade of a grinding wheel is a measure
of the bond's ability to retain the abrasive grains
in the wheel. The grading of a grinding wheel from
soft to hard grade does not mean that the bond
or the abrasive is soft or hard; it means that the
wheel has either a small amount of bond (soft
grade) or a large amount of bond (hard grade).
Figure 6-5 shows magnified portions of both soft
grade and hard grade wheels. You can see by the
illustration that a part of the bond surrounds the
abrasive grains, and the remainder of the bond
forms into posts which both hold the grains to
the wheel and hold them apart from each other.
The wheel with the larger amount of> bonding
material has thick bond posts and will offer great
resistance to pressures generated in grinding. The
wheel with the least amount of bond will offer
less resistance to the grinding pressures. In other
words, the wheel with a large amount of bond is
a hard grade and the wheel with a small amount
of bond is a soft grade.
ABKASIVE
GRAIN
BOND
" COATING
OPEN SPACE
BOND POST
m
WHEEL A
WHEEL B
Figure 6-5. — How bond affects the grade of the wheel. Wheel
A, softer; wheel B, harder.
Structure
The fourth station of the grinding wheel
marking is the structure. The structure is
designated by numbers from 1 to 15, as illustrated
in figure 6-4. The structure of a grinding wheel
refers to the open space between the grains, as
shown in figure 6-5. Wheels with grains that are
very closely spaced are said to be dense; when
grains are wider apart, the wheels are said to be
open. The metal removal will be greater for open-
grain wheels than for close-grain wheels. Also
dense, or close grain, wheels will normally pro-
duce a finer finish. The structure of a grinding
wheel comprises about 20% of the grinding wheel.
Bond Type
The fifth station of the grinding wheel mark-
ing is the bond type. The bond comprises the
remaining 40% of the grinding wheel and is one
of the most important parts of the wheel. The
bond determines the strength of the wheel. The
6-4
VITRIFIED BOND.— Designated by the
letter V, this is the most common bond used in
grinding wheels. Approximately 15% of all
grinding wheels are made with vitrified bond. This
bond is not affected by oil, acid, or water.
Vitrified bond wheels are strong and porous, and
rapid temperature changes have little or no effect
on them. Vitrified bond is composed of special
clays. When heated to approximately 2300 °F the
clays form a glass-like cement. Vitrified wheels
should not be run faster than 6500 surface feet
per minute.
SILICATE BOND.— Silicate bond wheels are
designated by the letter S. The bond is made of
silicate of soda. Silicate bond wheels are used
mainly for large, slow rpm machines where a
cooler cutting action is desired. Silicate bond
wheels are softer than vitrified wheels; they release
the grains more readily than vitrified wheels.
Silicate bond wheels are heated to approximately
500 °F when they are made. This type of wheel,
like the vitrified bond wheel, must not be run at
a speed greater than 6500 surface feet per minute.
RUBBER BOND.— Rubber bond wheels are
designated by the letter R. The bond consists of
rubber with sulphur added as a vulcanizing agent.
The bond is made into a sheet into which the
grains are rolled. The wheel is stamped out of this
sheet and heated in a pressurized mold until the
vulcanizing action is completed. Rubber bond
wheels are very strong and are elastic. They are
used for thin cutoff wheels. Rubber bond wheels
produce a high finish and can be run at speeds
between 9,500 and 16,000 surface feet per minute.
RESINOID BOND.— Resinoid bond wheels
are designated by the letter B. Resinoid bond is
made from powdered or liquid resin with a
plasticizer added. The wheels are pressed and
molded to size and fired at approximately 320 °F.
Resinoid wheels are shock resistant and very
strong. They are used for rough grinding and as
cutoff wheels. Resinoid wheels, like rubber bond
wheels, can be run at a speed of 9,500 to 16,000
surface feet per minute.
SHELLAC BOND.— Shellac bond wheels are
designated by the letter E. Wheels of this type are
made from a secretion from Lac bugs. The
abrasive and bond are mixed and molded to shape
cutting action when used as cutoff wheels. Shellac
bond wheels can be run at speeds between 9,500
and 12,500 surface feet per minute.
OXYCHLORIDE BOND.— Oxychloride
bond wheels are designated by the letter O.
Oxychloride bond is made from chemicals and is
a form of cold-setting cement. This bond is
seldom used in grinding wheels but is used
extensively to hold abrasives on sanding disks.
Oxychloride bond wheels can be run at speeds
between 5,000 and 6,500 surface feet per minute.
Manufacturer's Record Symbol
The sixth station of the grinding wheel
marking is the manufacturer's record. This may
be a letter or number, or both. It is used by the
manufacturer to designate bond modifications or
wheel characteristics.
DIAMOND WHEELS
Diamond grinding wheels are classed by
themselves. Wheels of this type are very
expensive and should be used with care and only
for grinding carbide cutting tools. Diamond
wheels can be made from natural or manufactured
diamonds. They are marked similarly to
aluminum-oxide and silicon-carbide wheels,
although there is not a standard system. The first
station is the type of abrasive, designated D for
natural and SD for manufactured. The second
station is the grit size, which can range from 24
to 500. A 100-grain size might be used for rough
work, and a 220 for finish work. In a Navy
machine shop, you might find a 150-grain wheel
and use it for both rough and finish grinding. The
third station is the grade, designated by letters of
the alphabet. The fourth station is concentration,
designated by numbers. The concentration or
proportion of diamonds to bond might be
numbered 25, 50, 75, or 100, going from low to
high. The fifth station is the bond type, designated
B for resinoid, M for metal, and V for vitrified.
The sixth station may or may not be used; when
used it identifies bond modification. The seventh
station is the depth of the diamond section. This
is the thickness of the abrasive layer and ranges
from 1/32 to 1/4 inch. Cutting speeds range from
4,500 to 6,000 surface feet per minute.
6-5
GRAIN DEPTH OF CUT
On most ships, stowage space is limited.
Consequently, the inventory of grinding wheels
must be kept to a minimum. It would be
impractical and unnecessary to keep on hand a
wheel for every grinding job. With a knowledge
of the theory of grain depth of cut you can vary
the cutting action of the various wheels and with
a small inventory can perform practically any
grinding operation that may be necessary.
For ease in understanding this theory, assume
that a grinding wheel has a single grain. When
the grain reaches the point of contact with the
work, the depth of cut is zero. As the wheel and
the work revolve, the grain begins cutting into the
work, increasing its depth of cut until it reaches
a maximum depth at some point along the arc of
contact. This greatest depth is called the grain
depth of cut.
To understand what part grain depth of cut
plays in grinding, look at figure 6-6. Part A
illustrates a grinding wheel and a workpiece;
ab is the radial depth of cut, ad is the arc of
contact, and ef is the grain depth of cut. As the
wheel rotates, the grain moves from the point of
contact a to d in a given amount of time. During
the same time, a point on the workpiece rotates
RADIAL
DEPTH
OF CUT ob
ORIGINAL
WHEEL
amount of material represented by the shaded area
ade. Now refer to part B and assume that the
wheel has worn down to a much smaller size,
while the wheel and work speeds remain un-
changed. The arc of contact ad' of the smaller
wheel is shorter than the arc of contact ad of the
original (larger) wheel. Since the width of the
grains remains the same, decreasing the length of
the arc of contact will decrease the surface
(area = length x width) that a grain on the smaller
wheel covers in the same time as a grain on the
larger wheel. If the depth that each grain cuts into
the workpiece remains the same, the grain on the
smaller wheel will remove a smaller volume
(volume = length x width x depth) of material in
the same time as the grain on the larger wheel.
However, for both grains to provide the same
cutting action, they both have to remove the same
volume of material in the same length of time.
To make the volume of material the grain on the
smaller wheel removes equal that of the grain on
the larger wheel, you have to either make the grain
on the smaller wheel cut deeper into the workpiece
or cover a larger workpiece surface area at its
original depth of cut.
To make the grain cut deeper, you must
increase the feed pressure on the grain. This
increase of feed pressure will cause the grain to
be torn from the wheel sooner, making the wheel
act like a softer wheel. Thus, the grain depth of
cut theory says that as a grinding wheel gets
smaller, it will cut like a softer wheel because of
the increase in feed pressure required to maintain
its cutting action.
The opposite is true if the wheel diameter
increases. For example, if you replace a wheel that
is too small with a larger wheel, you must decrease
feed pressure to maintain the same cutting action.
The other previously mentioned way to make
a grain on a smaller wheel remove the same
amount of material as a grain on a larger wheel
is to keep the depth of cut the same (no increase
in feed pressure) while you increase the surface
area the grain contacts. Increasing the surface area
requires lengthening the contact area, since the
width remains the same. To lengthen the contact
area, you can either speed up the workpiece
rotation or slow down the wheel rotation. Either
of these actions will cause a longer surface strip
of the workpiece to come in contact with the grain
on the wheel, thereby increasing the volume of
material removed.
removing a larger volume of material, you must
decrease the surface of the workpiece with which
the grain comes into contact. You can do this by
either slowing down the workpiece rotation or
speeding up the wheel rotation.
Keep in mind that all of these actions are based
on the grain depth of cut theory. That is, making
adjustments to the grinding procedure to make
one wheel cut like another. The following
summary shows the actions you can take to make
a wheel act a certain way.
MAKE THE WHEEL ACT SOFTER (IN-
CREASE THE GRAIN DEPTH OF CUT)
Increase the work speed
Decrease the wheel speed
Reduce the diameter of the wheel and
increase feed pressure
MAKE THE WHEEL ACT HARDER
(DECREASE THE GRAIN DEPTH OF
CUT)
Decrease the work speed
Increase the wheel speed
Increase the diameter of the wheel and
decrease feed pressure
GRINDING WHEEL SELECTION
AND USE
The selection of grinding wheels for precision
grinding is based on such factors as the physical
properties of the material to be ground, the
amount of stock to be removed (depth of cut),
the wheel speed and work speed, and the finish
required. The selection of a grinding wheel that
has the proper abrasive, grain, grade, and bond
is determined by one or more of these factors.
An aluminum oxide abrasive is the most
suitable for grinding carbon and alloy steel, high-
speed steel, cast alloys and malleable iron. A
silicon carbide abrasive is the most suitable for
grinding nonferrous metals, nonmetallic
materials, and cemented carbides.
Generally, as you grind softer and more
ductile materials, you should select coarser grain
wheels. Also, if you need to remove a large
amount of material, use a coarse grain wheel
(except on very hard materials). If a good finish
is required, use a fine grain wheel. If the machine
6-7
you are using is worn, use may need to use a
harder grade to help offset the effects of wear on
the machine. Using a coolant also permits you to
use a harder grade of wheel. Table 6-1 lists
recommended grinding wheels for various
operations.
Figure 6-7 shows the type of grinding wheel
used on bench and pedestal grinders. When you
replace the wheel be sure that the physical
dimensions of the new wheel are correct for the
grinder on which it will be used. The outside
diameter, the thickness, and the spindle hole size
are the three dimensions that you must check. If
necessary, use an adapter (bushing) to decrease
the size of the spindle hole, so that it fits your
grinder.
The wheels recommended for grinding and
sharpening single point (lathe, planer, shaper, and
so on) tool bits made from high-carbon steel or
STRAIGHT WHEEL
Figure 6-7.— Grinding wheel for bench and pedestal grinders.
high-speed steel are A3605V (coarse wheel) and
A60M5V (fine or finish wheel). Stellite tools
should be ground on a wheel designated A46N5V.
These grinding wheels, which have aluminum
oxide as an abrasive material, should be used to
grind steel and steel alloys only. Grinding cast
iron, nonferrous metal or nonmetallic materials
with these grinding wheels will result in loading
or pinning of the wheel as the particles of the
material being ground become imbedded in the
Table 6-1. — Recommendations for Selecting Grinding Wheels
OPERATION
WHEEL DESIGNATION
MATERIAL
Abrasive
Grain
size
Grade
Structure
Bond
Mfg.
Symbol
Cylindrical
grinding
A
A
A
A
C
A
A
60
60
54
36
36
60
54
K
L
M
G
K
G
L
8
5
5
12
5
12
5
V
V
V
V
V
V
V
High-speed steel
Hardened steel
Soft steel
Stainless steel
Cast iron, brass,
aluminum
Nickel copper
(Monel)
General purpose
Surface grinding
A
A
A
A
C
A
A
46
60
46
36
36
60
24
H
F
J
G
J
G
H
8
12
5
12
8
12
8
V
V
V
V
V
V
V
High-speed steel
Hardened steel
Soft steel
Stainless steel
Cast iron and
bronze
Nickel copper
(Monel)
General purpose
Tool and
cutter grinding
A
A
A
46
54
60
K
L
K
8
5
8
V
V
V
High-speed steel or
cast alloy milling
cutter
Reamers
Taps
and possibly injure someone nearby.
WHEEL INSTALLATION
The wheel of a bench or pedestal grinder must
be properly installed; otherwise, the wheel will not
operate properly and accidents may occur. Before
a wheel is installed, it should be inspected for
visible defects and "sounded" to determine
whether it has invisible cracks. To properly sound
a wheel, hold it up by placing a hammer handle
or a short piece of cord through the spindle hole.
Using a nonmetallic object such as a screwdriver
handle or small wooden mallet, tap the wheel
lightly on its side. Rotate the wheel 1/4 of a turn
(90°) and repeat the test. A good wheel gives out
a clear ringing sound when tapped. If the tapping
produces a dull thud, the wheel is cracked and
should not be used.
You will find it easier to understand the
following information on mounting the wheel if
you refer to figure 6-8. Ensure that the shaft and
flanges are clean and free of grit and old blotter
material. Place the inner flange in place and
inch and no thicker than 0.125 inch for leather
or rubber. The blotter is used to ensure even
pressure on the wheel and to dampen the vibration
between the wheel and the shaft when the grinder
is operating.
Next, mount the wheel, and ensure that it fits
on the shaft without play, there should be a 0.002-
to 0.005 -inch clearance. You may need to scrape
or ream the lead bushing in the center of the wheel
to obtain this clearance. NEVER FORCE THE
WHEEL ONTO THE SHAFT. Forcing the wheel
onto the shaft may cause the wheel either to be
slightly out of axial alignment or to crack when
it is used.
The next item to install is another blotter,
followed by the outer flange. NOTE: the flanges
are recessed so they provide an even pressure on
the wheel. The flanges should be at least one-third
the diameter of the wheel.
Next, install the washer and secure the nut.
Tighten the securing nut sufficiently to hold the
wheel firmly; tightening too much may damage
the wheel.
TRUING AND DRESSING
THE WHEEL
Grinding wheels, like other cutting tools,
require frequent reconditioning of cutting surfaces
to perform efficiently. Dressing is the process of
cleaning their cutting face. This cleaning breaks
away dull abrasive grains and smoothes the
surface so that there are no grooves. Truing is the
removal of material from the cutting face of the
wheel so that the resulting surface runs absolutely
true to some other surface such as the grinding
wheel shaft.
The wheel dresser shown in figure 6-9 is used
for dressing grinding wheels on bench and
SAFETY HOOD
WHEEL-
Figure 6-8. — Method of mounting a grinding wheel.
Figure 6-9. — Using a grinding wheel dresser.
6-9
pedestal grinders. To dress a wheel with this tool,
start the grinder and let it come up to speed. Set
the wheel dresser on the rest as shown in figure
6-9 and bring it in firm contact with the wheel.
Move the wheel dresser across the periphery
of the wheel until the surface is clean and
approximately square with the sides of the wheel.
If grinding wheels get out of balance because
of out-of-roundness, dressing the wheel will
usually remedy the condition. A grinding wheel
can get out of balance if part of the wheel is
immersed in coolant. If this happens, remove the
wheel and dry it out by baking. If the wheel gets
out of balance axially, it probably will not affect
the efficiency of the wheel on bench and pedestal
grinders. This unbalance may be remedied simply
by removing the wheel and cleaning the shaft
spindle and spindle hole in the wheel and the
flanges.
CARBIDE TOOL GRINDER
The carbide tool grinder (fig. 6-10) looks much
like a pedestal grinder with the toolrest on the side
instead of on the front. The main components of
the carbide tool grinder are: a motor with the shaft
extended at each end for mounting the grinding
wheels; the pedestal which supports the motor and
is fastened to the deck; wheel guards which are
mounted around the circumference and back of
the grinding wheels as a safety device; and an
adjustable toolrest mounted in front of each wheel
for supporting the tool bits while they are being
ground.
Unlike the pedestal grinder where the grinding
is done on the periphery of the wheel, the carbide
tool bit grinder has the grinding done on the side
of the wheel. The straight cup wheel (fig. 6-11)
is similar to the wheels used on most carbide tool
bit grinders. Some carbide tool grinders have a
straight cup wheel on one side of the grinder and
a straight wheel, such as the type used on a
pedestal or bench grinder, on the other side.
The adjustable toolrest has an accurately
ground groove or keyway across the top of its
table. This groove is for holding a protractor
attachment which can be set to the desired cutting
edge angle. The toolrest will also adjust to permit
grinding the relief angle.
Some carbide tool grinders have a coolant
system. When coolant is available, the tool should
have an ample, steady stream of coolant directed
at the point of grinding wheel contact. An ir-
regular flow of coolant may allow the tool to heat
up and then be quenched quickly, resulting in
cracks to the carbide. If no coolant system is
available, do NOT dip the carbide into a container
of water when it becomes hot. Allow it to air cool.
Carbide tipped tool bits may have tips that are
(1) disposable, having three or more pre-ground
cutting edges or (2) brazed, having cutting edges
that must be ground. The disposable-tip type tool
bit needs no sharpening; the tips are disposed of
as their cutting edges become dull. The brazed-
tip type tool bit is sharpened on the carbide tool
bit grinder.
For best results in sharpening carbide tipped
tool bits, use a silicon carbide wheel for roughing
and a diamond impregnated wheel for finishing.
WORKING FACE
Figure 6-10.— Carbide tool grinder.
Figure 6-11. — Crown on the working face of a wheel for a
carbide tool bit grinder.
You can obtain the best results from carbide
tipped tools by using four different grinding
wheels to sharpen them. Use the aluminum
oxide wheel recommended for grinding high-speed
steel tools to grind the steel shank beneath the
carbide tip to the desired end and side cutting edge
angles with a relief angle of approximately 15 °.
This angle is approximately double the clearance
angle ground on the carbide tip. When you are
ready to grind the carbide tip, use wheels that have
silicon carbide as the abrasive material. Use a
C6018V wheel for rough grinding and a C100H8V
wheel for semifinish grinding. To finish grind the
tip, use a diamond impregnated grinding wheel
with the designation SD 220-P50V.
OPERATION OF THE CARBIDE
TOOL GRINDER
Use the following procedure to sharpen a
carbide tipped tool bit.
• Using a grinder with an ALUMINUM
OXIDE wheel, grind side relief and end
relief angles on the STEEL shanks.
Caution: NEVER grind steel shanks with
silicon carbide wheels.
• Dress the silicon carbide wheel with a star
type wheel dresser. Form a 1/16-inch
crown on the working face of the wheel
to minimize the amount of contact be-
tween the tip and the wheel (fig. 6-11).
• Using the graduated dial on the side of the
toolrest, adjust the toolrest to the desired
side clearance angle.
• Place the protractor on the toolrest with
the protractor key in the key way. Set the
protractor to the proper side cutting edge
angle.
• Hold the shank of the tool bit firmly
against the side of the protractor; move the
tool bit back and forth across the wheel,
keeping a steady, even pressure against the
wheel. To prevent burning the carbide tip,
keep the tool bit continually in motion
while grinding it.
Generally, when a carbide tool chip grinder
is available, the finish grinding operation is
performed on this machine with a diamond wheel.
The chip grinder is very similar to the carbide tool
bit grinder except that the wheels are smaller and
diamond impregnated.
If you use silicon carbide wheels, grind the car-
bide tip dry. If you use diamond wheels, be sure
to use coolant on both the tool and the wheel face.
NEVER allow the steel shank to come into con-
tact with a diamond wheel as this will immediately
load the wheel.
CHIP BREAKER GRINDER
A chip breaker grinder (fig. 6-12) is a
specialized grinding machine. It is designed
to permit accurate grinding of grooves or
Figure 6-12. — Chip breaker grinder.
6-11
indentations on the top surface of carbide tools,
so that the direction and length of the chips
produced in cutting metal can be controlled. A
description of the various types of chip breakers
that are commonly ground on carbide tools will
be presented later in this chapter.
The chip breaker grinder has a vise which can
be adjusted to four different angles to hold the
tool to be ground. These angles— the side cutting
edge, back rake, side rake, and the chip
breaker— are explained later in this chapter. The
vise is mounted so it can be moved back and forth
under the grinding wheel. Both the cross feed, for
positioning the tool under the grinding wheel, and
the vertical feed, for controlling the depth of the
chip breaker, are graduated in increments of 0.001
inch.
A diamond wheel is used on the chip breaker
grinder. The wheel is usually a type 1 straight
wheel but differs from other type 1 wheels in that
it is normally less than 1/4 inch thick. An
SD150R100B grinding wheel is normally
recommended.
Chip breaker grinders have a coolant system
that either floods or slowly drips coolant onto the
tool being ground. The main objective in using
coolant is to prevent the grinding wheel from
loading up or glazing over from the grinding
operation.
SINGLE-POINT CUTTING TOOLS
A single-point or single-edged cutting tool is
a tool which has only one cutting edge as opposed
to two or more cutting edges. Drill bits are
multiple-edged cutters; most lathe tools are single
edged. To properly grind a single-point cutting
tool, you must know the relief angles, the rake
angles, and the cutting edge angles that are
required for specific machines and materials. You
must know also what materials are generally used
for cutting tools and how tools for various
machines differ.
Cutting Tool Terminology
Figure 6-13 shows the application of the angles
and surfaces we use in discussing single-point
cutting tools. Notice that there are two relief
angles and two rake angles and that the angle of
keenness is formed by cutting a rake angle and
a relief angle.
SIDE RAKE ANGLE
A
FRONT
VIEW
B
BACK RAKE ANGLE
\
RIGHT
SIDE
VIEW
END RELIEF ANGLE
NOSE
SIDE CUTTING EDGE ANGLE
making a slope either away from or toward the
side cutting edge. Figure 6-1 3A shows a positive
side rake angle. When the side rake is cut toward
the side cutting edge, the side rake has a negative
angle. The amount of side rake influences to some
extent the size of the angle of keenness. It causes
the chip to "flow" to the side of the tool away
from the side cutting edge. A positive side rake
is most often used on ground single-point tools.
Generally, the side rake angle will be steeper (in
the positive direction) for cutting the softer metals
and will decrease as the hardness of the metal
increases. A steep side rake angle in the positive
direction causes the chip produced in cutting to
be long and stringy. Decreasing the angle will
cause the chip to curl up and break more quickly.
A negative side rake is recommended when the
tool will be subjected to shock, such as an
interrupted cut or when the metal being cut is
extremely hard.
BACK RAKE.— The back rake is the angle at
which the top surface of the tool is ground away
mainly to guide the direction of the flowing chips.
It is ground primarily to cause the chip cut by the
tool to "flow" back toward the shank of the tool.
Back rake may be positive or negative; it is
positive (fig. 6-13B) if it slopes downward from
the nose of the tool toward the shank, or negative
if a reverse angle is ground. The rake angles aid
in forming the angle of keenness and in directing
the chip flow away from the point of cutting.
The same general recommendations concerning
positive or negative side rake angles apply to the
back rake angle.
SIDE RELIEF.— The side relief (fig. 6-13A)
is the angle at which the side of the tool is ground
to prevent the tool bit from rubbing into the work.
The side relief angle, like the side rake angle,
influences the angle of keenness. A tool with
proper side relief causes the side thrust to be
concentrated on the cutting edge rather than
rubbing on the flank of the tool.
END RELIEF.— The end relief (fig. 6-13B)
is the angle at which the end surface of the tool
is ground so that the front face edge of the tool
leads the front surface.
ANGLE OF KEENNESS.— The angle of
keenness or wedge angle (fig. 6- 13 A) is formed
the sum of the side rake and side relief angles.
Generally, for cutting soft materials this angle is
smaller than for cutting hard materials.
SIDE CUTTING EDGE.— The side cutting
edge angle (fig. 6-13C) is ground on the side of
the tool that is fed into the work. This angle can
vary from 0 ° for cutting to a shoulder, up to 30 °
for straight turning. An angle of 15° is
recommended for most rough turning operations.
In turning long slender shafts, a side cutting edge
angle that is too large can cause chatter. Since the
pressure on the cutting edge and the heat
generated by the cutting action decrease as the side
cutting edge angle increases, the angle should be
as large as the machining operation will allow.
END CUTTING EDGE.— The end cutting
edge angle (fig. 6-13C) is ground on the end of
the tool to permit the nose to make contact with
the work without the tool dragging the surface.
An angle of from 8 ° to 30 ° is commonly used with
approximately 15° recommended for rough
urning operations. Finish operations can be made
with the end cutting edge angle slightly larger. Too
large an end cutting edge angle will reduce the
support given the nose of the tool and could cause
premature failure of the cutting edge.
NOSE.— The nose (fig. 6-13C) strengthens the
tip of the tool, helps to carry away the heat
generated by the cutting action and helps to obtain
good finish. A tool that is used with the nose
ground to a straight point will fail much more
rapidly than one which has had a slight radius
ground or honed on it. However, too large a
radius will cause chatter because of excessive tool
contact with the work. A radius (rounded end)
of from 1/64 to 1/32 inch is normally used for
turning operations.
GROUND-IN CHIP BREAKERS
Chip breakers are indentations ground on the
top surface of the tool that help reduce or prevent
the formation of long and dangerous chips. The
chip breaker will cause the chips to curl up and
break into short, safe, manageable chips. Chip
breakers are ground mostly on roughing tools, but
they can be ground on finishing tools used to
6-13
machine soft ductile metals. Figure 6-14 shows
four of the several types of chip breakers that can
be ground onto the cutting tool.
The dimensions given are general and can be
modified to compensate for the various feed rates,
depths of cut, and types of material being
machined. The groove type chip breaker must be
carefully ground to prevent it from coming too
close to the cutting edge which reduces the life
of the tool due to decreased support of the cutting
edge. Chip breakers on carbide tipped tools can
be ground with the diamond wheel on the chip
breaker grinder. High-speed tools must be ground
with an aluminum oxide grinding wheel. This can
be done on a bench grinder by dressing the wheel
until it has a sharp edge or by using a universal
vise which can be set to compound angles on a
mrface or tool and cutter grinder.
CUTTING TOOL MATERIALS
The materials used to make machine cutting
tools must have the hardness necessary to cut
other metals, be wear resistant, have impact
strength to resist fracture, and be able to
retain their hardness and cutting edge at high
temperatures. Several different materials are
used for cutting tools and each one has
properties different from the others. Selection of
a specific cutting tool material depends on the
metal being cut and conditions under which the
cutting is being done.
TOP VIEWS
'/6-3/l6 1/32
ijjll/'' , lit I/"
'/32
PARALLEL SHOULDER GROOVE ANGULAR
END VIEWS.
Figure 6-14.— Chip breakers.
CARBON TOOL STEEL
The carbon steel used to make cutting tools
usually contains from 0.90% to 1.40% carbon.
Some types contain small amounts of chrome or
vanadium to increase the degree of hardness or
toughness. Carbon steel is limited in its use as a
cutting tool material because of its low tolerance
to the high temperatures generated during the
cutting process. Tools made from carbon steel will
begin to lose their hardness, 50 to 64 Rockwell
"C," at a tempering range of approximately 350°
to 650 °F. Carbon steel tools perform best as lathe
cutting tools when used to take light or finishing
cuts on relatively soft materials such as brass,
aluminum, and unhardened low carbon steels.
The cutting speed for carbon steel tools
should be approximately 50% of the speeds
recommended for high-speed steel tools.
HIGH-SPEED STEEL
High-speed steel is probably the most common
cutting tool material used in Navy machine shops.
Unlike carbon steel tools, high-speed steel tools
are capable of maintaining their hardness and
abrasion resistance under the high temperatures
and pressures generated during the general cutting
process. Although the hardness of the high-speed
tool (60 to 70 Rockwell ''C") is not much greater
than that of carbon steel tools, the tempering
temperature at which high-speed steel begins to
lose its hardness is 1000° to 1100°F. There are
two types of high-speed tools which are generally
used in machine shops. They are tungsten high-
speed steel and molybdenum high-speed steel.
These designations are used to indicate the major
alloying element in each of the two types. Both
types are similar in their ability to resist abrasive
wear and to remain hard at high temperatures,
and in their degree of hardness. The molybdenum
type high-speed steel is tougher than the tungsten
type and is more effective in machinery operations
where interrupted cuts are made.
During interrupted cuts, such as cutting out-
of-round or slotted material, the cutter contacts
the material many times in a short period of time.
This "hammering" effect dulls or breaks cutters
which are not tough enough to withstand the
shock effect.
CAST ALLOYS
Cast alloy tool steel usually contains varying
amounts of cobalt, chrome, tungsten, and
C. \ A
high-speed steel, retaining their hardness up to
an operating temperature of approximately
1400°F. This characteristic allows cutting speeds
approximately 60% greater than for high-speed
steel tools. However, cast alloy tools are not as
tough as the high-speed steel tools and therefore
cannot be subjected to the same cutting stresses,
such as interrupted cuts. Clearances that are
ground on cast alloy cutting tools are less than
those ground on high-speed steel tools because of
the lower degree of toughness. Tools made from
this metal are generally known as Stellite,
Rexalloy, and Tantung.
CEMENTED CARBIDE
Cemented carbides, or sintered carbides as
they are sometimes called, can be used at cutting
speeds of two to four times those listed for high-
speed steel. The softest carbide grade is equal in
hardness to the hardest tool steel and is capable
of maintaining its hardness and abrasive resistance
up to approximately 1700°F. Carbide is much
more brittle than any of the other cutting tool
materials previously described in this chapter.
Because of this, interrupted cuts should be
avoided and the machine setup should be as rigid
and vibration free as possible. There are many
different grades of carbides, each grade being
more suited for a particular machining operation
and metal than the others. Carbide manufacturers
normally have available charts that match the
correct grade for any given cutting application.
Due to the brittleness of carbide, it is seldom used
in a solid form as a cutting tool. The most
common usage is as a tip on a steel shank or on
the cutting edge of a twist drill. Carbide tipped
lathe cutting tools are usually in the form of
carbide tips brazed onto the end of a steel shank
or as small variously shaped inserts, mechanically
held on the end of a steel shank. A brief
description of these two types of cutters is
included in the following paragraphs.
Brazed on Tip
The brazed on carbide tip cutting tool was the
first carbide cutting tool developed and made
available to the metal cutting industry. The
insert type of carbide tip has become more widely
used because of the ease in changing cutting
edges. There are some jobs which have shapes that
cannot be readily machined with a standard
of tools required in machinery, such as turning,
facing, threading, and grooving are available with
different grades of carbide tips already brazed
onto steel shanks. Small carbide blanks are also
available that you can braze onto a shank.
Brazing on a carbide tip is a relatively simple
operation that can be performed by anyone
qualified to operate an oxy acetylene torch. To
braze on a carbide tip, first, thoroughly clean the
steel shank by grinding or sandblasting and
degreasing it with an approved solvent. Next,
completely coat the steel shank and the carbide
tip with a flux to further remove any contamina-
tion and to prevent oxidation during brazing. A
thin shim-like brazing alloy is available that you
can cut to the size needed and place between the
shank and the carbide tip. This type of bronze
alloy is better than the rod type because it results
in a more uniform and stronger bronze. Begin
heating the tool at the bottom of the shank. Raise
the temperature slowly until the bronze alloy
melts. Tap the carbide tip gently to ensure a firm
seat onto the shank and then let the tool cool in
the air. Quenching the tool in water will either
cause the carbide tip to crack or prevent the
bronze bond from holding the tip in place. After
the tool is cooled, grind it to the shape desired.
Chip control, when cutting tools with
brazed-on carbide tips are used, may be provided
by either feeds and speeds or by chip breaker
grooves ground into the top of the carbide tip.
Using a chip breaker grinder with a diamond
impregnated wheel is the best way to grind a chip
breaker. However, it is possible to use a carbide
tool grinder or a pedestal grinder wheel dressed
so that it has a sharp edge. The depth of the chip
breakers averages about 1/32 inch, while the
width varies with the feed rate, depth of cut and
material being cut. Grind the chip breaker narrow
at first and widen it if the chip does not curl and
break quickly enough. You may also use these
same types of chip breakers on high-speed steel
cutters.
Mechanically Held Tip (Insert Type)
Mechanically held carbide inserts are available
in several different shapes— round, square,
triangular, diamond threading, and grooving—
and in different thicknesses, sizes, and nose radii.
The inserts may have either a positive, a neutral,
or a negative rake attitude to the part being cut.
The rake attitude is a combination of the back
rake of the toolholder, the amount of clearance
6-15
ground along the edge of the insert beneath the
cutting edge, and the ground-in chip breaker.
An insert and its toolholder must have the
same direction of rake. For instance, a negative
rake toolholder requires a negative rake insert.
Whenever possible, select the negative rake set-up
because both sides of the insert can be used, thus
doubling the number of cutting edges available
on positive or neutral inserts. Be sure to place a
specially made shim, having the same shape as the
insert, into the toolholder pocket beneath the
insert to provide a smooth and firm support for
the insert. Methods of holding the insert in the
toolholder vary from one manufacturer to
another. Some inserts are held in place by the cam-
lock action of a screw positioned through a hole
in their centers, while others are held against the
toolholder by a clamp.
Chip control for carbide insert tooling is
provided by two different methods. Some inserts
have a groove ground into their cutting surfaces.
Other inserts have a chip breaker plate held by
a clamp on top of their cutting surfaces.
CERAMIC
Other than diamond tools, ceramic cutting
tools are the hardest and most heat resistant
cutting tools available to the machinist. A ceramic
cutting tool is capable of machining metals that
are too hard for carbide tools to cut. Additionally,
ceramic can sustain cutting temperatures of up to
2000 °F. Therefore, ceramic tools can be operated
at cutting speeds two to four times greater than
cemented carbide tools.
Ceramic cutting tools are available as either
solid ceramic or as ceramic coated carbide in
several of the insert shapes available in cemented
carbides and are secured in the toolholder by a
clamp.
Whenever you handle ceramic cutting tools,
be very careful because they are very brittle and
will not tolerate shock or vibration. Be sure your
lathe setup is very rigid and do not try to take any
interrupted cuts. Also ensure that the lathe feed
rate does not exceed 0.015 to 0.020 inch per
revolution, as any rate exceeding this will subject
the insert to excessive forces and may result in
fracturing the insert.
ENGINE LATHE TOOLS
Figure 6-15 shows the most popular shapes
of ground lathe tool cutter bits and their
applications. In the following paragraphs each of
the types shown is described.
LEFT-HAND TURNING TOOL
This tool is ground for machining work when
fed from left to right, as indicated in figure 6- 15 A.
The cutting edge is on the right side of the tool
and the top of the tool slopes down away from
the cutting edge.
ROUND-NOSE TURNING TOOL
This tool is for general all-round machine
work and is used for taking light roughing cuts
and finishing cuts. Usually, the top of the cutter
bit is ground with side rake so that the tool may
be fed from right to left. Sometimes this cutter
bit is ground flat on top so that the tool may be
fed in either direction (fig. 6-15B).
RIGHT-HAND TURNING TOOL
This is just the opposite of the left-hand
turning tool and is designed to cut when fed from
right to left (fig. 6-15C). The cutting edge is on
the left side. This is an ideal tool for taking
roughing cuts and for general all-round machine
work.
LEFT-HAND FACING TOOL
This tool is intended for facing on the left-
hand side of the work, as shown in figure 6-15D.
The direction of feed is away from the lathe
center. The cutting edge is on the right-hand side
of the tool and the point of the tool is sharp to
permit machining a square corner.
THREADING TOOL
The point of the threading tool is ground to
a 60 ° included angle for machining V-f orm screw
threads (fig. 6-15E). Usually, the top of the tool
is ground flat and there is clearance on both sides
of the tool so that it will cut on both sides.
RIGHT-HAND FACING TOOL
This tool is just the opposite of the left-hand
facing tool and is intended for facing the right
end of the work and for machining the right side
of a shoulder. (See fig. 6-15F.)
SQUARE-NOSED PARTING
(CUT-OFF) TOOL
The principal cutting edge of this tool is on
the front. (See fig. 6-1 5G.) Both sides of the tool
LATHE TOOLHOLDER-STRAIGHT SHANK
CUTTER BIT-NOT GROUND
CUTTER BIT-GROUND TO FRORM
A
A B C D IT F 6
LEFT-HAND ROUND-NOSE RIGHT-HAND LEFT-HAND THREADING RIGHT-HAND CUT-OFF
TURNING TOOL TURNING TOOL TURNING TOOL FACE ING TOOL TOOL FACING TOOL TOOL
INSIDE
THREADING
TOOL
Figure 6-15.— Lathe tools and their application.
must have sufficient clearance to prevent
binding and should be ground slightly nar-
rower at the back than at the cutting edge.
This tool is convenient for machining necks,
grooves, squaring corners, and for cutting
off.
BORING TOOL
The boring tool is usually ground the san
shape as the left-hand turning tool so that tl
cutting edge is on the front side of the cutter b
and may be fed in toward the headstock.
6-17
INTERNAL-THREADING TOOL
The internal-threading (inside-threading) tool
is the same as the threading tool in figure 6-1 5E,
except that it is usually much smaller. Boring and
internal-threading tools may require larger relief
angles when used in small diameter holes.
GRINDING ENGINE LATHE
CUTTING TOOLS
The materials being machined and the
machining techniques used limit the angles of a
tool bit. When grinding the angles, however, you
must also consider the type of toolholder and the
position of the tool with respect to the axis of the
workpiece. The angular offset and the angular
vertical rise of the tool seat in a standard lathe
toolholder affect the cutting edge angle and the
end clearance angle of a tool when it is set up for
machining. The position of the point of the tool
bit with respect to the axis of the workpiece,
whether higher, lower, or on center, changes the
amount of front clearance.
Figure 6-16 shows some of the standard tool-
holders used in lathe work. Notice the angles at
which the tool bits sit in the various holders. You
must consider these angles with respect to the
angles ground in the tools and the angle that you
set the toolholder with respect to the axis of the
work. Also notice that a right-hand toolholder is
offset to the LEFT and a left-hand toolholder
is offset to the RIGHT. For most machining
operations, a right-hand toolholder uses a left-
hand turning tool and a left-hand toolholder uses
a right-hand turning tool. Study figure 6-15 and
6-16 carefully to clearly understand this apparent
contradiction. (Carbide tipped cutting tools should
be held directly in the toolpost or in heavy duty
holders similar to those used on turret lathes.)
The contour of a cutting tool is formed by the
side cutting edge angle and the end cutting edge
STRAIGHT SHANK TURNING TOOL
angle of the tool. (Parts A through G of fig. 6-15
illustrate the recommended contour of several
types of tools.) There are no definite guidelines
on either the form or the included angle of the
contour of pointed tool bits. Each machinist
usually forms the contour as he or she prefers.
For roughing cuts, it is recommended that the
included angle of the contour of pointed bits be
made as large as possible and still provide
clearance on the trailing side or end edge. Tools
for threading, facing between centers, and parting
have specific shapes because of the form of the
machined cut or the setup used.
STEPS IN GRINDING A TOOL BIT
The basic steps are similar for grinding a
single-edged tool bit for any machine. The
difference lies in shapes and angles. Use a coolant
when you grind tool bits. Finish the cutting edge
by honing it on an oilstone. The basic steps for
grinding a round nose turning tool are illustrated
in figure 6-17. A description of each step follows:
1 . Grind the left side of the tool, holding it
at the correct angle against the wheel to
form the necessary side clearance. Use the
coarse grinding wheel to remove most of
the metal, and then finish on the fine
grinding wheel. (If the cutting edge is
ground on the periphery of a wheel less
than 6 inches in diameter, it will be under-
cut and will not have the correct angle.)
Keep the tool cool while grinding.
2. Grind the right side of the tool, holding it
at the required angle to form the right side.
3. Grind the radius on the end of the tool. A
small radius (approximately 1/32 inch) is
' LEFT-HAND
TURNING TOOL
RIGHT-HAND
TURNING TOOL
:•:•*:"•. CUTTER
BIT
Figure 6-16. — Standard lathe toolholders.
Figure 6-17.— Grinding and honing a lathe cutter bit.
preferable, as a large radius may cause
chatter. Hold the tool lightly against the
wheel and turn it from side to side to
produce the desired radius.
4. Grind the front of the tool to the desired
front clearance angle.
5 . Grind the top of the tool, holding it at the
required angle to obtain the necessary side
rake and back rake. Try not to remove too
much of the metal. The more metal you
leave on the tool, the better the tool will
absorb the heat produced during cutting.
6. Hone the cutting edge all around and on
top with an oilstone until you have a keen
cutting edge. Use a few drops of oil on the
oil-stone when honing. Honing will not
only improve the cutting quality of the tool,
but will also produce a better finish on the
work, and the cutting edge of the tool will
stand up much longer than if it is not
honed. The cutting edge should be sharp
in order to shear off the metal instead of
tearing it off.
GRINDING TOOLS FOR
ROUGHING CUTS
A single-edged cutting tool used for roughing
cuts (relatively heavy depth of cut and heavy feed)
can be modified slightly and used for finishing
operations. In finishing, lighter feed and less
depth of cut are normally used to get a smooth
surface. To grind a finishing tool from a roughing
tool, it is usually necessary only to increase the
back rake angle, decrease the side rake and side
clearance angles, and grind a radius on the nose
of the tool. The only portion of a tool ground in
this manner that will be cutting is the nose.
Grinding a larger back rake angle makes a more
acute, chisel-type nose. Decreasing side rake and
side clearance provides more support for the
cutting edge. By increasing the radius of the nose,
you ensure that more of the cutting edge will be
in contact with the work during the cut; and thus,
by decreasing the feed rate of the tool, you will
have a finer cut (similar to a scraping) which
ensures a good finish.
In general machining work, you will find that
it is easy to grind a tool which can be used for
both roughing and finishing. To do this you grind
a roughing tool to increase the nose radius a little
more than usual. When you take the finish cut,
decrease the feed rate until you obtain the required
finish.
Table 6-2 gives recommended angles for
roughing and finishing cuts for tools made of
various materials. The values provided in table
6-2 are somewhat arbitrarily selected as the most
appropriate so that you can grind a minimum
Table 6-2.— Angles for Grinding Engine Lathe Tools
Material
Operation
Angle (Degrees)
Back
Rake
Side
Rake
Side
Relief
End
Relief
Mild steel
Roughing
Finishing
6-10
14-22
14-22
0
5-9
0
5-9
5-9
Hard steel and cast
iron
Roughing
Finishing
6-8
6-10
12-14
0
5-9
0
5-9
5-9
Brass and bronze
Roughing
Finishing
6-8
14-22
4-10
0
5-9
0
5-9
5-9
Copper and aluminum
Roughing
Finishing
8-10
8
16-24
16-24
5-9
0
5-9
5-9
Monel
Roughing
Finishing
4-8
14-22
10-14
0
5-9
0
5-9
5-9
number of tools for maximum use, with respect
to materials commonly machined in the shop. The
angles given in table 6-2 and other tables in this
chapter are intended as guidelines for the
beginner. As you gain experience, you will find
that you can grind tools that cut efficiently even
though the angles do not conform exactly to the
angles prescribed.
In table 6-2 you will note that the front
clearance angles are practically standard for
commonly used materials. The angle of side
clearance within the tolerance given is based on
the fact that small angles are necessary when a
light feed rate is used and larger angles are
necessary when a higher feed rate is used. The
front clearance angle should generally be increased
in proportion to the increase in the diameter of
the workpiece.
TURRET LATHE TOOLS
The angles of cutting tools for turret lathes
are quite similar to those for engine lathe tools.
However, the cutters themselves are usually much
larger than those used on an engine lathe because
the turret lathe is designed to remove large
quantities of metal rapidly.
The relative merits, limitations, and applica-
tions, as well as the grinding of carbon tool steel,
high-speed steel, Stellite, and carbide tool bits
have been discussed in relation to engine lathe
tools. That information is applicable to turret
lathe cutters, with a few exceptions which will be
discussed here.
The turret lathe cutter must withstand heavy
cutting pressures; therefore, its cutting edge must
be well supported. The amount of support
depends upon the amount of side clearance, side
rake, front clearance, and back rake given the
tool. The clearance and rake angles prescribed in
table 6-2 for tool bits are given in ranges, but a
turret lathe cutter clearance and rake angles must
be more specifically controlled. You must know
the exact tool angles and grind the cutter to those
angles. Table 6-3 lists the angles to which high-
speed and carbon steel cutters should be ground
Table 6-3.— Angles for Grinding Turrent Lathe Tools (High Speed and Carbon Steel)
Angle (D
egrees)
Material
Side
Clearance
Front
Clearance
Back
Rake
Side
Rake
Cast Iron
g
g
g
14
Copper
g
g
in
25
Brass, Soft
g
g
n
n
Hard Bronze
g
g
R
c;
Aluniinum
g
Q
g
1 g
Steels:
SAE XI 112 Spec Screw Stock
g
g
1 ^
?n
SAE X1315 Screw Stock
g
g
1 S
on
SAE 1020 Carbon Steel
8
8
15
15
SAE 1035 Carbon Steel
8
8
15
15
SAE 1045 Carbon Steel
8
8
10
12
SAE 1095 High Carbon Steel
8
8
5
10
SAE 2315 Nickel Alloy
8
8
15
15
SAE 2335 Nickel Alloy (Annealed)
8
8
15
15
SAE 2350 Nickel' Steel (Annealed)
8
8
10
12
SAE 3115 Nickel- Chromium Alloy
8
8
15
15
SAE 3140 Nickel- Chromium (Annealed)
SAE 3250 Nickel -Chromium (Annealed)
SAE 4140 Chromium-Molybdenum
SAE 4615 Nickel -Molybdenum
SAE 6145 Chromium- Vanadium
8
8
8
8
8
8
8
8
8
8
10
8
10
15
8
12
12
12
15
12
6-20
As carbide tips cannot tolerate bending but are
otherwise capable of withstanding heavy cutting
pressures, the tool angles prescribed for them are
somewhat different. Table 6-4 lists the clearance
and rake angles for carbide-tipped cutters. Notice
that the side and front clearance angles differ only
slightly from those prescribed for high-speed
steel cutters but that the rake angles differ
considerably. The reduction in back rake and side
rake angles for carbide-tipped tools provides a
bigger included angle for the cutting edge and,
therefore, greater resistance against bending
stress.
Before a carbide tip is ground, a clearance
angle is ground on the shank with a conventional
grinding wheel. This clearance angle must be
slightly larger than the angle to be ground on the
carbide tip. The clearance prevents loading the
grinding wheel with the soft material of the shank
when the clearance angles are ground on the tip.
Stellite cutters should be given tool angles
that lie approximately midway between those
prescribed for the high-speed steel and the carbide-
tipped types.
un ccuuna.1 control 101 its caips, cspciaouy
the cutter is to machine a tough ductile metal from
which the chip peels off in a continuous stream.
A long, hot chip, in addition to being hazardous
to you, will often interfere with the operation of
the other cutters or with the operation of the lathe
itself unless the direction of its run-off is
controlled. As some other factors are involved,
chip control will be discussed after the setting of
cutters has been taken up in chapter 10.
SHAPER AND PLANER TOOLS
Shaper and planer cutting tools are similar in
shape to lathe tools but differ mainly in their relief
angles. As these cutting tools are held practically
square with the work and do not feed during the
cut, relief angles are much less than those required
for turning operations. Nomenclature used for
shaper and planer tools is the same as that for
lathe tools; and the elements of the tool, such as
relief and rake angles, are in the same relative
position as shown in figure 6-13 . Both carbon and
high-speed steel are used for these tools.
Table 6-4.— Angles for Grinding Turret Lathe Tools (Carbide)
Material
Angle (Degrees)
Side
Clearance
Front
Clearance
Back
Rake
Side
Rake
Cast Iron
4-6
4-6
0-4
10-12
Aluminum
8-10
8-10
25
15
Copper
8-10
8-10
4
20
Brass
6
6
0
4
Bronze
6
6
0
4
Low carbon steel up to 0.20% carbon
8-10
8-10
4-6
10-12
Carbon steel up to 0 . 60% carbon
8-10
8-10
4-6
10-12
Tool steel over 0 . 60% carbon, and tough alloys
8-10
8-10
4-6
6-10
NOTE: Keep back rake angle as small as possible for greatest strength.
6-21
shaper or planer. Although the types differ
considerably as to shape, the same general rules
govern the grinding of each type. Hand forging
of shaper and planer tools is a thing of the past.
Toolholders and interchangeable tool bits have
replaced forged tools; this practice greatly reduces
the amount of tool steel required for each tool.
For an efficient cutting tool, the side relief and
end relief of the tool must be ground to give a
projecting cutting edge. If the clearance is
insufficient, the tool bit will rub the work, causing
excessive heat and producing a rough surface on
the work. If too much relief is given the tool, the
cutting edge will be weak and will tend to break
during the cut. The front and side clearance angles
seldom exceed 3 ° to 5 °.
In addition to having relief angles, the tool bit
must slope away from the cutting edge. This slope
is known as side rake and reduces the power
required to force the cutting edge into the work.
The side rake angle is usually 10° or more,
depending upon the type of tool and the metal
being machined. Roughing tools are given no back
rake although a small amount is generally required
for finishing operations.
The shape and use of various standard
cutting tools are illustrated in figure 6-18 and may
be outlined as follows:
ROUGHING TOOL (fig. 6-1 8 A): This tool
is very efficient for general use and is designed
A. ROUGHING
TOOL
8. DOWNCUTTING TOOLS
(RIGHT-ANO LEFT-HAND)
C.SHOVEL NOSE
TOOL
0. SIDE TOOLS
(RIGHT-ANO LEFT-HAND)
E. CUTTING-
OFF TOOL
F, SQUARING
TOOL
G. ANGLE CUTTING TOOLS
(RIGHT- AND LEFT-HAND)
H- SHEAR
TOOL
I. GOOSENECK
TOOL
Figure 6-18. — Standard shaper and planer tools.
operation as illustrated; for special applications,
the angles may be reversed for right-hand cuts.
No back rake is given this tool although the side
rake may be as much as 20° for soft metals.
Finishing operations on small flat pieces may be
performed with the roughing tool if a fine feed
is used.
DOWNCUTTING TOOL (fig. 6-18B): The
downcutting tool may be ground and set for either
right- or left-hand operation and is used for mak-
ing vertical cuts on edges, sides, and ends. The
tool is substantially the same as the roughing tool
described, with the exception of its position in the
toolholder.
SHOVEL NOSE TOOL (fig. 6-18C): This tool
may be used for downcutting in either a right- or
left-hand direction. A small amount of back rake
is required, and the cutting edge is made the widest
part of the tool. The corners are slightly rounded
to give them longer life.
SIDE TOOL (fig. 6-18D): Both right- and left-
hand side tools are required for finishing vertical
cuts. These tools may also be used for cutting or
finishing small horizontal shoulders after a ver-
tical cut has been made in order to avoid chang-
ing tools.
CUTTING-OFF TOOL (fig. 6-18E): This tool
is given relief on both sides to allow free cutting
action as the depth of cut is increased.
SQUARING TOOL (fig. 6-18F): This tool is
similar to the cutting-off tool and may be made
in any desired width. The squaring tool is used
chiefly for finishing the bottom and sides of
shoulder cuts, key ways, and grooves.
ANGLE CUTTING TOOL (fig. 6-1 8G): The
angle cutting tool is adapted for finishing
operations and is generally used following a
roughing operation made with the downcutting
tool. The tool may be ground for eight right- or
left-hand operation.
SHEAR TOOL (fig. 6-18H): This tool is used
to produce a high finish on steel and should be
operated with a fine feed. The cutting edge is
ground to form a radius of 3 to 4 inches, twisted
to a 20° to 30° angle, and given a back rake in
the form of a small radius.
6-22
so that the cutting edge is behind the backside of
the tool shank. This feature allows the tool to
spring away from the work slightly, reducing the
tendency for gouging or chattering. The cutting
edge is rounded at the corners and given a small
amount of back rake.
GRINDING HANDTOOLS
AND DRILLS
Tools and Their Uses, NAVEDTRA 10085
(series), contains detailed descriptions of the off-
hand grinding of twist drills and handtools.
Therefore, these subjects are not discussed here.
You should study NAVEDTRA 10085 (series) so
that you can accurately grind these tools that you
will often use in your work.
WHEEL CARE AND STORAGE
All grinding wheels can be broken or damaged
by mishandling and improper storage. Whenever
hard objects such as the grinder or other
wheels.
Grinding wheels should be stored in a
cabinet or on shelves large enough to allow
selection of a wheel without disturbing the
other wheels. The storage space should pro-
vide protection against high humidity, con-
tact with liquids, freezing temperatures, and
extreme temperature changes. Also, provisions
must be made to secure grinding wheels
aboard ship to prevent them from being
damaged when the ship is at sea. Thin cut-
off wheels should be stacked flat on a rigid
surface without any separators or blotters
between them, flaring cup wheels should be
stacked flat with the small ends together. All
other types of wheels may be stored upright on
their rims with blotters placed between them. A
sheet metal cabinet, lined with felt or corrugated
cardboard to prevent wheel chipping, is acceptable
for storage.
6-23
LATHES AND ATTACHMENTS
There are several types of lathes installed in
shipboard machine shops including the engine
lathe, horizontal turret lathe, vertical turret lathe,
and several variations of the basic engine lathe,
such as bench, toolroom, and gap lathes. All
lathes, except the vertical turret type, have one
thing in common for all usual machining
operations — the workpiece is held and rotated
around a horizontal axis while being formed to
size and shape by a cutting tool. In a vertical
turret lathe, the workpiece is rotated around a
vertical axis.
All of the lathes mentioned above, as well as
many of their attachments, are described in
this and the next three chapters. Engine lathe
operations and turret lathes and their operations
are covered later in this manual.
ENGINE LATHE
An engine lathe similar to the one shown in
figure 7-1 is found in every machine shop. It is
used mainly for turning, boring, facing, and screw
cutting, but it may also be used for drilling,
reaming, knurling, grinding, spinning, and spring
winding. The work held in an engine lathe can
be rotated at any one of a number of different
speeds. The cutting tool can be accurately
controlled by hand or power for longitudinal feed
and crossfeed. (Longitudinal feed is the movement
of the cutting tool parallel to the axis of the lathe;
crossfeed is the movement of the cutting tool
perpendicular to the axis of the lathe.)
Lathe size is determined by various methods
depending upon the manufacturer. Generally, the
size is determined by two measurements: (1) either
the diameter of work it will swing over the bed
or the diameter of work it will swing over the
cross-slide and (2) either the length of the bed or
the maximum distance between centers. For
example, a 14-inch x 6-foot lathe has a bed that
is 6 feet long and will swing work (over the bed)
up to 14 inches in diameter.
Engine lathes range in size from small bench
lathes with a swing of 9 inches to very large lathes
for turning work of large diameters, such as low-
pressure turbine rotors. A 16-inch swing lathe is
a good, average size for general purposes and is
usually the size installed in ships that have only
one lathe.
To learn the operation of a lathe, you must
be familiar with the names and functions of the
principal parts. In studying the principal parts in
detail, remember that lathes all provide the same
general functions even though the design may
differ among manufacturers. As you read the
description of each part, find its location on the
lathe pictured in figure 7-1. For specific details
on a given lathe, refer to the manufacturer's
technical manual for that machine.
BED AND WAYS
The bed is the base for the working parts of
the lathe. The main feature of the bed is the ways,
which are formed on its upper surface and run
the full length of the bed. The tailstock and
carriage slide on the ways in alignment with the
headstock. The headstock is permanently bolted
to the end at the operator's left.
Figure 7-2 shows the ways of a typical lathe.
The inset shows the inverted V-shaped ways
(1,3, and 4) and the flat way (2). The ways are
accurately machined parallel to the axis of the
spindle and to each other. The V-ways are guides
that allow the carriage and tailstock to move over
them only in their longitudinal direction. The flat
way, number 2, takes most of the downward
thrust. The carriage slides on the outboard V-ways
(1 and 4), which, because they are parallel to way
7-1
"'•;; ?•""-:"-•-:" j.1, •r----i\& '"' '--•-• ';lli|$
33 32 313,°29
/ / _/ /
18 19
1. Headstock spindle
2. Identification plate
3. Spindle speed index plate
4. Headstock spindle speed change
levers
5. Upper compound lever
6. Lower compound lever
7. Tumbler lever
8. Feed-thread index plate
9. Feed-thread lever
10. Spindle control lever
11. Electrical switch grouping
12. Apron handwheel
13. Longitudinal friction lever
14. Cross-feed friction lever
15. Feed directional control lever
16. Half nut closure lever
17. Spindle control lever
18. Leadscrew reverse lever
19. Reverse rod stop dog
20. Control rod
21. Feed rod
22. Lead screw
23. Reverse rod
24. Tailstock setover screw
25. Tailstock handwheel
26. Tailstock clamping lever
27. Tailstock spindle binder lever
28. Tailstock spindle
29. Chasing dial
30. Carriage binder clamp
31. Compound rest dial and handle
32. Thread chasing stop
33. Cross-feed dial and handle
28.69X
Figure 7-1.— Gear-head engine lathe.
7-2
28.70X
Figure 7-2. — Rear view of lathe.
number 3, keep the carriage aligned with the
headstock and the tailstock at all times — an
absolute necessity if accurate lathe work is to be
done. Some lathe beds have two V-ways and two
flat ways, while others have four V-ways.
For a lathe to perform satisfactorily, the ways
must be kept in good condition. A common fault
of careless machinists is to use the bed as an
anvil for driving arbors or as a shelf for hammers,
wrenches, and chucks. Never allow anything to
strike a hard blow on the ways or damage their
finished surfaces in any way. Keep them clean
and free of chips. Wipe them off daily with
an oiled rag to help preserve their polished
surface.
HEADSTOCK
The headstock carries the headstock spindle
and the mechanism for driving it. In the
belt-driven type the driving mechanism con-
sists merely of a cone pulley that drives
the spindle directly or through back gears.
When the spindle is driven directly, it rotates
with the cone pulley; when the spindle is
driven through the back gears, it rotates
more slowly than the cone pulley, which in
this case turns freely on the spindle. Thus
two speeds are available with each position
of the belt on the cone; if the cone pulley
has four steps, eight spindle speeds are avail-
able.
7-3
The geared headstock shown in figure 7-3 is
more complicated but more convenient to operate
because speed is changed by shifting gears.
This headstock is similar to an automobile
transmission except that it has more gear-shift
combinations and therefore has a greater number
of speed changes. A speed index plate, attached
to the headstock, shows the lever positions for the
different spindle speeds. Figure 7-4 shows this
plate for the geared headstock in figure 7-3.
Always stop the lathe when you shift gears to
avoid damaging the gear teeth.
Figure 7-3 shows the interior of a typical
geared headstock that has 16 different spindle
speeds. The driving pulley at the left is driven at
a constant speed by a motor located under the
headstock. Various combinations of gears in the
headstock transmit the power from the drive shaft
to the spindle through an intermediate shaft. Use
the speed-change levers to shift the sliding gears
on the drive and intermediate shafts to line up the
gears in different combinations. This produces the
gear ratios you need to obtain the various spindle
speeds. Note that the back gear lever has high and
low speed positions for each combination of the
other gears (figure 7-4).
PULLEY 500 RPM
CONTRACT No..
DATf Of
UAJWMCTUM
vw
16
19
26
42
52
65
81
98
121
152
Z46
305
385
76
28.73
Figure 7-4.— Speed index plate.
The headstock casing is filled with oil to
lubricate the gears and the shifting mechanism it
contains. Parts not immersed in the oil are
lubricated by either the splash produced by the
revolving gears or by an oil pump. Be sure to keep
the oil to the oil level indicated on the oil gauge,
and drain and replace the oil when it becomes
dirty or gummy.
The headstock spindle (fig. 7-5) is the main
rotating element of the lathe and is directly
connected to the work, which revolves with it. The
spindle is supported in bearings (4) at each end
28.72
28.74X
Figure 7-5. — Cross section of a belt-driven headstock.
of the headstock through which it projects. The
section of the spindle between the bearings
carries the pulleys or gears that turn the spindle.
The nose of the spindle holds the driving plate,
the faceplate, or a chuck. The spindle is hollow
throughout its length so that bars or rods can be
passed through it from the left (1) and held in a
chuck at the nose. The chuck end of the spindle
(5) is bored to a Morse taper to receive the LIVE
center. The hollow spindle also permits the use
j uy wijuc.ii uiv opinviiv VJ.AIVVO tiiw j.i*vu
and screw-cutting mechanism through a gear train
located on the left end of the lathe. A collar (3)
is used to adjust end play of the spindle.
The spindle is subjected to considerable torque
because it both drives the work against the
resistance of the cutting tool and drives the
carriage that feeds the tool into the work. For this
reason adequate lubrication and accurately
adjusted bearings are absolutely necessary. (Bear-
ing adjustment should be done only by an
experienced lathe repairman.)
TAILSTOCK
The primary purpose of the tailstock (fig. 7-6)
is to hold the DEAD or LIVE center to support
one end of work being machined on centers.
However, it can also be used to hold tapered
shank drills, reamers, and drill chucks. The
tailstock moves on the ways along the length of
the bed to accommodate work of varying lengths.
Nlft \L1
1. Tailstock base. 9.
2. Tailstock top. 10.
3. Tailstock nut. 11.
4. Key. 12.
5. Keyway (in spindle). 13.
6. Spindle. 14.
7. Tailstock screw. 15.
8. Internal threads in spindle. 16.
Handwheel.
Spindle binding clamp.
Dead center.
End of tailstock screw.
Tailstock clamp nut.
Tailstock set-over.
For oiling.
Tailstock clamp bolt.
Figure 7-6. — Cross section of a tailstock.
28.75X
7-5
It can be clamped in the desired position by the
tailstock clamping nut (13).
The dead center (1 1) is held in a tapered hole
(bored to a Morse taper) in the tailstock
spindle (6). To move the spindle back and forth
in the tailstock barrel for longitudinal adjustment,
turn the handwheel (9) which turns the spindle-
adjusting screw (7) in a tapped hole in the spindle
at (8). The spindle is kept from revolving by a key
(4) that fits a spline, or key way, (5) cut along the
bottom of the spindle as shown. After making the
final adjustment, use the binding clamp (10) to
lock the spindle in place.
The tailstock body is made in two parts. The
bottom, or base (1), is fitted to the ways; the top
(2) can move laterally on its base. The lateral
movement can be closely adjusted by setscrews.
Zero marks inscribed on the base and top indicate
the center position and provide a way to measure
setover for taper turning. Setover of the tailstock
for taper turning is described in a later chapter.
Before you insert a dead center, a drill, or a
reamer into the spindle, carefully clean the tapered
shank and wipe out the tapered hole of the
spindle. After you put a drill or a reamer into the
tapered hole of the spindle, be sure to tighten i
in the spindle so that the tool will not revolve. I
the drill or reamer is allowed to revolve, it wil
score the tapered hole and destroy its accuracy
The spindle of the tailstock is engraved witl
graduations which help in determining the deptl
of a cut when you drill or ream.
CARRIAGE
The carriage carries the crossfeed slide and th
compound rest which in turn carries the cuttinj
tool in the toolpost. The carriage slides on th
ways along the bed (fig. 7-7).
Figure 7-8 shows a top view of the carriage
The wings of the H-shaped saddle contain tin
bearing surfaces which are fitted to the V-way
of the bed. The crosspiece is machined to forn
a dovetail for the crossfeed slide. The crossfee<
slide is closely fitted to the dovetail and has ;
tapered gib which fits between the carriage
dovetail and the matching dovetail of th
crossfeed slide. The gib permits small adjustment
to remove any looseness between the two parts
The slide is securely bolted to the crossfeed nu
COMPOUND REST
CROSS-SLIDE
CARRIAGE
WAYS
BED
28.7
CROSS SECTION AT X.X TO SHOW
DOVETAIL FOR CROSS-SLIDE AND
RECESS FOR CROSSFEED NUT X
MICROMETER DIAL
CROSSFEED HANDLE
28.77X
Figure 7-8.— Carriage (top view).
which moves back and forth when the crossfeed
screw is turned by the handle. The micrometer dial
on the crossfeed handle is graduated to permit
accurate infeed. Depending on the manufacturer
of the lathe, the dial may be graduated
so that each division represents a 1 to 1 or a 2 to
1 ratio. The compound rest is mounted on top
of the crossfeed slide.
The carriage has T-slots or tapped holes for
clamping work for boring or milling. When the
lathe is used in this manner, the carriage move-
ment feeds the work to the cutting tool which is
revolved by the headstock spindle.
You can lock the carriage in any position on
the bed by tightening the carriage clamp screw.
Use the clamp screw only when doing such work
as facing or cutting-off for which longitudinal
feed is not required. Normally, keep the carriage
clamp in the released position. Always move the
carriage by hand to be sure it is free before you
apply the automatic feed.
APRON
The apron is attached to the front of the
carriage. It contains the mechanism that controls
the movement of the carriage for longitudinal feed
and thread cutting and controls the lateral move-
ment of the cross-slide. You should thoroughly
a mine ctpiuu wumcuus uic iuuu vy-
ing mechanical parts:
1. A longitudinal feed HANDWHEEL for
moving the carriage by hand along the bed.
This handwheel turns a pinion that meshes
with a rack gear secured to the lathe bed.
2. GEAR TRAINS driven by the feed rod.
These gear trains transmit power from the
feed rod to move the carriage along the
ways and to move the cross-slide across the
ways, thus providing powered longitudinal
feed and crossfeed.
3. FRICTION CLUTCHES operated by
knobs on the apron to engage or disengage
the power- feed mechanism. (Some lathes
have a separate clutch for longitudinal feed
and crossfeed; others have a single clutch
for both.) NOTE: The power feeds are
usually driven through a friction clutch to
prevent damage to the gears if excessive
strain is put on the feed mechanism. If
clutches are not provided, there is some
form of safety device that operates to
disconnect the feed rod from its driving
mechanism.
4. A selective FEED LEVER or knob for
engaging the longitudinal feed or crossfeed
as desired.
5. HALF-NUTS that engage and disengage
the lead screw when the lathe is used to cut
threads. They are opened or closed by a
lever located on the right side of the apron.
The half-nuts fit the thread of the lead
screw which turns in them like a bolt in a
nut when they are clamped over it. The
carriage is then moved by the thread of the
lead screw instead of by the gears of the
apron feed mechanisms. (The half -nuts are
engaged only when the lathe is used to cut
threads, at which time the feed mechanism
must be disengaged. An interlocking device
that prevents the half-nuts and the feed
mechanism from engaging at the same time
is usually provided as a safety feature.)
Aprons on lathes made by different manu-
facturers differ somewhat in construction and in
the location of controlling levers and knobs.
But they all are designed to perform the same
functions. The principal difference is in the
arrangement of the gear trains for driving the
automatic feeds. For example, in some aprons
7-7
there are two separate gear trains with separate
operating levers for longitudinal feed and cross
feed. In others, both feeds are driven from the
same driving gear on the feed rod through a
common clutch, with one feed at a time connected
to the drive by a selector lever. The apron shown
in figure 7-9 is of the latter type.
FEED ROD
The feed rod transmits power to the apron to
drive the longitudinal feed and cross feed
mechanisms. The feed rod is driven by the spindle
through a train of gears, and the ratio of its speed
to that of the spindle can be varied by changing
gears to produce various rates of feed. The
rotating feed rod drives gears in the apron.
These gears in turn drive the longitudinal
feed and crossfeed mechanisms through friction
clutches, as explained in the description of the
apron.
Lathes which do not have a separate feed rod
have spline in the lead screw to serve the same
purpose. The apron shown in figure 7-9 belongs
to a lathe of this type and shows clearly how the
worm which drives the feed mechanism is driven
by the spline in the lead screw. If a separate feed
rod were used, it would drive the feed worm in
the same manner, that is, by means of a spline.
The spline permits the worm, which is keyed to
it, to slide freely along its length to conform with
the movement of the carriage apron.
LEAD SCREW
The lead screw is used for thread cutting.
Along its length are accurately cut Acme threads
which engage the threads of the half-nuts in the
apron when half -nuts are clamped over it. When
the lead screw turns in the closed half -nuts, the
carriage moves along the ways a distance equal
to the lead of the thread in each revolution of the
lead screw. Since the lead screw is connected to
the spindle through a gear train (discussed later
in the section on quick-change gear mechanism),
the lead screw rotates with the spindle. There-
fore, whenever the half -nuts are engaged, the
longitudinal movement of the carriage is directly
controlled by the spindle rotation. The cutting tool
is moved a definite distance along the work for
each revolution that the spindle makes.
The ratio of the threads per inch of the thread
being cut and the thread of the lead screw is the
same as the ratio of the speeds of the spindle and
the lead screw. For example: If the lead screw and
spindle turn at the same speed, the number of
threads per inch being cut is the same as the
number of threads per inch of the lead screw.
If the spindle turns twice as fast as the lead
screw, the number of threads being cut is twice
the number of threads per inch of the lead
screw.
You can cut any number of threads by merely
changing gears in the connecting gear train to
get the desired ratio of spindle and lead screw
speeds.
28.79X
Figure 7-9. — Rear view of a lathe apron.
GEARING
First, consider the simplest possible arrange-
ment of gearing between the spindle and the lead
screw— a gear on the end of the spindle meshed
with a gear on the end of the lead screw, as shown
in figure 7-10. Let a be point of contact between
the spindle gear A and the screw gear B. As each
tooth on gear A passes point a, it causes a tooth
on gear B to pass this same point. Suppose gear
A has 20 teeth and gear B has 40 teeth. Then when
A makes one complete turn, 20 teeth will have
passed point a. Since B has 40 teeth around its
rim, only half of them will have passed point
a. Gear B has made just one-half of a revolution
while gear A has made one revolution. In other
words, gear B with 40 teeth will turn half as fast
as gear A with 20 teeth, or \heir speeds are
7-8
28.81X
Figure 7-10. — A simple gear arrangement.
inversely proportional to their size. The relation
may be expressed as follows:
rpm of B _ number of teeth on A
rpm of A number of teeth on B
By now you should have discovered that the
ratio in threads per inch of the thread to be cut
and the lead screw is identical to the ratio of the
number of teeth of the change gears. If the spindle
gear is smaller than the screw gear, the thread cut
will be finer (more threads per inch) than the lead
screw and vise versa.
Idler Gears
It is obviously impracticable to have the
spindle gear mesh directly with the screw gear
because, for one thing, the distance between them
is so great that the gears required would be too
large. Therefore, smaller gears of the desired ratio
are used, and idler gears bridge the gap between
them. You can place any number of idler gears
between the driving gear and the driven gear
without changing the original gear ratio. The idler
gears allow the lead screw and spindle gears to
rotate as if they were in direct contact.
In figure 7-11, I is an idler gear inserted
between the driving gear A and the driven gear B.
or
rpm of lead screw _ number of teeth on spindle gear A
rpm of spindle number of teeth on screw gear B
By using this formula, you can change the speed
of the screw relative to that of the spindle by
changing the gears to get the desired ratio.
In figure 7-10, the ratio is 20:40 or 1:2. Any
combination of gears that has a ratio of 1 :2, such
as 30 and 60 or 35 and 70, will cause the lead screw
to turn half as fast as the spindle.
Suppose you want to cut 8 threads per inch
on a lathe that has a lead screw with 6 threads
per inch. The carriage must carry the thread-
cutting tool 1 inch along the work while the work
makes eight complete revolutions. Since the lead
screw has 6 threads per inch, it must revolve six
times in the half-nuts to move the carriage 1 inch.
Therefore, you must gear the lathe to cause the
lead screw to make six revolutions while the
spindle makes eight revolutions. In other words,
the lead screw must turn 6/8 or 3/4 as fast as the
spindle. Since the speeds will be proportional to
the size of the gears, you can use any two gears
having this ratio, such as 30 and 40, 33 and 44,
28.82X
Figure 7-11. — Idler gear inserted between a driving gear and
a driven gear.
7-9
Suppose that A has 20 teeth. In making one
complete revolution, all of these 20 teeth will pass
a given point a and cause 20 teeth on I to pass
this same point. If 20 teeth on I pass point
a, an equal number of teeth on I will pass point
b where gear B meshes with it. Gear B will be
moved the same distance as it would if it were
directly meshed with A; so the ratio between their
speeds remains the same, but the direction of
rotation of B is reversed. Idler gears, then, are
used for two purposes: (1) to connect gears in a
gear train and (2) to reverse the direction of
rotation of a gear-driven mechanism.
Figure 7-12 is an example of simple gearing
used on a change gear lathe. The gear on the
spindle drives the stud gear shaft A at a fixed
ratio, usually 1 : 1 , in which the stud gear revolves
at the same speed as the spindle. Between the
spindle and the stud are the idler gears X and Y
mounted on the movable bracket controlled by
the reverse lever. When this lever is in the down
position, both X and Y are connected in the gear
train as shown, and the stud shaft revolves in a
direction opposite to that of the spindle; when the
lever is raised, gear X is disengaged from the train,
and gear Y is meshed directly between the spindle
and the stud, thereby reversing the previous
direction of the stud gear and all the gears that
follow it. NOTE: The reverse lever has a neutral
position that disconnects the spindle from the gear
train.
The lathe shown in figure 7-12 has per-
manently mounted spindle and idler gears
(X and Y). To vary the thread cutting gear ratios,
you must change the stud gear and the screw gear.
You can determine which gears on your machine
must be changed by reading the lathe's operating
instructions.
A simple rule to follow in determining what
stud and screw gears to use is: Multiply the desired
number of threads per inch and the number of
threads per inch in the lead screw by the same
number; if the products correspond to the number
of teeth in any two of the change gears at hand,
use those gears; if not, use some other multiplier
that will give products to match the gears
available. For example, if you want to cut a screw
containing 16 threads per inch on the lathe with
a lead screw that has 6 threads per inch, use 5 for
a multiplier:
5 x 16 = 80
5 x 6 = 30
If gears with 80 teeth and 30 teeth are on hand,
use the 30-tooth gear as the stud gear and the
80-tooth gear as the screw gear. If you do not have
those gears, try other multipliers until you arrive
at a combination corresponding to gears that you
do have.
If you cannot get the proper ratio of gears with
the change gears you have at hand or if the gears
would be too small or too large to connect
properly or conveniently (as would be the case if
28.83X
Figure 7-12. — Simple gearing on a lathe.
substituting two gears for an intermediate gear.
Compounding changes the ratio of the gear train
by the same ratio that the compounding gears bear
to each other.
Figure 7-13 shows a compound gear train on
a change gear lathe. The only way it differs from
the simple gear train (fig. 7-12) is that two extra
gears rotating as one on a common axis are
installed in the train following the stud gear.
Compounding gears for a lathe usually have a
ratio of 2 to 1 ; they double the ratio that would
exist if simple gearing were used.
If a 2:1 compound gear is installed in the
manner shown in figure 7-13, the speed
transmitted by the stud gear to the large
compound gear is reduced by half when it is
retransmitted by the small compound gear to the
gears that follow. It amounts to the same thing
as using a stud gear with half as many teeth.
The advantage of compounding is best
demonstrated by the following example:
Suppose a gear ratio of 10 to 1 is required to
cut a certain fine thread, and the smallest gear
you have that will fit the stud has 20 teeth. You
would need a screw gear with 200 teeth, but
such a gear is far too large. However, by
using a 2:1 compound gear in the manner
Quick-Change Gear Mechanism
To do away with the inconvenience and loss
of time involved in removing and replacing change
gears, most modern lathes have a self-contained
change gear mechanism, commonly called the
QUICK-CHANGE GEAR BOX. There are a
number of types used on different lathes but they
are all similar in principle.
The mechanism consists of a cone-shaped
group of change gears. You can instantly connect
any single gear to the gear train by moving a
sliding tumbler gear controlled by a lever. The
cone of gears is keyed to a shaft which drives the
lead screw (or feed rod) directly or through an
intermediate shaft. Each gear in the cluster has
a different number of teeth and hence produces
a different gear ratio when connected in the train.
The same thing happens as when the screw gear
in the gear train is changed, described previously.
Sliding gears also produce other changes in the
gear train to increase the number of different
ratios you can get with the cone of change gears
described above. All changes are made by shifting
appropriate levers Or knobs. An index plate or
chart mounted on the gear box indicates the
position for placing the levers to get the necessary
gear ratio to cut the thread or produce the feed
desired.
LARGE
COMPOUND
GEAR
SMALL
COMPOUND
GEAR
28.84X
Figure 7-13. — Compound gearing on a lathe.
7-11
Figure 7-14 is the rear view of one type of gear
box, showing the arrangement of gears. The
splined shaft F turns with gear G, which is driven
by the spindle through the main gear train on the
end of the lathe. Shaft F in turn drives shaft H
through the tumbler gear T which can be engaged
with any one of the cluster of eight different size
gears on shaft H by means of the lever C. Shaft
H drives shaft J through a double clutch gear,
which takes the drive through one of three gears,
depending on the position of lever B (right, center,
or left). Shaft J drives the lead screw through
gear L.
Either the lead screw or the feed rod can be
connected to the final driveshaft of the gear box
by engaging appropriate gears.
Twenty-four different gear ratios are pro-
vided by the quick-change gear box shown in
figure 7-15. The lower lever has eight positions,
each of which places a different gear in the
gear train and hence produces eight different
gear ratios. The three positions of the upper
level produce three different gear ratios for
each of the 8 changes obtained with the lower
lever, thus making 24 combinations in the
box alone. You can double this range by
using a sliding compound gear which provides
a high- and low-gear ratio in the main gear
train. This gives two ratios for every combina-
tion obtainable in the box, or 48 combinations
in all.
Figure 7-16 shows how the sliding compound
gear produces two different gear ratios when it
is moved in or out. The wide gear at the bottom
corresponds to gear G in figure 7-14.
INSTRUCTIONS FOR OPERATION.— If
you are to cut 16 threads per inch, locate the
number 16 on the index plate in the first column
and fourth line under SCREW THREADS PER
INCH (fig. 7-15). Adjust the sliding gear knob
(fig. 7-16) to the OUT position as indicated
opposite 16 in the first column at the left
(fig. 7-15). (You must stop the lathe to adjust the
sliding gear.) Start the lathe and set top lever B
(fig. 7-14) to the LEFT position as indicated in
the second column, opposite 16 (fig. 7-15).
With the lathe running, shift the tumble lever
C to the position directly under the column in
which 16 is located; rock it until the gears mesh
and the handle plunger latches in the hole pro-
vided. The lathe is now set to cut the desired
thread if the half-nuts are clamped onto the lead
screw.
28.85X
28.87X
Figure 7-15. — Quick-change gear box.
SLIDING GEAR
KNOB
SLIDING GEAR-
"OUT" POSITION
SLIDING GEAR
-IN" POSITION
DRIVE SHAFT TO
QUICK-CHANGE GEAR BOX
28.86X
Figure 7-16. — Showing how the gear ratio is changed by
sliding gear.
ADJUSTING THE GEAR BOX FOR
POWER FEEDS.— The index chart on the gear
box also shows the various rates of power
longitudinal feed per spindle revolution that
you can get by using the feed mechanism of the
apron. For example, in figure 7-15, note that
the finest longitudinal feed is 0.0030 inch per
revolution of spindle, the next finest is 0.0032
inch, and so on. To arrange the gear box for
power longitudinal feed, select the feed you wish
to use and follow the same procedure explained
for cutting screw threads, except that you
engage the power feed lever instead of the
half -nuts. Crossfeeds are not listed on the chart
but you can determine them by multiplying the
longitudinal feeds by 0.375, as noted on the
index plate.
On a lathe with a separate feed rod, a feed-
thread shifting lever located at the gear box
(part 9 in fig. 7-1) connects the drive to the feed
rod or the lead screw as desired. When the feed
rod is engaged, the lead screw is disengaged and
vice versa.
7-13
10-
16
14
8
1 ^
i
t
1
^**
• V.
*\
"i i
, \\ '<—
--1 i. -
tf T
r
40 «6 JO t
1. Cross-slide.
2. Compound rest swivel.
3. Compound rest top.
4. Compound rest nut.
5. Compound rest feed
screw handle.
6. Crossfeed nut.
7. Chip guard.
8. Swivel securing
bolts.
9. Toolpost.
10. Toolpost setscrew.
Figure 7-17. — Compound rest.
11. Toolpost wedge.
12. Toolpost ring.
13. Toolholder.
14. Cutting tool.
15. Micrometer collar.
16. Toolholder setscrew.
LOCKING NUT
BORING BAR
TOOLHOLDER
TOOL POST
28.88X
28.299
Figure 7-18. — Castle type toolpost and toolholder.
7-14
me ieaa screw to me spmaie gear tram mat
provides the correct conversion ratio. You can
find information on this in handbooks for
machinists, in the equipment technical manual,
and through direct correspondence with the equip-
ment manufacturer.
COMPOUND REST
The compound rest provides a rigid, adjust-
able mounting for the cutting tool. The compound
rest assembly has the following principal parts
(fig. 7-17):
1 . The compound rest SWIVEL (2) which can
be swung around to any desired angle and
clamped in position. It is graduated over
an arc of 90° on each side of its center
position for ease in setting to the angle you
select. This feature is used in machining
short, steep tapers such as the angle on
bevel gears, valve disks, and lathe centers.
2. The compound rest TOP, or TOPSLIDE
(3), is mounted as shown on the swivel
section (2) on a dovetailed slide. It is moved
along the slide by the compound rest feed
screw turning in nut (4), operated by handle
(5), in a manner similar to the cross feed
described previously (fig. 7-8). This
provides for feeding at any angle (deter-
mined by the angular setting of the swivel
section), while the cross-slide feed provides
only for feeding at a right angle to the axis
of the lathe. The graduated collar on the
compound rest feed screw reads in
thousandths of an inch for fine adjustment
in regulating the depth of cut.
ATTACHMENTS AND
ACCESSORIES
Accessories are the tools and equipment
used in routine lathe machining operations.
Attachments are special fixtures which may be
secured to the lathe to extend the versatility of
the lathe to include taper-cutting, milling, and
grinding. Some of the common accessories and
attachments used on lathes are described in the
following paragraphs.
quick change — are discussed in the following
paragraphs. The sole purpose of the toolpost is
to provide a rigid support for the toolholder.
The standard toolpost is mounted in the
T-slot of the compound rest top as shown in
figure 7-17. A toolholder (13) is inserted in the
slot in the toolpost and rests on the toolpost wedge
(11) and the toolpost ring (12). By tightening
setscrew (10), you clamp the whole unit firmly in
place with the tool in the desired position.
The castle type toolpost (fig. 7-18) is used with
boring bar type toolholders. It mounts in the
T-slot and the toolholder (boring bar) passes
through it and the holddown bolt. By tightening
the locking nut, you clamp the entire unit firmly
in place. Various size holes through the toolpost
allow the use of assorted diameter boring bars.
The quick change type toolpost (fig. 7-19) is
available in many Navy machine shops. It mounts
in the T-slots and is tightened in place by the
locknut, which clamps the toolpost firmly in
place. Special type toolholders are used in
conjunction with this type of toolpost and are held
in place by a locking plunger which is operated
by the toolholder locking handle. Some toolposts
have a sliding gib to lock the toolholder. With this
type of toolpost, only the toolholders are changed,
allowing the toolpost to remain firmly in place,
28.300
Figure 7-19.— Quick change toolpost.
7-15
TOOLHOLDERS
Lathe toolholders are designed to be used with
the various types of toolposts. Only the three most
commonly used types — standard, boring bar, and
quick change — are discussed in this chapter. The
toolholder holds the cutting tool (toolbit) in a rigid
and stable position. Toolholders are generally
made of a softer material than the cutting tool.
They are large in size and help to carry the heat
generated by the cutting action away from the
point of the cutting tool.
STRAIGHT SHANK TURNING TOOL
BORING TOOL
LEFT HAND
TURNING TOOL
RIGHT HAND
TURNING TOOL
STRAIGHT CUT-OFF TOOL
28.67
Standard toolholders were discussed briefly in
chapter 6 of this manual. However, there are more
types (fig. 7-20) than those discussed in chapter
6. Two that differ slightly from others are
the threading and knurling toolholders. (See
fig. 7-21.)
The THREADING TOOL shown in figure
7-21 has a formed cutter which needs to be ground
on the top surface only for sharpening, the thread
form being accurately shaped over a large arc of
the tool. As the surface is worn away by grinding,
you can rotate the cutter to the correct cutting
position and secure it there by the setscrew.
NOTE: The threading tool is not commonly used.
It is customary to use a regular toolholder with
an ordinary tool bit ground to the form of the
thread desired.
A KNURLING TOOL (fig. 7-21) carries
pattern on the work by being fed into the work
as it revolves. The purpose of knurling is to give
DIAMOND
PATTERN
STRAIGHT
PATTERN
Figure 7-20.— Standard lathe toolholders.
KNURLING TOOL
THREADING TOOL
COARSE MEDIUM FINE COARSE MEDIUM FINE
: i
'
KNURLING PRODUCED BY KNURLING PRODUCED BY
PAIRS OF RIGHT AND PAIRS OF STRAIGHT
LEFT-HAND STANDARD LINE KNURLS
FACE KNURLS
28.67
Figure 7-21.— Knurling and threading tools.
28.301
Figure 7-22. — Types of knurling rollers.
knurled roller comes in a wide variety of patterns.
(See fig. 7-22.)
The BORING BAR toolholder is nothing
more than a piece of round stock with a screw-on
cap. (See fig. 7-18.) The caps are available with
square holes broached through them at various
angles (fig. 7-18) and sizes. When the proper size
toolbit is inserted into the cap and the cap is
screwed on to the threaded end of the piece of
round stock, the entire unit becomes a very rigid
boring tool which is used with the castle type
toolpost.
The QUICK CHANGE toolholder (fig. 7-23)
is mounted on the toolpost by sliding it from
28.302
Figure 7-23.— Quick change toolpost and toolholder.
MORSE TAPER
PLAIN TOOLBIT THREADING PARTING
kVSVJUlVAlllV.L 110.3 a H^lgliL aUJUOllllg HAAg LV^ «,J.iV TI _j vw.
to set the proper height prior to locking it in place.
The quick change toolholder comes in a wide
range of styles. A few of these styles are shown
in figure 7-24.
LATHE CHUCKS
The lathe chuck is a device for holding lathe
work. It is mounted on the nose of the spindle.
The work is held by jaws which can be moved in
radial slots toward the center to clamp down on
the sides of the work. These jaws are moved in
and out by screws turned by a chuck wrench
applied to the sockets located at the outer ends
of the slots.
The 4-JAW INDEPENDENT lathe chuck,
figure 7-25, is the most practical for general work.
The four jaws are adjusted one at a time, making
it possible to hold work of various shapes and to
adjust the center of the work to coincide with the
axial center of the spindle.
There are several different styles of jaws for
4-jaw chucks. You can remove some of the chuck
jaws by turning the adjusting screw and then
re-inserting them in the opposite direction. Some
chucks have two sets of jaws, one set being the
reverse of the other. Another style has jaws that
are bolted onto a slide by two socket-head bolts.
On this style you can reverse the jaws by
28.303
Figure 7-24.— Quick change toolholder.
28.304
Figure 7-25.— Four-jaw independent chuck.
7-17
removing the bolts, reversing the jaws, and
re-inserting the bolts. You can make special
jaws for this style chuck in the shop and
machine them to fit a particular size OD or
ID.
The 3-JAW UNIVERSAL or scroll chuck
(fig. 7-26) can be used only for holding round or
hexagonal work. All three jaws move in and out
together in one operation. They move
simultaneously to bring the work on center
automatically. This chuck is easier to operate than
the four-jaw type, but when its parts become worn
you cannot rely on its accuracy in centering.
Proper lubrication and constant care in use are
necessary to ensure reliability. The same styles of
jaws available for the 4-jaw chuck are also
available for the 3 -jaw chuck.
COMBINATION CHUCKS are universal
chucks that have independent movement of each
jaw in addition to the universal movement.
Figures 7-3 and 7-5 illustrate the usual means
provided for attaching chucks and faceplate to
lathes. The tapered nose spindle (fig. 7-3) is
usually found on lathes that have a swing greater
than 12 inches. Matching internal tapers and
keyways in chucks for these lathes ensure accurate
alignment and radial locking. A free turning,
internally threaded collar on the spindle screws
onto a boss on the back of the chuck to secure
the chuck to the spindle nose. On small lathes,
chucks are screwed directly onto the threaded
spindle nose. (See fig. 7-5.)
The DRAW-IN COLLET chuck is used to
hold small work for machining. It is the most
accurate type of chuck and is intended for preci-
sion work.
Figure 7-27 shows the 5 parts of the collet
chuck assembled in place in the lathe spindle. The
collet, which holds the work, is a split cylinder
with an outside taper that fits into the tapered
closing sleeve and screws into the threaded end
of the hollow drawbar that passes through the
hollow spindle. When the handwheel, which is
attached by threads to the outside of the drawbar,
is turned clockwise, the drawbar pulls the collet
into the tapered sleeve, thereby decreasing the
diameter of the hole in the collet. As the collet
is closed around the work, the work is centered
accurately and is held firmly by the chuck.
Collets are made with hole sizes ranging from
1/64 inch up, in 1/64-inch steps. The best results
are obtained when the diameter of the work is
exactly the same size as the dimension stamped
on the collet.
To ensure accuracy of the work when using
the draw-in collet chuck, be sure that the contact
surfaces of the collet and the closing sleeve are
free of chips and dirt. NOTE: The standard collet
has a round hole, but special collets for square
and hexagonal shapes are available.
The RUBBER COLLET CHUCK (fig. 7-28)
is designed to hold any bar stock from 1/16 inch
up to 1 3/8 inch. It is different from the draw-in
type collet previously mentioned in that the bar
stock does not have to be exact in size.
The rubber flex collet consists of rubber and
hardened steel plates. The nose of the chuck has
28.305
Figure 7-26.— Three-jaw universal chuck.
28.91X
Figure 7-27. — Draw-in collet chuck assembled.
NOSE
LOCKING
RING
7/8"- 1" COLLET
1/16"- 1/8" COLLET
28.306
Figure 7-28.— Rubber flex collet chuck.
external threads, and, by rotating the handwheel
(fig. 7-28), you compress the collet around the bar.
This exerts equal pressure from all sides and
enables you to align the stock very accurately. The
locking ring, when pressed in, gives a safe lock
that prevents the collet from coming loose when
the machine is in operation.
DRILL CHUCKS are used to hold center
drills, straight shank drills, reamers, taps, and
small rods. The drill chuck is mounted on a
tapered shank or arbor which fits the Morse taper
hole in either the headstock or tailstock spindle.
Figure 7-29 shows the three-jaw type. A revolving
sleeve operated by a key opens or closes the three
jaws simultaneously to clamp and center the drill
in the chuck.
FACEPLATES are used for holding work
that cannot be swung on centers or in a chuck
because of its shape or dimensions. The T-slots
and other openings on the surface of the faceplate
provide convenient anchor points for bolts and
clamps used to secure the work to the faceplate.
28.92X
Figure 7-29.— Drill chuck.
The faceplate is mounted on the nose of the
spindle.
The DRIVING PLATE is similar to a small
faceplate and is used primarily for driving work
that is held between centers. A radial slot receives
the bent tail of a lathe dog clamped to the work
to transmit rotary motion to the work.
LATHE CENTERS
The lathe centers shown in figure 7-30 provide
a means for holding the work between points so
it can be turned accurately on its axis. The
60" POINTS
TAPERED SHANK (MORSE TAPER)
SH*NK (MORSE TAPER)
LIVE CENTER
DEAD CENTER
28.93
Figure 7-30.— Lathe centers.
7-19
headstock spindle center is called the LIVE center
because it revolves with the work. The tailstock
center is called the DEAD center because it does
not turn. Both live and dead centers have shanks
turned to a Morse taper to fit the tapered holes
in the spindles; both have points finished to an
angle of 60°. They differ only in that the dead
center is hardened and tempered to resist the
wearing effect of the work revolving on it. The
live center revolves with the work and is usually
left soft. The dead center and live center must
NEVER be interchanged. A dead center requires
a lubricant between it and the center hole to
prevent seizing and burning of the center. NOTE:
There is a groove around the hardened tail center
to distinguish it from the live center.
The centers fit snugly in the tapered holes of
the headstock and tailstock spindles. If chips, dirt,
or burrs prevent a perfect fit in the spindles, the
centers will not run true.
Figure 7-31. — Pipe center.
To remove the headstock center, insert a brass
rod through the spindle hole and tap the center
to jar it loose; you can then pull it out with your
hand. To remove the tailstock center, run the
spindle back as far as it will go by, turning the
handwheel to the left. When the end of the
tailstock screw bumps the back of the center, it
will force the center out of the tapered hole. (See
fig. 7-6.)
For machining hollow cylinders, such as pipe,
use a bull-nosed center called a PIPE CENTER.
Figure 7-31 shows its construction. The taper
shank A fits into the head and tail spindles in the
same manner as the lathe centers. The conical disk
B revolves freely on the collared end. Different
size disks are supplied to accommodate various
ranges of pipe sizes.
Ballbearing or nonfriction centers contain
bearings that allow the point of the center to rotate
with the workpiece while the shank remains
stationary in the tailstock spindle. The center hole
does not need a lubricant when this type or center
is used.
LATHE DOGS
Lathe dogs are used with a driving plate or
faceplate to drive work being machined on centers
whenever the frictional contact alone between the
live center and the work is not sufficient to drive
the work.
LATHE
BED
28.95X
Fieure 7-32. — Lathe doos.
28.96X
TJV1 fantar root
has a regular section (square, hexagon, octagon).
The piece to be turned is held firmly in hole A
by setscrew B. The bent tail C projects through
a slot or hole in the driving plate or faceplate, so
that when the faceplate revolves with the spindle,
it also turns the work. The clamp dog illustrated
at the right in figure 7-32 may be used for
rectangular or irregularly shaped work. Such work
is clamped between the jaws.
CENTER REST
The center rest, also called the steady rest, is
used for the following purposes:
1 . To provide an intermediate support or rest
for long slender bars or shafts being
machined between centers. It prevents them
from springing due to cutting pressure or
sagging as a result of their otherwise un-
supported weight.
2. To support and provide a center bearing
for one end of work, such as a spindle,
being bored or drilled from the end when
it is too long to be supported by the chuck
alone. The center rest, kept aligned by
the ways, can be clamped at any desired
position along the bed, as illustrated in
figure 7-33. It is important that the jaws
A be carefully adjusted to allow the work B
THE WORK
ADJUSTABLE
JAWS
lathe. The top half of the frame is hinged
at C to make it easier to place the center
rest in position without removing the work
from the centers or changing the position
of the jaws.
FOLLOWER REST
The follower rest is used to back up work of
small diameter to keep it from springing under
the pressure of cutting. This rest gets its name
because it follows the cutting tool along the work.
As shown in figure 7-34, it is attached directly to
the saddle by bolts B. The adjustable jaws bear
directly on the finished diameter of the work
opposite and above the cutting tool.
TAPER ATTACHMENT
The taper attachment, illustrated in figure
7-35, is used for turning and boring tapers. It is
bolted to the back of the carriage saddle. In opera-
tion, it is connected to the cross-slide so that it
moves the cross-slide laterally as the carriage
moves longitudinally, thereby causing the cutting
tool to move at an angle to the axis of the work
to produce a taper.
The angle of the desired taper is set on the
guide bar of the attachment, and the guide bar
support is clamped to the lathe bed.
Since the cross-slide is connected to a shoe that
slides on the guide bar, the tool follows along a
28.97X
28.98X
Figure 7-34. — Follower rest.
Figure 7-35. — A taper attachment.
7-21
28.100X
28.99X
Figure 7-37.— Micrometer carriage stop.
Figure 7-36.— Thread dial indicator.
28
Figure 7-38.-Grinder mounted on compound rest.
line that is parallel to the guide bar and hence at
an angle to the work axis corresponding to the
desired taper.
The operation and application of the taper
attachment will be explained further under the
subject of taper turning in chapter 10.
THREAD DIAL INDICATOR
The thread dial indicator, shown in figure
7-36, lets you quickly return the carriage to the
beginning of the thread to set up successive cuts.
This eliminates the necessity of reversing the lathe
and waiting for the carriage to follow the thread
back to its beginning. The dial, which is geared
to the lead screw, indicates when to clamp the
half-nuts on the lead screw for the next cut.
The threading dial consists of a worm wheel
which is attached to the lower end of a shaft and
meshed with the lead screw. The dial is located
on the upper end of the shaft. As the lead screw
revolves, the dial turns. The graduations on the
dial indicate points at which the half-nuts may be
engaged. When the threading dial is not being
used, it should be disengaged from the lead screw
to prevent unnecessary wear to the worm wheel.
CARRIAGE STOP
You can attach the carriage stop to the bed
at any point where you want to stop the carriage.
The carriage stop is used principally in turning,
facing, or boring duplicate parts; it eliminates the
need for repeated measurements of the same
dimension. To operate the carriage stop, set the
stop at the point where you want to stop the feed.
Just before the carriage reaches this point, shut
off the automatic feed and carefully run the
carriage up against the stop.
Carriage stops are provided with or without
micrometer adjustment. Figure 7-37 shows a
micrometer carriage stop. Clamp it on the ways
in the approximate position required and then
adjust it to the exact setting using the micrometer
adjustment. NOTE: Do not confuse this stop with
the automatic carriage stop that automatically
stops the carriage by disengaging the feed or
stopping the lathe.
GRINDING ATTACHMENT
The grinding attachment, illustrated in figure
7-38, is a portable grinder with a base that fits
on the compound rest in the same manner as the
toolpost. Like the cutting tool, the grinding
attachment can be fed to the work at any angle.
It is used for grinding hard-faced valve disks and
seats, for grinding lathe centers, and for all kinds
of cylindrical grinding. For internal grinding,
small wheels are used on special quills (extensions)
screwed onto the grinder shaft.
MILLING ATTACHMENT
The milling attachment adapts the lathe to
perform milling operations on small work,
such as cutting key ways, slotting screwheads,
machining flats, and milling dovetails. Figure 7-39
illustrates the setup for milling a dovetail.
The milling cutter is held in an arbor driven
by the lathe spindle. The work is held in a vise
on the milling attachment. The milling attachment
is mounted on the cross-slide and therefore its
movement can be controlled by the longitudinal
feed and cross feed of the lathe. The depth of the
cut is regulated by the longitudinal feed while the
length of the cut is regulated by the cross feed.
Vertical motion is controlled by the adjusting
screw at the top of the attachment. The vise can
be set at any angle in a horizontal or vertical plane.
28.102X
Figure 7-39. — Milling attachment.
28.103X
Figure 7-40. — A bench lathe.
A milling attachment is unnecessary in shops
equipped with milling machines.
TRACING ATTACHMENTS
A tracing attachment for a lathe is useful
whenever you have to make several parts that are
identical in design. A tracer is a hydraulically
actuated attachment that carries the cutting tool
on a path identical to the shape and dimensions
of a pattern or template of the part to be made.
The major parts of the attachment are a hydraulic
power unit, a tracer valve to which the stylus that
follows the template is attached, a cylinder and
slide assembly that holds the cutting tool and
moves in or out on the command of the tracer
valve hydraulic pressure output, and a template
rail assembly that holds the template of the
part to be made. There are several different
manufacturers of tracers, and each tracer has a
slightly different design and varying operating
features. Tracers can be used for turning,
facing, and boring and are capable of main-
taining a dimensional tolerance equal to that
of the lathe being used. Templates for the
tracer can be made from either flat steel or
aluminum plate or from round bar stock. It is
mismachined dimension will be reproduced on the
parts to be made.
OTHER TYPES OF LATHES
The type of engine lathe that has been
described in this chapter is the general-purpose,
screw cutting precision lathe that is universally
used in the machine shops of ships in the Navy.
Repair ships also carry other types. A short
description of some other types follows.
TOOLROOM LATHE is the name com-
monly applied to an engine lathe intended
tools.
A BENCH LATHE (fig. 7-40) is a small
engine lathe mounted on a bench. Such lathes are
sometimes used in the toolroom of repair ships.
The GAP (EXTENSION) LATHE shown in
figure 7-41 has a removable bed piece shown on
the deck in front of the lathe. This piece can be
removed from the lathe bed to create a gap into
which work of larger diameter may be swung.
Some gap lathes are designed so that the ways can
be moved longitudinally to create the gap.
7-25
BASIC ENGINE LATHE OPERATIONS
In chapter 7 you became familiar with the
basic design and functions of the engine lathe and
the basic attachments used with the engine lathe.
In this chapter, we will discuss the fundamentals
of engine lathe operations.
PREOPERATIONAL PROCEDURES
As a Machinery Repairman you will be
required to know and use specific procedures that
you must follow both prior to and during opera-
tion of the engine lathe. First, you must be fully
aware of and comply with all machine operator
safety precautions. Second, you must be familiar
with the specific type of engine lathe you are going
to operate.
LATHE SAFETY PRECAUTIONS
In machine operations, there is one sequence
of events that you must always follow. SAFETY
FIRST, ACCURACY SECOND, AND SPEED
LAST. With this in mind, we will discuss the
safety of lathe operations first.
1 . Prepare yourself by rolling up your shirt
sleeves and removing your watch, rings,
and other jewelry that might become
caught while you operate a machine.
2. Wear safety glasses or an approved face
shield at all times when you operate a lathe
or when you are in the area of lathes that
are in operation.
3. Be sure the work area is clear of obstruc-
tions that might cause you to trip or fall.
4. Keep the deck area around your machine
clear of oil or grease to prevent the
possibility of anyone slipping and falling
into the machine.
5. Always get someone to help you handle
heavy or awkward parts, stock, or
machine accessories.
6. Never remove chips with your bare hands;
use a stick or brush. (Stop the machine
while you remove the chips.)
7. Prevent long chips from being caught in
the chuck by using good chip control
procedures on your setup.
8. Disengage the machine feed before you
talk to anyone.
9. Know how to stop the machine quickly
if an emergency arises.
10. Be attentive, not only to the operation of
your machine, but the events going on
around it.
1 1 . If you must operate a lathe while under-
way, be especially safety conscious.
(Machines should be operated only in
relatively calm seas.)
12. Know where the cutting tool is while you
take measurements or make adjustments
to the machine.
13. Always observe the specific safety
precautions posted for the machine you
are operating.
MACHINE CHECKOUT
Before you attempt to operate any lathe, make
sure you know how to run it. Read all operating
instructions supplied with the machine. Know
where the various controls are and how to operate
them. When you are satisfied that you know how
the controls work, check to see that the spindle
clutch and the power feeds are disengaged; then
8-1
phases of operation, as follows:
1. Shift the speed change levers into the
various combinations; start and stop the spindle
after each change. Get the feel of this operation.
2. With the spindle running at its slowest
speed, try out the operation of the power feeds
and observe their action. Take care not to run the
carriage too near the limits of its travel. Learn
how to reverse the direction of feeds and how to
disengage them quickly. Before engaging either
of the power feeds, operate the hand controls
to be sure the parts involved are free for
running.
3. Try out the operation of engaging the
lead screw for thread cutting. Remember
that you must disengage the feed mechanism
before you can close the half-nuts on the lead
screw.
4. Practice making changes with the QUICK
CHANGE GEAR MECHANISM by referring
to the thread and feed index plate on the
lathe you intend to operate. Remember that
you may make changes in the gear box
with the lathe running slowly, but you must
stop the lathe to make speed changes by
shifting gears in the main gear train.
Maintenance is an important operational
procedure for lathes and must be performed
according to the Navy's Planned Maintenance
System (PMS). This subject is covered in detail
in the Military Requirements for Petty Officers
training manual. In addition to the regular
planned maintenance, make it a point to oil
your lathe daily wherever oil holes are provided.
Oil the ways often, not only to lubricate
them but to protect their scraped surfaces.
Oil the lead screw often while it is in use
to preserve its accuracy. A worn lead screw
lacks precision in thread cutting. Be sure
the headstock is filled up to the oil level;
drain out and replace the oil when it becomes
dirty or gummy. If your lathe is equipped
with an automatic oiling system for some parts,
be sure all those parts are getting oil. Make it a
habit to CHECK frequently for lubrication of all
moving parts.
Do not treat your machine roughly. When you
shift gears to change speed or feed, remember that
into engagement. Disengage the clutch and stop
the lathe before shifting gears.
Before engaging the longitudinal feed, be
certain that the carriage clamp screw is loose and
that the carriage can be moved by hand. Avoid
running the carriage against the headstock or
tailstock while the machine is under power feed;
carriage pressure against the headstock or the
tailstock puts an unnecessary strain on the lathe
and may jam the gears.
Do not neglect the motor just because it may
be out of sight; check its lubrication. If it does
not run properly, notify the Electrician's Mate
whose duty it is to care for motors. He or she will
cooperate with you to keep it in good condition.
In a machine that has a belt drive from the motor
to the lathe, avoid getting oil or grease on the belt
when you oil the lathe or the motor.
Keep your lathe CLEAN. A clean and orderly
machine is an indication of a good mechanic. Dirt
and chips on the ways, the lead screw, or the cross
feed screws will cause serious wear and impair the
accuracy of the machine.
Never put wrenches, files, or other tools on
the ways. If you must keep tools on the bed, use
a board to protect the finished surfaces of the
ways.
Never use the bed or carriage as an anvil;
remember that the lathe is a precision machine
and nothing must be allowed to destroy its
accuracy.
SETTING UP THE LATHE
Before starting a lathe machining operation,
always ensure that the machine is set up for the
job you are doing. If the work is mounted between
centers, check the alignment of the dead center
with the live center and make any required
changes. Ensure that the toolholder and the
cutting tool are set at the proper height and angle.
Check the workholding accessory to ensure that
the workpiece is held securely. Use the center rest
or follower rest to support long workpieces.
PREPARING THE CENTERS
The first step in preparing the centers is to see
that they are accurately mounted in the headstock
8-2
will impair accuracy by preventing a perfect fit
of the bearing surfaces. Be sure that there are no
burrs in the spindle hole. If you find burrs,
remove them by carefully scraping or reaming
the surface with a Morse taper reamer. Burrs
will produce the same inaccuracies as chips and
dirt.
Center points must be accurately finished to
an included angle of 60°. Figure 8-1 shows the
method of checking the angle with a center gauge.
The large notch of the center gauge is intended
for this particular purpose. If the test shows that
the point is not perfect, true the point in the lathe
by taking a cut over the point with the compound
rest set at 30°. To true a hardened tail center,
either anneal it and then machine it or grind it
if a grinding attachment is available.
Aligning and Testing
To turn a shaft straight and true between
centers, be sure the centers are in the same plane
parallel to t!ie ways of the lathe. You can align
the centers by releasing the tailstock from the ways
and then moving the tailstock laterally with two
adjusting screws. At the rear of the tailstock are
two zero lines, and the centers are approximately
aligned when these lines coincide. To check the
approximate alignment, move the tailstock up
until the centers almost touch and observe their
relative positions as shown in figure 8-2. To
28.106X
Figure 8-2.— Aligning lathe centers.
produce very accurate work, especially if it is long,
use the following procedure to determine and
correct errors in alignment not otherwise detected.
Mount the work to be turned, or a piece of
stock of similar length, on the centers. With a
turning tool in the toolpost, take a small cut to
a depth of a few thousandths of an inch at the
headstock end of the work. Then remove the work
from the centers to allow the carriage to be run
back to the tailstock without withdrawing the tool.
Do not touch the tool setting. Replace the work
in the centers, and with the tool set at the previous
depth take another cut coming in from the
tailstock end. Compare the diameters of these cuts
with a micrometer. If the diameters are exactly
the same, the centers are in perfect alignment. If
they are different, adjust the tailstock in the direc-
tion required by using the set-over adjusting
screws. Repeat the above test and adjustment until
a cut at each end produces equal diameters.
28.105
Figure 8-1. — Checking center point with a center gauge.
8-3
You can also check for positive alignment of
the centers by placing a test bar between the
centers and checking both ends of the bar with
a dial indicator clamped in the toolpost (fig. 8-3).
If the reading on the dial is zero at both ends of
the bar, the centers are aligned. The tailstock must
be clamped to the ways and the test bar must be
properly adjusted between centers so there is no
end play when you take the indicator readings.
Another method you can use to check for
positive alignment of lathe centers is to take a light
cut over the work held between centers. Then
measure the work at each end with a micrometer.
If the readings differ, adjust the tailstock to
remove the difference. Repeat the procedure until
the centers are aligned.
Truing and Grinding
To machine or true a lathe center, remove the
faceplate from the spindle. Then insert the live
center into the spindle and set the compound rest
at an angle of 30° with the axis of the spindle,
as shown in figure 8-4. Place a round-nose tool
in the toolpost and set the cutting edge of the tool
at the exact center point of the lathe center.
Machine a light cut on the center point and test
the point with a center gauge. All lathe centers,
regardless of their size, are finished to an included
angle of 60°.
Recall that if you must true the tailstock
spindle lathe center, anneal it and machine it in
the headstock spindle, following the same opera-
tions described for truing a live center; then
remove, harden, and temper the spindle. It is now
ready for use in the tailstock.
Also if a toolpost grinder is available, you may
true the hardened center by grinding it without
annealing it. As in machining, the first step after
placing the center in the headstock spindle is to
28.108X
Figure 8-4. — Machining a lathe center.
set the compound rest over to 30 ° with the axis
of the lathe. Second, mount a toolpost grinder
or grinding attachment on the lathe as shown in
figure 8-5. Third, cover the exposed ways of the
lathe with cloth or paper to keep the grinding grit
out of the bearing surfaces of the bed and cross-
slides. Fourth, put the headstock in gear to give
approximately 200 rpm to the spindle and take
a light cut over the center point, feeding the wheel
across the point with the compound rest feed
handle. Continue to feed the wheel back and forth
until it is cutting evenly all around the entire length
of the center point. Then check the angle with a
center gauge. Reset the compound rest if necessary
and continue grinding until the center fits the
center gauge exactly. To check the accuracy of
the fit, place a light beneath the center and look
for light between the center point surface and the
edge of the center point gauge.
HEADSTOCK CENTER
TEST BAR
TAIL
STOCK
CENTER
__„
••; •; ; •••••-•••••?••
s
• ' i i, i 'V i , ' 1 1 , '
K
!'>!k^
DIAL INDICATOR
28.107
LATHE
CENTER
GRINDING
WHEEL
LATHE
SPINDLE
AXIS
TOOLPOST.
GRINDER
Figure 8-5.— Grinding a lathe center.
Additional information on the operation of
the toolpost grinder is provided later in this
chapter.
SETTING THE TOOLHOLDER
AND CUTTING TOOL
The first requirement for setting the tool is to
have it rigidly mounted on the tool post holder.
Be sure the tool sits squarely in the toolpost and
that the setscrew is tight. Reduce overhang
as much as possible to prevent the tool from
springing during cutting. If the tool has too much
spring the point of the tool will catch in the work,
causing chatter and damaging both the tool and
the work. The relative distances of A and B in
figure 8-6 show the correct overhang for the tool
28.110X
Figure 8-6. — Tool overhang.
UIC W1UU1 \JL LUC CUlllil
the shank when you use a carbide insert type
cutting tool.
The point of the tool must be correctly
positioned on the work. When you are using a
high-speed cutting tool to straight turn steel, cast
iron, and other relatively hard metals, set the point
on center. The point of a high-speed steel cutting
tool being used to cut aluminum, copper, brass,
and other soft metals should be set exactly on
center. The point of cast alloy (stellite and so
on), carbide, and ceramic cutting tools should be
placed exactly on center regardless of the material
being cut. The tool point should be placed on
center for threading, turning tapers, parting
(cutting-off) or boring.
You can adjust the height of the tool in the
toolholder illustrated in figure 8-6 by moving the
half-moon wedge beneath the toolholder in or out
as required. The quick-change type toolholder
usually has an adjusting screw to stop the tool at
the correct height. Some square turret type
toolholders require a shim beneath the tool to
adjust the height.
There are several methods you can use to set
a tool on center. You can place a dead center in
the tailstock and align the point of the tool with
the point of the center. The tailstock spindle on
many lathes has a line on the side that represents
the center. You can also place a 6-inch rule against
the workpiece in a vertical position and move the
cross-slide in until the tool lightly touches the rule
and holds it in place. Look at the rule from
the side to determine if the height of the
tool is correct. The rule will be straight up
and down when the tool is exactly on center and
will be at an angle when the tool is either high
or low.
METHODS OF HOLDING
THE WORK
You cannot perform accurate work if the work
is improperly mounted. Requirements for proper
mounting are:
1. The work centerline must be accurately
centered along the axis of the lathe spindle.
8-5
2. The work must be held rigidly while being
turned.
3. The work must not be sprung out of shape
by the holding device.
4. The work must be adequately supported
against any sagging caused by its own weight and
against springing caused by the action of the
cutting tool.
There are four general methods of holding
work in the lathe: (1) between centers, (2) on a
mandrel, (3) in a chuck, and (4) on a faceplate.
Work may also be clamped to the carriage for
boring and milling; the boring bar or milling cutter
is held and driven by the headstock spindle.
Other methods of holding work to suit special
conditions are: (1) one end on the live center or
in a chuck with the other end supported in a center
rest, and (2) one end in a chuck with the other
end on the dead center.
HOLDING WORK BETWEEN CENTERS
To machine a workpiece between centers, drill
center holes in each end to receive the lathe
centers. Secure a lathe dog to the workpiece and
then mount the work between the live and dead
centers of the lathe.
Centering the Work
To center drill round stock such as drill-rod
or cold-rolled steel, secure the work to the head
spindle in a universal chuck or a draw-in collet
chuck. If the work is too long and too large to
be passed through the spindle, use a center rest
to support one end. It is good shop practice to
first take a light finishing cut across the face of
the end of the stock to be center drilled. This will
provide a smooth and even surface and will help
prevent the center drill from "wandering" or
breaking. The centering tool is held in a drill chuck
in the tailstock spindle and fed to the work by the
tailstock hand wheel (fig. 8-7).
If you must center a piece very accurately,
bore the tapered center hole after you center drill
CENTERING
TOOL
to correct any run-out of the drill. You can do
this by grinding a tool bit to fit a center gauge
at a 60° angle. Then, with the toolholder held in
the toolpost, set the compound rest at 30° with
the line of center as shown in figure 8-8. Set the
tool exactly on the center for height and adjust
the tool to the proper angle with the center gauge
as shown at A. Feed the tool as shown at B to
correct any run-out of the center. The tool bit
should be relieved under the cutting edge as shown
at C to prevent the tool from dragging or rubbing
in the hole.
For center drilling a workpiece, the combined
drill and countersink is the most practical tool.
Combined drills and countersinks vary in size and
the drill points also vary. Sometimes a drill point
on one end will be 1/8 inch in diameter and the
drill point on the opposite end will be 3/16 inch
in diameter. The angle of the center drill is always
60 ° so that the countersunk hole will fit the angle
of the lathe center point.
If a center drill is not available, you may center
the work with a small twist drill. Let the drill enter
the work a sufficient depth on each end; then
follow with a countersink which has a 60° point.
The drawing and tabulation in figure 8-9 show
the correct size of the countersunk center hole for
the diameter of the work.
In center drilling, use a drop or two of oil on
the drill. Feed the drill slowly and carefully to
prevent breaking the tip. Use extreme care when
the work is heavy, because it is then more difficult
to "feel" the proper feed of the work on the
center drill.
If the center drill breaks in countersinking and
part of the broken drill remains in the work, you
must remove the broken part. Sometimes you can
jar it loose, or you may have to drive it out by
using a chisel. But it may stick so hard that you
-E3
Figure 8-7.— Drilling center hole.
Figure 8-8. — Boring center hole.
w
COMBINED DRILL & COUNTERSINK
NO.OFCOMB.DRILL
AND COUNTERSINK
DIA.OF WORK
(W)
LARGE DIAMETER OF
COUNTERSUNK HOLE(C;
DIA.OF DRILL
(D)
DIA. OF BODY
(F)
1
3/i6"T05/l6"
1/8"
1/16"
13/64"
2
3/8" TO l"
1/16"
3/32"
3/16"
3
1 1/4" TO 2"
1/4"
1/8"
5/16"
4
2 1/4" TO 4"
5/16"
5/32"
7/16"
28.113X
Figure 8-9. — Correct size of center holes.
cannot easily remove it. If so, anneal the broken
part of the drill and drill it out.
The importance of having proper center holes
in the work and a correct angle on the point of
the lathe centers cannot be overemphasized. To
do an accurate job between centers on the lathe,
you must countersink holes of the proper size and
depth, and be sure the points of the lathe centers
are true and accurate.
Figure 8-10 shows correct and incorrect
countersinking for work to be machined on
centers. In example A, the correctly countersunk
hole is deep enough so that the point of the lathe
centers does not come in contact with the bottom
of the hole.
In example B of figure 8-10, the countersunk
hole is too deep, causing only the outer edge of
CORRECT
the hole to rest on the lathe center. Work cannot
be machined on centers countersunk in this
manner.
Example C shows a piece of work that has
been countersunk with a tool having too large an
angle. This work rests on the point of the lathe
center only. It is evident that this work will soon
destroy the end of the lathe center, thus making
it impossible to do an accurate job.
Mounting the Work
Figure 8-11 shows correct and incorrect
methods of mounting work between centers. In
Tl
CORRECT
INCORRECT
28.114X 28.115X
Figure 8-10. — Examples of center holes. Figure 8-11. — Examples of work mounted between centers.
to the work and rigidly held by the setscrew. The
tail of the dog rests in the slot of the drive plate
and extends beyond the base of the slot so that
the work rests firmly on both the headstock center
and tailstock center.
In the incorrect example, the tail of the dog
rests on the bottom of the slot on the faceplate
at A, thereby pulling the work away from the
center points, as shown at B and C, causing the
work to revolve eccentrically.
When you mount work between centers for
machining, there should be no end play between
the work and the dead center. However, if the
work is held too tightly by the tail center, when
the work begins revolving it will heat the center
point and destroy both the center and the work.
To prevent overheating, lubricate the tail center
with a heavy oil or a lubricant specially made for
this purpose.
HOLDING WORK ON A MANDREL
Many parts, such as bushings, gears, collars,
and pulleys, require all the finished external
surfaces to run true with the hole which extends
through them. That is, the outside diameter must
be true with the inside diameter or bore.
General practice is to finish the hole to a
standard size, within the limit of the accuracy
desired. Thus, a 3/4-inch standard hole will have
a finished dimension of from 0.7505 to 0.7495
inch, or a tolerance of one-half of one thousandth
of an inch above or below the true standard size
of exactly 0.750 inch. First, drill or bore the hole
to within a few thousandths of an inch of the
finished size; then remove the remainder of the
material with a machine reamer.
Press the piece on a mandrel tightly enough
so the work will not slip while it is machined and
clamp a dog on the mandrel, which is mounted
between centers. Since the mandrel surface runs
true with respect to the lathe axis, the turned
surfaces of the work on the mandrel will be true
with respect to the hole in the piece.
A mandrel is simply a round piece of steel of
convenient length which has been centered
and turned true with the centers. Commercial
mandrels are made of tool steel, hardened and
ground with a slight taper (usually 0.0005 inch per
inch). On sizes up to 1 inch the small end is usually
one-half of one thousandth of an inch under the
standard size of the mandrel, while on larger sizes
an inch under standard. This taper allows th«
standard hole in the work to vary according tc
the usual shop practice, and still provides the
necessary fit to drive the work when the mandre
is pressed into the hole. However, the taper is noi
great enough to distort the hole in the work. Th(
countersunk centers of the mandrel are lapped foi
accuracy, while the ends are turned smaller thar
the body of the mandrel and are provided witl
flats, which give a driving surface for the lath<
dog.
The size of the mandrel is always marked 01
the large end to avoid error and for convenient
in placing work on it. The work is driven O]
pressed on from the small end and removed th<
same way.
When the hole in the work is not standard size
or if no standard mandrel is available, make a sof
mandrel to fit the particular piece to be machined
Use a few drops of oil to lubricate the surface
of the mandrel before pressing it into the work
because clean metallic surfaces gall or stick whei
pressed together. If you do not use lubricant, yoi
will not be able to drive the mandrel out withou
ruining the work.
Whenever you machine work on a mandrel
be sure that the lathe centers are true an<
accurately aligned; otherwise, the finished turne<
surface will not be true. Before turning accurat
work, test the mandrel on centers before placinj
any work on it. The best test for run-out is on
made with a dial indicator. Mount the indicate
on the toolpost so the point of the indicator jus
touches the mandrel. As the mandrel is turnei
slowly between centers, any run-out will b
registered on the indicator dial.
If run-out is indicated and you cannot correc
it by adjusting the tailstock, the mandrel itself i
at fault (assuming that the lathe centers are true
and cannot be used. The countersunk holes ma
have been damaged, or the mandrel may hav
been bent by careless handling. Be sure you alway
protect the ends of the mandrel when you pres
or drive it into the work. A piece of work mounte
on a mandrel must have a tighter press fit to th
mandrel for roughing cuts than for finishing cuts
Thick-walled work can be left on the mandrel fo
the finishing cut but thin-walled work should b
removed from the mandrel after the roughing ci
8-8
and lightly reloaded on the mandrel before the
finish cut is taken.
In addition to the standard lathe mandrel just
described, there are expansion mandrels, gang
mandrels, and eccentric mandrels.
An EXPANSION mandrel is used to hold
work that is reamed or bored to nonstandard
size. Figure 8-12 shows an expansion mandrel
composed of two parts: a tapered pin that has a
taper of approximately 1/16 inch for each inch'
of length and an outer split shell that is tapered
to fit the pin. The split shell is placed in the work
and the tapered pin is forced into the shell, caus-
ing it to expand until it holds the work properly.
A GANG mandrel (fig. 8-13) is used for
holding several duplicate pieces such as gear
WORK
MANDREL
Figure 8-13.— Gang mandrel.
blanks. The pieces are held tightly against a
shoulder by a nut at the tailstock end.
An ECCENTRIC mandrel has two sets of
countersunk holes, one pair of which is off-center
28.116
Fionrp 8.12.. — A snlit-sh<>ll pvnnnsinn mandrel.
an amount equal to the eccentricity of the work
to be machined. Figure 8-14 illustrates its applica-
tion: A is to be machined concentric with the hole
in the work, while B is to be machined eccentric
to it.
HOLDING WORK IN CHUCKS
The independent chuck and universal chuck
are used more often than other workholding
devices in lathe operations. A universal chuck is
used for holding relatively true cylindrical work
when accurate concentricity of the machined
surface and holding power of the chuck are
secondary to the time required to do the job. An
independent chuck is used when the work is
irregular in shape, must be accurately centered,
or must be held securely for heavy feeds and depth
of cut.
Four-Jaw Independent Chuck
Figure 8-15 shows a rough casting mounted
in a four- jaw independent lathe chuck on the
spindle of the lathe. Before truing the work,
determine which part you wish to turn true. To
mount a rough casting in the chuck, proceed as
follows:
1. Adjust the chuck jaws to receive the
casting. Each jaw should be concentric with the
ring marks indicated on the face of the chuck. If
there are no ring marks, set the jaws equally
distant from the circumference of the chuck body.
2. Fasten the work in the chuck by turning
the adjusting screw on jaw No. 1 and jaw No. 3,
a pair of jaws which are opposite each other. Next
tighten jaws No. 2 and No. 4 (opposite each
other).
3. At this stage the work should be held in
the jaws just tightly enough so it will not fall out
of the chuck while being trued.
Figure 8-14.— Work on an eccentric mandrel.
COMPOUND REST
Figure 8-15. — Work mounted in a 4-jaw independent chuck.
4. Revolve the spindle slowly, and with a piece
of chalk mark the high spot (A in fig. 8-15) on
the work while it is revolving. Steady your hand
on the toolpost while holding the chalk.
5. Stop the spindle. Locate the high spot on
the work and adjust the jaws in the proper
direction to true the work by releasing the jaw
opposite the chalk mark and tightening the one
nearest the tank.
6. Sometimes the high spot on the work will
be located between adjacent jaws. When it is,
loosen the two opposite jaws and tighten the jaws
adjacent to the high spot.
7. When the work is running true in the
chuck, tighten the jaws gradually, working the
jaws in pairs as described previously, until all four
jaws clamp the work tightly. Be sure that the back
of the work rests flat against the inside face of
the chuck, or against the faces of the jaw stops
(B in figure 8-15).
Use the same procedure to clamp semi-finished
or finished pieces in the chuck, except center these
pieces more accurately in the chuck. If the run-
out tolerance is very small, use a dial indicator
to determine the run-out.
Figure 8-16 illustrates the use of a dial test
indicator in centering work that has a hole bored
in its center. As the work is revolved, the high spot
is indicated on the dial of the instrument to a
thousandth of an inch. The jaws of the chuck are
adjusted on the work until the indicator hand
registers no deviation as the work is revolved.
When the work consists of a number of
duplicate parts that are to be tightened in the
28.120X
Figure 8-16.— Centering work with a dial indicator.
chuck, release two adjacent jaws and remove the
work. Place another piece in the chuck and
retighten the two jaws just released.
Each jaw of a lathe chuck, whether an
independent or a universal chuck, has a number
stamped on it to correspond to a similar number
on the chuck. When you remove a chuck jaw for
any reason, always put it back into the proper slot.
When the work to be chucked is frail or light,
tighten the jaw carefully so the work will not
bend, break, or spring.
To mount rings or cylindrical disks on a
chuck, expand the chuck jaws against the inside
of the workpiece. (See fig. 8-17.)
Regardless of how you mount the workpiece,
NEVER leave the chuck wrench in the chuck while
the chuck is on the lathe spindle. If the lathe
should be started, the wrench could fly off the
chuck and injure you or a bystander.
Three-Jaw Universal Chuck
A three-jaw universal, or scroll, chuck allows
all jaws to move together or apart in unison. A
universal chuck will center almost exactly at the
first clamping, but after a period of use it may
develop inaccuracies of from .002 to .010 inch in
centering the work, requiring the run-out of the
work to be corrected. Sometimes you can make
the correction by inserting a piece of paper or thin
shim stock between the jaw and the work on the
HIGH SIDE.
28.121
Figure 8-17.— Work held from inside by a 4-jaw independent
chuck.
When you chuck thin sections, be careful not
to clamp the work too tightly, since the diameter
of the piece will be machined while the piece is
distorted. Then, when you release the pressure of
the jaws after finishing the cut, there will be as
many high spots as there are jaws, and the turned
surface will not be true.
Draw-In Collet Chuck
A draw-in collet chuck is used for very fine
accurate work of small diameter. Long work can
be passed through the hollow drawbar, and short
work can be placed directly into the collet from
the front. Tighten the collet on the work by
rotating the drawbar handwheel to the right.
This draws the collet into the tapered closing
sleeve. Turn the handle to the left to release the
collet.
You will get the most accurate results when
the diameter of the work is the same as the
dimension stamped on the collet. The actual
diameter of the work may vary from the collet
dimension by ±0.001 inch. However, if the work
diameter varies more than this, the accuracy of
the finished work will be affected. Most draw-in
collet chuck sets are sized in 1/64-inch increments
to allow you to select a collet within the required
tolerances.
8-11
Rubber Flex Collet Chuck
A rubber flex collet chuck is basically the same
as the draw-in type collet, except that the size
of the stock held is not as critical. The rubber
collets are graduated in 1/1 6-inch steps and will
tighten down with accuracy on any size within the
1/16-inch range.
CARE OF CHUCKS
To preserve a chuck's accuracy, handle it
carefully and keep it clean. Never force a chuck
jaw by using a pipe as an extension on the chuck
wrench.
Before mounting a chuck, remove the live
center and fill the hole with a rag to prevent chips
and dirt from getting into the tapered hole of the
spindle.
Clean and oil the threads of the chuck and the
spindle nose. Dirt or chips on the threads will
not allow the chuck to seat properly against the
spindle shoulder and will prevent the chuck from
running true. Screw the collar carefully onto the
chuck and tighten it enough to make it difficult
to remove the chuck. Never use mechanical power
to install a chuck, but rotate the collar with your
left hand while you support the chuck in the
hollow of your right arm.
To remove a chuck, place a chuck wrench in
the square hole in one of the jaws and strike a
smart blow on the wrench handle with your hand
in the direction you wish the chuck to rotate.
When you mount or remove a heavy chuck, lay
a board across the bed ways to protect them and
to help support the chuck as you put it on or take
it off. Most larger chucks are drilled and tapped
to accept a padeye for lifting with a chainfall.
The procedures for mounting and removing
faceplates are the same as for mounting and
removing chucks.
Figure 8-18 shows a simple device made of
brass wire for cleaning the threads of a chuck or
faceplate.
HOLDING WORK ON A FACEPLATE
A faceplate used for mounting work that can-
not be chucked or turned between centers because
of its peculiar shape. A faceplate is also used when
holes are to be accurately machined in flat work,
as in figure 8-19, or when large and irregularly
shaped work is to be faced on the lathe.
Work is secured to the faceplate by bolts,
clamps, or any suitable clamping means. The
holes and slots in the faceplate are used to anchor
the holding bolts. Angle plates may be used to
locate the work at the desired angle, as shown in
figure 8-20. (Note the counterweight added for
balance.)
For work to be mounted accurately on a
faceplate, the surface of the work in contact
with the faceplate must be accurate. Check the
accuracy with a dial indicator. If you find run-
out, reface the surface of the work that is in
contact with the faceplate. It is good practice to
place a piece of paper between the work and the
faceplate to keep the work from slipping.
Before securely clamping the work, move it
about on the surface of the faceplate until the
point to be machined is centered accurately over
the axis of the lathe. Suppose you wish to bore
a hole, the center of which has been laid out and
marked with a prick punch. First, clamp the work
to the approximate position on the faceplate.
Then slide the tailstock up to where the dead
n
28.122X
Figure 8-18.— Tool for cleaning thread of a chuck or
faceplate.
28.123X
Figure 8-19. — Eccentric machining of work mounted on a
faceplate.
8-12
center just touches the work. Note, the dead
center should have a sharp, true point. Now
revolve the work slowly and, if the work is off
center, the point of the dead center will scribe a
circle on the work. If the work is on center, the
point of the dead center will coincide with the
prick punch mark.
HOLDING WORK ON THE CARRIAGE
If a piece of work is too large or bulky to
swing conveniently in a chuck or on a faceplate,
you can bolt it to the carriage or the cross-slide
and machine it with a cutter mounted on the
spindle. Figure 8-21 shows a piece of work being
machined by a fly cutter mounted in a boring bar
which is held between centers and driven by a lathe
dog.
USING THE CENTER REST
AND FOLLOWER REST
Long slender work often requires support
between its ends while it is turned; otherwise
the work would spring away from the tool and
chatter. The center rest is used to support such
work so it can be turned accurately at a faster feed
28.128X
Figure 8-21. — Work mounted on a carriage for boring.
and cutting speed than would be possible without
the center rest. (See fig. 8-22).
Place the center rest where it will give the
greatest support to the piece to be turned. This
is usually at about the middle of its length.
Ensure that the center point between the jaws
of the center rest coincides exactly with the axis
of the lathe spindle. To do this, place a short piece
of stock in a chuck and machine it to the diameter
of the workpiece to be supported. Without
removing the stock from the chuck, clamp the
center rest on the ways of the lathe and adjust the
28.124X
Figure 8-20. — Work clamped to an angle plate.
28.125X
Figure 8-22.— Use of a center rest to support work between
centers.
8-13
jaws to the machined surface. Without changing
the jaw settings, slide the center rest into position
to support the workpiece. Remove the stock used
for setting the center rest and set the workpiece
in place. Use a dial indicator to true the workpiece
at the chuck. Figure 8-23 shows how a chuck and
center rest are used to machine the end of a
workpiece.
The follower rest differs from the center rest
in that it moves with the carriage and provides
support against the forces of the cut. To use the
tool turn a "spot" to the desired finish diameter
and about 5/8 to 3/4 inch wide on the workpiece.
Then, adjust the jaws of the follower rest against
the area you just machined. The follower rest will
move with the cutting tool and support the point
being machined.
The follower rest (fig. 8-24) is indispensable
for chasing threads on long screws, as it allows
the cutting of a screw with a uniform pitch
diameter. Without the follower rest, the screw
would be inaccurate because it would spring away
from the tool.
Use a sufficient amount of grease, oil or other
available lubricant on the jaws of the center rest
and follower rest to prevent "seizing" and scoring
the workpiece. Check the jaws frequently to see
that they do not become hot. The jaws may
expand slightly if they get hot and push the work
out of alignment (when the follower rest is used)
or binding (when the center rest is used).
MACHINING OPERATIONS
Up to this point, you have studied the
preliminary steps leading up to performing
machine work on the lathe. You have learned how
to mount the work and the tool, and which tools
are used for various purposes. The next step is
to learn how to use the lathe to turn, bore, and
face the work to the desired form or shape.
TURNING is the machining of the outside
surface of a cylinder.
BORING is the machining of the inside
surface of a cylinder.
FACING is the machining of flat surfaces.
Remember that accuracy is the prime requisite
of a good machine job; so before you start, be
sure that the centers are true and properly aligned,
that the work is mounted properly, and that the
cutting tools are correctly ground and sharpened.
PLANNING THE JOB
It is important for you to study the blueprint
of the part to be manufactured before you begin
machining. Check over the dimensions and note
the points or surfaces from which they are laid
out. Plan the steps of your work in advance to
determine the best way to proceed. Check the
overall dimensions and be sure the stock you
intend to use is large enough for the job. For
example, small design features, such as collars on
pump shafts or valve stems, will require that you
use stock of much larger diameter than that
required for the main features of the workpiece.
CUTTING SPEEDS AND FEEDS
Cutting speed is the rate at which the surface
of the work passes the point of the cutting tool.
It is expressed in feet per minute (fpm).
To find the cutting speed, multiply the
diameter of the work (DIA) in inches times 3.1416
28.126X
Figure 8-23.— Work mounted in a chuck and center rest.
28.127X
Figure 8-24. — Follower rest supporting screw while thread
is being cut.
_ DIAX3.1416 xrpm
The result is the peripheral or cutting speed
in feet per minute. For example, a 2-inch diameter
part turning at 100 rpm will produce a cutting
speed of
TYPE OF MATERIAL
Cutting
Speed (fpm)
2 x 3. 1416 x IQO
12
= 52.36 fpm
If you have selected a recommended cutting
speed from a chart for a specific type of metal,
you will need to figure what rpm is required to
obtain the recommended cutting speed. Use the
following formula:
CS x 12
rpm DIAxS.1416
Table 8-1 gives the recommended approximate
cutting speeds for various metals, using a high-
speed steel tool bit. To obtain an approximate
cutting speed for the other types of cutting
tool materials multiply the cutting speeds
recommended in table 8-1 and other charts, which
you will find in different handbooks, by the
following factors:
Carbon steel tools
50% of HSS, multiply by
0.5
Cast alloy tools — 160% of HSS, multiply
by 1.6
Carbide tools
Ceramic tools
200% to 400% of HSS,
multiply by 2.0 to 4.0
400% to 1600% of HSS,
multiply by 4.0 to 16.0
FEED is the amount the tool advances in each
revolution of the work. It is usually expressed in
thousandths of an inch per revolution of the
spindle. The index plate on the quick-change gear
box indicates the setup for obtaining the feed
desired. The amount of feed to use is best
determined from experience.
Cutting speeds and tool feeds are determined
by various considerations: the hardness and
toughness of the metal being cut; the quality,
shape, and sharpness of the cutting tool; the depth
Low carbon steel
Medium carbon steel
High carbon steel
Stainless steel, Cl 302, 304
Stainless steel, Cl 310,316
Stainless steel, Cl 410
Stainless steel, Cl 416
Stainless steel, Cl 17-4, pH
Alloy steel, SAE 4 130, 4140
Alloy steel, SAE 4030
Gray cast iron
Aluminum alloys
Brass
Bronze
Nickel alloy, Monel 400
Nickel alloy, Monel K500
Nickel alloy, Inconel
Titanium alloy
40-140
70-120
65-100
60
70
100
140
50
70
90
20-90
600-750
200-350
100-110
40-60
30-60
5-10
20-60
of the cut; the tendency of the work to spring
away from the tool; and the rigidity and power
of the lathe. Since conditions vary, it is good
practice to find out what the tool and work will
stand, and then select the most practical and
efficient speed and feed consistent with the finish
desired.
If the cutting speed is too slow, the job takes
longer than necessary and the work produced is
8-15
often unsatisfactory because of a poor finish.
On the other hand, if the speed is too fast
the tool edge will dull quickly and will require
frequent regrinding. The cutting speeds possible
are greatly affected by the use of a suitable
cutting lubricant. For example, steel that can
be rough turned dry at 60 rpm can be turned
at about 80 rpm when flooded with a good
cutting lubricant.
When ROUGHING parts down to size,
use the greatest depth of cut and feed per
revolution that the work, the machine, and
the tool will stand at the highest practical
speed. On many pieces, when tool failure is
the limiting factor in the size of the roughing
cut, it is usually possible to reduce the speed
slightly and increase the feed to a point that
the metal removed is much greater. This will
prolong tool life. Consider an example of when
the depth of cut is 1/4 inch, the feed is 20
thousandths of an inch per revolution, and the
speed is 80 fpm. If the tool will not permit
additional feed at this speed, you can usually drop
the speed to 60 fpm and increase the feed to about
40 thousandths of an inch per revolution without
having tool trouble. The speed is therefore
reduced 25% but the feed is increased 100% . The
actual time required to complete the work is less
with the second setup.
On the FINISH TURNING OPERATION, a
very light cut is taken since most of the stock has
been removed on the roughing cut. A fine feed
can usually be used, making it possible to run a
high surface speed. A 50% increase in speed
over the roughing speed is commonly used. In
particular cases, the finishing speed may be twice
the roughing speed. In any event, run the work
as fast as the tool will withstand to obtain the
maximum speed in this operation. Use a sharp
tool to finish turning.
Cutting Lubricant
A cutting lubricant serves two main purposes:
(1) It cools the tool by absorbing a portion of the
heat and reduces the friction between the tool and
the metal being cut. (2) It keeps the cutting edge
of the tool flushed clean. A cutting lubricant
generally allows you to use a higher cutting speed,
heavier feeds, and depths of cut than if you
performed the machining operation dry. The life
of the cutting tool is also prolonged by lubricants.
Some common materials and their cutting
lubricants are as follows:
Cast iron — usually worked dry or with a
soluble oil mixture of 1 part of oil to 30 parts
of water, or mineral lard oil.
Alloy steel — soluble oil mixture of 1 part of
oil to 10 parts of water, or mineral lard oil.
Low/medium carbon steel— soluble oil
mixture of 1 part of oil to 20 parts of water,
or mineral lard oil.
Brasses and bronzes — soluble oil mixture of
1 part of oil to 20 parts of water, or mineral
lard oil.
Stainless steel — soluble oil mixture of 1 part
of oil to 5 parts of water, or mineral lard oil.
Aluminum — soluble oil mixture of 1 part of
oil to 25 parts of water, or dry.
Nickel alloys/Monel — soluble oil mixture of
1 part of oil to 20 parts of water, or a
sulfur /based oil.
Babbitt— dry or with a mixture of mineral lard
oil and kerosene.
While the use of a lubricant for straight turn-
ing is desirable, it is very important for threading.
The various operations used and materials
machined on a lathe may cause problems in the
selection of the proper lubricant. A possible
solution is to select a lubricant that is suitable for
the majority of the materials you plan to work
with.
Chatter
A symptom of improper lathe operation is
known as "chatter." Chatter is vibration in either
the tool or the work. The finished work surface
will appear to have a grooved or lined finish
instead of the smooth surface that is expected. The
vibration is set up by a weakness in the work,
work support, tool, or tool support and is perhaps
the most elusive thing you will find in the entire
field of machine work. As a general rule,
strengthening the various parts of the tool
support train will help. It is also advisable to
support the work with a center rest or follower
rest.
8-16
excessive. Since excessive speed is probably the
most frequent cause of chatter, reduce the speed
and see if the chatter stops. You may also increase
the feed, particularly if you are taking a rough
cut and the finish is not important. Another
adjustment you can try is to reduce the lead angle
of the tool (the angle formed between the surface
of the work and the side cutting edge of the tool).
You may do this by positioning the tool closer
and perpendicular to the work.
If none of the above actions works, examine
the lathe and its adjustments. Gibs may be loose
or bearings may be worn after a long period of
heavy service. If the machine is in perfect
condition, the fault may be in the tool or the tool
setup. Check to be sure the tool has been properly
sharpened to a point or as near to a point as the
specific finish will permit. Reduce the overhang
of the tool as much as possible and recheck the
gib and bearing adjustments. Finally, be sure that
the work is properly supported and that the
cutting speed is not too high.
Direction of Feed
Regardless of how the work is held in the
lathe, the tool should feed toward the headstock.
This causes most of the pressure of the cut to be
exerted on the workholding device and the
spindle thrust bearings. When you must feed the
cutting tool toward the tailstock, take lighter cuts
at reduced feeds. In facing, the general practice
is to feed the tool from the center of the workpiece
toward the periphery.
FACING
Facing is the machining of the end surfaces
and shoulders of a workpiece. In addition to
squaring the ends of the work, facing will let you
accurately cut the work to length. Generally, in
facing the workpiece you will need to take only
light cuts since the work has already been cut to
approximate length or rough machined to the
shoulder.
Figure 8-25 shows how to face a cylindrical
piece. Place the work on centers and install a dog.
Using a right-hand side tool, take one or two light
cuts from the center outward to true the work.
If both ends of the work must be faced,
reverse the piece so the dog drives the end just
faced. Use a steel ruler to layout the required
length, measuring from the faced end to the end
SIDE VIEW
28.129X
Figure 8-25. — Right-hand side tool.
to be faced. After you ensure that there is no burr
on the finished end to cause an inaccurate
measurement, mark off the desired dimension
with a scribe and face the second end.
Figure 8-26 shows the facing of a shoulder
having a fillet corner. First, take a finish cut on
the outside of the smaller diameter section. Next
machine the fillet with a light cut by manipulating
the apron handwheel and the crossfeed handle in
unison to produce a smooth rounded surface.
Finally, use the tool to face from the fillet to the
outside diameter of the work.
In facing large surfaces, lock the carriage in
position since only cross feed is required to
traverse the tool across the work. With the
compound rest set at 90 ° (parallel to the axis of
the lathe), use the micrometer collar to feed the
tool to the proper depth of cut in the face. For
greater accuracy in getting a given size when
finishing a face, set the compound rest at 30 °. In
this position, .001-inch movement of the
compound rest will move the tool exactly
.0005-inch in a direction parallel to the axis of the
lathe. (In a 30° - 60° right triangle, the length of
the side opposite the 30 ° angle is equal to one-
half of the length of the hypotenuse.)
28.130X
Figure 8-26.— Facing a shoulder.
8-17
TURNING
Turning is the machining of excess stock from
the periphery of the workpiece to reduce the
diameter. Bear in mind that the diameter of the
work being turned is reduced by the amount equal
to twice the depth of the cut; thus, to reduce the
diameter of a piece by 1/4 inch, you must remove
1/8 inch of metal from the surface.
To remove large amounts of stock in most
lathe machining, you will take a series of roughing
cuts to remove most of the excess stock and then
a finishing cut to accurately "size" the workpiece.
Rough Turning
Figure 8-27 illustrates a lathe taking a heavy
cut. This is called rough turning. When a great
deal of stock is to be removed, you should take
heavy cuts in order to complete the job in the least
possible time.
Be sure to select the proper tool for taking a
heavy chip. The speed of the work and the amount
of feed of the tool should be as great as the tool
will stand.
When taking a roughing cut on steel, cast iron,
or any other metal that has a scale on its surface,
be sure to set the tool deeply enough to get under
the scale in the first cut. If you do not, the scale
on the metal will dull the point of the tool.
Rough machine the work to almost the
finished size; then be very careful in taking
measurements on the rough surface.
Often the heat produced during rough turning
will expand the workpiece, and the lubricant will
flow out of the live center hole. This will result
in both the center and the center hole becoming
worn. Always check the center carefully and
adjust as needed during rough turning operations.
Figure 8-28 shows the position of the tool for
taking a heavy chip on large work. Set the tool
so that if anything causes it to change position
during the machining operation, the tool will
move away from the work, thus preventing
damage to the work. Also, setting the tool in this
position may prevent chatter.
Finish Turning
When you have rough turned the work to
within about 1/32 inch of the finished size, take
a finishing cut. A fine feed, the proper lubricant,
and above all a keen-edged tool are necessary to
produce a smooth finish. Measure carefully to be
sure you are machining the work to the proper
dimension. Stop the lathe whenever you take any
measurements.
If you must finish the work to extremely close
tolerances, wait until the piece is cool before
taking the finish cut. If the piece has expanded
slightly because of the heat generated by turning
and you turn it to size while it is hot, the piece
will be undersize after it has cooled and
contracted.
If you plan to finish the work on a cylindrical
grinder, leave the stock slightly oversize to allow
for the metal the grinder will remove.
Perhaps the most difficult operation for a
beginner in machine work is taking accurate
measurements. So much depends on the accuracy
s,
28.131X
Figure 8-27.— Rough turning.
28.132X
Figure 8-28.— Position of tool for heavy cut.
instruments. You will develop a certain "feel"
through experience. Do not be discouraged if your
first efforts do not produce perfect results.
Practice taking measurements on pieces of known
dimensions. You will acquire the skill if you are
persistent.
Turning to a Shoulder
A time saving procedure for machining a
shoulder is illustrated in figure 8-29. First, locate
and scribe the exact location of the shoulder on
the work. Next, use a parting tool to machine a
groove 1/32 inch from the scribe line toward the
smaller finish diameter end and 1/32 larger than
the smaller finish diameter. Then take heavy cuts
up to the shoulder made by the parting tool.
Finally, take a finish cut from the small end to
the shoulder scribe line. This procedure eliminates
detailed measuring and speeds up production.
PARTING AND GROOVING
One of the methods of cutting off a piece of
stock while it is held in a lathe is a process called
parting. This process uses a specially shaped tool
with a cutting edge similar to that of a square nose
tool. The parting tool is fed into the rotating
work, perpendicular to its axis, cutting a
progressively deeper groove as the work rotates.
When the cutting edge of the tool gets to the center
of the work being parted, the work drops off as
if it were sawed off. Parting is used to cut off parts
that have already been machined in the lathe or
to cut tubing and bar stock to required lengths.
Parting tools can be the inserted blade type
or can be ground from a standard tool blank.
of the cutting portion of the blade that extends
from the holder should be only slightly greater
than half the diameter of the work to parted. The
end cutting edge of the tool must feed directly
toward the center of the workpiece. To ensure
this, place a center in the tailstock and align the
parting tool vertically with the tip of the center.
The chuck should hold the work to be parted with
the point at which the parting is to occur as close
as possible to the chuck jaws. Always make the
parting cut at a right angle to the centerline of
the work. Feed the tool into the revolving work
with the cross-slide until the tool completely
separates the work.
Cutting speeds for parting are usually slower
than turning speeds. You should use a feed that
STRAIGHT HOLDER
INSERTED
BLADE
RIGHT HAND
OFFSET
A. HOLDERS
OFFSET
28.133X
Figure 8-29. — Machining to a shoulder.
B. TOOL OFFSET
Figure 8-30.— Parting tools.
8-19
will keep a thin chip coming from the work. If
chatter occurs, decrease the speed and increase the
feed slightly. If the tool tends to gouge or dig in,
decrease the feed.
Grooves are machined in shafts to provide for
tool runout in threading to a shoulder, to allow
clearance for assembly of parts, to provide
lubricating channels, or to provide a seating
surface for seals and O-rings. Square, round, and
"V" grooves and the tools which are used to
produce them are shown in figure 8-31.
The grooving tool is a type of forming tool.
It is ground without side rake or back rake and
is set to the work at center height with a minimum
of overhang. The side and end relief angles are
generally somewhat less than for turning tools.
When you machine a groove, reduce the spindle
speed to prevent chatter which often develops at
high speeds because of the greater amount of tool
contact with the work.
DRILLING AND REAMING
Drilling operations performed in a lathe differ
very little from drilling operations performed in
a drilling machine. For best results, start the drill-
ing operation by drilling a center hole in the work,
using a combination center drill and countersink.
The combination countersink-center drill is held
in a drill chuck which is mounted in the tailstock
spindle. After you have center drilled the work,
replace the drill chuck with a taper shank drill.
(Note: BEFORE you insert any tool into the
tailstock spindle inspect the shank of the tool for
burrs. If the shank is burred, remove the burrs
with a handstone.) Feed the drill into the work
by using the tailstock handwheel. Use a
coolant/lubricant whenever possible and maintain
sufficient pressure on the drill to prevent chatter,
but not enough to overheat the drill.
If the hole is quite long, back the drill out
occasionally to clear the flutes of metal chips.
Large diameter holes may require you to drill a
pilot hole first. This is done with a drill that is
smaller than the finished diameter of the hole.
SQUARE
GROOVE
ROUND [_£] "V
GROOVE/O GROOVE
Figure 8-31. — Three common types of grooves.
After you have drilled the pilot hole to the
proper depth, enlarge the hole with the finish drill.
If you plan to drill the hole completely through
the work, slow down the feed as the drill nears
the hole exit. This will produce a smoother exit
hole by causing the drill to take a finer cut as it
exits the hole.
If the twist drill is not ground correctly, the
drilled hole will be either excessively oversized or
out of round. Check the drill for the correct angle,
clearance, cutting edge lengths and straightness
before setting it up for drilling. It is almost
impossible to drill a hole exactly the same size as
the drill regardless of the care taken in ensuring
an accurately ground drill and the proper selection
of speeds and feeds. For this reason, any job
which requires close tolerances or a good finish
on the hole should be reamed or bored to the
correct size.
If the job requires that the hole be reamed,
it is good practice to first take a cleanup cut
through the hole with a boring tool. This will true
up the hole for the reaming operation. Be sure
to leave about 1/64 inch for reaming. The
machine reamer has a taper shank and is held in
and fed by the tailstock. To avoid overheating the
reamer, set the work speed at about half that used
for the drilling operation. During the reaming
operation, keep the reamer well lubricated. This
will keep the reamer cool and also flush the chips
from the flutes. Do not feed the reamer too fast;
it may tear the surface of the hole and ruin the
work.
BORING
Boring is the machining of holes or any
interior cylindrical surface. The piece to be bored
must have a drilled or core hole, and the hole must
be large enough to insert the tool. The boring
process merely enlarges the hole to the desired size
or shape. The advantage of boring is that you get
a perfectly true round hole. Also, you can bore
two or more holes of the same or different
diameters at one setting, thus ensuring absolute
alignment of the axis of the holes.
It is usual practice to bore a hole to within a
few thousandths of an inch of the desired size and
then to finish it to the exact size with a reamer.
Work to be bored may be held in a chuck,
bolted to the faceplate, or bolted to the carriage.
Long pieces must be supported at the free end of
a center rest.
When the boring tool is fed into the hole in
work being rotated on a chuck or faceplate, the
nuin nit iiioiuc. me cuiiing cugc ui me uuimg
tool resembles that of a turning tool. Boring tools
may be the solid forged type or the inserted cutter
bit type.
When the work to be bored is clamped to the
top of the carriage, a boring bar is held between
centers and driven by a dog. The work is fed to
the tool by the automatic longitudinal feed of the
i carriage. Three types of boring bars are shown
in figure 8-32. Note the countersunk center holes
at the ends to fit the lathe centers.
Part A of figure 8-32 shows a boring bar fitted
with a fly cutter held by a headless setscrew. The
other setscrew, bearing on the end of the cutter,
is for adjusting the cutter to the work.
Part B of figure 8-32 shows a boring bar fitted
with a two-edge cutter held by a taper key. This
is more of a finishing or sizing cutter, as it cuts
on both sides and is used for production work.
The boring bar shown in part C of figure 8-32
is fitted with a cast iron head to adapt it for
boring work of large diameter. The head is fitted
with a fly cutter similar to the one shown in part
A. The setscrew with the tapered point adjusts the
cutter to the work.
Figure 8-33 shows a common type of boring
bar holder and applications of the boring bar for
boring and internal threading. When threading
is to be done in a blind hole, it sometimes becomes
Figure 8-32. — Various boring bars.
28.135
Figure 8-33. — Application of boring bar holder.
necessary to undercut or relieve the bottom of the
hole. This will enable mating parts to be screwed
all the way to the shoulder and make the threading
operation much easier to do.
KNURLING
Knurling is the process of rolling or squeezing
impressions into the work with hardened steel
rollers that have teeth milled into their faces.
Examples of the various knurling patterns are
shown in chapter 7, figure 7-22. Knurling provides
a gripping surface on the work; it is also used for
decoration. Knurling increases the diameter of the
workpiece slightly when the metal is raised by the
forming action of the knurl rollers.
The knurling tool (fig. 7-23) is set up so the
faces of the rollers are parallel to the surface of
the work and with the upper and lower rollers
equally spaced above and below the work axis or
centerline. The spindle speed should be about half
the roughing speed for the type of metal being
machined. The feed should be between 0.015 inch
and 0.025 inch per revolution. The work should
8-21
be rigidly mounted in the tailstock to help offset
the pressure exerted by the knurling operation.
The actual knurling operation is simple if you
follow a few basic rules. The first step is to make
sure that the rollers in the knurling tool turn freely
and are free of chips and imbedded metal between
the cutting edges. During the knurling process,
apply an ample supply of oil at the point of
contact to flush away chips and provide lubrica-
tion. Position the carriage so that 1/3 to 1/2 of
the face of the rollers extends beyond the end of
the work. This eliminates part of the pressure
required to start the knurl impression. Force the
knurling rollers into contact with the work.
Engage the spindle clutch. Check the knurl to see
if the rollers have tracked properly, as shown in
figure 8-34, by disengaging the clutch after the
work has revolved 3 or 4 times and by backing
the knurling tool away from the work.
If the knurls have double tracked, as shown
in figure 8-34, move the knurling tool to a new
location and repeat the operation. If the knurl is
correctly formed, engage the spindle clutch and
the carriage feed. Move the knurling rollers
into contact with the correctly formed knurled
impressions. The rollers will align themselves with
the impressions. Allow the knurling tool to feed
to within about 1/32 inch of the end of the surface
to be knurled. Disengage the carriage feed and
with the work revolving, feed the carriage by hand
to extend the knurl to the end of the surface. Force
the knurling tool slightly deeper into the work,
reverse the direction of feed and engage the
carriage feed. Allow the knurling tool to feed until
the opposite end of the knurled surface is reached.
Never allow the knurls to feed off the surface.
Repeat the knurling operation until the
diamond impressions converge to a point. Passes
made after the correct shape is obtained will result
in stripping away the points of the knurl. Clean
DOUBLE
IMPRESSION
NCORRECT
the knurl with a brush and remove any burrs or
sharp edges with a file. When knurling, do not
let the work rotate while the tool is in contact with
it if the feed is disengaged. This will cause
rings to be formed on the surface, as shown in
figure 8-35.
SETTING UP THE
TOOLPOST GRINDER
The toolpost grinder is a portable grinding
machine that can be mounted on the compound
rest of a lathe in place of the toolpost. It can be
used to machine work that is too hard to cut by
ordinary means or to machine work that requires
a very fine finish. Figure 8-36 shows a typical
toolpost grinder.
The grinder must be set on center, as shown
in figure 8-37. The centering holes located on the
spindle shaft are used for this purpose. The
grinding wheel takes the place of a lathe cutting
tool; it can perform most of the same operations
as a cutting tool. Cylindrical, tapered, and
internal surfaces can be ground with the toolpost
grinder. Very small grinding wheels are mounted
on tapered shafts, known as quills, to grind
internal surfaces.
The grinding wheel speed is changed by using
various sizes of pulleys on the motor and spindle
shafts. An instruction plate on the grinder gives
both the diameter of the pulleys required to
obtain a given speed and the maximum safe speed
for grinding wheels of various diameters. Grinding
wheels are safe for operation at a speed just below
the highest recommended speed. A higher than
recommended speed may cause the wheel to
disintegrate. For this reason, wheel guards are
furnished with the toolpost grinder to protect
against injury.
Always check the pulley combinations given
on the instruction plate of the grinder when
CORRECT
IMPRESSION
RINGS ON WORK CAUSED BY STOPPING
TOOL TRAVEL WITH WORK REVOLVING
Figure 8-34,— Knurled impressions.
Figure 8-35. — Rings on a knurled surface.
BELT
BELT
GUARD
SPINDLE
CLAMP
Figure 8-36.— Toolpost grinder.
WHEEL
GUARD
GRINDING
WHEEL
TOOL POST GRINDER SPINDLE
HEADSTOCK
SPINDLE
Figure 8-37.— Mounting the grinder at center height.
you mount a wheel. Be sure that the combination
is not reversed, because this may cause the
wheel to run at a speed far in excess of that
recommended. During all grinding operations,
wear goggles to protect your eyes from flying
abrasive material.
Before you use the grinder, dress and true the
wheel with a diamond wheel dresser. The dresser
is held in a holder that is clamped to the chuck
or faceplate of the lathe. Set the point of the
diamond at center height and at a 10 ° to 1 5 ° angle
in the direction of the grinding wheel rotation,
as shown in figure 8-38. The 10° to 15° angle
prevents the diamond from gouging the wheel.
Lock the lathe spindle by placing the spindle speed
control lever in the low rpm position. (Note: The
lathe spindle does not revolve when you are
dressing the grinding wheel.)
Figure 8-38. — Position of the diamond dresser.
Bring the grinding wheel into contact with the
diamond dresser by carefully feeding the cross-
slide in by hand. Move the wheel slowly by hand
back and forth over the point of the diamond,
taking a maximum cut of .0002 inch. Move the
carriage if the face of the wheel is parallel to the
ways of the lathe. Move the compound rest if the
face of the wheel is at an angle. Make the final
depth of cut of 0.0001 inch with a slow, even feed
to obtain a good wheel finish. Remove the
diamond dresser holder as soon as you finish
dressing the wheel and adjust the grinder to begin
the grinding operation.
Rotate the work at a fairly low speed during
the grinding operation. The recommended surface
speed is 60 to 100 feet per minute (fpm). The depth
of cut depends upon the hardness of the work,
the type of grinding wheel, and the desired finish.
Avoid taking grinding cuts deeper than 0.002 inch
until you gain experience. Use a fairly low rate
of feed. You will soon be able to judge whether
the feed should be increased or decreased. Never
stop the work or the grinding wheel while they
are in contact with each other.
To refinish a damaged lathe center, as shown
in figure 8-5, first ensure that the spindle holes,
drill sleeves, and centers are clean and free of
burrs. Install the lathe center to be refinished in
the headstock. Next, position the compound rest
parallel to the ways; then, mount the toolpost
grinder on the compound rest. Make sure that
the grinding wheel spindle is at center height
and aligned with the lathe centers. Move the
compound rest 30 ° to the right of the lathe spindle
axis, as shown in figure 8-5. Mount the wheel
dresser, covering the ways and carriage with rags
to protect them from abrasive particles. Wear gog-
gles to protect your eyes.
Start the grinding motor, by alternately
turning it on and off (let it run a bit longer each
8-23
time) until the abrasive wheel is brought up to top
speed. Dress the wheel, feeding the grinder with
the compound rest. Then move the grinder clear
of the headstock center and remove the wheel
dresser. Set the lathe for the desired spindle speed
and engage the spindle. Pick up the surface of the
center. Take a light depth of cut and feed the
grinder back and forth with the compound rest.
Do not allow the abrasive wheel to feed entirely
off the center. Continue taking additional cuts
until the center cleans up. To produce a good
finish, reduce the feed rate and the depth of cut
to .0005 inch. Grind off the center's sharp point,
leaving a flat with a diameter about 1/32 inch.
Move the grinder clear of the headstock and turn
it off.
Figure 8-39 illustrates refacing the seat of a
high-pressure steam valve which has a hard,
Stellite-faced surface. The refacing must be done
with a toolpost grinder. Be sure that all inside
diameters run true before starting the machine
work. Spindle speed of the lathe should be about
40 rpm or less. Too high a speed will cause the
grinding wheel to vibrate. Set the compound rest
to correspond with the valve seat angle. Use the
cross-slide hand feed or the micrometer stop on
the carriage for controlling the depth of cut; use
the compound rest for traversing the grinding
28.136
Figure 8-39.— Refacing seat of high-pressure steam valve.
wheel across the work surface. Remember,
whenever you grind on a lathe, always place a
cloth across the ways of the bed and over any
other machined surfaces that could become
contaminated from grinding dust.
8-24
CHAPTER 9
ADVANCED ENGINE LATHE OPERATIONS
In chapter 8 you studied a number of lathe
operations, the various methods of holding and
centering work on the engine lathe, and how to
set lathe tools. This chapter is a continuation
of engine lathe operations and deals primarily
with cutting tapers, boring, and cutting screw
threads.
TAPERS
Taper is the gradual decrease in the diameter
of thickness of a piece of work toward one end.
To find the amount of taper in any given length
of work, subtract the size of the small end from
the size of the large end. Taper is usually expressed
as the amount of taper per foot of length, or as
an angle. The following examples explain how to
determine taper per foot of length.
EXAMPLE 1 : Find the taper per foot of a
piece of work 2 inches long: Diameter of the
small end is 1 inch; diameter of the large end is
2 inches.
The amount of the taper is 2 inches minus 1
inch, which equals 1 inch. The length of the taper
is given as 2 inches. Therefore, the taper is 1 inch
in 2 inches of length. In 12 inches of length it
would be 6 inches. (See fig. 9-1).
EXAMPLE 2: Find the taper per foot of a
piece 6 inches long. Diameter of the small
end is 1 inch; diameter of the large end is
2 inches.
The amount of taper is the same as in
example 1; that is, 1 inch. (See fig. 9-1).
However, the length of this taper is 6 inches; hence
the taper per foot is 1 inch x 12/6 = 2 inches per
foot.
From the foregoing, you can see that the
length of a tapered piece is very important in
computing the taper. If you bear this in mind
oof ..,---•
Figure 9-1. — Tapers.
when machining tapers, you will not go wrong.
Use the formula:
TPF = TPI x 12
where:
TPF = TAPER PER FOOT
TPI = TAPER PER INCH
Other formulas used in figuring tapers are as
follows:
T
TPT = —
1F1 L
where:
TPI = TAPER PER INCH
T = TAPER (Difference between large and
small diameters, expressed in inches
L = LENGTH of taper, expressed in inches
x
T =
and T = TPI x L (in inches)
TPI =
TPF
12
9-1
Tapers are frequently cut by setting the angle
of the taper on the appropriate lathe attachment.
There are two angles associated with a taper —
the included angle and the angle with the center
line. The included angle is the angle between the
two angled sides of the taper. The angle with the
center line is the angle between the center line and
either of the angled sides. Since the taper is turned
about a center line, the angle between one side
and the center line is always equal to the angle
between the other side and the center line.
Therefore, the included angle is always twice the
angle with the center line. The importance of this
relationship will be shown later in this chapter.
Table 9-1 is a machinist's chart showing the
relationship between taper per foot, included
angle, and angle with the center line.
There are several well-known tapers that are
used as standards for machines on which they are
used. These standards make it possible to make
or get parts to fit the machine in question without
detailed measuring and fitting. By designating the
name and number of the standard taper being
used, you can immediately find the length, the
diameter of the small and large ends, the taper
per foot, and all other pertinent measurements in
appropriate tables found in most machinist's
handbooks.
There are three standard tapers with which you
should be familiar: (1) the MORSE TAPER
(approximately 5/8 inch per foot) used for the
tapered holes in lathe and drill press spindles and
the attachments that fit them, such as lathe
centers, drill shanks, and so on; (2) the BROWN
& SHARPE TAPER (1/2 inch per foot, except
No. 10, which is 0.5161 inch per foot) used for
milling machine spindle shanks; and (3) the
JARNO TAPER (0.600 inch per foot) used by
some manufacturers because of the ease with
which its dimensions can be determined:
T^- * n j taper number
Diameter of large end = — — — 5 -
TV t u A taper number
Diameter of small end = — - — -
T . .
Length of taper =
taper number
-
Two additional tapers that are considered
standard are the tapered pin and pipe thread
tapers. Tapered pins have a taper of 1/4 inch per
foot while tapered pipe threads have a taper of
3/4 inch per foot.
A copy of a Morse taper table is shown in
figure 9-2. You will no doubt have more use for
this taper than any other standard taper.
Table 9-1.— Tapers Per Foot/ Angles
Taper per
foot
Angle included
Angle with centerline
Taper per inch
1/8
Degrees
0
0
1
1
1
2
2
2
3
3
3
3
4
4
4
9
Minutes
36
54
12
30
47
5
23
41
0
17
35
53
11
28
46
32
Degrees
0
0
0
0
0
1
1
1
1
1
1
1
2
2
2
4
Minutes
18
27
36
45
54
3
12
21
30
38
47
56
5
14
23
46
Inches
0.01042
.01563
.02083
.02604
.03125
.03646
.04167
.04688
.05208
.05729
.06250
.06771
.07292
.07813
.08333
. 16667
3/16
1/4
5/16
3/8
7/16
1/2
9/16
5/8
11/16. . . .
3/4
13/16 ....
7/8
15/16. . . .
1
2
9-2
Key 8<> 19'=
Taper 1H in 12
Y&/A
DETAIL DIMENSIONS
Number of Taper
0
1
2
3
4
5
6
7
Diameter of plug at small end . . D
Diameter at end of socket .... A
Shank:
Whole length of shank B
0.252
.3561
2-11/32
2-7/32
2-1/32
2
5/32
1/4
.235
.160
9/16
1-15/16
.625
.05208
0
0.369
.475
2-9/16
2-7/16
2-3/16
2-1/8
13/64
3/8
.343
.213
3/4
2-1/16
.600
.05
1
0.572
.700
3-1/8
2-15/16
2-5/8
2-9/16
1/4
7/16
17/32
.260
7/8
2-1/2
.602
.05016
2
0.778
.938
3-7/8
3-11/16
3-1/4
3-3/16
5/16
9/16
23/32
.322
1-3/16
3-1/16
.602
.05016
3
1.020
1.231
4-7/8
4-5/8
4-1/8
4-1/16
15/32
5/8
31/32
.478
1-1/4
3-7/8
.623
.05191
4
1.475
1.748
6-1/8
5-7/8
5-1/4
5-3/16
5/8
3/4
1-13/32
.635
1-1/2
4-15/16
.630
.0525
5
2.116
2.494
8-9/16
8-1/4
7-3/8
7-1/4
3/4
1-1/8
2
.760
1-3/4
7
.626
.05216
6
2.750
3.270
11-5/8
11-1/4
10-1/8
10
1-1/8
1-3/8
2-5/8
1.135
2-5/8
9-1/2
.625
.05208
7
Shank depth S
Depth of hole H
Standard plug depth P
Tongue:
Thickness of tongue t
Length of tongue T
Diameter of tongue d
Keyway:
Width of keyway . . . W
Length of keyway L
End of socket to keyway K
Taper per foot
Taper per inch
Number of key
28.138X
Figure 9-2. — Morse tapers.
METHODS OF TURNING TAPERS
In ordinary straight turning, the cutting tool
moves along a line parallel to the axis of the work,
causing the finished job to be the same diameter
throughout. If, however, in cutting, the tool
moves at an angle to the axis of the work, a taper
will be produced. Therefore, to turn a taper, you
must either mount the work in the lathe so the
axis on which it turns is at an angle to the axis
of the lathe, or cause the cutting tool to move at
an angle to the axis of the lathe.
There are three methods in common use for
turning tapers:
1. SET OVER THE TAILSTOCK, which
moves the dead center away from the axis of
the lathe and causes work supported between
centers to be at an angle with the axis of the
lathe.
2. USE THE COMPOUND REST set at
an angle, which causes the cutting tool to be
fed at the desired angle to the axis of the
lathe.
3. USE THE TAPER ATTACHMENT,
which also causes the cutting tool to move at an
angle to the axis of the lathe.
In the first method, the cutting tool is fed by
the longitudinal feed parallel to the lathe axis, but
a taper is produced because the work axis is at
an angle. In the second and third methods, the
work axis coincides with the lathe axis, but a taper
is produced because the cutting tool moves at an
angle.
Setting Over the Tailstock
As stated in chapter 7, you can move the
tailstock top sideways on its base by using the
adjusting screws. In straight turning you use these
adjusting screws to align the dead center with the
tail center by moving the tailstock to bring it on
the center line of the spindle axis. For taper
turning, you deliberately move the tailstock off
center, and the amount you move it determines
the taper produced. You can approximate the
amount of setover by using the zero lines inscribed
on the base and top of the tailstock as shown in
figure 9-3. Then for final adjustment, measure the
setover with a scale between center points as
illustrated in figure 9-4.
In turning a taper by this method, the distance
between centers is of utmost importance. To
illustrate, figure 9-5 shows two very different
tapers produced by the same amount of setover
of the tailstock, because for one taper the length
of the work between centers is greater than for
the other. THE CLOSER THE DEAD CENTER
IS TO THE LIVE CENTER, THE STEEPER
WILL BE THE TAPER PRODUCED. Suppose
28.140X
Figure 9-4. — Measuring setover of dead center.
28.141X
Figure 9-5. — Setover of tailstock showing importance of
considering length of work.
you want to turn a taper on the full length of a
piece 12 inches long with one end having a
diameter of 3 inches, and the other end a diameter
of 2 inches. The small end is to be 1 inch smaller
than the large end; so you set the tailstock over
one-half of this amount or 1/2 inch in this
example. Thus, at one end the cutting tool will
be 1/2 inch closer to the center of the work than
at the other end; so the diameter of the finished
job will be 2 x 1/2 or 1 inch less at the small end.
Since the piece is 12 inches long, you have
produced a taper of 1 inch per foot. Now, if you
wish to produce a taper of 1 inch per foot on a
piece only 6 inches long, the small end will be only
1/2 inch less in diameter than the larger end, so
you should set over the tailstock 1/4 inch or one-
half of the distance used for the 12-inch length.
By now you can see that the setover is
proportional to the length between centers.
Setover is computed by using the following
formula:
S -lx^
S - 2 X 12
where:
S = setover in inches
T = taper per foot in inches
L *= length of taper in inches
28.139X
Figure 9-3. — Tailstock setover lines for taper turning.
T = length in feet of taper
a mandrel, L is the length of the mandrel between
centers. You cannot use the setover tailstock
method for steep tapers because the setover would
be too great and the work would not be properly
supported by the lathe centers. The bearing
surface becomes less and less satisfactory as the
setover is increased. CAUTION: DO NOT
EXCEED .250-inch setover.
After turning a taper by the tailstock setover
method, do not forget to realign the centers for
straight turning of your next job.
Using the Compound Rest
The compound rest is generally used for short,
steep tapers. Set it at the angle the taper will make
with the center line (that is, half of the included
angle of the taper). Then feed the tool to the work
at this angle by using the compound rest feed
screw. The length of taper you can machine is
short because the travel of the compound rest is
limited.
One example of using the compound rest for
taper work is the truing of a lathe center. Other
examples are ref acing an angle type valve disk and
machining the face of a bevel gear. Such jobs are
often referred to as working to an angle rather
than as taper work.
The graduations marked on the compound
rest provide a quick means for setting it to the
angle desired. When the compound rest is set at
zero, the cutting tool is perpendicular to the lathe
axis. When the compound rest is set at 90° on
either side of zero, the cutting tool is parallel to
the lathe axis.
To set up the compound rest for taper turning,
first determine the angle to be cut, measured
from the center line. This angle is half of the
included angle of the taper you plan to cut.
Then set the compound rest to the complement
of the angle to be cut (90° minus angle
to be cut). For example, to machine a 50 ° included
angle (25° angle with the center line), set the
compound rest at 90° - 25°, or 65°.
When you must set the compound rest very
accurately, to a fraction of a degree for example,
to the required angle. Hold the blade of the
protractor on the flat surface of the faceplate and
hold the base of the protractor against the finished
side of the compound rest.
For turning and boring long tapers with
accuracy, the taper attachment is indispens-
able. It is especially useful in duplicating
work; you can turn and bore identical tapers with
one setting of the taper guide bar. Set the guide
bar at an angle to the lathe that corresponds to
the desired taper. The tool cross slide will be
moved laterally by a shoe, which slides on the
guide bar as the carriage moves longitudinally.
The cutting tool will move along a line parallel
to the guide bar. The taper produced will have
the same angular measurement as that set on the
guide bar. The guide bar is graduated in degrees
at one end and in inches per foot of taper at the
other end to provide for rapid setting. Figure 9-6
is a view of the end that is graduated in inches
per foot of taper.
When you prepare to use the taper attach-
ment, run the carriage up to the approximate
position of the work to be turned. Set the
tool on line with the center of the lathe.
Then bolt or clamp the holding bracket
to the ways of the bed (the attachment
itself is bolted to the back of the carriage saddle)
28.142X
Figure 9-6. — End view of taper guide bar.
9-5
bar now controls the lateral movement of the cross
slide. Set the guide bar for the taper desired; the
attachment is ready for operation. To make the
final adjustment of the tool for size, use the
compound rest feed screw, since the crossfeed
screw is inoperative.
There will be a certain amount of lost motion
or backlash when the tool first starts to feed along
the work. This is caused by looseness between the
crossfeed screw and the cross-slide nut. If the
backlash is not eliminated, a straight portion will
be turned on the work. You can remove the
backlash by moving the carriage and tool slightly
past the start of the cut and then returning the
carriage and tool to the start of the cut.
TAPER BORING
Taper boring is usually done with either the
compound rest or the taper attachment. The rules
the boring of taper holes. Begin by drilling the
hole to the correct depth with a drill of the same
size as the specified small diameter of the taper.
This gives you the advantage of boring to the right
size without having to remove metal at the bottom
of the bore, which is rather difficult, particularly
in small, deep holes.
For turning and boring tapers, set the tool
cutting edge exactly at the center of the work.
That is, set the point of the cutting edge even with
the height of the lathe centers; otherwise, the taper
may be inaccurate.
Cut the hole and measure its size and taper
using a taper plug gauge and the "cut and try"
method.
1 . After you have taken one or two cuts, clean
the bore.
28.1433
Figure 9-7. — Turning a taper using taper attachment.
9-6
l_
3. Insert the gauge into the hole and turn it
SLIGHTLY so the chalk (or prussian blue) rubs
from the gauge onto the surface of the hole. If
the workpiece is to be mounted on a spindle, use
the tapered end of the spindle instead of a gauge
to test the taper.
4. Areas that do not touch the gauge will be
shown by a lack of chalk (or prussian blue).
5. Continue making minor corrections until
all, or an acceptable portion, of the hole's
surface touches the gauge. Be sure the taper
diameter is correct before you turn the taper to
its finish diameter.
Figure 9-8 shows a Morse standard taper plug
and a taper socket gauge. They not only give the
proper taper, but also show the proper distance
that the taper should enter the spindle.
28.144X
Figure 9-8. — Morse taper socket gauge and plug gauge.
Much of the machine work performed by a
Machinery Repairman includes the use of screw
threads. The thread forms you will be working
with most are V-form threads, Acme threads, and
square threads. Each of these thread forms is
used for specific purposes. V-form threads are
commonly used on fastening devices such as bolts
and nuts as well as on machine parts. Acme screw
threads are generally used for transmitting
motion, such as between the lead screw and lathe
carriage. Square threads are used to increase
mechanical advantage and to provide good
clamping ability as in the screw jack or vise screw.
Each of these screw forms is discussed more fully
later in the chapter.
There are several terms used in describing
screw threads and screw thread systems that you
must know before you can calculate and machine
screw threads. Figure 9-9 illustrates some of the
following terms:
EXTERNAL THREADS: A thread on the
outside surface of a cylinder.
INTERNAL THREAD: A thread on the in-
side surface of a hollow cylinder.
RIGHT-HAND THREAD: A thread that,
when viewed axially, winds in a clockwise and
receding direction.
LEFT-HAND THREAD: A thread that,
when viewed axially, winds in a counterclockwise
and receding direction.
CREST
ROOT.
FLANKS
•60
THREAD ANGLE
EXTERNAL THREAD
Figure 9-9. — Screw thread nomenclature.
9-7
LEAD: The distance a threaded part moves
axially in a fixed mating part in one complete
revolution.
PITCH: The distance between corresponding
points on adjacent threads.
SINGLE THREAD: A single (single start)
thread whose lead equals the pitch.
MULTIPLE THREAD: A multiple (multiple
start) thread whose lead equals the pitch
multiplied by the number of starts.
CLASS OF THREADS: A group of threads
designed for a certain type of fit. Classes of
threads are distinguished from each other by the
amount of tolerance and allowance specified.
THREAD FORM: The view of a thread along
the thread axis for a length of one pitch.
FLANK: The side of the thread.
CREST: The top of the thread (bounded by
the major diameter on external threads; by the
minor diameter on internal threads).
ROOT: The bottom of the thread (bounded
by the minor diameter on external threads; by the
major diameter on internal threads).
THREAD ANGLE: The angle formed by
adjacent flanks of a thread.
PITCH DIAMETER: The diameter of an
imaginary cylinder that is concentric with the
thread axis and whose periphery passes through
the thread profile at the point where the widths
of the thread and the thread groove are equal. The
pitch diameter is the diameter that is measured
when the thread is machined to size. A change
in pitch diameter changes the fit between the
thread being machined and the mating thread.
NOMINAL SIZE: The size that is used for
identification. For example, the nominal size of
a 1/2-20 thread is 1/2 inch, but its actual size
slightly smaller to provide clearance.
ACTUAL SIZE: The measured size.
BASIC SIZE: The theoretical size. The basic
size is changed to provide the desired clearance
or fit.
MAJOR DIAMETER: The diameter of an
imaginary cylinder that passes through the crests
of an external thread or the roots of an internal
thread.
MINOR DIAMETER: The diameter of an
imaginary cylinder that passes through the roots
of an external thread or the crests of an internal
thread.
HEIGHT OF THREAD: The distance from
the crest to the root of a thread measured along
a perpendicular to the axis of the threaded piece
(also called straight depth of thread).
SLANT DEPTH: The distance from the crest
to the root of a thread measured along the angle
forming the side of the thread.
ALLOWANCE: An intentional difference
between the maximum material limits of mating
parts. It is the minimum clearance (positive
allowance) or maximum interference (negative
allowance) between such parts.
TOLERANCE: The total permissible varia-
tion of a size. The tolerance is the difference
between the limits of size.
THREAD FORM SERIES: Threads are made
in many different shapes, sizes, and accuracies.
When special threads are required by the product
designer, he will specify in detail all the thread
characteristics and their tolerances for production
information. When a standard thread is selected,
however, the designer needs only to specify size,
number of threads per inch, designation of the
standard series and class of fit. With these
specifications, all other information necessary for
production can be obtained from the established
standard, as published. The abbreviated designa-
tions for the different series are as follows:
Abbreviation Full Title of Standard Series
UNC Unified coarse thread series
UNF Unified fine thread series
UNEF Unified extra fine thread series
NC American National coarse
thread series
NF American National fine thread
series
NEF American National extra-fine
thread series
UN Unified constant pitch series
including 4, 6, 8, 12, 16, 20,
28, and 32 threads per inch
NA American National Acme thread
series
NPT American National tapered pipe
thread series
NFS American National straight pipe
thread series
NH American National hose cou-
pling thread series
NS American National Form thread-
special pitch
N BUTT National Buttress Thread
per inch, series symbol, and class symbol,
in that order. For example, the designation
1/4-20 UNC-3A specifies a thread with the follow-
ing characteristics:
Nominal thread diameter = 1/4 inch
Number of threads per inch = 20
Series (Unified coarse) = UNC
Class = 3
External thread = A
Unless the designation LH (left hand) follows the
class designation, the thread is assumed to be a
right-hand thread. An example of the designation
for a left-hand thread is: 1/4-20 UNC-3A-LH.
V-FORM THREADS
The three forms of V-threads that you must
know how to machine are the V-sharp, the
American National and The American Standard
unified. All of these threads have a 60 ° included
angle between their sides. The V-sharp thread has
a greater depth than the others and the crest and
root of this thread have little or no flat. The
external American Standard unified thread has
slightly less depth than the external American
National thread but is otherwise similar. The
American Standard unified thread is actually a
modification of the American National thread.
This modification was made so that the unified
series of threads, which permits interchangeability
of standard threaded fastening devices manufac-
tured in the United States, Canada, and the
United Kingdom, could be included in the
threading system used in the United States. The
Naval Sea Systems Command and naval procure-
ment activities use American Standard unified
threading system specifications whenever possible;
this system is recommended for use by all naval
activities.
To cut a V-form screw thread, you need to
know (1) the pitch of the thread, (2) the straight
depth of the thread, (3) the slant depth of the
thread, and (4) the width of the flat at the root
of the thread. The pitch of a thread is the basis
for calculating all other dimensions and is equal
to 1 divided by the number of threads per inch.
The tap drill size is equal to the thread size minus
the pitch, or the thread size minus ONE divided
by the number of threads per inch.
Tap Drill Size = Thread Size -
the thread), use the slant-depth to determine how
far to feed the tool into the work. The point of
the threading tool must have a flat equal to the
width of the flat at the root of the thread (external
or internal thread, as applicable). If the flat at
the point of the tool is too wide, the resulting
thread will be too thin. If the flat is too narrow,
the thread will be too thick.
The following formulas will provide the
information you need for cutting V-form threads:
1. V-SHARP THREAD
Pitch — - or 1 -f- number of threads per
inch
Straight Depth of thread = 0.886 x pitch
2. AMERICAN NATIONAL THREAD
Pitch = 1 -r number of threads per inch
orn
Straight depth of external thread = 0.64952
x pitch or 0.541266p
Straight depth of internal thread
= 0.541266 x pitch or 0.64952p
Width of flat at point of tool for external
and internal threads = 0.125 x pitch or
0.125p
Slant depth of external thread = 0.750
x pitch or 0.750p
Slant depth of internal thread = 0.625
x pitch or 0.625p
3. AMERICAN STANDARD UNIFIED
Pitch =14- number of threads per inch
or!
n
Straight depth of external thread = 0.61343
inch x pitch or 0.61343p
Straight depth of internal thread = 0.54127
inch x pitch or 0.54127p
Width of flat at root of external thread
= 0.125 inch x pitch or 0.125p
Width of flat at crest of external thread
= 0.125 inch x pitch or 0.125p
Double height of external thread = 1 .22687
inch x pitch or 1 .22687p
Double height of internal thread = 1 .08253
inch x pitch or 1.08253p
9-9
American Standard form of the buttress thread
has a 7 ° angle on the pressure flank; other forms
have 0 °, 3 °, or 5 °. However, the American Stan-
dard form is most often used, and the formulas
in this section apply to this form. The buttress
thread can be designed to either push or pull
against the internal thread of the mating part into
which it is screwed. The direction of the thrust
will determine the way you grind your tool for
machining the thread. An example of the designa-
tion symbols for an American Standard Buttress
thread form is as follows:
6 - 10 («-N BUTT-2)
where 6 = basic major diameter of 6.000
inches
10 = 10 threads per inch
(*• = internal member to push against
external member)
N BUTT = National Buttress Form
2 = class of fit
NOTE: A symbol such as "*-(" indicates that
the internal member is to pull against the external
member.
The formulas for the basic dimensions of the
American Standard Buttress external thread are
as follows:
Pitch -£
Width of flat at crest = 0.1631 x pitch
Root radius = 0.0714 x pitch
Depth of thread = 0.6627 x pitch
The classes of fit are: 1 = free, 2 = medium,
3 = close. The specific dimensions involved
concern the tolerance of the pitch diameter and
the major diameter and vary according to the
nominal or basic size. Consult a handbook for
specific information on the dimensions for the
various classes of fit.
an included angle of 60 ° and a flat on the crest
and the root of the thread. Pipe threads can be
either tapered or straight, depending on the in-
tended use of the threaded part. A description of
the two types is given in the following para-
graphs.
TAPERED PIPE THREADS
Tapered pipe threads are used to provide a
pressure-tight joint when the internal and external
mating parts are assembled correctly. Depending
on the closeness of the fit of the mating parts, you
may need to use a sealing tape or a sealer (pipe
compound) to prevent leakage at the joint. The
taper of the threads is 3/4 inch per foot. Machine
and thread the section of pipe at this angle. The
hole for the internal threads should be slightly
larger than the minor diameter of the small end
of the externally threaded part.
An example of a pipe thread is shown below.
NPT 1/4-18
where NPT = tapered pipe thread
1/4 — inside diameter of the pipe in
inches
18 = threads per inch
Figure 9-15 shows the typical dimensions of
the most common tapered pipe threads.
STRAIGHT PIPE THREADS
Straight pipe threads are similar in form to
tapered pipe threads except that they are not
tapered. The same nominal outside diameter and
thread dimensions apply. Straight pipe threads are
used for joining components mechanically and are
not satisfactory for high-pressure applications.
Sometimes a straight pipe thread is used with a
tapered pipe thread to form a low-pressure seal
in a vibration free environment.
PIPE THREADS
American National Standard Pipe threads are
CLASSES OF THREADS
Classes of fit for threads are determined by
M 6 F
ANGLE BETWEEN SIDES OF THREAD IS 60°. TAPER OF THREAD, ON
DIAMETER, IS J INCH PER FOOT.
THE BASIC THREAD DEPTH IS 0.8 X PITCH OF THREAD AND THE
CREST AND ROOT ARE TRUNCATED AN AMOUNT EQUAL TO 0.039 X PITCH.
EXCEPTING 8 THREADS PER INCH WHICH HAVE A BASIC DEPTH OF 0.788
X PITCH AND ARE TRUNCATED 0.045 X PITCH AT THE CREST AND 0.033
X PITCH AT THE ROOT.
PIPE SIZE
Of)1
QO
£E<Z
UJUj —
5°Q=tr
2xu
i1-"-
PITCH DIAMETER
U-uj
°>0
XH<
i-IOUJ
O^O:
ZU.X
yfcH
LENGTH OF
HAND-TIGHT
ENGAGEMENT
IMPERFECT
THREADS
*9~.
xSx
i_o:<
az2
uii---'
a
&S
5|
£f
3s
SuJ
aj
oc<
OS
z<n
*S
.gO
<IU
0-1
*<
3*
3w
*$
NOMINAL
PIPE SIZE
OUTSIDE
DIAMETER
U. -J
o<o
_z«
OQ.-UJ
5e£
H-XI-
<UJ
fc-1
0<Q
§iS
g£*
55'-
A
B
F
E
c
D
K
G
H
1/8
0.405
27
0.36351
0.37476
0.2638
0.180
0.1285
0.02963
0.03704
0.334
0.39
1/4
0.540
18
0.47739
0.48989
0.4018
0.200
0.1928
0.04444
0.05556
0.433
0.52
3/8
0.675
18
0.61201
0.62701
0.4078
0.240
0.1928
0.04444
0.05556
0.568
0.65
1/2
0.840
14
0.75843
0.77843
0.5337
0.320
0.2478
0.05714
0.07143
0.701
0.81
3/4
1.050
14
0.96768
0.98887
0.5457
0.339
0.2478
0.05714
0.07143
0.911
0.02
1
1.315
ll'/z
1.21363
1.23863
0.6828
0.400
0.3017
0.06957
0.08696
1.144
1.28
Figure 9-15. — Taper pipe thread dimensions.
for each particular class. The tolerance (amount
that a thread may vary from the basic dimension)
decreases as the class number increases. For
example, a class 1 thread has more tolerance than
a class 3 thread. The pitch diameter of the
thread is the most important thread element in
controlling the class of fit. The major diameter
for an external thread and the minor diameter
or bore size for an internal thread are also
important, however, since they control the crest
and root clearances more than the actual fit of
the thread. A brief description of the different
classes of fit follows:
• Classes 1A and IB: Class 1A (external
threads) and class IB (internal) threads are used
where quick and easy assembly is necessary and
where a liberal allowance is required to permit
ready assembly, even with slightly bruised or dirty
threads.
© Classes 2 A and 2B: Class 2A (external) and
class 2B (internal) threads are the most commonly
used threads for general applications including
production of bolts, screws, nuts and similar
threaded fasteners.
• Classes 3A and 3B: Class 3A (external) and
class 3B (internal) threads are used where closeness
of fit and accuracy of lead and angle of thread
are important. These threads require consistency
that is available only through high quality
production methods combined with a very
efficient system of gauging and inspection.
Tables of the basic dimensions and the
maximum and minimum dimensions for each size
and class of fit of threads are found in most
publications and handbooks for machinists. An
example of the dimensions required to accurately
9-13
machine a specific class of fit on a thread is shown
in Table 9-2.
MEASURING SCREW THREADS
Thread measurement is needed to ensure that
the thread and its mating part will fit properly.
It is important that you know the various measur-
ing methods and the calculations that are used to
determine the dimensions of threads.
The use of a mating part to estimate and
check the needed thread is common practice
when average accuracy is required. The thread
is simply machined until the thread and the mating
part will assemble. A snug fit is usually desired
with very little, if any, play between the
parts.
You will sometimes be required to machine
threads that need a specific class of fit, or you
may not have the mating part to use as a gauge.
In these cases, you must measure the thread to
make sure you get the required fit.
An explanation of the various methods
normally available to you is given in the follow-
ing paragraphs.
THREAD MICROMETER
Thread micrometers are used to measure the
pitch diameter of threads. They are graduated and
read in the same manner as ordinary micrometers.
However, the anvil and spindle are ground to the
shape of a thread, as shown in figure 9-16. Thread
micrometers come in the same size ranges as
ordinary micrometers: 0 to 1 inch, 1 to 2 inches,
and so on. In addition, they are available
in various pitch ranges. The number of threads
per inch must be within the pitch range of the
thread.
RING AND PLUG GAUGES
Go and no-go-gauges, such as those shown in
figure 9-17, are often used to check threaded
parts. The thread should fit the "go" portion
of the gauge, but should not screw into or
onto the "no-go" portion. Ring and plug
gauges are available for the various sizes and
classes of fit of thread. They are probably the
most accurate method of checking threads because
they envelop the total thread form, and in effect,
check not only the pitch diameter and the major
and minor diameters, but also the lead of the
thread.
Table 9-2.— Classes of Fit and Tolerances for 1/4-20 UNC Thread
1/4-20 UNIFIED SCREW THREAD (EXTERNAL)
Designation
Basic
Major
Diameter
Maximum
Major
Diameter
Minimum
Major
Diameter
Basic
Pitch
Diameter
Maximum
Pitch
Diameter
Minimum
Pitch
Diameter
1/4-20UNC-1A
1/4-20 UNC-2A
1/4-20UNC-3A
0.250
0.250
0.250
0.2489
0.2489
0.2500
0.2367
0.2408
0.2419
0.2175
0.2175
0.2175
0.2164
0.2164
0.2175
0.2108
0.2127
0.2147
1/4-20 UNIFIED SCREW THREAD (INTERNAL)
Designation
Basic
Minor
Diameter
(Bore Size)
Maximum
Minor
Diameter
(Bore Size)
Minimum
Minor
Diameter
(Bore Size)
Basic
Pitch
Diameter
Maximum
Pitch
Diameter
Minimum
Pitch
Diameter
1/4-20 UNC- IB
1/4-20 UNC-2B
1/4-20 UNC-3B
0.1876
0.1876
0.1887
0.196
0.196
0.196
0.207
0.207
0.2067
0.2175
0.2175
0.2175
0.2248
0.2223
0.2211
0.2175
0.2175
0.2175
ANVIL
SPINDLE
Figure 9-16. — Measuring threads with a thread micrometer.
SPINDLE
MICROMETER
SCREW
DOUBLE END LIMIT PLUG THREAD GAGE
GO RING GAGE
NO GO RING GAGE
ADJUSTABLE THREAD SNAP GAGE
Figure 9-17. — Thread gauges.
THREE WIRE METHOD
The pitch diameter of a thread can be
accurately measured by an ordinary micrometer
and three wires, as shown in figure 9-18.
MAJOR
DIA
MICROMETER ANVIL
Figure 9-18. — Measuring threads using three wires.
The wire size you should use to measure the
pitch diameter depends on the number of threads
per inch. You will obtain the most accurate results
when you use the best wire size. The best size is
not always available, but you will get satisfactory
results if you use wire diameters within a given
range. Use a wire size as close as possible to the
best wire size. To determine the wire sizes, use
these formulas:
Best wire size = 0.57735 inch x pitch
Smallest wire size = 0.56 inch x pitch
Largest wire size = 0.90 inch x pitch
For example, the diameter of the best wire for
measuring a thread that has 10 threads per inch
9-15
is 0.0577 inch, but you could use any size between
0.056 inch and 0.090 inch.
NOTE: The wires should be fairly hard and
uniform in diameter. All three wires must be the
same size. You can use the shanks of drill bits as
substitutes for the wires.
Use the following formulas to determine what
the measurement over the wires should be for a
given pitch diameter.
Measurement = pitch diameter - (0.86603
x pitch) + (3 x wire diameter)
M = PD - (0.86603 x P) + (3 x W)
Use the actual size of the wires in the formula,
not the calculated size.
Example: What should the measurement be
over the wires for a 3/4-10 UNC-2A thread? First,
determine the required pitch diameter for a class
2A 3/4-10 UNC thread. You can find this
information in charts in several handbooks for
machinists. The limits of the pitch diameter for
this particular thread size and class are between
0.6832 and 0.6773 inch. Use the maximum size
(0.6832 inch) for this example. Next, calculate the
pitch for 10 threads per inch. The formula, "one
divided by the number of threads per inch" will
give you pitch = -. For 10 TPI, the pitch is
0. 100 inch. As previously stated, the best wire size
for measuring 10 TPI is 0.0577 inch, so assume
that you have this wire size available. Now make
the calculation. The data collected so far are:
Thread - 3/4-10 UNC - 2A
Pitch diameter (PD) = 0.6832 in.
Pitch (P) = 0.100 in.
Wire size (W) = 0.0577 in.
The standard formula for the measurement
over the wires was M = PD - (0.86603 x p)
+ (3 x W). Enter the collected data in the correct
positions of the formula:
M = 0.6832 in. - (0.86603 in. x 0.100 in.)
4- (3 x 0.0577 in.)
M = 0.6832 in. - 0.086603 in. + 0.1731 in.
M = 0.769697 in.
The measurement over the wires should be
0.769697 in. or when rounded to four decimal
places, 0.7697 in.
As mentioned in the beginning of the section
on classes of threads, the major diameter is a
factor also considered in each different class of
fit. The basic or nominal major diameter is seldom
the size actually machined on the outside diameter
of the part to be threaded. The actual size is
smaller than the basic size. In the case of the
3/4 - 10 UNC - 2A thread, the basic size is 0.750
in.; however, the size that the outside diameter
should be machined to is between 0.7482 and
0.7353 in.
CUTTING SCREW THREADS
ON A LATHE
Screw threads are cut on the on the lathe by
connecting the headstock spindle of the lathe with
the lead screw through a series of gears to get a
positive carriage feed. The lead screw is driven
at the required speed in relation to the headstock
spindle speed. You can arrange the gearing
between the headstock spindle and lead screw so
that you can cut any desired pitch. For example,
if the lead screw has 8 threads per inch and you
arrange the gears so the headstock spindle revolves
four times while the lead screw revolves once, the
thread you cut will be four times as fine as the
thread on the lead screw, or 32 threads per inch.
With the quick-change gear box, you can quickly
and easily make the proper gearing arrangement
by placing the levers as indicated on the index
plate for the thread desired.
When you have the lathe set up to control the
carriage movement for cutting the desired thread
pitch, your next consideration is shaping the
thread. Grind the cutting tool to the shape
required for the form of the thread to be cut, that
is — V-form, Acme, square, and so on.
MOUNTING WORK IN THE LATHE
When you mount work between lathe centers
for cutting screw threads, be sure the lathe dog
is securely attached before you start to cut the
thread. If the dog should slip, the thread will be
ruined. Do not remove the lathe dog from the
work until you have completed the thread. If you
must remove the work from the lathe before the
thread is completed, be sure to replace the lathe
dog in the same slot of the driving plate.
9-16
When you thread work in the lathe chuck, be
sure the chuck jaws are tight and the work is well
supported. Never remove the work from the
chuck until the thread is finished.
When you thread long slender shafts, use a
follower rest. You must use the center rest to
support one end of long work that is to be
threaded on the inside.
POSITIONING OF COMPOUND REST
FOR CUTTING SCREW THREADS
Ordinarily on threads of fine lead, you feed
the tool straight into the work in successive cuts.
For coarse threads, it is better to set the compound
rest at one-half of the included angle of the thread
and feed in along the side of the thread. For the
last -few finishing cuts, you should feed the tool
straight in with the crossfeed of the lathe to make
a smooth, even finish on both sides of the thread.
In cutting V-form threads and when maximum
production is desired, it is customary to place the
compound rest of the lathe at an angle of 29 1/2 °,
as shown in Part A of figure 9-19. When you set
the compound rest in this position and use the
compound rest screw to adjust the depth of cut,
you remove most of the metal by using the left
side of the threading tool (B of fig. 9-19). This
permits the chip to curl out of the way better than
if you feed the tool straight in, and keeps the
thread from tearing. Since the angle on the side
of the threading tool is 30 °, the right side of the
tool will shave the thread smooth and produce a
better finish; although it does not remove enough
metal to interfere with the main chip, which is
taken by the left side of the tool.
USING THE THREAD-CUTTING STOP
Because of the lost motion caused by the play
necessary for smooth operation of the change
gears, lead screw, half-nuts, and so forth, you
must withdraw the thread-cutting tool quickly at
the end of each cut. If you do not withdraw the
tool quickly the point of the tool will dig into the
thread and may break off.
To reset the tool accurately for each successive
cut and to regulate the depth of the chip, use the
thread-cutting stop.
First, set the point of the tool so that it just
touches the work, then lock the thread-cutting
stop by turning the thread-cutting stop screw A
DIRECTION OF
FEED
B
28.150X
(fig. 9-20) until the shoulder is tight against stop
B (fig. 9-20). When you are ready to take the first
chip, run the tool rest back by turning the
crossfeed screw to the left several times, and move
the tool to the point where the thread is to start.
Then, turn the crossfeed screw to the right until
the thread-cutting stop screw strikes the thread-
cutting stop. The tool is now in the original
position. By turning the compound rest feed screw
in 0.002 inch or 0.003 inch, you will have the tool
in a position to take the first cut.
For each successive cut after returning the
carriage to its starting point, you can reset the tool
accurately to its previous position. Turn the
crossfeed screw to the right until the shoulder of
screw A strikes stop B. Then, you can regulate
the depth of the next cut by adjusting the
compound rest feed screw as it was for the first
chip.
For cutting an internal thread, set the
adjustable thread-cutting stop with the head of
the adjusting screw on the inside of the stop.
Withdraw the tool by moving it toward the center
or axis of the lathe.
You can use the micrometer collar on the
crossfeed screw in place of the thread-cutting stop,
if you desire. To do this, first bring the point of
the threading tool up so that it just touches the
work; then adjust the micrometer collar on the
crossfeed screw to zero. Make all adjustments for
obtaining the desired depth of cut with the
compound rest screw. Withdraw the tool at the
end of each cut by turning the crossfeed screw to
the right one turn, stopping at zero. You can then
adjust the compound rest feed screw for any
desired depth.
MICROMETER
COLLAR
ENGAGING THE THREAD
FEED MECHANISM
When cutting threads on a lathe, clamp the
half-nuts over the lead screw to engage the
threading feed and release the half nut lever at
the end of the cut by means of the threading lever.
Use the threading dial (discussed in chapter 7 and
illustrated in fig. 7-37) to determine when to
engage the half-nuts so the cutting tool will follow
the same path during each cut. When an index
mark on the threading dial aligns with the witness
mark on its housing, engage the half-nuts. For
some thread pitches you can engage the half-nuts
only when certain index marks are aligned with
the witness mark. On most lathes you can engage
the half -nuts as follows:
For all even-numbered threads per inch, close
the half -nuts at any line on the dial.
For all odd-numbered threads per inch, close
the half-nuts at any numbered line on the dial.
For all threads involving one-half of a thread
in each inch, such all 1/2, close the half-nuts
at any odd-numbered line.
CUTTING THE THREAD
After setting up the lathe, as explained
previously, take a very light trial cut just deep
enough to scribe a line on the surface of the work,
as shown in A of figure 9-21 . The purpose of this
trial cut is to be sure that the lathe is arranged
for cutting the desired pitch of thread.
To check the number of threads per inch,
place a rule against the work, as shown in B of
figure 9-21, so that the end of the rule rests on
the point of a thread or on one of the scribed lines.
Count the scribed lines between the end of the rule
)-CUTTING
STOP
B
28.151X
• M *-. ji4sxw% M«sv»M****l j-vwft
28.152X
and the first inch mark. This will give the number
of threads per inch.
It is quite difficult to accurately count fine
pitches of screw threads. A screw pitch gauge,
used as illustrated in figure 9-22, is very
convenient for checking the finer screw threads.
The gauge consists of a number of sheet metal
plates in which are cut the exact forms of threads
of the various pitches; each plate is stamped with
a number indicating the number of threads per
inch for which it is to be used.
LUBRICANTS FOR CUTTING
THREADS
To produce a smooth thread in steel, use lard
oil as a lubricant. If you do not use oil, the
cutting tool will tear the steel, and the finish will
be very rough.
If lard oil is unavailable, use any good
cutting oil or machine oil. If you experience
trouble in producing a smooth thread, add a
little powdered sulfur to the oil.
Apply the oil generously before each cut. A
small paint brush is ideal for applying the oil when
you cut external screw threads. Since lard oil is
quite expensive, many machinists place a small
tray or cup just below the cutting tool on the lathe
cross slide to catch the surplus oil that drips off
the work.
RESETTING THE TOOL OR PICKING
UP THE EXISTING THREAD
If the thread-cutting tool needs resharpening
or gets out of alignment or if you are chasing the
threads on a previously threaded piece, you must
reset the tool so it will follow the original thread
groove. To reset the tool, you may (1) use the
compound rest feed screw and crossfeed screw to
jockey the tool to the proper position, (2)
disengage the change gears and turn the spindle
until the tool is positioned properly, or (3) loosen
the lathe dog (if used) and turn the work until the
tool is in proper position in the thread groove.
Regardless of which method you use, you will
usually have to reset the micrometer collars on
the crossfeed screw and the compound rest screw.
Before adjusting the tool in the groove, use
the appropriate thread gauge to set the tool square
with the workpiece. Then with the tool a few
thousandths of an inch away from the workpiece,
start the machine and engage the threading
mechanism. When the tool has moved to a
position near the groove into which you plan to
put the tool, such as that shown by the solid tool
in figure 9-23, stop the lathe without disengaging
the thread mechanism.
To reset the cutting tool into the groove, you
will probably use the compound rest and crossfeed
positioning method. By adjusting the compound
rest slide forward or backward, you can move the
tool laterally to the axis of the work as well as
toward or away from the work. When the point
of the tool coincides with the original thread
¥Tiaiir0 QJJ.1 _
nifrh
28.153 28.154X
Fianre 0.1.1. — Tool must hp reset tn nrioinfil ornnvp.
groove (phantom view of the tool in fig. 9-23),
use the crossfeed screw to bring the tool point
directly into the groove. When you get a good fit
between the cutting tool and the thread groove,
set the micrometer collar on the crossfeed screw
on zero and set the micrometer collar on the
compound rest feed screw to the depth of cut
previously taken.
NOTE: Be sure that the thread mechanism is
engaged and the tool is set square with the work
before adjusting the position of the tool along the
axis of the workpiece.
If it is inconvenient to use the compound rest
for readjusting the threading tool, loosen the lathe
dog (if used); turn the work so that the threading
tool will match the groove, and tighten the lathe
dog. If possible, however, avoid doing this.
Another method, which is sometimes used, is
to disengage the reverse gears or the change gears;
turn the headstock spindle until the point of the
threading tool enters the groove in the work, and
then reengage the gears.
as the lathe must be run very slowly to obtain
satisfactory results with the drilled hole.
LEFT-HAND SCREW THREADS
A left-hand screw (fig. 9-25) turns counter-
clockwise when advancing (looking at the head
of the screw), or just the opposite to a right-hand
screw. Left-hand threads are used for the
crossfeed screws of lathes, the left-hand end of
axles, one end of a turnbuckle, or wherever an
opposite thread is desired.
The directions for cutting a left-hand thread
on a lathe are the same as those for cutting a right-
hand thread, except that you swivel the compound
rest to the left instead of to the right. Figure 9-26
shows the correct position for the compound rest.
The direction of travel for the tool differs from
a right-hand thread in that it moves toward the
tailstock as the thread is being cut.
Before starting to cut a left-hand thread, it is
good practice, if feasible, to cut a neck or groove
into the workpiece. (See fig. 9-25). Such a groove
FINISHING THE END
OF A THREADED PIECE
The end of a thread may be finished by any
one of several methods. The 45 ° chamfer on the
end of a thread, as shown in A of figure 9-24,
is commonly used for bolts and capscrews. For
machined parts and special screws, the end is often
finished by rounding it with a forming tool, as
shown in B of figure 9-24.
It is difficult to stop the threading tool
abruptly, so some provision is usually made for
clearance at the end of the cut. In A of figure 9-24,
a hole has been drilled at the end of the thread;
in B of figure 9-24, a neck or groove has been
cut around the shaft. The groove is preferable,
FINISHING END OF THREAD
WITH 45° CHAMFER
FINISHING END OF THREAD
WITH FORM TOOL
28.155X
Figure 9-24.— Finishing the d of a threaded piece.
28.156X
Figure 9-25. — A left-hand screw thread.
DIRECTION OF TOOL TRAVEL
Figure 9-26. — Setup for left-hand external threads.
enables you to run the tool in for each pass, as
you do for a right-hand thread.
Make the final check for both diameter and
pitch of the thread, whether right-hand or left-
hand, with the nut that is to be used, or with a
ring thread gauge if one is available. The nut
should fit snugly without play or shake but should
not bind on the thread at any point.
MULTIPLE SCREW THREADS
A multiple thread, as shown in figure 9-27,
is a combination of two or more threads, parallel
to each other, progressing around the surface
into which they are cut. If a single thread is
thought of as taking the form of a helix, that is
of a string or cord wrapped around a cylinder,
a multiple thread may be thought of as several
cords lying side by side and wrapped around a
cylinder. There may be any number of threads,
and they start at equally spaced intervals around
the cylinder. Multiple threads are used when rapid
movement of the nut or other attached parts is
desired and when weakening of the thread must
be avoided. A single thread having the same lead
as a multiple thread would be very deep compared
to the multiple thread. The depth of the thread
is calculated according to the pitch of the thread.
The tool selected for cutting multiple threads
has the same shape as that of the thread to be cut
and is similar to the tool used for cutting a single
thread except that greater side clearance is
necessary. The helix angle of the thread increases
as the number of threads increases. The general
method for cutting multiple threads is about the
same as for single screw threads, except that the
lathe gearing must be based on the lead of the
thread (number of single threads per inch), and
not the pitch, as shown in figure 9-27. Provisions
must also be made to obtain the correct spacing
of the different thread grooves. You can get the
proper spacing by using the thread-chasing dial,
setting the compound rest parallel to the ways,
using a faceplate, or using the change gear box
mechanism.
The use of the thread-chasing dial (fig. 9-28)
is the most desirable method for cutting 60° multi-
ple threads. With each setting for depth of cut
with the compound, you can take successive cuts
on each of the multiple threads so that you can
use thread micrometers.
To determine the possibility of using the
thread-chasing dial, first find out if the lathe can
be geared to cut a thread identical to one of the
multiple threads. For example, if you want to cut
10 threads per inch, double threaded, divide the
number of threads per inch (10) by the multiple
(2) to get the number of single threads per inch
(5). Then gear the lathe for 5 threads per inch.
To use the thread-chasing dial on a specific
machine, refer to instructions usually found
attached to the lathe apron. To cut 5 threads per
inch, on most lathes, engage the half -nut at any
numbered line on the dial, such as points 1 and
2 shown in figure 9-28. The second groove of a
double thread lies in the middle of the flat
surface between the grooves of the first thread.
Engage the half -nut to begin cutting the second
thread when an unnumbered line passes the
index mark, as shown in figure 9-28. To ensure
that you cut each thread to the same depth, engage
the half-nut first at one of the numbered positions
and cut in the first groove. Then engage the half
nut at an unnumbered position so that alternate
BEGIN THREAD
NUMBER 1
BEGIN THREAD
NUMBER 2
FOR FIRST THREAD, SPIIT
NUT CLOSED AT POINT "l"
FOR SECOND THREAD, SFLIT
NUT CLOSED AT POINT ~2*
SINGLE THREAD DOUBLE THREAD TRIPLE THREAD
TOOL IN LINE
FOR FIRST THREAD
TOOL IN LINE FOR
SECOND THREAD
Figure 9-27. — Comparison of single and multiple-lead
threads.
Figure 9-28.— Cutting multiple threads using the thread-
chasing dial.
cuts bring both thread grooves down to size
together. To cut a multiple thread with an even
number of threads, first use the thread-chasing
dial to cut the first thread. Then use one of the
other multiple thread cutting procedures to cut
the second thread.
Cutting of multiple threads by positioning the
compound rest parallel to the ways should be
limited to square and Acme threads. To use this
method, set the compound rest parallel to the
ways of the lathe and cut the first thread to the
finished size. Then feed the compound rest and
tool forward, parallel to the thread axis a distance
equal to the pitch of the thread and cut the next
thread.
The faceplate method of cutting multiple
threads involves changing the position of the work
between centers for each groove of the multiple
thread. One method is to cut the first thread
groove in the conventional manner. Then, remove
the work from between centers and replace it bet-
ween centers so the tail of the dog is in another
slot of the drive plate, as shown in figure 9-29.
Two slots are necessary for a double thread, three
slots for a triple thread, and so on. The number
of multiples you can cut by this method depends
on the number of equally spaced slots there are
in the drive plate. There are special drive or
index plates available, so that you can accurately
cut a wide range of multiples by this method.
Another method of cutting multiple threads
is to disengage either the stud gear or the spindle
gear from the gear train in the end of the lathe
after you cut a thread groove. Then turn the work
and the spindle the required part of a revolution,
and reengage the gears for cutting the next thread.
If you are to cut a double thread on a lathe that
has a 40-tooth gear on the spindle, cut the first
thread groove in the ordinary manner. Then mark
one of the teeth on the spindle gear that meshes
with the next driven gear. Carry the mark onto
the driven gear, in this case the reversing gear.
Also mark the tooth diametrically opposite the
marked spindle gear tooth (the 20th tooth of the
40-tooth gear). Count the tooth next to the
marked tooth as tooth number one. Then
disengage the gears by placing the tumbler
(reversing) gears in the neutral position, turn the
spindle one-half revolution or 20 teeth on the
spindle gear, and reengage the gear train. You
may index the stud gear as well as the spindle gear.
If the ratio between the spindle and stud gears is
B
28.158X
Figure 9-30. — Cutting thread on tapered work.
DOG REVOLVED 180°
FOR DOUBLE THREAD
Figure 9-29.— Use of face plate.
not 1 to 1 , you will have to give the stud gear a
proportional turn, depending upon the gearing
ratio. The method of indexing the stud or
spindle gears is possible only when you can evenly
divide the number of teeth in the gear indexed by
the multiple desired. Some lathe machines have
a sliding sector gear that you can readily insert
into or remove from the gear train by shifting a
lever. Graduations on the end of the spindle show
when to disengage and to reengage the sector gear
for cutting various multiples.
THREADS ON TAPERED WORK
Use the taper attachment when you cut a
thread on tapered work. If your lathe does not
have a taper attachment, cut the thread on tapered
work by setting over the tailstock. The setup is
the same as for turning tapers.
Part A of figure 9-30 shows the method
of setting the threading tool with the thread
gauge when you use the taper attachment.
Part B of figure 9-30 shows the same
operation for using the tailstock setover
method.
Note that in both methods illustrated in
figure 9-30, you set the threading tool square with
the axis by placing the center gauge on the straight
part of the work, NOT on the tapered section.
This is very important.
CHAPTER 10
TURRET LATHES AND
TURRET LATHE OPERATIONS
Horizontal and vertical turret lathes are
generally used to produce several identical
workpieces. Because turret lathes are designed for
production work, they have many automatic
features that are not found on engine lathes. For
greatest efficiency, a turret lathe must be set up
so the operator can perform the machining steps
with a minimum amount of control.
In this chapter we shall discuss turret lathes
and some of the important factors in the tooling
setup.
• NEVER completely trust the auto-
matic stops on a turret lathe. Be alert at all
times to the progress and movement of the cutting
tool(s).
• NEVER exceed the recommended depth of
cut, cutting speeds, and feeds.
• Before starting a vertical turret lathe,
always be alert for tools, clamping devices, or
other materials adrift on the lathe table.
TURRET LATHE SAFETY
Before learning to operate a turret lathe, you
must realize the importance of observing safety
precautions. As in all machine operations,
you have one guideline: SAFETY FIRST,
ACCURACY SECOND, AND SPEED LAST.
The safety precautions listed in chapter 8 for
engine lathes apply also to turret lathes. Listed
below are additional safety precautions that you
must observe to safely operate both horizontal
and vertical turret lathes.
• Do NOT use a turret lathe that you are not
authorized and fully qualified to operate.
@ Wear goggles or a face shield whenever you
operate a turret lathe.
• Be sure that long stock extending from
the turret lathe is properly guarded and
supported.
• Be aware of tools mounted on the
turret heads. If you are not careful they will
strike you when the turrets rotate to a new
station.
HORIZONTAL TURRET LATHES
The horizontal turret lathe is a modification
of the engine lathe. The biggest difference is
that the turret lathe has two multifaced tool-
holders. One toolholder (or turret head, as it is
called) is located where the tailstock is on an
engine lathe. In a typical turret lathe, the
turret head has six faces, on each of which
can be fastened various single tools or groups
of cutting tools. The other turret toolholder
(usually square and therefore called the square
turret) is mounted on a cross slide found on
an engine lathe. A typical cross slide turret
can hold one cutting tool on each face. However,
some types can mount two or more tools on one
face. Each turret rotates about an upright
axis. Thus, if you mount the proper cutting
tools on the turrets, you can do several different
machining operations in rapid sequence by merely
rotating another tool or set of tools into position
for feeding into the work. Moreover, you can do
simultaneous machining operations. For instance,
on a particular job, the cross slide turret tool
may be taking an external cut on the workpiece
while a tail-mounted tool on the turret head is
performing an internal machining operation on
the piece, such as boring, reaming, drilling, or
tapping.
10-1
Figure 10-1. — Bar machine.
CLASSIFICATION OF HORIZONTAL
TURRET LATHES
Figures 10-1 and 10-2 show two types of
horizontal turret lathes, the bar machine and the
chucking machine. One main difference between
the two is the size and shape of the work they will
machine. Bar machines are used for making parts
out of bar stock or for machining castings or
forgings of a size and shape similar to bar stock.
(Note that the bar machine (fig. 10-1) has a stock
feed attachment.) Chucking machines are used for
28.159
A-BAR TURNING SETUP
28.160
Figure 10-2.— Chucking machine.
B-CHUCK1NG SETUP
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.161X
Figure 10-3. — Hexagonal turret turning tool setups.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.342X
Figure 10-4. — Ram type bar machine.
machining castings, forgings, and cut bar stock
that must be held in a chuck or fixture because
of their large size or odd shape. The other main
difference between bar and chucking machines is
in the types of turning tools and holders used with
the machines.
Since the bar machine is designed to machine
pieces that have a relatively small cross section,
its hexagonal turret turning tools must be able to
support the work during cutting; otherwise, the
workpiece will very likely bend away from the
cutting tool.
The stock material which the chucking
lathe is designed to machine is usually rigid
enough to withstand heavy cutting forces
without support. Figure 10-3 illustrates the
difference between a bar setup and chucking
setup for a hexagonal turret.
Bar machines and chucking machines may be
either the ram type (fig. 10-4) or the saddle type
(fig. 10-5). On the ram type, the turret head is
mounted on a ram slide, which you can move
longitudinally on a saddle that is clamped to the
bedways of the machine. The ram has both
hand and power longitudinal feeds. To make
adjustments, you must manually move the
saddle, on which the ram is mounted, along the
bedways. The stroke of the ram is relatively short.
For this reason, the ram type is not used for
working material that requires longitudinal
machining with hexagonal turret-held tools.
The saddle type lathe has the turret head
mounted directly on the saddle which, with its
apron or gear box, moves back and forth on the
bedways. The length of the longitudinal cut you
can make with a hexagonal turret-held tool is
limited only by the length of the bedways.
Hexagonal turrets found on board ship do not
normally have cross feed. However, cross feed is
available on some saddle type lathes. An example
of a cross-sliding hexagonal turret is shown in
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.343X
Figure 10-5. — Saddle type chucking machine.
figure 10-5. The small handwheel just to the left
of the large saddle hand feed wheel controls the
manual crossfeed. There are levers for engaging
power feed. The hexagonal turret realigns with
the spindle axis when the cross slide is returned
to its starting position.
Standard toolholders are used to provide cross
feed for the ram type and the fixed center turret
saddle type.
COMPONENTS
Many of the components of turret lathes
are similar to those of engine lathes. We
will discuss only the main components of
the turret lathe that differ in principle of
operation from the engine lathe components.
If you clearly understand the construction
and functions of an engine lathe, you will have
little difficulty in learning the construction and
functions of turret lathes.
Headstock
The first important unit of any turret lathe is
the headstock. Many lathes have a multiple-speed
motor coupled directly to the spindle. Others
have all-geared heads, which provide an even
wider range of spindle or chuck speeds. The all-
geared heads come in a variety of designs, each
having a different number of speeds and a dif-
ferent method of selecting and changing the
speeds. Some models have a preselector that lets
you set up the different speeds you will need for
a job before you begin. On these machines, speed
changes are made through a minimum number of
rapid changes without interfering with the timing
of the operation.
Feed Train
The feed train of a turret lathe (fig. 10-6)
transmits power from the spindle of the machine
to both the cross slide and the hexagonal
turret. The feed train consists of a head end
gear box, a feed shaft, a square turret carriage
apron or gear box, and a hexagonal turret apron
or gear box.
The number of different feeds varies,
depending upon the size and model of the
machine. On any machine, first select a range of
feeds by shifting or changing the gears in the head
SQUARE TURRET
APRON (GEAR BOX)
FEED
SHAFT
HEXAGONAL TURRET
APRON (GEAR BOX)
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.165X
Figure 10-6.— Saddle type turret lathe feed train.
end gear box. Then shift the levers in the aprons
to select the desired feed.
Feed Trips and Stops
To save time in making a number of duplicate
parts, many horizontal turret lathes have feed trips
and positive stops on the cross slide unit and the
hexagonal turret unit saddle or ram which, when
set, eliminate the need for measuring each piece.
A 6-station stop roll (fig. 10-7) in the carriage
and an adjustable stop rod in the head bracket
allow for duplicating sizes cut with a longitudinal
movement of the cross slide carriage. Stop screws
in the stop roll let you set the cutoff for any
particular operation, and a master adjusting screw
in the end of the stop rod lets you make an overall
setup adjustment without disturbing the individual
stop screws. The dial clips shown in figure 10-7
are used as a reference for accurately sizing a piece
by hand feed after the power crossfeed has been
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.166X
Figure 10-7.— Typical longitudinal feed stop arrangement
for cross slide.
knocked off by the crossfeed trips shown in
figure 10-8.
Turret stop screws on the ram type machine
are mounted in a stop roll (fig. 10-9) carried in
the other end of the turret slide. The screw in the
lowest position of the stop roll controls the travel
of the working face of the turret. The stop roll
is connected to the turret so that when a particular
face of the turret is positioned for work, its mating
stop screw is automatically brought into the
correct position.
To set the hexagonal turret stops on ram type
machines:
1 . Run a cut from the turret to get the desired
dimensions and length.
2. Stop the spindle, engage the feed lever, and
clamp the turret slide.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.168X
Figure 10-9. — Hexagonal turret feed-stop roll on a ram type
machine.
3. Turn the stop screw in until the feed knocks
off; then continue turning the screw in until it hits
the dead stop.
On saddle type machines, the stop roll for the
hexagonal turret is located under the saddle and
Photo courtesy of the Warner <& Swasey Company, Solon, Ohio
between the ways (fig. 10-10). The stop roll does
not move endwise; it automatically rotates as the
turret revolves. To set the stops:
1. Move all the dogs back to the other end of
the roll, where they will be in a convenient
position. Selected a turret face and allow the
master stop to engage the loosened stop dog After
you take the trial cut, the stop dog will slide ahead
of the master stop.
2. After you have taken the proper length of
cut, stop the spindle, engage the longitudinal feed
lever and clamp the saddle. Then, adjust the stop
dog to the nearest locking position with the screw
Photo courtesy of the Warner & Swsey Company. Solon, Ohio
Figure lO-lO.-Hexagonal turret feed stops on a saddle type
machine.
nearest the master stop. When the end of the dog
is flush with the edge of a locking groove on the
stop roll, the locking screw nearest the master stop
will line up automatically with the next locking
groove. 5
3. Screw down the first lock screw, at the
same time pressing the stop dog toward the head
end of the machine.
4. Screw down the second lock screw and then
adjust the stop screw until it moves the master
stop back to a point where the feed lever knocks
off. Then tighten the center screw to bind the stop
in position. p
Threading Mechanisms
There are several different methods for
producing screw threads on a turret lathe The
most common method is to use taps and dies
attached to the hexagon turret. The design and
proper use of these tools will be covered later in
J£? tnhf{f n A thread chasinS attachment
(tig. 10-11) allows the machining of screw threads
on a surface up to about 7 inches long. There are
two major parts to this attachment. The leader
is a hollow cylindrical shaft that clamps over the
feed rod of the turret lathe. You can position it
anywhere along the feed rod for alignment with
the surface requiring threads. The follower is a
halt-nut type arrangement, similar to that on an
engine lathe. It is bolted to the carriage and
engaged over the threaded part of the leader
Disengagement is either manual or automatic
depending on the model. This attachment can
normally be installed on existing equipment. An
attachment that requires factory installation is the
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
lead screw threading attachment. This attachment
gives the turret lathe the same threading capability
as an engine lathe. A lead screw extends the work-
ing length of the lathe to allow for threading long
workpieces. A quick-change gear box on the head-
stock end of the lathe provides for a wide and
rapid selection of a number of threads per inch.
TURRET LATHE OPERATIONS
Aside from additional control levers and
additional automatic features, the principal
differences between operating an engine lathe and
a turret lathe lie in the methods of tooling and
in the methods of setting up the work. In this
section we will discuss turret lathe tooling
principles and methods of doing typical jobs in
horizontal and vertical turret lathes.
Proper maintenance is important for efficient
production on a turret lathe. Specific maintenance
procedures for a specific turret lathe are given in
the manufacturer's technical manual. Before
starting a lathe, ensure that all bearings are
lubricated and that the machine is clean. Turret
lathes have pressurized lubrication systems and
have peepholes at strategic points in the system
so you can tell at a glance whether oil is being
circulated to the areas where it is required.
ADJUSTABLE
CUTTER HOLDER
FLANGED TOOL HOLDER
(LONG)
SLIDE TOOLS (FLANGED MOUNTING
REVERSIBLE
ADJUSTABLE CUTTER HOLDER
MULTIPLE
TURNING HEAD
FLOATING REAMER HOLDER
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
Figure 10-12.— Turret lathe chucking tools. 28.345X
Whenever you clean a lathe, use a cloth or a brush
to remove chips. DO NOT use compressed air.
Compressed air is likely to blow foreign matter
into the precision fitted parts, causing extensive
damage.
TOOLING HORIZONTAL
TURRET LATHES
As previously mentioned, horizontal turret
lathes fall into two general classes, the bar
machines and the chucking machines. The
principal differences between the two classes are
in the size and shape of the workpieces they
handle, the type of workholding device, and the
type of turning tools used on the hexagonal
turret. In the following paragraphs which describe
workholding devices, grinding and setting cutters,
and various machining procedures, we do not
specify the class of machine involved, because it
will usually be obvious; where it is not obvious,
the information applies to horizontal turret lathes
in general. The preceding comment also applies
to the two types of machines, the ram type and
the saddle type. Examples of some of the
commonly used tools for a chucking machine are
shown in figure 10-12 and tools for a bar machine
in figure 10-13.
CENTER
DRILLING TOOL
FLANGED TOOL
HOLDER
I SHORT)
ADJUSTABLE KNEE
TOOL
COMBINATION BAR STOP
AND STARTING DRILL
COMBINATION TURNER
AND END FORMER
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
Figure 10-13.— Turret lathe bar tools. 28.346X
BLOCKED OFF
FACE
INTERNAL
FACE & FORM
CUT OFF
ROUGH TURN
,--• NECK
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.171X
Figure 10-14. — Square turret tool positions.
As a good turret lathe operator, your aim
should be to tool and operate the machine to turn
out a job as rapidly and as accurately as possible.
Always keep in mind the following factors:
• Keep the total time for a job at a minimum
by balancing setup time, work-handling time,
machine-handling time, and actual cutting time.
• Reduce setup time by using universal
equipment and by arranging the heavier flanged
type tools in a logical order.
• Select proper standard equipment. Use
special equipment only when it is justified by the
quantity of work to be produced.
® Reduce machine handling time by using the
right size machine and by taking as many multiple
cuts as possible.
® Reduce cutting time by the following
methods: (1) Take two or more cuts at the same
time from one tool station, (2) take cuts from the
hexagonal turret and the cross slide at the same
time, and (3) increase feeds by making the setup
as rigid as possible by reducing tool overhang and
using rigid toolholders.
PLUNGER HEAD FINGER HOLDER JJJJJJ SPINDLE
HOOD
C
L.
COLLET
0
SPRING TYPE PUSHOUT COLLET
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.172X
• Never block off stations on the square
turret (See fig. 10-14).
• Keep the distance that each tool projects
from the hex turret as equal as possible. This will
minimize the length of travel required to retract
each tool for indexing to the next one.
Holding the Work
Horizontal turret lathes are generally used for
turning out duplicate machine parts rapidly in
quantity. The workholding device must allow you
to quickly place stock material in the machine.
Moreover, once you have set the tools, the
workholding device must be able to position and
hold each succeeding raw workpiece without your
having to stop to take measurements or make
adjustments. (Remember: SAFETY FIRST,
ACCURACY SECOND, SPEED LAST.) The
semiautomatic collets, arbors, and chucks
described in the following sections are able to do
this.
COLLETS.— The spring-type pushout collet
shown in figure 10-15 is the most widely used. It
is made in different sizes for use on bar stock up
to 2 1/2 inches in diameter. The principle upon
which it works is as follows: When you engage
the feed head (fig. 10-15A) to advance the stock,
you simultaneously loosen the grip of the collet.
When the end of the bar stock butts against a
stock stop mounted on one face of the hexagonal
turret, the plunger (Part A in fig. 10-15B) forces
the partially split tapered end of collet D into the
taper of the hood C, causing the collet to grip the
stock firmly. Your one simple movement
automatically sets the stock material into position
for machining.
There are several variations of the spring-type
collet, but they all depend on the plunger head
principle for gripping and releasing the stock,
differing only in the direction of taper on the
collet.
ARBORS. — For mounting small, rough
castings or for mounting workpieces of second
operations, you will often use quick-acting arbors.
Figure 10-16 is an expanding bushing-type
arbor. In this type arbor, as draw bar C is pulled
back, the split bushing D climbs the taper of the
arbor body, expanding to grip workpiece A tightly
along its entire length and at the same time forcing
the workpiece against stop plate B. This type of
arbor is suitable for roughing work or first
operations, where a firm grip for heavy feeds is
more important than accuracy.
The expanding plug-type arbor (fig. 10-17)
centers the workpiece more accurately and is
usually used for second or finishing operations.
In this type of arbor, when the taperheaded screw
is pulled to the left by the action of the draw bar
C, it expands the outer end of the partially split
plug D enough to grip the workpiece A internally
and at the same time forces the workpiece tightly
against the stop plate B. This type or arbor is used
for holding workpieces that have been bored or
reamed to size internally, rough machined to size
externally, and need only a light finishing cut as
a final operation.
CHUCKS.— These workholding devices fall into
three classes: (1) universal chucks of the geared
scroll, geared screw, or box type that have three
jaws that move at the same time; (2) independent
chucks, that have jaws that operate independently;
and (3) combination chucks, that have jaws that
may be operated either independently, or as a
group.
B A
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
The 2-jaw chuck is used mostly for holding
small or irregularly shaped work. The jaw screw
operates both jaws at the same time. Use an
adapter to attach chuck jaws of various shapes
to the master jaws.
The 3-jaw, geared scroll chuck is used more
than any other type. With standard jaw equip-
ment, it holds work of regular shape; but it can
be adapted to hold irregularly shaped work.
Figure 10-18 shows a 4-jaw combination chuck
that has two-piece master-jaw construction and
an independent jaw screw between sections. The
bottom or master part of the jaw is moved
by the scroll, and the top part is moved by the
independent jaw screw. Chucks of this type are
used mostly to hold irregularly shaped work or
when a jaw needs to be offset from a true
circle. On the combination chuck, you use the
independent movable jaws to true the work in the
first chuckings. You can then use the same chuck
for second operations by using the geared scroll
to operate the jaws when gripping on a finished
diameter. Soft metal (such as copper shims) is
often used with chuck jaws for chucking second
operation work to prevent marring the finish of
the workpiece.
Some machines have a power chuck wrench
that you use with 3-jaw chucks. This attachment
lets you open and close the chuck by using a lever
located on the headstock. There is a control knob
for adjusting the pressure of the chuck to allow
for gripping different workpieces. An example of
such an attachment can be seen on the turret lathe
in figure 10-5 (indicated by the arrow).
Grinding and Setting Turret Lathe Tools
The angles to which a turret lathe tool is
ground and the position at which it is set can
change the angle that the cutting edge of the tool
forms with the work. The angles ground and the
position set affect the chip flow, the pressure
exerted on the tool, and the amount of feed and
depth of cut that can be used. Consequently,
accurate tool angles and proper tool position are
essential to production when you use a turret
lathe.
GRINDING. — Some important points to keep
in mind when you grind turret lathe tools are
• Some cutters are ground wet; others are
ground dry. High-speed steel cutters are usually
ground wet, while Stellite and carbide cutters are
usually ground dry. When grinding a cutter wet,
keep it well-flooded to prevent heating; nothing
will ruin a cutter quicker than a wet grinding that
is partially dry. On the other hand, if the cutter
C (UNDERSIDE)
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.175X
A (TOP)
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.176X
shuold be ground dry, do not dip the tip in
coolant. Sudden cooling will cause surface cracks,
which once started will eventually cause the
cutter tip to fail.
• When a carbide-tipped cutter requires
sharpening, use the grinder specified in your shop
for that purpose. Grinding wheels suitable for
high-speed steel will ruin carbide cutters.
• When you grind a carbide-tipped cutter,
always be sure that the pressure of the grinding
is toward the seat of the carbide tip rather than
away from it.
The tool angles of single cutters and multiple
turning head cutters for the square turret and
hexagonal turret, respectively, are quite similar
to those of engine lathe tool bits or turning tools.
But the cutters themselves are usually much larger
than those used on an engine lathe because the
turret lathe is designed to remove large quantities
of metal rapidly. Bar turner cutters, or box tools
as they are often called, are ground in a different
manner.
Bar turner cutters are usually held in a
semi vertical position. That is, the cutting edge or
tool point, which is located near the center of the
cutter end, points slightly toward the cut and
toward the center of the work. In this position,
the pressure of the cut is downward through the
shank of the cutter.
Bar turner cutters are ground to form the tool
point on the end of the cutter, near the centerline,
somewhat like a chisel point. The bar turner cutter
in figure 10-19 is in the position it would be held
in the holder. Normally, in sharpening, you grind
only angle surface A (the top). You hone angle
SMALL CHIP
surfaces B and C to remove burrs which result
from grinding surface A. After repeated sharpen-
ings, angle surfaces B and C will become too small
and you must then grind them. The tool angles
for a bar turner cutter are the same as those on
a cross slide mounted cutter, but they appear to
be vastly different because of the difference in tool
point location.
CONTROLLING CHIPS.— You can control
chips in one of two ways: (1) get the right
combination of back and side rake angles in
combination with speeds and feeds or (2) grind
on the back rake face of the cutter a chip breaker
groove that will curl and break chips into short
lengths. Method (1) is usually the best way. By
changing the angle slightly, it is possible to throw
chips in one direction or the other. If you use
method (2), start the chip breaker groove just
behind the cutting edge; be careful not to carry
it through the point of the cutter. A chip breaker
groove through the point of the cutter will tend
to break down the cutting point, produce a poor
quality of finish, and may produce a double chip
(fig. 10-20).
SETTING SINGLE AND MULTIPLE
TURNING CUTTERS.— To retain all of its small
front clearance angle, a turret lathe cutter must
be set in its holder so that its active cutting edge
is on the same plane as the centerline of the work,
and not above center as tool bits are often set in
engine lathe operation. Part A of figure 10-21
shows a cutter in the correct position. This cutter-
workpiece relation is very important when the
workpiece diameter is small. Observe in part B
of figure 10-21 the effect of raising the cutter
15° ACTUAL
BACK RAKE
Figure 10-20.— Double chip caused by grinding a chip
breaker groove too close to the cutting edge.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.178X
Figure 10-21. — Keep cutters on center.
above center. A cutter set in the position shown
has only a fraction of the amount of front
clearance needed under its cutting lip and has an
unnecessarily large back rake angle. On the other
hand, if a cutter is set below center for cutting
small diameter work, the work is very likely to
climb the cutter, or at least cause violent chatter.
Figure 10-22 shows how to set a square turret
and a "reach over" or rear-tool station cutter on
center. Notice that the cutter in the "reach over"
toolpost is inverted; the reason for this is that the
work surface rolls up from underneath.
In square turrets, you can raise or lower the
cutter to the correct position by either shims or
rockers, depending upon the type of base plate
(fig. 10-23).
Another factor to consider in setting a cutter
is the amount of its overhang from the holder.
Too much overhang will cause the cutter to
chatter, and insufficient overhang will cause the
holding device to foul the work. When possible,
you should keep the amount of overhang equal
to or slightly less than twice the thickness of the
cutter shank.
Each time you regrind a cutter (other than a
carbide-tipped type), the height of the tool
point and the length of the cutter itself are
reduced; therefore, after each grinding you must
reposition the cutter in its holder to place the tool
point on center. If you use a shim-type holder,
raise the cutter to center by adding a shim of
appropriate thickness (fig. 10-23B) When using
a rocker arrangement, you need an entirely
different approach; elevating the reground tool
point to center by adjusting the rocker will cause
the clearance and rake angle to change. The best
way to maintain the proper angles and yet keep
SQUARE TURRET
MEASURE FROM TOP OF TURRET, USING
CUTTER GRINDING AND SETTING GAGE
REAR TOOLPOST
USE A SCALE TO MEASURE THE CORRECT
POSITION OF THE CUTTER PROM TOP OF
THE CROSS-SLIDE
6
Figure 10-22.— Setting square turret and "reach over"
toolpost cutters on center.
Figure 10-23.— A. Use of rockers. B. Use of shims.
the tool point on center, when using the rocker
arrangement, is to decrease the top (back and side)
rake angles and increase the front clearance angle
slightly at each grinding. This will allow you to
account for the change in cutter position caused
by removal of metal from the tool point. Figure
10-23A shows how this is done.
The dimensions of carbide-tipped cutters are
relatively unaffected by grinding; therefore, the
cutters seldom require alteration in holder setup
after they have been reground. The shim-type
holder provides a stable horizontal base for the
cutter shank and is best for holding carbide-tipped
cutters. The cutters can be taken out, reground,
and placed back in and on center without undue
manipulation.
The overhead turning cutters, which are
mounted on the hexagonal turret, must also be on
center in relation to the work. The principle in-
volved in setting these cutters is not different from
that involved in setting the square turret-mounted
cutters, though at first it may appear to be differ-
ent. In order to assure yourself that this is so, look
at figure 10-21 and turn the book so the cutters
10-14
point toward the work from above rather than
from the side.
Figure 10-24 shows how to set an overhead
turning cutter on center by using a scale for
reference in bringing the shank and tool position
of the cutter into radial line with the center of the
turning head, which is in alignment with the center
of the spindle.
SETTING BAR TURNER CUTTERS.— Bar
turners are held on the hexagonal turret and
combine in one unit a cutter holder and a backrest
that travel with the cutter and support the
workpiece. The backrest holds the work against
the cutter so that deep cuts can be taken at heavy
feeds.
Backrests on bar turners usually have rollers
to eliminate wear and to make high-speed opera-
tion possible. Bar turners that have V-backrests
are used for turning brass where there is no
problem of wear and where small chips might get
under rollers and mar the workpiece.
The rollers on a ROLLER-TYPE TURNER
may be either ahead of or behind the cutter. If
they are behind the cutter, they burnish the
workpiece. This burnishing is often an important
factor; it may eliminate the need for polishing or
grinding operations. When a diameter is turned
so that it is concentric with a finished diameter,
the rollers are run ahead of the cutter on
the previously finished surface. Figure 10-25
illustrates rollers behind and ahead of a cutter.
The rollers on a UNIVERSAL TURNER are
set ahead of or behind the cutter by adjusting the
movable cutter with the rollers remaining in fixed
MULTIPLE TURNING HEAD
position. The universal bar turner is illustrated in
figure 10-26A. Another type, the single-bar turner
(fig. 10-26B), has adjustable roller arms; the cut-
ter is fixed, and the rollers can be moved ahead
of or behind the cutter.
Use the following steps in setting up a
SINGLE BAR TURNER:
1. Extend the bar stock about 1 1/2 to 2
inches from the collet. Then with a cutter in the
square turret on the cross slide, turn the bar to
0.001 inch under the size desired for a length of
1/2 to 1 inch.
2. With the roller jaw swung out of position
(fig. 10-27 A) and with the cutter set above center
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.182X
Figure 10-25. — Rollers. A. Behind cutter. B. Ahead of cutter.
Photo courtesy of the Warner & Swasey Company. Solon, Ohio
28.183X
Figure 10-26. — A. Universal bar turner. B. Single bar turner.
ROLLERS
SHINE MARK
B
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.181X
Figure 10-27. — Rubbing a shine mark to establish a center.
A. Roll jaws out of position. B. Shine mark on the turned
and 20° from the perpendicular bisector, adjust
the cutter slide of the turner against the turned
portion of the bar stock and rub a shine mark on
the turned portion, as indicated in figure 10-27B.
3. Set the cutter at the center of the shine
mark, clamp the cutter tightly in its slide, turn
the spindle to move the shine mark away from
the cutter point, and adjust the slide until the
cutter is 0.0015 inch from the turned diameter.
You now have the cutter set. Position the rollers
endwise and adjust them to size.
4. Align the rollers with the back of the point
radius of the cutter, as shown in figure 10-28.
Adjust the rollers with the clamping screws, and
then clamp them tightly. The rollers are in proper
adjustment when LIGHT PRESSURE WILL
STOP THEM FROM TURNING as the bar stock
is revolved.
5 . Push the cutter to cutting position with the
withdrawal lever and take a trial cut. If you have
a proper setup, the size of the workpiece will be
accurate to ±0.001 inch.
BAR TURNING.— The following pointers
will be helpful in bar turning:
• To prevent making marks on the work as
you bring back the turret, always use the
withdrawal lever before the return stroke of the
turret.
• When rollers are set to follow the cutter,
it is usually true that the heavier the cut the better
the finish. The heavier the cut the greater is the
pressure against the rollers, and the greater is the
burnishing action.
® If you are using light cuts, special rollers
with a steep taper will sometimes produce a better
finish.
FACE OF ROLLER IN
LINE WITH BACK OF i==
RADIUS OF CUTTER
© Regardless of the depth of cut, there are
three factors that you must watch to get a high
grade finish: (1) the faces of the two rollers must
be in line, (2) the leading corners of the rollers
must be perfectly round and exactly equal, and
(3) end play in the rollers should not exceed 0.003
inch.
Selecting Speeds and Feeds
The general rules for feeds and speeds in
chapter 8 of this manual for engine lathe opera-
tion apply also to turret lathes. However, since
the cutters and the machine itself are designed for
production work, you can take heavier roughing
cuts than you ordinarily would with an engine
lathe.
Bear in mind that the spindle speed of the
turret lathe must be governed by the surface speed
at the point of work of the cutter farthest from
the rotating axis. That is, if you are going to use
two cutters on a workpiece with one cutter to turn
a small diameter and the other to cut a much
larger diameter, the headstock rpm you select
must be based on the surface speed at the large
diameter. Disregard the fact that the cutter at the
small diameter will be cutting at well below its
usual rate.
Using Coolants
Using coolants makes it possible to run the
lathe at higher speeds, take heavier cuts, and use
cutters for longer periods without regrinding, thus
getting maximum service from the lathe. Coolants
flush away chips, protect machined parts against
corrosion, and help give a better finish to the
work. A coolant also helps to provide greater
accuracy by keeping the work from overheating
and becoming distorted. Figure 10-29 shows the
correct and incorrect ways to apply cutting oil or
coolant.
Some coolants and the materials with which
they are used are listed below:
CAST IRON— Soluble oil 1 to 30 ratio, or
mineral lard oil, or dry
ALLOY STEEL— Soluble oil 1 to 10 ratio, or
mineral lard oil
LOW/MEDIUM CARBON STEEL— Soluble
oil 1 to 20 ratio, or mineral lard oil
Figure 10-28.— Rollers aligned with the cutter.
BRASSES AND BRONZES— Soluble oil 1 to
INCORRECT
CORRECT
Figure 10-29. — Correct and incorrect ways to apply coolant.
STAINLESS STEEL— Soluble oil 1 to 5 ratio,
or mineral lard oil
ALUMINUM— Soluble oil 1 to 25 ratio, or
dry
MONEL/NICKEL ALLOYS— Soluble oil 1
to 20 ratio, or a sulfur-based oil
The selection of the best coolant or cutting
fluid depends on the cutting tool materials, the
toughness of the metal being machined and the
type of operation being performed. Simple turn-
ing may require a coolant that just keeps the
temperature down and flushes chips away. A
mixture of soluble oil that has a low oil ratio will
do this very efficiently. An operation such as
threading or heavy turning requires something
that not only cools but also lubricates. A heavier
soluble oil mixture or mineral lard oil satisfies
these requirements.
BORING
Two general types of boring cutters are
used — tool bits held in boring bars and solid
forged boring cutters. Tool bits held in boring bars
are most common. This combination allows great
flexibility in sizes and types of work that can be
done. Solid forged cutters, however, are used to
bore holes too small to be cut with a boring bar
and inserted cutter.
The cutter in a STUB BORING BAR is held
either at a right angle to the bar or extended
beyond the end of the bar at an angle. This
extension of the cutter makes it possible to bore
up to shoulders and in blind holes. The angular
cutting bar has the added advantage of an
adjusting screw behind the cutter.
When the stub boring bar or forged boring bar
is used, the overhang should be as short as the
hole and the setup will permit. You should always
select the largest possible size of boring bar to give
the cutter as rigid a mounting as possible. Never
extend the boring cutter farther than is actually
necessary. You can use sleeves to increase the
rigidity of small stub boring bars and to reduce
the effect of overhang. The increased rigidity helps
to make the work more accurate and allows for
heavier feeds.
The HEXAGON TURRET is ordinarily used
in making boring cuts, although the boring tools
can be held on the cross slide. The advantages of
taking a boring cut from the hexagon turret are:
1 . You can take turning or facing cuts with
the cross slide at the same time you take a boring
cut with the turret.
2. You can combine boring cutters with
turning cutters in multiple- or single-turning
heads.
3. You can mount various size cutters,
eliminating the need to adjust the cutter as the
bore size increases.
4. When a quantity of like pieces is required,
you can increase boring feed by using a boring
bar with two cutters. It is good practice when
using double cutters to rough bore with a piloted
boring bar to obtain rigidity for heavy feeds and
then to finish the hole with a stub boring bar held
in a slide tool.
Piloted boring bars require a machine with a
long stroke — the saddle type — so the turret can
be moved far enough to pull the piloted bar from
the pilot bushing and the work before indexing
the turret. Usually, when the pilot bushing is
mounted in the chuck close to the work, the
effective travel of the turret must be about 2 1 /2
times the length of the workpiece.
Grinding Boring Cutters
Boring cutters are ground in the same manner
as other types of cutters, with one major
difference. The clearance angles of boring cutters
must be greater to prevent rubbing since a boring
tool cuts on the inside instead of on the outside
of the work. However, the clearance angle must
not be too great, or the cutting edge will break
down because of insufficient support. The exact
amount of front clearance angle will depend on
the size of the hole you are boring. The smaller
the hole, the more clearance required. There are
no set rules for exact clearance angles; knowledge
of what will be the best angle comes with
experience.
Figure 10-30 shows how to center a vertical
slide tool-held boring cutter.
Forming
One of the fastest methods of producing a
finished diameter or shape is by using a cutter with
a cutting edge that matches the shape to be
machined. This procedure is known as forming.
In planning a setup, you should study the work
to determine if forming tools can be used. It is
possible, on many jobs, to combine two or more
cuts into one operation by using a specially
designed forming cutter. Forming cutters are also
used to produce irregular and curved shapes that
are difficult to produce in any other way. There
are three types of forming cutters you will use-
forged, dovetail, and circular.
FORGED FORMING CUTTERS are made
in the shop from forged blanks and ordinarily are
mounted directly in the square turret or toolpost.
These cutters are the least expensive to make.
They have, however, the shortest production life.
DOVETAIL FORMING CUTTERS are
cutters that may be either bought or made. They
VERTICAL SLIDE TOOL
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.187X
Figure 10-30. — Setting a boring cutter on center.
are attached by dovetails to toolholders mounted
on the cross slide. Their shape or contour is
machined and ground the full length of the face,
and the cutters are set in the holder at an angle
to provide front clearance. When the cutter wears,
you need to regrind only the top. Dovetail
cutters cost more than forged cutters, but they
have a longer production life, are more easily set
up, maintain their form after grinding, are more
rigid, and can be operated under heavier feeds.
CIRCULAR FORMING CUTTERS (fig.
10-31) have an even longer life than dovetail
cutters. The shape of circular cutters is ground
on the entire circumference and, as the cutting
edge wears away, you regrind only the top. After
grinding a new cutting edge, move the cutter to
a new cutting position by rotating the cutter about
its axis.
NEVER regrind circular forming cutters on
a bench grinder. Regrind them on a toolroom
grinder where they can be rigidly supported and
ground to maintain the original relief angles.
Threading
For turret lathe operations, dies and taps
provide a way to cut threads easily and quickly
and, usually, in only one pass over the work. Dies
and taps for turret lathes are divided into
three general types: Solid, solid adjustable, and
collapsing or self-opening.
Solid taps and dies are usually held in a
positive drive holder that has an automatic release
(fig. 10-12). A longitudinal floating action (not
to be confused with a floating die holder) allows
CUTTER
<t OF
SPINDLE
HOLDERS USED ON
FRONT AND REAR
OF CROSS-SLIDE Bf
TURNING ECCENTRC
BUSHING ,180°
FRONT
REAR
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.188X
Figure 10-31.— Circular forming cutter diagram.
the tap or die to follow the natural lead of the
thread. Solid dies are used only when the thread
to be cut is too coarse for the self-opening die head
or a solid adjustable die head, or when the tool
interferes with the setup.
Solid adjustable taps and dies should be used
in place of collapsing taps and self-opening die
heads only when lathe speed is low and when time
required for a backing out is not important.
Collapsing taps (fig. 10-32) are used for
internal threading. They are time-savers because
you do not have to reverse the spindle to withdraw
the tap. The pull-off trip type, which is collapsed
by simply stopping the feed, is the most frequently
used.
Various types of self-opening die heads are
used. One type is shown in figure 10-33. Some
have flanged backs for bolting directly to the
turret face; others have shanks which fit into a
holder. The die heads are fitted with several
different types of chasers. The tangential and
circular type chasers can be ground repeatedly
without destroying the thread shape. They are a
bit more difficult to set, but they are better
adapted than flat chasers for long runs of
identical threads.
Die heads come with either a longitudinal float
or a rigid mounting. The floating type die head
should be used for heavy duty turret lathe work,
for fine pitch threading, and for finishing rough-
cut threads.
Figure 10-33. — Pull-off trip self-opening die head.
On some types of work it is necessary to take
both roughing and finishing cuts. They are
normally taken when threading a tough material
or when a smooth finish is required. Some types
of die heads have both roughing and finishing
attachments. If such die heads are not available,
roughing and finishing cuts can be taken with
separate dies or taps set up on different turret
stations.
As mentioned earlier in this chapter, some
horizontal turret lathes can cut or chase threads
with a single-point tool. In such machines, there
are two methods of feeding the threading tool into
the work. The first method is to get an angular
feed to the cutter by means of the compound
cross-slide (fig. 10-34) or by using the angular
Figure 10-32. — Universal collapsing tap.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.189X
Figure 10-34. — Compound cross-slide angular feed-in for
thread cutting.
threading toolholder (fig. 10-35). By the first
method, the cutter is fed into the work at an
angle until the final polishing passes are
made. For the final polishing passes, the
cutter is fed straight in by means of the
cross-slide. The second method is to feed
the cutter straight into the work for each
pass, as indicated in figure 10-36. With this
latter method you apply by hand a slight
drag to the carriage or saddle during the
roughing cut and remove the drag during
the final polishing passes. It takes more
skill to use the second method, but it produces
better threads.
2. The finish must meet requirements.
3. The taper angle must be accurate.
It is best to use the roller rest taper turner for
long taper bar jobs. You can quickly set this tool
for size by using the graduated dial and then can
control the angle of taper accurately by using the
taper guide bar.
Taper attachments are provided for the cross
slide of most turret lathes, both ram and saddle
type. These attachments can be quickly set to
produce either internal or external tapers. They
Taper Turning
Tapers may be produced on a turret lathe with
(1) forming cutters, (2) roller rest taper turners,
or (3) taper attachments.
Forming cutters of the forged, circular, or
straight dovetail types may be used to produce
tapers when the workpiece is rigid enough or can
be supported in such a way that it will with-
stand the heavy forming cut. If work cannot
be formed, other methods (described later) must
be used.
Work should be shaped with forming cutters
only under the following conditions:
1. The work is either self-supporting or is
supported by a center rest so that chatter is
prevented.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.191X
Figure 10-36. — Straight-in feeding method of threading.
;••?—. BACKLASH
J3-V ELIMINATOR
8 7
1. GUIDE PLATE
2. BASE PLATE
3. CARRIAGE PLATE
4. EXTENSION ROD
5. SETSCREW
6. BINDER SCREW
7. STOP COLLAR
8. LATCH
Photo courtesy of the Warner A Swasey Company, Solon, Ohio
28.190X
Figure 10-35. — Angular feed-in with adjustable threading
toolholder.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.192X
Figure 10-37. — Detail of a cross-slide taper attachment for
a saddle-type machine.
do not interfere with normal operation when
not in use. Most taper attachments are movable
and can be quickly placed at any position on the
bed.
Taper attachments all have a pivoting guide
plate which can be adjusted to any taper angle.
Figure 10-37 shows a saddle-type taper attachment
in detail.
The guide plate (1) pivots on the base plate
(2), which slides into carriage plate (3). When you
plan to use the attachment, clamp the extension
rod (4) to the machine with the setscrew (5),
and loosen the binder screw (6). You can use the
stop collar (7) and the latch (8) for locating the
cross slide unit on the bed of the machine. To use
the stop collar and the latch, move the cross slide
unit to the left until the stop collar comes in
contact with the latch. This locates the entire unit.
Taper attachments are fitted with a backlash
eliminator nut (fig 10-37) for the slide screws.
Tightening this nut against the feed screw removes
all play between the feed screw and the nut.
To duplicate accurate sizes when you use a
taper attachment with other tools in a setup,
remember these three things; (1) you must locate
the attachment in the same position in relation
to the cross slide each time you use it, (2) you
must locate the cross slide in exactly the same
spot on the bed when you clamp the extension
rod with the setscrew, tighten the binder screw,
and loosen the extension rod, and (3) be sure
the cross slide is in exactly the same position
as in (1) above.
You can produce either internal or external
threads with the taper attachment in conjunction
with a lead screw thread chasing attachment. (See
fig. 10-38). Notice, however, that taper cutting
with hexagonal turret held cutters is possible
only on lathes that have a cross-sliding hexagonal
turret.
HORIZONTAL TURRET
LATHE TYPE WORK
Regardless of the job, your aim as a good
turret lathe operator is to tool up the machine and
operate it so the job can be turned out as rapidly
and as accurately as possible. The following
examples show you how.
EXTERNAL TAPER THREAD
SQUARE TURRET ADJ.
THD'G TOOLHOLDER
INTERNAL TAPER THREAD
TAPER
ATTACHMENT
LEADER AND
FOLLOWER
OR LEAD SCREW
TAPER ATTACHMENT
THREADING TOOL:
HOLDER
LEAD SCREW
OR
LEADER AND FOLLOWER
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
A Shoulder Stud Job
A shoulder stud, shown in part A of figure
10-39, is a typical bar job (universal bar equip-
ment is used) for a small ram-type turret lathe that
has a screw feed cross slide. The tooling setup for
the shoulder stud is shown in part B of figure
10-39. The diameter (5), which must be held to
a clearance of 0.001-inch tolerance, is formed with
a cutter on the front of the cross slide. Diameters
(2) and (3) are turned from the hexagon turret with
cutters held in the multiple cutter turner. After
this operation, the radius on the end of the
workpiece is machined in a combination end facer
and turner, then the thread is cut, and the piece
is cut off.
A Tapered Stud Job
A tapered stud, shown in part B of figure
10-40, does not offer much opportunity for taking
multiple cuts. However, cuts from the cross slide
can be combined with cuts taken by the hexagon
turret. The tooling setup for the taper stud, shown
in part A of figure 10-40, is used for small lot
production. The almost identical tooling layout
in part C of figure 10-40 shows the setup for
medium quantity production.
In both small and medium lot production, the
turning of diameter (6) and the forming of
diameter (7) can be combined with the turning
of diameter (3). In addition, the facing and
chamfering of the end (2) can be combined with
the turning of diameter (7).
For small lot production (part A of fig. 10-40)
the taper is generally formed with a standard wide
cutter, ground to the proper angle. These cuts will
not be very accurate, but as the taper will be
ground in a later operation, the job will be
satisfactory if sufficient stock is left for grinding.
If a forming tool wide enough to cut the taper
in one cut is available, it should be used.
For medium lot production (part C of fig.
10-40) the cross slide taper attachment may be set
up and used for single point turning of the taper.
The same amount of time will probably be
required to turn the taper (part C, fig. 10-40) as
to form the taper (part A, fig 10-40). However,
the turned taper will be more accurate and require
less stock for grinding. In addition, the grinding
operation will take less time.
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
vm^ *' , A */ . / >
-
rP
/0 -'
v
TAPKR
courtesy of the Warner & Swasey Company, Solon, Ohio
126. HX
Figure 10-40.— A. Tooling setup for a taper stud— small lot production. B. A taper stud. C. Tooling setup for a taper stud-
medium lot production.
Figure 10-41 shows a simple setup for the
second operation of the taper stud. The setup is
the same for producing either a small or a medium
size quantity.
VERTICAL TURRET LATHES
A vertical turret lathe works much like an
engine lathe turned up on end. You can perform
practically all of the typical lathe operations in
a vertical turret lathe, including turning, facing,
boring, machining tapers, and cutting internal and
external threads.
The characteristic features of this machine are:
(1) a horizontal table or faceplate that holds the
work and rotates about a vertical axis; (2) a side
head that can be fed either horizontally or
vertically; and (3) a turret slide, mounted on a
crossrail that can feed nonrotating tools either
vertically or horizontally.
Figures 10-42 and 10-43 show vertical turret
lathes similar to those generally found in repair
ships and tenders. The main advantage of the
vertical turret lathe over the engine lathe is that
heavy or awkward parts are easier to set up on
the vertical turret lathe and, generally, the
vertical turret lathe will handle much larger
workpieces than the engine lathe. The size of the
vertical turret lathe is designated by the diameter
of the table. For instance, a 30-inch lathe has a
table 30 inches in diameter. The capacity of a
(1 ) Main turret head
(2) Turret slide
(3) Swivel plate
(4) Saddle
(5) Main rails
(6) Upright bedways
(7) Side turret
(8) Side head
28.170X
Figure 10-42.— A 30-inch vertical turret lathe.
1 CHUCK
V BEHOVE
Photo courtesy of the Warner & Swasey Company, Solon, Ohio
28.349X
Figure 10-43.— A 36-inch vertical turret lathe.
specific lathe is related to but not necessarily
limited to the size of the table. A 30-inch vertical
lathe (fig. 10-42) can hold and machine (using
both the main and the side turrets) a workpiece
up to 34 inches in diameter. If only the main
turret is used, the workpiece can be as large as
44 inches in diameter.
The main difference between the vertical
turret lathe and the horizontal turret lathe is in
the design and operating features of the main
10-25
IU.1..LVI J.1VC4.U.. 4.WJ.VJ. \,\J
turret slide (2) is mounted on a swivel plate (3)
which is attached to the saddle (4). The swivel
plate allows the turret slide to be swung up to 45 °
to the right or left of the vertical, depending on
the machine model. The saddle is carried on, and
can traverse, the main rails (5). The main rails are
gibbed and geared to the upright bedways (6) for
vertical movement. This arrangement allows you
to feed main turret tools either vertically or
horizontally, as compared to one direction on the
horizontal turret lathe. Also, you can cut tapers
by setting the turret slide at a suitable angle.
The side turret and side head of the vertical
turret lathe correspond to the square turret and
cross slide of the horizontal turret lathe. A typical
vertical turret lathe has a system of feed trips
and stops that function similarly to those on a
horizontal turret lathe. In addition, the machine
has feed disengagement devices to prevent the
heads from going beyond safe maximum limits
and bumping into each other.
Vertical turret lathes have varying degrees of
capabilities, including feed and speed ranges,
angular turning limits, and special features such
as threading.
You can expect to find a more coarse
minimum feed on the earlier models of vertical
turret lathes. Some models have a minimum of
0.008 inch per revolution of the table or chuck,
while other models will go as low as 0.001 inch
per revolution. The maximum feeds obtainable
vary considerably also; however, this is usually
less of a limiting factor in job setup and
completion.
The speeds available on any given vertical
turret lathe tend to be much slower than those
available on a horizontal lathe. This reduction of
speed is often required due to the large and
oddly shaped sizes of work done on vertical turret
lathes in Navy machine shops. A high speed could
cause a workpiece to be thrown out of the
machine, causing considerable equipment damage
and possible injury to the machine operator or
bystanders.
One of the major differences in operator
controls between the vertical turret lathes shown
in figures 10-42 and 10-43 is in the method used
to position the cutter to the work. The lathe
in figure 10-42 has a handwheel for manually
positioning the work. The lathe in figure 10-43
uses an electric drive controlled by a lever. When
the feed control lever is moved to the creep
position, the turret head moves in the direction
selected in increments as low as 0.0001 inch per
revolution and can be made with the table
stopped.
An attachment available on some machines
permits threading of up to 32 threads per inch
with a single point tool. The gears, as specified
by the lathe manufacturer, are positioned in the
attachment to provide a given ratio between the
revolutions per minute of the table and the rate
of advance of the tool.
The same attachment also lets the operator
turn or bore an angle of 1 ° to 45 ° in any quadrant
by positioning certain gears in the gear train. The
angle is then cut by engaging the correct feed lever.
Details for turning tapers on a vertical turret
lathe without this attachment are given later in
this chapter.
TOOLING VERTICAL
TURRET LATHES
The principles involved in the operation of a
vertical turret lathe are not very different from
those just described for the horizontal turret lathe.
The only significant difference, aside from the
machine being vertical, is in the main turret. As
previously mentioned, you can feed the main
head, which corresponds to the hexagonal turret
of the horizontal machine, vertically toward the
headstock (down); horizontally; or at an angle,
either by engaging both the horizontal and
vertical feeds or by setting the turret slide at an
angle from the vertical and using the vertical feed
only.
The tool angles for the cutters of the vertical
machine correspond to those used on cutters in
the horizontal turret lathe and are an important
factor in successful cutting. Also, the same
importance is attached to setting cutters on center
and maintaining the clearance and rake angles in
the process. Again, we cannot overemphasize the
importance of holding the cutters rigidly.
In vertical turret lathe work, you must often
use offset or bent-shank cutters, special sweep
tools, and forming tools, particularly when you
machine odd-shaped pieces. Many such cutting
tools are designed to take advantage of the great
flexibility of operation provided in the main head.
In a repair ship, the vertical turret lathe is
normally used for jobs other than straight
production work. For example, a large valve can
be mounted on the horizontal face of its worktable
or chuck much more conveniently than in almost
any other type of machine used to handle large
work. Figure 10-44 shows a typical valve seat
10-26
Figure 10-44.— Refacing a valve seat in a vertical turret lathe.
refacing job in progress in a vertical turret lathe.
Figure 10-45 shows the double tooling principle
applied to a machining operation.
The tooling principles and the advantage of
using coolants for cutting as previously described
for horizontal turret lathes apply equally to
vertical machines.
TAPER TURNING ON A
VERTICAL TURRET LATHE
The following information regarding taper
turning on a vertical lathe is based on a Bullard
vertical turret lathe. (See fig. 10-42.)
There are several ways to cut a taper on a ver-
tical turret lathe. You can cut a 45 ° taper with
either a main turret-held cutter or a side head-held
cutter by engaging the vertical and horizontal
feeds simultaneously. To cut a taper of less than
30° with a main turret-held tool, set the turret slide
for the correct degree of taper and use only
the vertical feed for the slide. The operation
corresponds to cutting a taper by using the
compound rest on an engine lathe; the only
difference is that you use the vertical power feed
instead of advancing the cutter by manual feed.
By swiveling the main turret head, you can cut
30° to 60° angles on the vertical turret lathe
without having to use special attachments. To
machine angles greater than 30 ° and less than 60 °
from the vertical, engage both the horizontal feed
Figure 10-45.— Double tooling.
and the vertical feed simultaneously and swivel the
head. Determine the angle to which you swivel the
head in the following manner. For angles between
30° and 45°, swivel the head in the direction
opposite to the taper angle being turned, as
illustrated in figure 10-46. The formula for
Figure 10-46.— Head setting for 30° to 45° angles.
10-27
determining the proper angle is A = 90° - 2B °.
A sample problem from figure 10-46 follows:
Formula A 4- 90° ~ 2B°
Example B = 35 °
Therefore A = 90° - (2 x 35 °)
A = 90° - 70°
ANGLE A =20°
For angles between 46° and 60°, swivel
the head in the same direction as the taper
angle being turned. (See fig. 10-47.) The
formula for determining the proper angle is
ANGLE A = 2B° - 90°. A sample problem
from figure 10-47 follows:
Formula A = 2B ° - 90 °
Example B = 56°
Therefore A = (2 x 56°) - 90°
A= 112° - 90°
ANGLE A = 22°
Whenever you turn a taper by using the main
turret slide swiveling method, use great care to
set the slide in a true vertical position after you
complete the taper work and before you use the
main head for straight cuts. A very small
departure of the slide from the true vertical will
produce a relatively large taper on straight work.
Figure 10-47.— Head setting for 45° to 60° angles.
Unless you are alert to this, you may inadvertently
cut a dimension undersize before you are aware
of the error.
Still another way to cut tapers with either a
main head-held or side head-held tool is to use
a sweep-type cutter ground and set to the desired
angle. Then feed it straight to the work to
produce the desired tapered shape. This, of
course, is feasible only for short taper cuts.
10-28
MILLING MACHINES
AND MILLING OPERATIONS
The milling machine removes metal with a
revolving cutting tool called a milling cutter. With
various attachments, milling machines can be used
for boring, slotting, circular milling, dividing, and
drilling; cutting keyways, racks, and gears; and
fluting taps and reamers.
Bed-type and knee and column type milling
machines are generally found in most Navy
machine shops. The bed-type milling machine has
a vertically adjustable spindle. The horizontal
boring mill discussed later in this chapter is
a typical bed-type mill. The knee and column
milling machine has a fixed spindle and a vertically
adjustable table. There are several classes of
OVERARM-
INNER ARBOR
SUPPORT
OUTER 1 \
ARBOR f
SUPPORT-\II
TAILSTOCK-
TABLE-
ARBOR SPINDLE NOSE
COLUMN
• f
DIVIDING
.HEAD
ENCLOSED
DIVIDING HEAD
LEAD DRIVE
[MECHANISM
ELEVATION SCREWI
28.362X
Figure 11-1. — Universal milling machine.
milling machines within these types but only the
classes with which you will be concerned are
discussed in this chapter.
You must be able to set up the milling machine
to machine flat, angular, and formed surfaces.
Included in these jobs are the milling of keyways,
hexagonal and square heads on nuts and bolts,
T-slots and dovetails, and spur gear teeth. To set
up a milling machine, you must compute feeds
and speeds, select and mount the proper holding
device, and select and mount the proper cutter to
handle the job.
Like other machines in the shop, milling
machines have manual and power feed systems,
a selective spindle speed range, and a coolant
system.
KNEE AND COLUMN
MILLING MACHINES
The Navy uses three types of knee and column
milling machines; the universal type, the plain
type, and the vertical spindle type. Wherever only
one type of machine can be installed, the universal
type is usually selected.
The UNIVERSAL MILLING MACHINE
(fig. 11-1) has all the principal features of the
other types of milling machines. It can handle
practically all classes of milling work. You can
take vertical cuts by feeding the table up or down.
You can move the table in two directions in the
horizontal plane — either at a right angle to the axis
of the spindle or parallel to the axis of the spin-
dle. The principal advantage of the universal mill
over the plain mill is that you can swivel the table
on the saddle. Thus, you can move the table in
the horizontal plane at an angle to the axis of the
spindle. This machine is used to cut most types
of gears, milling cutters, and twist drills, and is
used for various kinds of straight and taper work.
11-1
TILT LOCK
SCREWS
CROSS SLIDE
Figure ll-2.-Plain Milling Machine.
2S.365X
v. ., 2S.364X
Figure ll-4.-Small vertical milling machine.
STARTING LEVER <
VERTICAL HEAD CLAMP. X
ARBOR-LOCK
SPINDLE NOSE
SPEED CHANGE
DIAL
SPEED
CALCULATOR
SPINDLE
REVERSE
LEVER
TABLE
TRAVERSE am
HANDWHEEL
AUTOMATIC
LUBRICATION
KNEE
CLAMP
REAR TABLE FEED
ENGAGING LEVER
FOUR POSITION
TURRET STOP
POWER FEED ENGAGING
FOR VERTICAL HEAD
VERTICAL HEAD
HANDWHEEL
AUTOMATIC BACKLASH
ELIMINATOR KNOB
TELESCOPIC
COOLANT RETURN
OIL FILTER
Figure 11-3.— Vertical spindle milling machine.
28.363X
a lew 01 me icaiures lounu on me otner macmnes.
You can move the table in three directions:
longitudinally (at a right angle to the spindle),
transversely (parallel to the spindle), and vertically
(up and down). The ability of this machine to
take heavy cuts at fast speeds is its chief
value and is made possible by the machine's rigid
construction.
The VERTICAL SPINDLE MILLING
MACHINE (fig. 1 1-3) has the spindle in a vertical
position and at a right angle to the surface of the
table. The spindle has a vertical movement, and
the table can be moved vertically, longitudinally,
and transversely. Movement of both the spindle
and the table can be controlled manually or by
power. The vertical-spindle milling machine can
be used for face milling, profiling, die sinking,
various smaii vertical spincue mining macnmes
(fig. 11 -4) are also available for light, precision
milling operations.
MAJOR COMPONENTS
You must know the name and purpose of each
of the main parts of a milling machine to under-
stand the operations discussed later in this
chapter. Keep in mind that although we are
discussing a knee and a column milling machine
you can apply most of the information to the
other types.
Figure 11-5, which illustrates a plain knee and
column milling machine, and figure 11-6, which
illustrates a universal knee and column milling
SPINDLE
STARTING LEVER
REAR POWER TABLE
FEED LEVER
SPINDLE SPEED
SELECTOR DIAL
POWER VERTICAL
FEED LEVER
28.365X
Figure 11-5. — Plain milling machine, showing operation controls.
11-3
o
N
A. SPINDLE
B. ARBOR SUPPORT
C. SPINDLE CLUTCH LEVER
D. SWITCH
E. OVERARM
F. COLUMN
G. SPINDLE SPEED SELECTOR LEVERS
H. SADDLE AND SWIVEL
I. LONGITUDINAL HANDCRANK
J. BASE
K. KNEE
L. FEED DIAL
M. KNEE ELEVATING CRANK
N. TRANSVERSE HANDWHEEL
O. VERTICAL FEED CONTROL
P. TRANSVERSE FEED LEVER
Q. TABLE FEED TRIP DOG
R. LONGITUDINAL FEED CONTROL
Figure 11-6.— Universal knee and column milling machine with horizontal spindle.
28.366
11-4
machine, will help you to become familiar with
the location of the parts.
COLUMN: The column, including the base,
is the main casting which supports all the other
parts of the machine. An oil reservoir and a pump
in the column keep the spindle lubricated. The
column rests on a base that contains a coolant
reservoir and a pump that you can use when you
perform any machining operation that requires
a coolant.
KNEE: The knee is the casting that supports
the table and the saddle. The feed change gear-
ing is enclosed within the knee. It is supported
and can be adjusted by turning the elevating
screw. The knee is fastened to the column by
dovetail ways. You can raise or lower the knee
by either hand or power feed. You usually use
hand feed to take the depth of cut or to position
the work and power feed to move the work during
the machining operation.
SADDLE and SWIVEL TABLE: The saddle
slides on a horizontal dovetail (which is parallel
to the axis of the spindle) on the knee. The swivel
table (on universal machines only) is attached to
the saddle and can be swiveled approximately 45 °
in either direction.
POWER FEED MECHANISM: The power
feed mechanism is contained in the knee and
controls the longitudinal, transverse (in and out)
and vertical feeds. You can obtain the desired rate
of feed on machines, such as the one shown in
figure 1 1-5, by positioning the feed selection levers
as indicated on the feed selection plate. On
machines such as the one in figure 11-6, you get
the feed you want by turning the speed selection
handle until the desired rate of feed is indicated
on the feed dial. Most milling machines have a
rapid traverse lever that you can engage when you
want to temporarily increase the speed of the
longitudinal, transverse, or vertical feeds. For
example, you would engage this lever to position
or align the work.
NOTE: For safety reasons, you must exercise
extreme caution whenever you use the rapid
traverse controls.
TABLE: The table is the rectangular casting
located on top of the saddle. It contains several
T-slots for fastening work or workholding devices
to it. You can move the table by hand or by
power. To move the table by hand, engage and
turn the longitudinal handcrank. To move it by
power, engage the longitudinal directional feed
control lever. You can position the longitudinal
directional feed control lever to the left, to
the right, or in the center. Place the end of the
directional feed control lever to the left to feed
the table toward the left. Place it to the right to
feed the table toward the right. Place it in the
center position to disengage the power feed or to
feed the table by hand.
SPINDLE: The spindle holds and drives the
various cutting tools. It is a shaft mounted on
bearings supported by the column. The spindle
is driven by an electric motor through a train of
gears, all mounted within the column. The front
end of the spindle, which is near the table, has
an internal taper machined in it. The internal taper
(3 1/2 inches per foot) permits you to mount
tapered-shank cutter holders and cutter arbors.
Two keys, located on the face of the spindle,
provide a positive drive for the cutter holder, or
arbor. You secure the holder or arbor in the
spindle by a drawbolt and jamnut, as shown in
figure 11-7. Large face mills are sometimes
mounted directly to the spindle nose.
J AMNUT
•wilriilililili
J
DRAWBOLT
ARBOR SHANK
SPINDLE
OVERARM: The overarm is the horizontal
beam to which you fasten the arbor support. The
overarm may be a single casting that slides in
dovetail ways on the top of the column (fig. 11-6)
or it may consist of one or two cylindrical bars
that slide through holes in the column, as shown
in figure 11-6. To position the overarm on some
machines, you first unclamp locknuts and then
extend the overarm by turning a crank. On others,
TOOLMAKERS UNIVERSAL VISE
you move the overarm by simply pushing on it.
You should extend the overarm only far enough
to position the arbor support to make the setup
as rigid as possible. To place arbor supports on
an overarm such as the one shown as B, in figure
11-6, extend one of the bars approximately 1 inch
farther than the other bar. Tighten the locknuts
after positioning the overarm. On some milling
machines the coolant supply nozzle is fastened to
the overarm. You can mount the nozzle with a
split clamp to the overarm after you have placed
the arbor support in position.
ARBOR SUPPORT: The arbor support is a
casting that contains a bearing which aligns the
outer end of the arbor with the spindle. This helps
to keep the arbor from springing during cutting
operations. Two types of arbor supports are
commonly used. One type has a small diameter
bearing hole, usually 1-inch maximum diameter.
The other type has a large diameter bearing hole,
usually up to 2 3/4 inches. An oil reservoir in the
arbor support keeps the bearing surfaces
lubricated. You can clamp an arbor support at
any place you want on the overarm. Small arbor
supports give additional clearance below the
arbor supports when you are using small diameter
cutters. However, small arbor supports can
provide support only at the extreme end of the
arbor. For this reason they are not recommended
for general use. Large arbor supports can provide
support near the cutter, if necessary.
NOTE: Before loosening or tightening the
arbor nut, you must install the arbor support. This
will prevent bending or springing of the arbor.
SIZE DESIGNATION: All milling machines
are identified by four basic factors: size,
horsepower, model, and type. The size of a milling
machine is based on the longitudinal (from left
to right) table travel in inches. Vertical, cross, and
longitudinal travel are all closely related as far as
overall capacity is concerned. For size designa-
tion, only the longitudinal travel is used. There
are six sizes of knee-type milling machines, with
each number representing the number of inches
of travel.
BROWN & SHARPE Manufacturing Company, North Kingstown, RJ
28.199X
Figure 11-8.— Milling machine vises.
Standard Size
No. 1
No. 2
No. 3
No. 4
No. 5
No. 6
Longitudinal Table Travel
22 inches
28 inches
34 inches
42 inches
50 inches
60 inches
11-6
brands. The TYPE of milling machine is
designated as plain or universal, horizontal or
vertical, and knee and column or bed. In
addition, machines may have other special type
designations.
Standard equipment used with milling
machines in Navy ships includes workholding
devices, spindle attachments, cutters, arbors, and
any special tools needed for setting up the
machines for milling. This equipment allows you
to hold and cut the great variety of milling jobs
you will encounter in Navy repair work.
WORKHOLDING DEVICES
The following workholding devices are the
ones that you will probably use most frequently.
vise provides the most support for a rigid
workpiece. The swivel vise is similar to the flanged
vise, but the setup is less rigid because the
workpiece can be swiveled in a horizontal plane
to any required angle. The toolmaker's universal
vise provides the least rigid support because it is
designed to set up the workpiece at a complex
angle in relation to the axis of the spindle and to
the surface of the table.
INDEXING EQUIPMENT
Indexing equipment (fig. 11-9) is used to hold
and turn the workpiece so that a number of
accurately spaced cuts can be made (gear teeth for
example). The workpiece may be held in a chuck
or a collet, attached to the dividing head spindle,
or held between a live center in the dividing
~' - "r.j.":'.r.'".':".:::r—" •
CENTER REST|
BRACKETS FOR
MOUNTING CHANGE
GEARS
DIVIDING
HEAD
CENTER
[FOOTSTOCK]
[INDEX PLATES
CHANGE GEARS!
BROWN & SHARPS Manufacturing Company, North Kingstown, RI
28.200X
Figure 11-9. — Indexing equipment.
11-7
index head and a dead center in the footstock.
The center of the footstock can be raised or
lowered for setting up tapered workpieces. The
center rest can be used to support long slender
work.
Dividing Head
The internal components of the dividing head
are shown in figure 11-10. The ratio between the
worm and the gear is 40 to 1. By turning the
worm one turn, you rotate the spindle 1/40 of a
revolution. The index plate has a series of
concentric circles of holes, which you can use to
gauge partial turns of the worm shaft and to turn
the spindle accurately in amounts smaller than
1/40 of a revolution. You can secure the index
plate either to the dividing head housing or to a
rotating shaft and you can adjust the crankpin
radially for use in any circle of holes. You can
also set the sector arms as a guide to span any
number of holes in the index plate to provide a
guide for rotating the index crank for partial
turns. To rotate the workpiece, you can turn the
dividing head spindle either directly by hand by
disengaging the worm and drawing the plunger
back* or by the index crank through the worm
and worm gear.
The spindle is set in a swivel block so that you
can set the spindle at any angle from slightly below
horizontal to slightly past vertical. As mentioned
previously, most index heads have a 40:1 ratio.
One well-known exception has a 5 to 1 ratio
(see fig. 11-11). This ratio is made possible by a
5 to 1 gear ratio between the index crank and the
dividing head spindle. The faster movement of the
spindle with one turn of the index crank permits
speedier production. It is also an advantage in
truing work or testing work for run out with a
dial indicator. Although made to a high standard
SECTOR ARM
DIVIDING
HEAD SPINDLE
WORM GEAR
(40 TEETH)
WORM
SECTOR ARM
INDEX > WORM
PLATE SHAFT
Photo courtesy of Kearney & Trecker Corporation, Milwaukee, Wis.
28.368X
Figure 11-11.— Universal spiral dividing head with a
5 to 1 ratio between the spindle and the index crank.
of accuracy, the 5 to 1 ratio dividing head
does not permit as wide a selection of
divisions by simple indexing. Differential indexing
(discussed later in this chapter) can be done on
the 5 to 1 ratio dividing head by using a
differential indexing attachment.
LEAD
SCREW
Fieure 11-10. — Dividino head mechanism.
Fiaure 11-12.-
28.307X
-Enclosed drivinc mechanism.
the work — as required for helical and spiral
milling. The index head may have one of several
driving mechanisms. The most common of these
is the ENCLOSED DRIVING MECHANISM,
which is standard equipment on some makes of
plain and universal knee and column milling
machines. The enclosed driving mechanism has
a lead range of 2 1/2 to 100 inches and is driven
directly from the lead screw.
Gearing Arrangement
Figure 11-12 illustrates the gearing arrange-
ment used on most milling machines. The gears
are marked as follows:
A = Gear on the worm shaft (driven)
B = First gear on the idler stud (driving)
E and F = Idler gears
LOW LEAD DRIVE.— For some models and
makes of milling machines a low lead driving
mechanism is available; however, additional parts
must be built into the machine at the factory. This
driving mechanism has a lead range of 0.125 to
100 inches.
LONG AND SHORT LEAD DRIVE.—
When an extremely long or short lead is required,
you can use the long and short lead attachment
(fig. 11-13). As with the low lead driving
mechanism, the milling machine must have
certain parts built into the machine at the factory.
In this attachment, an auxiliary shaft in the table
drive mechanism supplies power through the gear
BROWN & SHARPE Manufacturing Company, North Kingstown, Rl
126.27X
Figure 11-13. — The long and short lead attachment.
11-9
train to the dividing head. It also supplies the
power for the table lead screw which is disengaged
from the regular drive when the attachment is
used. This attachment provides leads in the range
between 0.010 and 1000 inches.
CIRCULAR MILLING ATTACHMENT.—
The circular milling attachment, or rotary table
(fig. 11-14), is used for setting up work that
must be rotated in a horizontal plane. The
worktable is graduated (1/2° to 360°) around its
circumference. You can turn the table by
hand or by the table feed mechanism through
a gear train (fig. 11-14). An 80 to 1 worm
and gear drive contained in the rotary table
and index plate arrangement makes this device
BROWN & SHARPS Manufacturing Company, North Kingstown, RI
SPECIAL ATTACHMENTS
The universal milling (head) attachment,
shown in figure 11-15, is clamped to the column
of the milling machine. The cutter can be secured
in the spindle of the attachment and then can be
set by the two rotary swivels so that the cutter will
ment is driven by gearing connected to the milling
machine spindle.
SLOTTING ATTACHMENT
Although special machines are designed for
cutting slots (such as key ways and splines), this
type of machine frequently is not available.
Consequently, the machinist must devise other
means for cutting slots. The slotting attachment
CIRCULAR
MILLING
ATTACHMENT
(ROTARY TABLE)
28.202X
Figure 11-15. —Circular milling attachments (rotary table) and universal (head) attachment.
11-11
in figure 11-16, when mounted on the column and
the spindle of a plain or universal milling machine,
will perform such operations.
The attachment is designed so that the rotating
motion of the spindle is changed to reciprocating
motion of the tool slide on the slotter, similar to
the ram on a shaper. A single point cutting tool
is used. Since the tool slide can be swiveled
through 360°, slotting can be done at any angle,
and the stroke can be set to from 0 to 4 inches.
INDEXING THE WORK
Indexing is done by the direct, plain,
compound, or differential method. The direct and
plain methods are the most commonly used; the
compound and differential methods are used only
when the job cannot be done by plain or direct
indexing.
DIRECT INDEXING
Direct indexing, sometimes referred to as rapid
indexing, is the simplest method of indexing.
Figure 1 1-17 shows the front index plate attached
to the work spindle. The front index plate usually
has 24 equally spaced holes. These holes can be
engaged by the front index pin, which is spring-
loaded and moved in and out by a small lever.
Rapid indexing requires that the worm and the
worm wheel be disengaged so that the spindle can
be moved by hand. Numbers that can be divided
into 24 can be indexed in this manner. Rapid in-
dexing is used when a large number of duplicate
parts are to be milled.
To find the number of holes to move the
index plate, divide 24 by the number of divisions
required.
Number of holes to move = 24/N where
N = required number of divisions
Example: Indexing for a hexagon head bolt:
because a hexagon head has six flats,
~ = 24 = 4 holes
N 6
IN ANY INDEXING OPERATION AL-
WAYS START COUNTING FROM THE
HOLE ADJACENT TO THE CRANKPIN.
During heavy cutting operations, clamp the
spindle by the clamp screw to relieve strain on the
index pin.
BROWN & SHARPS Manufacturing Company, North Kingstown, RI
28.369X
Figure 11-16.— Slotting a bushing using a slotting
attachment.
BROWN & SHARPE Manufacturing Company, North Kingstown, R.
28.2093
Figure 11-17.— Direct index plate.
PLAIN INDEXING
Plain indexing, or simple indexing, is used
when a circle must be divided into more parts than
is possible by rapid indexing. Simple indexing
requires that the spindle be moved by turning an
index crank, which turns the worm that is meshed
with the worm wheel. The ratio between worm
and the worm wheel is 40 to 1 (40:1). One turn
of the index crank turns the index head spindle
1/40 of a complete turn. Therefore, forty turns
of the index crank are required to revolve the
spindle chuck and the job one complete turn. To
determine the number of turns or fractional parts
of a turn of the index crank necessary to cut any
required number of divisions, divide 40 by the
number of divisions required.
40
Number of turns of the index crank = -rr
where N = number of divisions required
Example (1): Index for five divisions
40 40 Q .
N" ~ T turns
There are eight turns of the crank for each
division.
Example (2): Index for eight divisions
40 40
N 8
5 turns
Example (3): Index for ten divisions
40 40 , ,
N = 10 = 4 turns
When the number of divisions required does
not divide evenly into 40, the index crank must
be moved a fractional part of a turn with index
plates. A commonly used index head comes with
three index plates. Each plate has six circles of
holes which we shall use as an example.
Plate one: 15-16-17-18-19-20
Plate two: 21-23-27-29-31-33
Plate three: 37-39-41-43-47-49
The previous examples of using the indexing
the index crank. This seldom happens on the
typical indexing job. For example, indexing for
18 divisions
40 40 ~4 .
N = 18 = 218 turns
The whole number indicates the complete
turns of the index crank, the denominator of the
fraction represents the index circle, and the
numerator represents the number of holes to use
on that circle. Because there is an 18-hole index
circle, the mixed number 2 4/18 indicates that the
index crank will be moved 2 full turns plus 4 holes
on the 18-hole circle. The sector arms are
positioned to include 4 holes and the hole in which
the index crank pin is engaged. The number of
holes (4) represents the movement of the index
crank; the hole that engages the index crank pin
is not included.
When the denominator of the indexing
fraction is smaller or larger than the number of
holes contained in any of the index circles, change
it to a number representing one of the circles of
holes. Do this by multiplying or dividing the
numerator and the denominator by the same
number. For example, to index for the machining
of a hexagon (N = 6):
4Q = 40 3 = 120
6 63 18
12 2
= 6 turns
The denominator 3 will divide equally into the
following circles of holes, so you can use any plate
that contains one of the circles.
Plate one: 15 and 18
Plate two: 21 and 33
Plate three: 39
To apply the fraction 2/3 to the circle you choose,
convert the fraction to a fraction that has the
number of holes in the circle as a denominator.
For example, if you choose the 15 hole circle, the
fraction 2/3 becomes 10/15. If plate 3 happens
to be on the index head, multiply the denominator
3 by 13 to equal 39. In order not to change the
value of the original indexing fraction, also
multiply the numerator by 13
2X13 = 26
3 13 39
The original indexing rotation of 6 2/3 turns
full turns and 26 holes on the 39-hole circle.
When the number of divisions exceeds 40,
you may divide both the numerator and the
denominator of the fraction by a common divisor
to obtain an index circle that is available. For
example, if 160 divisions are required, N = 160;
the fraction to be used is
40
N
_
160
Because there is no 160-hole circle this fraction
must be reduced. To use a 16-hole circle, divide
the numerator and denominator by 10.
40/10 4
160/10 16
Turn 4 holes on the 16-hole circle.
It is usually more convenient to reduce the
original fraction to its lowest terms and then
multiply both terms of the fraction by a factor
that will give a number representing a circle of
holes.
40
160
4 4" 16
The following examples will further clarify the
use of this formula:
Example 1: Index for 9 divisions.
40 = 40 _ A
N 9 49
If an 18-hole circle is used, the fraction
becomes 4/9 x 2/2 = 8/18. For each division,
turn the crank 4 turns and 8 holes on an 18-hole
circle.
Example 2: Index for 136 divisions.
4C I
N
40 5
136 17
There is a 17-hole circle, so for each division
turn the crank 5 holes on a 17-hole circle.
In setting the sector arms to space off the
required number of holes on the index
circle, do not count the hole that the
index crank pin is in.
Most manufacturers provide different plates
for indexing. Later model Brown and Sharpe
index heads use two plates with the following
circle of holes:
Plate one: 15, 16, 19, 23, 31, 37, 41, 43, 47
Plate two: 17, 18, 20, 21, 27, 29, 33, 39, 47
The standard index plate supplied with the
Cincinnati index head is provided with 1 1 different
circles of holes on each side.
Side one: 24-25-28-30-34-37-38-39-4-42-43
Side two: 46-47-49-51-53-54-57-58-59-62-66
ANGULAR INDEXING
When you must divide work into degrees or
fractions of a degree by plain indexing, remember
that one turn of the index crank will rotate a point
on the circumference of the work 1/40 of a revolu-
tion. Since there are 360 ° in a circle, one turn of
the index crank will revolve the circumference of
the work 1 /40 of 360 °, or 9 °. Hence, in using the
index plate and fractional parts of a turn, 2 holes
in an 18-hole circle equal 1 ° (1/9 turn x 9°/turn),
1 hole in a 27-hole circle equals 1/3° (1/27
turn x 9°/turn), 3 holes in a 54-hole circle equal
1/2° (1/18 turn x9°/turn). To determine the
number of turns and parts of a turn of the index
crank for a desired number of degrees, divide the
number of degrees by 9. The quotient will
represent the number of complete turns and
fractions of a turn that you should rotate the
index crank. For example, the calculation for
determining 15° when an index plate with a
54-hole circle is available, is as follows:
36
or one complete turn plus 36 holes on the 54-hole
circle. The calculation for determining 13 1/2°
11-14
or one complete turn plus 9 holes on the 18-hole
circle.
When indexing angles are given in minutes,
and approximate divisions are acceptable, move-
ment of the index crank and the proper index plate
may be determined by the following calculations.
You can determine the number of minutes
represented by one turn of the index crank by
multiplying the number of degrees covered in one
turn of the index crank by 60 minutes/degree.
9 ° x 60 min/degree = 540 min
Therefore, open turn of the index crank will rotate
the index head spindle 540 minutes.
The number of minutes (540) divided by
the number of minutes in the division desired,
indicates the total number of holes there
should be in the index plate used. (Moving
the index crank one hole will rotate the index
head spindle through the desired number of
minutes of angle.) This method of indexing
can be used only for approximate angles since
ordinarily the quotient will come out in mixed
numbers or in numbers for which there are
no index plates available. However, when the
quotient is nearly equal to the number of
holes in an available index plate, the nearest
number of holes can be used and the error
will be very small. For example the calculation
for 24 minutes would be:
540
24
22.5
1
or one hole on the 22.5 hole circle. Since there
is no 22.5-hole circle on the index plate, a 23-hole
circle plate would be used.
If a quotient is not approximately equal
to an available circle of holes, multiply by
any trial number which will give a product
equal to the number of holes in one of the
available index circles. You can then move
the crank the required number of holes to
give the desired division. For example, the
calculation for determining 54 minutes when
540 10 2 20 (20-hole circle)
or 2 holes on the 20-hole circle.
COMPOUND INDEXING
Compound indexing is a combination of two
plain indexing procedures. One number of
divisions is indexed using the standard plain
indexing method; another number of divisions is
indexed by turning the index plate (leaving the
crank pin engaged in the hole as set in the first
indexing operation) by a required amount. The
difference between the amount indexed in the first
operation and the amount indexed in the second
operation results in the spindle turning the
required amount for the number of divisions.
Compound indexing is seldom used because (1)
differential indexing is easier, (2) high number
index plates are usually available to provide any
range of divisions normally required and (3) the
computation and actual operation are quite
complicated, making it easy for errors to be
introduced.
Compound indexing is briefly described in the
following example. To index 99 divisions proceed
as follows:
1 . Multiply the required number of divisions
by the difference between the number of holes in
two circles selected at random. Divide this
product by 40 (ratio of spindle to crank) times
the product of the two index hole circles. Assume
that the 27-hole circle and 3 3 -hole circle have been
selected. The resulting equation is:
99 x (33 - 27) 99 x 6
40 x 33 x 27 40 x 33 x 27
2. To make the problem easier to solve,
factor each term of the equation into its lowest
prime factors and cancel where possible. For
example:
(2 x
x 2)
(2 x 2 x 2 x 5)(17 x 2f)(3 x 2 x 3) 60
The result of this process must be in the form of
a fraction as given (that is, 1 divided by some
number). Always try to select the two circles which
11-15
have factors that will cancel out the factors in the
numerator of the problem. When the numerator
of the resulting fraction is greater than 1 , divide
it by the denominator and use the quotient (to
nearest whole number) instead of the denominator
of the fraction.
3. The denominator of the resulting fraction
derived in step two is the term used to find the
number of turns and holes for indexing the spindle
and index plate. To index for 99 divisions, turn
the spindle by an amount equal to 60/33 or one
complete turn plus 27 holes in the 33-hole circle;
turn the index plate by an amount equal to 60/27,
or two complete turns plus 6 holes in the 27-hole
circle. If you turn the index crank clockwise, turn
the index plate counterclockwise and vice versa.
DIFFERENTIAL INDEXING
Differential indexing is similar to compound
indexing except that the index plate is turned
during the indexing operation by gears connected
to the dividing head spindle. Because the index
plate movement is caused by the spindle move-
ment, only one indexing procedure is required.
The gear train between the dividing head spindle
and the index plate provides the correct ratio of
movement between the spindle and the index
plate.
Figure 11-18 shows a dividing head set up for
differential indexing. The index crank is turned
as it is for plain indexing, thus turning the spindle
gear and then the compound gear and the idler
to drive the gear which turns the index plate.
Specific procedures for installing the gearing
and arranging the index plate for differential in-
dexing (and compound indexing) are given in
manufacturers' technical manuals.
To index 57 divisions, for example, take the
following steps:
1 . Select a number greater or lesser than the
required number of divisions for which an
available index plate can be used (60 for example).
2. The number of turns for plain indexing 60
divisions is: 40/60 or 14/21, which will require
14 holes in a 21 -hole circle in the index plate.
3. To find the required gear ratio, subtract the
required number of divisions from the selected
28.210X
Figure 11-18. — Differential indexing.
number or vice versa (depending on which is
larger), and multiply the result by 40/60 (formula
for indexing 60 divisions). Thus:
gear ratio = (60 - 57) x — =
The numerator indicates the spindle gear; the
denominator indicates the driven gear.
4. Select two gears that have a 2 to 1 ratio (for
example a 48-tooth gear and a 24-tooth gear).
5 . If the selected number is greater than the
actual number of divisions required, use one or
three idlers in the simple gear train; if the selected
number is smaller, use none or two idlers. The
reverse is true for compound gear trains. Since
the number is greater in this example, use one or
three idlers.
6. Now turn the index crank 14 holes in the
21-hole circle of the index plate. As the crank
turns the spindle, the gear train turns the index
plate slightly faster than the index crank.
Wide Range Divider
In the majority of indexing operations, you
can get the desired number of equally spaced
divisions by using either direct or plain indexing.
11-16
By using one or the other of these methods, you
may index up to 2,640 divisions. To increase the
range of divisions, use the high number index
plates in place of the standard index plate. These
high number plates have a greater number of
circles of holes and a greater range of holes in the
circles than the standard plates. This increases the
range of possible divisions from 1,040 to 7,960.
In some instances, you may need to index
beyond the range of any of these methods. To
further increase the range, use a universal dividing
head that has a wide range divider. This type of
indexing equipment enables you to index divisions
from 2 to 400,000. The wide range divider (Fig.
11-19) consists of a large index plate with sector
arms and a crank and a small index plate with
sector arms and a crank. The large index plate
(A, fig 11-19) has holes drilled on both sides and
contains eleven circles of holes on each side of
the plate. The number of holes in the circles on
one side are 24, 28, 30, 34, 37, 38, 39, 41, 42, 43,
and 100. The other side of the plate has circles
containing 46, 47, 49, 51, 53, 54, 57, 58, 59, 62,
and 66 holes. The small index plate has two circles
of holes and is drilled on one side only. The outer
circle has 100 holes and the inner circle has 54
holes.
The small index plate (C, fig. 11-19) is
mounted on the housing of the planetary gearing
(G, fig. 11-19), which is built into the index crank
(B, fig. 11-19) of the large plate. As the index
crank of the large plate is rotated, the planetary
gearing assembly and the small index plate and
crank rotate with it.
As with the standard dividing head, the large
index crank rotates the spindle in the ratio of 40
to 1 . Therefore, one complete turn of the large
index crank rotates the dividing head spindle 1/40
of a turn, or 9 °. By using the large index plate
and the crank, you can index in the conventional
manner. Machine operation is the same as it is
with the standard dividing head.
When the small index crank (D, fig. 11-19) is
rotated, the large index crank remains stationary
but the main shaft that drives the work revolves
in the ratio of 1 to 100. This ratio, superimposed
on the 40 to 1 ratio between the worm and worm
Figure 11-19. — The wide range divider.
126.28X
wheel (fig. 1 1-20), causes the dividing head spindle
to rotate in the ratio of 4,000 to 1. This means
that one complete revolution of the spindle will
require 4,000 turns of the small index crank.
Turning the small crank one complete turn will
rotate the dividing head spindle 5 minutes, 24
seconds of a degree. If one hole of the 100-hole
circle on the small index plate were to be indexed,
the dividing head spindle would make 1/400,000
of a turn, or 3.24 seconds of a degree.
You can get any whole number of divisions
up to and including 60, and hundreds of others,
by using only the large index plate and the crank.
The dividing head manufacturer provides tables
listing many of the settings for specific divisions
that may be read directly from the table with no
further calculations necessary. If the number of
divisions required is not listed in the table or if
there are no tables, use the manufacturer's manual
or other reference for instructions on how to
compute the required settings.
Adjusting the Sector Arms
To use the index head sector arms, turn the
left-hand arm to the left of the index pin, which
is inserted into the first hole in the circle of holes
that is to be used. Then loosen the setscrew (fig.
11-19E) and adjust the right-hand arm of the
sector so that the correct number of holes will be
contained between the two arms (fig. 11-21). After
making the adjustments, lock the setscrew to hold
the arms in position. When setting the arms, count
the required number of holes from the one in
which the pin is inserted, considering this hole as
zero. By subsequent use of the index sector, you
will not need to count the holes for each division.
When using the index crank to revolve the spindle,
you must unlock the spindle clamp screw;
however, before cutting work held in or on the
index head, lock the spindle again to relieve the
strain on the index pin.
CUTTERS AND ARBORS
When you perform a milling operation, you
move the work into a rotating cutter. On most
milling machines, the cutter is mounted on an
arbor that is driven by the spindle. However, the
spindle may drive the cutter directly. We will
discuss cutters in the first part of this section and
arbors in the second part.
CUTTERS
There are many different milling machine
cutters. Some cutters can be used for several
• CLAMPING STRAPS
SWIVEL BLOCK
INDEX- PIN INDEX CRANK
ECCENTRIC
FOR
DISENGAGING
WORM
TRUNNION
INDEX PLATE
\
INDEX PLATE
STOP PIN
INDEX
CRANK
WORM
SHAFT NUT
INDEX PLATE
28.371X
Figure 11-21. — Principal parts of a late model Cincinnati
universal spiral index head.
operations, while others can be used for only one
operation. Some cutters have straight teeth and
others have helical teeth. Some cutters have
mounting shanks and others have mounting holes.
You must decide which cutter to use. To make
this decision, you must be familiar with the
various milling cutters and their uses. The
information in this section will help you to select
the proper cutter for each of the various
operations you will perform. In this section we
will cover cutter types and cutter selection.
Standard milling cutters are made in many
shapes and sizes for milling both regular and
irregular shapes. Various cutters designed for
specific purposes also are available; for example,
a cutter for milling a particular kind of curve on
some intermediate part of the workpiece.
Milling cutters generally take their names from
the operation that they perform. The most
common cutters are: (1) plain milling cutters of
various widths and diameters, used principally for
milling flat surfaces that are parallel to the axis
of the cutter: (2) angular milling cutters, designed
for milling V-grooves and the grooves in reamers,
taps, and milling cutters; (3) face milling cutters,
used for milling flat surfaces at a right angle to
the axis of the cutter; and (4) forming cutters, used
to produce surfaces with an irregular outline.
Milling cutters may also be classified as arbor-
mounted, or shank-mounted. Arbor-mounted
cutters are mounted on the straight shanks of
arbors. The arbor is then inserted into the milling
machine spindle. We will discuss the methods of
mounting arbors and cutters in greater detail later
in this chapter.
Milling cutters may have straight, right-hand,
left-hand, or staggered teeth. Straight teeth are
parallel to the axis of the cutter. If the helix angle
twists in a clockwise direction (viewed from either
end), the cutter has right-hand teeth. If the helix
angle twists in a counterclockwise direction, the
cutter has left-hand teeth. The teeth on staggered-
tooth cutters are alternately left-hand and right-
hand.
Types and Uses
There are many different types of milling
cutters. We will now discuss these types and their
uses.
PLAIN MILLING CUTTER.— You will use
plain milling cutters to mill flat surfaces that are
parallel to the cutter axis. As you can see in figure
1 1-22, a plain milling cutter is a cylinder with teeth
28.372
SmiWA 11 _'>•} Dlain millinn
cut on the circumference only. Plain milling
cutters are made in a variety of diameters and
widths. Note in figure 11-23, that the cutter teeth
may be either straight or helical. When the width
is more than 3/4 inch, the teeth are usually helical.
The teeth of a straight cutter tool are parallel to
axis of the cutter. This causes each tooth to cut
along its entire width at the same time, causing
a shock as the tooth starts to cut. Helical teeth
eliminate this shock and produce a free cutting
action. A helical tooth begins .the cut at one end
and continues across the work with a smooth
shaving action. Plain milling cutters usually have
radial teeth. On some coarse helical tooth cutters
the tooth face is undercut to produce a smoother
cutting action. Coarse teeth decrease the tendency
of the arbor to spring and give the cutter greater
strength.
RADIAL RELIEF
ANGLE
CLEARANC SURFACE
LAND
HEEL
FLUTE
TOOTH
RADIAL RAKE ANGLE
(POSITIVE SHOWN)
OFFSET
PERIPHERAL
CUTTING EDGE
TOOTH FACE
CLEARANCE
SURFACE
CONCAVITY
AXIAL RELIEF
ANGLE
FILLET
LIP ANGLE
HELICAL TEETH
HELICAL RAKE ANGLE
(LH HELIX SHOWN }
RADIAL RAKE ANGLE
(POSITIVE SHOWN)'
RADIAL RELIEF
TOOTH
FILLET
TOOTH FACE
AXIAL RELIEF —
OFFSET
A plain milling cutter has a standard size
arbor hole for mounting on a standard size
arbor. The size of the cutter is designated by the
diameter and width of the cutter, and the diameter
of the arbor hole in the cutter.
SIDE MILLING CUTTER.— The side milling
cutter (fig. 11-24) is a plain milling cutter with
teeth cut on both sides as well as on the periphery
or circumference of the cutter. You can see that
the portion of the cutter between the hub and the
side of the teeth is thinner to give more chip
clearance. These cutters are often used in pairs
to mill parallel sides. This process is called straddle
milling. Cutters more than 8 inches in diameter
are usually made with inserted teeth. The size
designation is the same as for plain milling cutters.
HALF-SIDE MILLING CUTTER.— Half-
side milling cutters (fig. 11-25) are made
particularly for jobs where only one side of the
cutter is needed. These cutters have coarse, helical
teeth on one side only so that heavy cuts can be
made with ease.
SIDE MILLING CUTTER (INTERLOCK-
ING).— Side milling cutters whose teeth interlock
(fig. 1 1-26) can be used to mill standard size slots.
The width is regulated by thin washers inserted
between the cutters.
METAL SLITTING SAW.— You can use a
metal slitting saw to cut off work or to mill
narrow slots. A metal slitting saw is similar to a
plain or side milling cutter, with a face width
usually less than 3/16 inch. This type of cutter
usually has more teeth for a given diameter than
a plain cutter. It is thinner at the center than at
the outer edge to give proper clearance for milling
Figure 11-25. — Half-side milling cutter.
Figure 11-24. — Side milling cutter.
Figure 11-26. — Interlocking teeth side milling cutter.
deep slots. Figure 11-27 shows a metal slitting saw
with teeth cut in the circumference of the cutter
only. Some saws, such as the one in figure 1 1-28,
have side teeth which achieve better cutting
action, break up chips, and prevent dragging when
you cut deep slots. For heavy sawing in steel, there
are metal slitting saws with staggered teeth, as
shown in figure 11-29. These cutters are usually
3/16 inch to 3/8 inch thick.
SCREW SLOTTING CUTTER.— The screw
slotting cutter (fig. 11-30) is used to cut shallow
slots, such as those in screw heads. This cutter
has fine teeth cut on its circumference. It is made
in various thicknesses to correspond to American
Standard gauge wire numbers.
ANGLE CUTTER.-— Angle cutters are used
to mill surfaces that are not at a right angle to
Figure 11-27. —Metal slitting saw.
Figure 11-29.— Slitting saw with staggered teeth.
Figure 11-30.— Screw slotting cutter.
Figure ll-28.-Slitting saw with side teeth. Figure ll-31.-Single angle cutter.
11-22
cutter axis. You can use angle cutters for a variety
of work, such as milling V-grooves and dovetail
ways. On work such as dovetailing, where you
cannot mount a cutter in the usual manner on an
arbor, you can mount an angle cutter that has a
threaded hole, or is constructed like a shell end
Figure 11-32. — Double angle cutter.
mill, on the end of a stub or shell end mill
arbor. When you select an angle cutter for a job
you should specify the type, hand, outside
diameter, thickness, hole size, and angle.
There are two types of angle cutters — single
and double. The single angle cutter, shown in
figure 1 1-31, has teeth cut at an oblique angle with
one side at an angle of 90 ° to the cutter axis and
the other usually at 45°, 50°, or 80°.
The double angle cutter (fig. 11-32) has two
cutting faces, which are at an angle to the cutter
axis. When both faces are at the same angle to
the axis, you obtain the cutter you want by
specifying the included angle. When they are
different angles, you specify the angle of each side
with respect to the plane of intersection.
FLUTING CUTTER.— A fluting cutter is a
double angle form tooth cutter with the points of
the teeth well rounded. It is generally used to mill
flutes in reamers. Fluting cutters are marked with
the range of diameters they are designed to mill.
END MILL CUTTERS.— End mill cutters
may be the SOLID TYPE with the teeth and the
shank as an integral part (fig. 1 1-33), or they may
(A) Two-flute single-end; (B) Two-flute double-end; Carbide-tipped, straight flutes; (H) Carbide-tipped, RH
(C) Three-flute single-end; (D) Multiple-flute single-end; helical flutes; (I) Multiple-flute with toper shank; (J)
(E) Four-flute double-end; (F) Two -flute ball-end; (G) Carbide -tipped with taper shank and helical flutes.
Figure 11-34.— Shell end mill.
be the SHELL TYPE (fig. 11-34) in which the
cutter body and the shank or arbor are separate.
End mill cutters have teeth on the circumference
and on the end. Those on the circumference may
be either straight or helical (fig. 11-35).
Except for the shell type, all end mills have
either a straight shank or a tapered shank which
is mounted into the spindle of the machine for
STANDARD
MILLING CUTTERS AND END MILLS
LENGTH OF OVERALL
END CUTTING EDGE
CONCAVITY ANGLE
TOOTH FACE
^J N\
RADIAL RAKE ANGLE
(POSITIVE SHOWN)
END CLEARANCE
AXIAL
RELIEF ANGLE
END GASH
HELIX ANGLE
TOOTH FACE
C RADIAL
JUTTING EDGE
FLUTE
ENLARGED SECTION
OF END MILL
RADIAL LAND
RADIAL CLEARANCE ANGLE
ENLARGED SECTION
nr Fwn MII i rnnrw
driving the cutter. There are various types of
adapters for securing end mills to the machine
spindle.
End milling involves the machining of surfaces
(horizontal, vertical, angular, or irregular) with
end mill cutters. Common operations include the
milling of slots, keyways, pockets, shoulders, and
flat surfaces, and the profiling of narrow surfaces.
End mill cutters are used most often on
vertical milling machines. However, they also are
used frequently on machines with horizontal
spindles. Many different types of end mill cutters
are available in sizes ranging from 1/64 inch to
2 inches. They may be made of high-speed steel,
may have cemented carbide teeth, or may be of
the solid carbide type.
TWO-FLUTE END MILLS have only two
teeth on their circumference. The end teeth can
cut to the cutter. Hence, they may be fed into the
work like a drill; they can then be fed lengthwise
to form a slot. These mills may be either the
single-end type with the cutter on one end only,
or they may be the double-end type. (See fig.
11-33.)
MULTIPLE-FLUTE END MILLS have
three, four, six, or eight flutes and normally are
available in diameters up to 2 inches. They may
be either the single-end or the double-end type
(fig. 11-33).
BALL END MILLS (fig. 1 1-33) are used for
milling fillets or slots with a radius bottom, for
rounding pockets and the bottom of holes, and
for all-around die sinking and die making work.
Two-flute end mills with end cutting lips can be
used to drill the initial hole as well as to feed
longitudinally. Four-flute ball end mills with
center cutting lips also are available. These work
well for tracer milling, fillet milling and die
sinking.
SHELL END MILLS (fig. 1 1-34) have a hole
for mounting the cutter on a short (stub) arbor.
The center of the shell is recessed for the screw
or nut that fastens the cutter to the arbor. These
mills are made in larger sizes than solid end mills,
normally in diameters from 1 1/4 to 6 inches.
Cutters of this type are intended for slabbing or
surfacing cuts, either face milling or end milling,
and usually have helical teeth.
FACE MILLING CUTTER.— Inserted tooth
face milling cutters (fig. 1 1-36) are similar to shell
Figure 11-36. — Inserted tooth face milling cutter.
end mills in that they have teeth on the
circumference and on the end. They are attached
directly to the spindle nose and use inserted,
replaceable teeth made of carbide or any alloy
steel.
T-SLOT CUTTER.— The T-slot cutter
(fig. 11-37) is a small plain milling cutter
with a shank. It is designed especially to mill
the "head space*' of T-slots. T-slots are cut
in two operations. First, you cut a slot with
an end mill or a plain milling cutter, and then
you make the cut at the bottom of the slot
with a T-slot cutter.
Figure 11-37.— T-slot cutter.
11-25
Figure 11-38.— Woodruff keyseat cutter.
Figure 11-40.— Concave cutter.
\jLJ
Figure 11-39.— Involute gear cutter.
Figure 11-41.— Convex cutter.
Figure 11-42.— Corner rounding cutter.
11-26
WOODRUFF KEYSEAT CUTTER.— A
Woodruff keyseat cutter (fig. 1 1-38) is used to cut
curved keyseats. A cutter less than 1 1/2 inches
in diameter has a shank. When the diameter
is greater than 1 1/2 inches, the cutter is
usually mounted on an arbor. The larger cutters
have staggered teeth to improve the cutting
action.
GEAR CUTTERS.— There are several types
of gear cutters, such as bevel, spur, involute, and
so on. Figure 1 1-39 shows an involute gear cutter.
You must select the correct type of cutter to cut
a particular type of gear.
CONCAVE AND CONVEX CUTTERS.—
A concave cutter (fig. 11-40) is used to mill a
convex surface, and a convex cutter (fig. 11-41)
is used to mill a concave surface.
WIDTH
KEYWAY
HOLE
./"""
tr
UJ UJ
o h-
^ uj
05
Figure 11-43.— Sprocketed wheel cutter.
CORNER ROUNDING CUTTER. -Corner
rounding cutters (fig. H-42) are formed cutters
that are used to round corners up to one-quarter
of a circle.
SPROCKET WHEEL CUTTER.— The
sprocket wheel cutter (fig. 11-43) is a formed
cutter that is used to mill teeth on sprocket wheels.
GEAR HOB.— The gear hob (fig. 1 1-44) Is a
formed milling cutter with teeth cut like threads
on a screw.
FLY CUTTER.— The fly cutter (fig. 11-45)
is often manufactured locally. It is a single-point
cutting tool similar in shape to a lathe or shaper
tool. It is held and rotated by a fly cutter arbor.
There will be times when you need a special
formed cutter for a very limited number of cutting
or boring operations. This will probably be the
type of cutter you will use since you can grind it
to almost any form you desire.
We have discussed a number of the more
common types of milling machine cutters. For a
more detailed discussion of these and other types
of cutters and their uses, consult the Machinery's
Handbook^ machinist publications, or the
applicable technical manual. We will now discuss
the selection of cutters.
Figure 11-44.— Gear hob.
Figure 11-45.— Fly cutter arbor and fly cutters.
Naval Education and
Training Command
NAVEDTRA 12204
May 1990
0502-LP-2 13-11 00
Training Manual
(TRAMAN)
Machinery
Repairman 3 & 2
«?
'•I
c
z
3
g
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
Nonfederal government personnel wanting a copy of this document
must use the purchasing instructions on the inside cover.
O
r—
m
S/N0502-LP-213-1100
1 3/4 inches. The numbers representing common
milling machine spindle tapers and their sizes are
as follows:
Number
10
20
30
40
50
60
Large Diameter
5/8 inch
7/8 inch
11/4 inches
13/4 inches
2 3/4 inches
41/4 inches
Standard arbors are available in styles A and
B, as shown in figure 1 1-47. Style A arbors have
a pilot type bearing usually 11/32 inch in
diameter. Style B arbors have a sleeve type out-
board bearing. Numerals identify the outside
diameter of the bearing sleeves, as follows:
Sleeve Number Outside Diameter
3 1 7/8 inches
4 21/8 inches
5 23/4 inches
The inside diameter can be any one of several
standard diameters that are used for the arbor
shaft.
Style A arbors sometimes have a sleeve bearing
that permits the arbor to be used as either a style
A or a style B arbor. A code system, consisting
of numerals and a letter, identifies the size and
style of the arbor. The code number is stamped
into the flange or on the tapered portion of the
arbor. The first number of the code identifies the
diameter of the taper. The second (and if used,
the third number) indicates the diameter of the
arbor shaft. The letter indicates the type of bear-
ing. The numbers following the letter indicate the
usable length of the arbor shaft. Sometimes an
additional number is used to indicate the size of
sleeve type bearings. The meaning of a typical
code number 5-1 1/4- A- 18-4 is as follows:
5 = taper number — 50 (the 0 is omitted
in the code)
11/4 = shaft diameter — 1 1/4 inches
A = Style A bearing — pilot type
18 = usable shaft length — 18 inches
4 = bearing size — 2 1/8 inches diameter
STUB ARBOR. —Arbors that have very short
shafts, such as .the one shown in figure 11-48, are
called stub arbors. Stub arbors are used when it
is impractical to use a longer arbor.
You will use arbor spacing collars of various
lengths to position and secure the cutter on the
arbor. You tighten the spacers against the cutter
when you tighten the nut on the arbor.
Remember, never tighten or loosen the arbor nut
unless the arbor support is in place.
SHELL END ARBOR.— Shell end mill arbors
(fig. 11-49) are used to hold and drive shell end
mills. The shell end mill is fitted over the short
boss on the arbor shaft. It is driven by two keys
and is held against the face of the arbor by a bolt.
You use a special wrench, shown in figure 1 1-48,
ALINEMENT BOSS
LOCK BOLT
Figure 11-48.— Stub arbor.
Figure 11-49.— Shell end mill arbor.
to tighten and loosen the bolt. Shell end mill
arbors are identified by a code similar to the
standard arbor code. The letter C indicates a shell
end mill arbor. The meaning of a typical shell mill
arbor code 4-1 1/2C-7/8 is as follows:
4 = taper code number — 40
11/2 = diameter of mounting hole in end
mill — 1 1/2 inches
C = style C arbor — shell end mill
7/8 = length of shaft— 7/8 inch
FLY CUTTER ARBOR.— Fly cutter arbors
are used to hold single-point cutters. These
cutters, which can be ground to any desired shape
and held in the arbor by a locknut, are shown in
figure 11-44. Fly cutter arbor shanks may have
a standard milling machine spindle taper, a Brown
and Sharpe taper, or a Morse taper.
SCREW SLOTTING CUTTER ARBOR.—
Screw slotting cutter arbors are used with screw
slotting cutters. The flanges support the cutter and
prevent the cutter from flexing. The shanks on
screw slotting cutter arbors may be straight or
tapered, as shown in figure 11-50.
SCREW ARBOR.— Screw arbors (fig. 11-51)
are used with cutters that have threaded mounting
holes. The threads may be left- or right-hand.
TAPER ADAPTER.— Taper adapters are
used to hold and drive taper-shanked tools, such
as drills, drill chucks, reamers, and end mills, by
inserting them into the tapered hole in the adapter.
The code for a taper adapter indicates the number
representing the standard milling machine spindle
taper and the number and series of the internal
n
r\
u
FOR DRAW-IN ROD
\-
TAPER SHANK
Figure 11-50. — Screw slotting cutter arbor.
Figure 11-51. — Screw arbor.
taper. For example, the taper adapter code
number 43 M means:
4 = taper identification number— 40
3M = internal taper — number 3 Morse
If a letter is not included in the code number, the
taper is understood to be a Brown and Sharpe.
For example, 57 means:
5 = taper number— 50
7 = internal taper— number 7 B and S
and 50-10 means:
50 = taper identification number
10 = internal taper — number 10 B and S
Figure 11-52 shows a typical taper adapter.
Some cutter adapters are designed to be used with
tools that have taper shanks and a cam locking
feature. The cam lock adapter code indicates the
number of the external taper, number of the
internal taper (which is usually a standard milling
machine spindle taper), and the distance that the
adapter extends from the spindle of the machine.
For example, 50-20-3 5/8 inches means:
50 = taper identification number (external)
20 = taper identification number (internal)
35/8 = distance adapter extends from spindle
is 3 5/8 inches
CUTTER ADAPTER.— Cutter adapters,
such as shown in figure 1 1-53, are similar to taper
adapters except that they always have straight,
rather than tapered holes. They are used to hold
straight shank drills, end mills, and so on. The
cutting tool is secured in the adapter by a setscrew.
The code number indicates the number of the
taper and the diameter of the hole. For example,
SPRING COLLET
ADAPTER
LOCK NUT
Figure 11-52. — Taper adapter.
SPANNER WRENCH
Figure 11-54. — Spring collet chuck adapter.
LOCK SCREW
ALLEN WRENCH
Figure 11-53.— Cutter adapter.
50-5/8 means that the adapter has a number 50
taper and a 5/8-inch-diameter hole.
SPRING COLLET CHUCK.— Spring collet
chucks (fig. 11-54) are used to hold and drive
straight-shanked tools. The spring collet chuck
consists of a collet adapter, spring collets, and a
cup nut. Spring collets are similar to lathe
collets. The cup forces the collet into the mating
taper, causing the collet to close on the straight
shank of the tool. The collets are available in
several fractional sizes.
Mounting and Dismounting Arbors
Mounting and dismounting arbors are
relatively easy tasks. Take care not to drop the
arbor on the milling machine table or the floor.
Use figure 11-7 as a guide. To MOUNT an
arbor, use the following procedure:
1. Place the spindle in the lowest speed.
2. Disengage the spindle clutch lever.
3. Turn off the motor switch.
4. Clean the spindle hole and the arbor
thoroughly to ensure accurate alignment of the
arbor inside the spindle.
5 . Stand near the column at a point where you
can reach both ends of the milling machine. Align
the arbor keyseats with the keys in the spindle.
6. Insert the tapered shank of the arbor into
the spindle.
7. Hold the arbor in place with one hand and
screw the drawbolt into the arbor with your other
hand.
NOTE: Turn the drawbolt a sufficient number
of turns to ensure that the drawbolt extends into
the arbor shank a distance approximately equal
to the major diameter of the threads being used.
This will help to prevent striping the threads on
the drawbolt or in the arbor shank when the jam-
nut is tightened.
8. Hold the arbor in position by pulling back
on the drawbolt and tighten the jamnut by hand.
9. Tighten the jamnut with one wrench while
using a second wrench to keep the drawbolt from
turning
To DISMOUNT an arbor, use the following
procedure:
1. Place the spindle in the lowest speed.
2. Turn off the motor.
3. Loosen the jamnut approximately two
turns.
4. Use one wrench to turn the jamnut and
another wrench to keep the drawbolt from
turning.
5. Hold the arbor with one hand and gently
tap the end of the drawbolt with a lead mallet until
you feel the arbor break free.
6. Hold the arbor in place with one hand and
unscrew the drawbolt with your other hand.
7. Remove the arbor from the spindle.
MILLING MACHINE OPERATIONS
The milling machine is one of the most
versatile metalworking machines. It is capable of
performing simple operations, such as milling a
flat surface or drilling a hole, or more complex
operations, such as milling helical gear teeth. It
would be impractical to attempt to discuss all of
the operations that the milling machine can do.
We will limit these machining operations to plain,
face, and angular milling; milling flat surfaces on
cylindrical work, slotting, parting, and milling
keyseats and flutes; and drilling, reaming, and
boring. Even though we will discuss only the more
common operations, you will find that by using
a combination of operations, you will be able to
produce a variety of work projects. We will
conclude the chapter by discussing the milling
machine attachments and gearing and gear
cutting.
PLAIN MILLING
Plain milling is the process of milling a flat
surface in a plane parallel to the cutter axis. You
get the work to its required size by individually
milb'ng each of the flat surfaces on the workpiece.
Plain milling cutters, such as the ones shown in
figure 11-22, are used for plain milling. If
possible, select a cutter that is slightly wider than
the width of the surface to be milled. Make the
work setup before you mount the cutter. This
precaution will keep you from accidentally
striking the cutter and cutting your hands as you
set up the work. You can mount the work in a
vise or fixture, or clamp it directly to the milling
machine table. You can use the same methods that
you used to hold work in a shaper to hold work
in a milling machine. Clamp the work as closely
as possible to the milling machine column so that
you can mount the cutter near the column. The
closer you place the cutter and the work to the
column, the more rigid the setup will be.
The following steps explain how to machine
a rectangular work blank (for example, a spacer
for an engine test stand).
1 . Mount the vise on the table and position
the vise jaws parallel to the table length.
NOTE: The graduations on the vise are
accurate enough because we are concerned only
with machining a surface in a horizontal plane.
2. Place the work in the vise, as shown in
figure 11-55.
3. Select the proper milling cutter and arbor.
4. Wipe off the tapered shank of the arbor
and the tapered hole in the spindle with a clean
cloth.
5. Mount the arbor in the spindle.
6. Clean and position the spacing collars and
place them on the arbor so that the cutter is above
the work.
7. Wipe off the milling cutter and any
additional spacing collars that may be needed.
Then place the cutter, the spacers, and the arbor
bearing on the arbor, with the cutter keyseat
aligned over the key. Locate the bearing as closely
as possible to the cutter. Make sure that the work
and the vise will clear all parts of the machine.
8. Install the arbor nut and tighten it finger
tight only.
9. Position the overarm and mount the ar-
bor support.
10. After supporting the arbor, tighten the
arbor nut with a wrench.
C PARALLELS D
Figure 11-55.— Machining sequence to square a block.
11-32
11. Set the spindle directional control lever to
give the required direction of cutter rotation.
12. Determine the required speed and feed,
and set the spindle speed and feed controls.
13. Set the feed trip dogs for the desired
length of cut and center the work under the cutter.
14. Lock the saddle.
15. Engage the spindle clutch and pick up the
cut.
16. Pick up the surface of the work by holding
a long strip of paper between the rotating cutter
and the work; very slowly move the work toward
the cutter until the paper strip is pulled between
the cutter and the work. BE CAREFUL! Keep
your fingers away from the cutter. A rotating
milling cutter is very dangerous.
17. Move the work longitudinally away from
the cutter and set the vertical feed graduated
collar at ZERO.
18. Compute the depth of the roughing cut
and raise the knee this distance.
19. Lock the knee, and direct the coolant flow
on the work and the outgoing side of the cutter.
20. Position the cutter to within 1/16 inch of
the work, using hand table feed.
21 . After completing the cut, stop the spindle.
22. Return the work to its starting point on
the other side of the cutter.
23. Raise the table the distance required for
the finish cut.
24. Set the finishing speed and feed, and take
the finish cut.
25. When you have completed the operation,
stop the spindle and return the work to the
opposite side of the cutter.
26. Deburr the work and remove it form the
vise.
To machine the second side, plate the work
in the vise as shown in figure 1 1-55B. Rough and
finish machine side 2, using the same procedures
that you used for side 1. When you have
completed side 2, deburr the surface and remove
the work from the vise.
Place the work in the vise, as shown in figure
11-55C with side 3 up. Then rough machine side
3. Finish machine side 3 for a short distance,
disengage the spindle and feed, and return the
work to the starting point, clear of the cutter. Now
you can safely measure the distance between sides
2 and 3. If this distance is correct, you can
continue the cut with the same setting. If it is not,
adjust the depth of cut as necessary. If the trial
finishing cut is not deep enough, raise the work
slightly and take another trial cut. If the trial cut
is too deep, you will have to remove the backlash
from the vertical feed before taking the new depth
of cut. To remove the backlash:
1 . Lower the knee well past the original depth
of the roughing cut.
2. Raise the knee the correct distance for the
finishing cut.
3. Engage the feed.
4. Stop the spindle.
5. Return the work to the starting point on
the other side of the cutter.
6. Deburr the work.
7. Remove the work from the vise.
Place side 4 in the vise, as shown in figure
11-55D and machine the side, using the same
procedure as for side 3. When you have completed
side 4, remove the work from the vise and check
it for accuracy.
This completes the machining of the four sides
of the block. If the block is not too long, you can
rough and finish mill the ends to size in the same
manner in which you milled the sides. Do this by
placing the block on end in the vise. Another
method of machining the ends is by face milling.
FACE MILLING
Face milling is the milling of surfaces that
are perpendicular to the cutter axis, as shown in
figure 1 1-56. You do face milling to produce flat
surfaces and to machine work to the required
length. In face milling, the feed can be either
horizontal or vertical.
Cutter Setup
You can use straight-shank or taper-shank end
mills, shell end mills, or face milling cutters for
face milling. Select a cutter that is slightly larger
in diameter than the thickness of the material that
you are machining. If the cutter is smaller in
diameter than the thickness of the material, you
will be forced to make a series of slightly over-
lapping cuts to machine the entire surface. Mount
the arbor and the cutter before you make the work
setup. Mount the cutter by any means suitable for
the cutter you have selected.
Work Setup
Use any suitable means to hold the work for
face milling as long as the cutter clears the
workholding device and the milling machine
table. You can mount the work on parallels, if
necessary, to provide clearance between the cutter
and the table. Feed the work from the side of the
cutter that will cause the cutter thrust to force
the work down. If you hold the work in a vise,
position the vise so that the cutter thrust is toward
the solid jaw. The ends of the work are usually
machined square to the sides of the work.
Therefore, you will have to align the work
properly. If you use a vise to hold the work, you
can align the stationary vise jaw with a dial
indicator, as shown in figure 1 1-57. You can also
use a machinist's square and a feeler gauge, as
shown in figure 11-58.
Operation
To face mill the ends of work, such as the
engine mounting block that we discussed
previously:
1. Select and mount a suitable cutter.
2. Mount and position a vise on the milling
machine table, as shown in figure 11-56 so the
thrust of the cutter is toward the solid vise jaw.
28.402
COLUMN
SOLID JAW
Figure 11-57. — Aligning vise jaws using an indicator.
3. Align the solid vise jaw square with the
column of the machine, using a dial indicator for
accuracy.
4. Mount the work in the vise, allowing the
end of the work to extend slightly beyond the vise
jaws.
5 . Raise the knee until the center of the work
is approximately even with the center of the cutter.
6. Lock the knee in position.
7. Set the machine for the proper roughing
speed, feed, and table travel.
8. Start the spindle and pick up the end
surface of the work by hand feeding the work
toward the cutter.
9. Place a strip of paper between the cutter
and the work as shown in figure 1 1-59 to help pick
up the surface. When the cutter picks up the
paper there is approximately .003-inch clearance
between the cutter and the material being cut.
VISE
Figure 11-59. — Picking up the work surface.
-1« <f .f jCO A IStfVMIMSY «T*OA IfWWKrO IttCTIMtfV
10. Once the surface is picked up, set the
saddle feed graduated dial at ZERO.
1 1 . Move the work away from the cutter with
the table and direct the coolant flow onto the
cutter.
12. Set the roughing depth of cut, using the
graduated dial, and lock the saddle.
1 3 . Position the work to about 1/16 inch from
the cutter, then engage the power feed.
14. After completing the cut, stop the spin-
dle, and move the work back to the starting point
before the next cut.
15. Set the speed and feed for the finishing
cut, and then unlock the saddle.
16. Move the saddle in for the final depth of
cut and relock it.
17. Engage the spindle and take the finish cut.
18. Stop the machine and return the work to
the starting place.
19. Shut the machine off.
20. Remove the work form the vise. Handle
it very carefully to keep from cutting yourself
before you can deburr the work.
21. Next, mount the work in the vise so the
other end is ready for machining. Mill this end
in the same manner as the first, but be sure to
measure the length before taking the finishing cut.
Before removing the work from the vise, check
it for accuracy and remove the burrs from the
newly finished end.
ANGULAR MILLING
Angular milling is the milling of a flat surface
that is at an angle to the axis of the cutter. You
can use an angular milling cutter, as shown in
figure 11-60. However, you can perform angular
milling with a plain, side, or face milling cutter
by positioning the work at the required angle.
Many maintenance or repair tasks involve
machining flat surfaces on cylindrical work. These
tasks include milling squares and hexagons, and
milling two flats in the same plane.
HORIZONTAL SPINDLE
SINGLE ANGULAR
CUTTER
DOUBLE
ANGULAR CUTTER
53-483
Figure 11-60. — Angular milling.
A square or hexagon is milled on an object
to provide a positive drive, no slip area for various
tools, such as wrenches and cranks. You will
machine squares and hexagons frequently on the
ends of bolts, taps, reamers, or other items that
are turned by a wrench and on drive shafts and
other items that require a positive drive. The
following information will help you to understand
the machining of squares and hexagons.
Cutter Setup
The two types of cutters you will use most
often to machine squares or hexagons are side and
end milling cutters. You can use side milling
cutters for machining work that is held in a chuck
and for heavy cutting. You can use end mills for
work that is held in a chuck or between centers
and for light cutting. If you use a side milling
cutter, be sure the cutter diameter is large enough
so you can machine the full length of the square
or hexagon without interference from the arbor.
If you use an end mill, be sure it is slightly larger
in diameter than the length of the square or
hexagon. The cutter thrust for both types should
be up when the work is mounted vertically and
down when it is mounted horizontally in order
to use conventional (or up) milling.
The reason for what appears to be a contra-
diction in the direction of thrust is the difference
in the direction of the feed. You can see this by
comparing figures 11-61 and 11-62. The cutter
Figure 11-61. —Milling a square on work held vertically.
28.407
Figure 11-62.— Milling a square on work held horizontally.
shown in figure 11-61 rotates in a counterclock-
wise direction and the work is fed toward the left.
The cutter shown in figure 11-62 rotates in a
clockwise direction and the work is fed upward.
Work Setup
We have already discussed the methods that
you will usually use to mount the work.
Regardless of the workholding method that you
use, you must align the index spindle in either
the vertical or the horizontal plane. If you are
machining work between centers, you must also
align the footstock center. If you use a screw-on
chuck, take into consideration the cutter rotary
thrust applied to the work. Always cut on the side
11-37
D — CUTTER DIAMETER
I— LENGTH OF SQUARE
A. LOCK SCREW FOR DOG
B. DRIVE PLATE
C. TAP
D. END MILL
E. TAP SQUARE
F. FOOTSTOCK
G. INDEX HEAD
Figure 11-63.— Milling a square using an end mill.
Figure 11-64. — Diagram of a square.
of the work that will tend to tighten the chuck
on the index head spindle. When you mount work
between centers, a dog rotates the work. The drive
plate, shown in figure 11-63, contains two lock
screws. One lock screw clamps the drive plate to
the index center and ensures that the drive plate
moves with the index spindle. The other lock
screw clamps the tail of the dog against the side
of the drive plate slot as shown in figure 1 1-63A.
This eliminates any movement of the work during
the machining operation. It may be necessary,
especially if you are using a short end mill, to
position the index head (fig. 11-63G) near the
cutter edge of the table to ensure the cutter and
the work make contact.
Calculations
The following information will help you
determine the amount of material you must
remove to produce a square or a hexagon. The
dimensions of the largest square or hexagon that
you can machine from a piece of stock must be
calculated.
The size of a square (H in fig. 11-64) is
measured across the flats. The largest square that
you can cut from a given size of round stock
equals the diameter of the stock in inches
11-38
Opposite side = Side of a square
Hypotenuse = Diagonal of square
45° =90° bisected
^ «-,«-, Opposite side
H = 0x0.707 or ^yPpotenuse - sine 45°
The diagonal of a square equals the distance
across the flats times 1.414. This is expressed as
G = H x 1.414 or Hypotenuse _
Opposite side
The amount of material that you must remove
to machine each side of the square is equal to one-
half the difference between the diameter of the
stock and the distance across the flats.
1 =
G - H
You use the same formula
G -
(1 =
z-
to determine the amount of material to remove
when you are machining a hexagon.
The size of the largest hexagon that you can
machine from a given size of round stock (H in
figure 1 1-65) is equal to the diagonal (the diameter
of the stock) of the hexagon times 0.866 or
Opposite side = Largest hexagon that can be' machined
Hypotenuse = Diagonal or diameter of round stock
The diagonal of a hexagon equals the distance
across the flats times 1.155, or
The length of a flat is equal to one-half the
length of the diagonal,
r 2
Figure 11-65. — Diagram of a hexagon.
We will explain two methods of machining a
square or hexagon: machining work mounted in
a chuck and machining work mounted between
centers.
You can machine a square or hexagon on
work mounted in a chuck by using either a side
milling cutter or an end mill. We will discuss using
the side milling cutter first. Before placing the
index head on the milling machine table, be sure
that the table and the bottom of the index head
have been cleaned of all chips and other foreign
matter. Spread a thin film of clean machine oil
over the area of the table to which the index head
will be attached to prevent corrosion.
NOTE: Because most index heads are quite
heavy and awkward, you should get someone to
help you place the head on the milling machine
table.
After you have mounted the index head on the
table, position the head spindle in the vertical
position, as shown in figure 1 1-61 . Use the degree
graduations on the swivel block. This is accurate
enough for most work requiring the use of the
index head. The vertical position will allow you
to feed the work horizontally.
Then, tighten the work in the chuck to keep
it from turning due to the cutter's thrust. Install
the arbor, cutter, and arbor support. The cutter
should be as close as practical to the column.
Remember, this is done so the setup will be more
rigid. Set the machine for the correct roughing
speed and feed.
1 . With the cutter turning, pick up the cut on
the end of the work.
11-39
2. Move the work sideways to clear the
cutter.
3. Raise the knee a distance equal to the
length of the flat surfaces to be cut.
4. Move the table toward the revolving cutter
and pick up the side of the work. Use a piece of
paper in the same manner as discussed earlier in
this chapter.
5 . Set the crossfeed graduated dial at ZERO.
6. Move the work clear of the cutter.
Remember, the cutter should rotate so that the
cutting action takes place as in "up milling.*'
7 . Feed the table in the required amount for
a roughing cut.
8. Engage the power feed and the coolant
flow.
9. When the cut is finished, stop the spin-
dle and return the work to the starting point.
10. Loosen the index head spindle lock.
1 1 . Rotate the work one-half revolution with
the index crank.
12. Tighten the index head spindle lock.
13. Take another cut on the work.
14. When this cut is finished, stop the cutter
and return the work to the starting point.
15. Measure the distance across the flats to
determine whether the cutter is removing the same
amount of metal from both sides of the work. If
not, check your calculations and the setup for a
possible mistake.
16. If the work measures as it should, loosen
the index head spindle lock and rotate the work
one-quarter revolution, tighten the lock, and take
another cut.
17. Return the work to the starting point
again.
18. Loosen the spindle lock.
19. Rotate the work one-half revolution.
20. Take the fourth cut.
21 . Return the work again to the starting point
and set the machine for finishing speed and feed.
22. Now, finish machine opposite sides
(1 and 3), using the same procedures already
mentioned.
23. Check the distance across these sides. If
it is correct, finish machine the two remaining
sides.
24. Deburr the work and check it for
accuracy.
NOTE: You can also machine a square or
hexagon with the index head spindle in the
horizontal position, as shown in figures 1 1-62 and
11-63. If you use the horizontal setup, you must
feed the work vertically.
Square or Hexagon Work
Mounted Between Centers
Machining a square or hexagon on work
mounted between centers is done in much the
same manner as when the work is held in a chuck.
1 . Mount the index head the same way, only
with the spindle in a horizontal position. The feed
will be in a vertical direction.
2. Insert a center into the spindle and align
it with the footstock center.
3. Select and mount the desired end mill,
preferably one whose diameter is slightly greater
than the length of the flat you are to cut, as shown
in figure 11-63.
4. Mount the work between centers. Make
sure that the drive dog is holding the work
securely.
5. Set the machine for roughing speed and
feed.
6. Pick up the side of the work and set the
graduated crossfeed dial at ZERO.
7. Lower the work until the cutter clears the
footstock.
8. Move the work until the end of the work
is clear of the cutter.
9. Align the cutter with the end of the work.
Use a square head and rule, as shown in figure
11-66.
NOTE: Turn the machine off before aligning
the cutter by this method.
SQUARE HEAD
Figure 11-66. — Aligning the work and the cutter.
12. While feeding the work vertically,
machine side 1. Lower the work to below the
cutter when you have completed the cut.
13. Loosen the index head spindle lock and
index the work one-half revolution to machine the
fiat opposite side 1.
14. Tighten the lock.
15. Engage the power feed. After completing
the cut, again lower the work to below the cutter
and stop the cutter.
16. Measure the distance across the two flats
to check the accuracy of the cuts. If it is correct,
index the work one-quarter revolution to machine
another side. Then lower the work, index one-half
revolution, and machine the last side. Remember
to lower the work to below the cutter again.
17. Set the machine for finishing speed, feeds,
and depth of cut, and finish machine all the sides.
18. Deburr the work and check it for
accuracy.
Machining Two Flats in One Plane
Ybu will often machine flats on shafts to serve
as seats for setscrews. One flat is simple to
machine. You can machine in in any manner with
a side or end mill, as long as you can mount the
work properly. However, machining two flats in
one plane, such as the flats on the ends of a
mandrel, presents a problem since the flats must
align with each other. A simple method of
machining the flats is to mount the work in a vise
or on V-blocks in such a manner that you can
machine both ends without moving the work once
it has been secured.
We will describe the method that is used when
the size or shape of the work requires reposition-
ing it to machine both flats.
1 . Apply layout dye to both ends of the work.
2. Place the work on a pair of V-blocks, as
shown in figure 11-67.
3. Set the scriber point of the surface gauge
to the center height of the work. Scribe horizontal
lines on both ends of the work, as illustrated in
figure 11-67.
4. Mount the index head on the table with its
spindle in the horizontal position.
5. Again, set the surface gauge scriber point,
but to the centerline of the index head spindle.
SCRIBED LINE
SURFACE 6UAGE
Figure 11-67. — Layout of the work.
6. Insert the work in the index head chuck
with the end of the work extended far enough to
permit all required machining operations.
7. To align the surface gauge scriber point
with the scribed horizontal line, rotate the index
head spindle.
8. Lock the index head spindle in position.
These flats can be milled with either an end
mill or a side mill or a side milling cutter.
CAUTION
Rotate the cutter in a direction that will
cause the thrust to tighten the index head
chuck on the spindle when you use a screw-
on type chuck.
9. Raise the knee with the surface gauge still
set at center height until the cutter centerline is
aligned with the scriber point. This puts the
centerlines of the cutter and the work in align-
ment with each other.
10. Position the work so that a portion of the
flat to be machined is located next to the cutter.
Because of the shallow depth of cut, compute the
speed and feed as if the cuts were finishing cuts.
1 1 . After starting the machine, feed the work
by hand so the cutter contacts the side of the work
on which the line is scribed.
11-41
12. Move the work clear of the cutter and stop
the spindle.
13 . Check to see if the greater portion of the
cutter mark is above or below the layout line.
Depending on its location, rotate the index head
spindle as required to center the mark on the
layout line.
14. Once the mark is centered, take light "cut
and try" depth of cuts until you reach the desired
width of the flat.
15. Machine the flat to the required length.
16. When one end is completed, remove the
work from the chuck. Turn the work end for end
and reinsert it in the chuck.
17. Machine the second flat in the same
manner as you did the first.
18. Deburr the work and check it for
accuracy.
19. Check the flats to see if they are in the
same plane by placing a matched pair of parallels
on a surface plate and one flat on each of the
parallels. If the flats are in the same plane, you
will not be able to wobble the work.
SLOTTING, PARTING, AND MILLING
KEYSEATS AND FLUTES
Slotting, parting, and milling key seats and
flutes are all operations that involve cutting
grooves in the work. These grooves are of various
shapes, lengths, and depths, depending on the
requirements of the job. They range from flutes
in a reamer to a keyseat in a shaft, to the parting
off of a piece of metal to a predetermined length.
Slotting
You can cut internal contours, such as internal
gears and splines and six- or twelve-point sockets
by slotting. Most slotting is done with a milling
machine attachment called a slotting attachment,
as shown in figure 11-68. The slotting attachment
is fastened to the milling machine column and
driven by the spindle. This attachment changes
the rotary motion of the spindle to a reciprocating
motion much like that of a shaper. You can vary
the length of the stroke within a specified range.
A pointer on the slotting attachment slide
indicates the length of the stroke. You can pivot
the head of the slotting attachment and position
it at any desired angle. Graduations on the base
of the slotting attachment indicate the angle at
which the head is positioned. The number of
MACHINE COLUMN
GRADUATIONS
SLOTTING ATTACHMENT
— *•
.--•
SLOTTING TOOL
Figure 11-68. — Slotting attachment.
strokes per minute is equal to the spindle rpm and
is determined by the formula:
Strokes per minute =
CFSx4
length of stroke
The cutting tools used with slotting attach-
ments are ground to any desired shape from high-
speed steel tool blanks and are clamped to the
front of the slide or ram. You can use any suitable
means for holding the work, but the most
common method is to hold the work in an index
head chuck. If the slotted portion does not
extend through the work, you will have to
machine an internal recess in the work to provide
clearance for the tool runout. When it is possible,
position the slotting attachment and the work in
the vertical position to provide the best possible
view of the cutting action of the tool.
Parting
Use a metal slitting saw for sawing or parting
operations and for milling deep slots in metals and
in a variety of other materials. Efficient sawing
depends to a large extent on the slitting saw you
select. The work required of slitting saws varies
greatly. It would not be efficient to use the same
saw to cut very deep narrow slots, part thick
stock, saw thin stock, or saw hard alloy steel. Soft
metals, such as copper and babbitt, or nonmetallic
materials, such as bakelite, fiber, or plastic,
require their own style of slitting saw.
Parting with a slitting saw leaves pieces that
are reasonably square and that require the
removal of a minimum of stock in finishing the
surface. You can cut off a number of pieces of
varying lengths and with less waste of material
than you could saw by hand.
A coarse-tooth slitting saw is best for sawing
brass and for cutting deep slots. A fine-tooth
slitting saw is best for sawing thin metal, and a
staggered-tooth slitting saw is best for making
heavy deep cuts in steel. You should use slower
feeds and speeds to saw steels to prevent cutter
breakage. Use conventional milling in sawing
thick material. In sawing thin material, however,
clamp the stock directly to the table and use down
milling. Then the slitting saw will tend to force
the stock down on the table. Position the work
so the slitting saw extends through the stock and
into a table T-slot.
External Keyseat
Machining an external keyseat on a milling
machine is less complicated than machining it on a
shaper. In milling, starting an external keyseat is no
problem. You simply bring the work into contact
with a rotating cutter and start cutting. It should
not be difficult for you to picture in your mind
how you would mill a straight external keyseat with
a plain milling cutter or an end mill. If the speci-
fied length of the keyseat exceeds the length you
can obtain by milling to the desired depth, you
can move the work in the direction of the slot to
obtain the desired length. Picturing in your mind
how you would mill a Woodruff keyseat should
be easier. The secret is to select a cutter that has
the same diameter and thickness as the key.
CUTTER
THIN PAPER
Straight External Keyseats
Normally, you would use a plain milling
cutter to mill a straight external keyseat. You
could use a Woodruff cutter or a two-lipped end
mill.
Before you can begin milling the keyseat, you
must align the axis of the work with the midpoint
of the width of the cutter. Figure 1 1-69 shows one
method of alignment.
Suppose that you are going to cut a keyseat
with a plain milling cutter. Move the work until
the side of the cutter is tangent to the
circumference of the work. With the cutter
turning very slowly and before contact is made,
insert a piece of paper between the work and the
side of the cutter. Continue moving the work
toward the cutter until the paper begins to tear.
When it does, lock the graduated dial at ZERO
on the saddle feed screw. Then lower the milling
machine knee. Use the saddle feed dial as a guide,
and move the work a distance equal to the radius
of the work plus one-half the width of the cutter
to center the cutter over the centerline of the
keyseat to be cut.
You use a similar method to align work with
an end mill. When you use an end mill, move the
work toward the cutter while you hold a piece of
paper between the rotating cutter and the work,
as shown in figure 11-70. After the paper tears,
lower the work to just below the bottom of the
PAPER
V-BLOCK
Figure 11-69.— Aligning the cutter using a paper strip.
Figure 11-70. — Aligning an end mill with the work.
RULE
Figure 11-71. — Visual alignment of a cutter.
end mill. Then move the work a distance equal
to the radius of the work plus the radius
of the end mill to center the mill over the
centerline of the keyseat to be cut. Move
the work up, using hand feed, until a piece
of paper held between the work and the
bottom of the end mill begins to tear, as
shown in figure 11-70B. Then move the table
and work away from the bottom of the end mill.
Set and lock the graduated dial at ZERO on the
vertical feed, and then feed up for the roughing
cut. You can determine the cutter rpm and the
longitudinal feed in the same manner as you do
for conventional milling cutters. Because of the
higher speeds and feeds involved, more heat is
generated, so flood the work and the cutter with
coolant.
When extreme accuracy is not required, you
can align the work with the cutter visually, as
shown in figure 11-71. Position by eye the work
as near as possible to the midpoint of the cutter.
Make the final alignment by moving the work in
or out a slight amount, as needed. The cutter
should be at the exact center of the work diameter
measurement of the steel rule. You can use this
Table 11-1.— -Values for Factor (f) for Various Sizes of Shafts
WIDTH OF KEY IN INCHES
DIAMETER
OF SHAFT
(INCHES)
1/16
3/32
1/8
5/32
3/16
7/32
1/4
5/16
SHAFT SIZE
FACTOR (f)
1/2
. 002
. 004
. 008
. 013
. 018
. 025
. 033
...
5/8
. 001
. 003
. 006
. 010
. 014
. 019
. 025
. 042
3/4
. 001
. 003
. 005
. 008
. 012
. 016
. 022
. 034
7/8
. 001
. 002
. 004
. 007
. 010
. 014
. 018
. 028
1
. 001
. 002
. 004
. 006
. 009
. 012
. 015
. 024
1 1/8
. 002
. 003
. 005
. 008
. Oil
. 014
. 022
1 1/4
. 002
. 003
. 005
. 007
. 010
. 013
. 019
1 1/2
. 001
. 002
. 004
. 006
. 008
.011
. 016
1 3/4
. 001
. 002
. 003
. 005
. 007
. 009
. 014
square key seat by using the following formula
based on dimensions shown in figure 11-72.
Figure 11-72.— Keyseat dimensions for a straight square key.
method with both plain milling cutters and end
mills.
Before you begin to machine the keyseat, you
should measure the width of the cut. You cannot
be certain that the width will be the same as the
thickness of the cutter. The cutter may not run
exactly true on the arbor or the arbor may not
run exactly true on the spindle. The recommended
practice is to nick the end of the work with the
cutter and then to measure the width of the cut.
Specifications for the depth of cut are usually
furnished. When specifications are not available,
you can determine the total depth of cut for a
where
Total depth of cut (T) = d + f
W
d = -5- = depth of the keyseat
f = R - VR2 - (y) = height of arc
W = width of the key
R = radius of the shaft
The height of arc (f) for various sizes of
shafts and keys is shown in table 11-1. Keyseat
dimensions for rounded end and rectangular keys
are contained in the Machinery's Handbook.
Check the keyseats for accuracy with rules, out-
side and depth micrometers, vernier calipers, and
go-no-go gauges. Use table 11-1 for both square
and Woodruff keyseats, which will be explained
next.
Woodruff Keyseat
A Woodruff key is a small half-disk of metal.
The rounded portion of the key fits in the slot in
the shaft. The upper portion fits into a slot in a
mating part, such as a pulley or gear. You align
the work with the cutter and measure the width
of the cut in exactly the same manner as you do
for milling straight external keyseats.
A Woodruff keyseat cutter (fig. 11-73) has
deep flutes cut across the cylindrical surface of
Figure 11-73. — Woodruff keyseat cutter.
28.416
Figure 11-74.— Milling a Woodruff keyseat.
Figure 11-75. — Dimensions for a Woodruff keyseat.
of the teeth than it is at the center. This feature
provides clearance between the sides of the slot
and the cutter. Cutters with a 2-inch diameter
and larger have a hole in the center for arbor
mounting. On smaller cutters the cutter and the
shank are one piece. Note that the shank is
"necked" in back of the cutting head to give
additional clearance. Also, note that large cutters
usually have staggered teeth to improve their
cutting action.
As discussed earlier, to mill a Woodruff
keyseat in a shaft, you use a cutter that has the
same diameter and thickness as the key. Cutting
a Woodruff keyseat is relatively simple. You
simply move the work up into the cutter until you
obtain the desired keyseat depth. The work may
be held in a vise, chuck, between centers, or
clamped to the milling machine table. The cutter
is held on an arbor, or in a spring collet or drill
chuck that has been mounted in the spindle of the
milling machine, as in figure 11-74.
In milling the keyseat, centrally locate the
cutter over the position in which the keyseat is
to be cut and parallel with the axis of the work.
Raise the work by using the hand vertical feed
until the revolving cutter tears a piece of paper
held between the teeth of the cutter and the work.
At this point, set the graduated dial on the
vertical feed at ZERO and set the clamp on the
table. With the graduated dial as a guide, raise
the work by hand until the full depth of the
keyseat is cut. If specifications for the total depth
of cut are not available, use the following formula
to determine the correct value:
Total depth (T) = d + f
where
W
d (depth of the keyseat) = H -
^
H = total height of the key
W = width of the key
The most accurate way to check the depth of
a Woodruff keyseat is to insert a Woodruff key
of the correct size in the keyseat. Measure over
the key and the work with an outside micrometer
to obtain the distance M in figure 1 1-75. Measure
the correct micrometer reading over the shaft and
using the formula
\* ^ , (W) f
(2) ~
where
M = micrometer reading
D = diameter of the shaft
W = width of the key
f = height of the arc between the top of
the slot and the top of the shaft.
NOTE: Tables in some references may differ
slightly from the above calculation for the value
M, due to greater allowance for clearance at the
top of the key.
Straight Flutes
The flutes on cutting tools serve three
purposes. They form the cutting edge for the tool,
provide channels for receiving and discharging
chips, and let coolant reach the cutting edges. The
shape of the flute and the tooth depends on the
cutter you use to machine the flute. The following
information pertains specifically to taps and
reamers. Since flutes are actually special purpose
grooves, you can apply much of the information
to grooves in general.
Tap Flutes
You usually use a convex cutter to machine
tap flutes. This type of cutter produces a
"hooked" flute as shown in figure 11-76. The
CONVEX CUTTER
CUTTER WIDTH 1/2
TAP DIAMETER
HOOKED PLAJTE
-DEPTH OF FLUTE
1/6 TAP DIAMETER
Figure 11-76. — Hooked tap flutes.
11-47
number of flutes is determined by the diameter
of the tap. Taps 1/45 inch to 1 3/4 inches in
diameter usually have four flutes, and taps 1 7/8
inches (and larger) in diameter usually have six
flutes. The width of the convex cutter should be
equal to one-half the tap diameter. The depth of
the flute is normally one-fourth the tap diameter.
The minimum length of the full depth of the flute
should be equal to the length of the threaded
portion of the tap. Table 11-2 lists the width of
the cutter and the depth of the flutes for taps of
various diameters. You usually mount the tap
blank between centers and feed it longitudinally
past the cutter. For appearance sake, the flutes
are usually cut in the same plane as the sides of
the square on the tap blank.
You can mill the flutes on a tap blank in the
following manner.
1. Mount and align the index centers.
2. Set the surface gauge to center height.
3. Place the tap blank between the centers
with one flat of the square on the tap shank in
a vertical position.
4. Align the flat with a square head and blade.
5. Scribe a horizontal line on the tap shank.
6. Remove the tap blank, place a dog on the
shank, and remount the blank between centers.
7 . Align the scribed line with the point of the
surface gauge scriber.
8. Make sure that the surface gauge is still at
center height.
Table 11-2.— Tap Flute Dimensions
Diameter of tap
(inches)
Width of cutter
(inches )
Depth of flute
(inches )
1/8
1/16
1/32
1/4
1/8
1/16
1/2
1/4
1/8
3/4
3/8
3/16
1
1/2
1/4
1 1/4
5/8
5/16
1 1/2
3/4
3/8
1 3/4
7/8
7/16
2
1
1/2
2 1/4
1 1/8
9/16
2 1/2
1 1/4
5/8
2 3/4
1 3/4
11/16
3
1 1/2
3/4
Table 11-3.— Reamer Fluting Cutter Numbers
Cutter number
Reamer diam-
eter (inches)
Number of
reamer flutes
1
1/8 to 3/16
6
2
1/4 to 5/16
6
3
3/8 to 7/16
6
4
1/2 to 11/16
6 to 8
5
3/4 to 1
8
6
1 1/16 to 1 1/2
10
7
1 9/16 to 2 1/8
12
8
2 1/4 to 3
14
11-48
9. Mount the convex cutter.
10. Make sure that the direction of the cutter
rotation is correct for conventional (or up) milling
and that the thrust is toward the index head.
1 1 . Align the center of the cutter with the axis
of the tap blank.
12. Pick up the surface of the tap.
13. Set the table trip dogs for the correct
length of cut.
14. Set the machine for roughing speed and
feed.
15. Rough mill all flutes to within 0.015 to
0.020 inch of the correct depth.
16. Set the machine for finishing speed and
feed and finish machine all flutes to the correct
size.
17. Remove the work, deburr it, and check
it for accuracy.
Reamer Flutes
You may mill flutes on reamers with angular
fluting cutters, but you normally use special
formed fluting cutters. The advantages of cutting
the flutes with a formed cutter rather than with
an angular cutter are that the chips are more
readily removed and the flute cutting teeth are
stronger. Also, the teeth are less likely to crack
or warp during heat treatment. Formed reamer
fluting cutters have a 6 ° angle on one side and
FORMED REAMER
CUTTER
ARBOR
AMOUNT OF OFFSET
a radius on the other side. The size of the radius
depends on the size of the cutter. Reamer fluting
cutters are manufactured in eight sizes. The
size of the cutter is identified by a number
(1 through 8). Reamers from 1/8 inch to 3 inches
in diameter are fluted by the eight sizes of cutters.
The correct cutters for fluting reamers of various
diameters are given in table 11-3. You machine
reamer teeth with a slight negative rake to help
prevent chatter. To obtain the negative rake,
position the work and cutter slightly ahead of the
reamer center, as shown in figure 11-77.
Table 11-4 lists the recommended offset for
reamers of various sizes. Straight reamer flutes
are usually unequally spaced to help prevent
chatter. To obtain the unequal spacing, index
the required amount as each flute is cut. The
recommended variation is approximately 2°.
Machinists' publications, such as Machinery's
Handbook, contain charts that list the number of
holes to advance or retard the index crank to
machine a given number of flutes when you use
a given hole circle. You normally mill the flutes
in pairs. After you have machined one flute,
index the work one-half revolution and mill the
opposite flute.
The depth of the flute is determined by trial
and error. The approximate depth of flute to
obtain the recommended width of land is one-
eighth the diameter for an eight-fluted reamer,
one-sixth the diameter for a six-fluted reamer, and
so on.
Table 11-4.— Required Offset
REAMER
Size of reamer
(inches)
Offset of cutter
(inches)
1/4
0.011
3/8
0.016
1/2
0.022
5/8
0.027
3/4
0.033
7/8
0.038
1
0.044
1 1/4
0.055
1 1/2
0.066
1 3/4
0.076
2
0.087
2 1/4
0.098
2 1/2
0.109
2 3/4
0.120
3
0.131
Figure 11-77.— Negative rake tooth.
You can machine the flutes on a hand reamer
in the following manner:
1 . Mount the reamer blank between centers
and the reamer fluting cutter on the arbor.
2. Align the point of the cutter with the
reamer blank axis and just touch the surface of
the reamer with the rotating cutter.
3. Remove the work blank.
4. Then raise the table a distance equal to the
depth of the flute plus one-half the grinding
allowance.
5. Rotate the cutter until a tooth is in the
vertical position.
6. Shut off the machine.
7. Move the table until the point of the
footstock center is aligned with the tooth that is
in the vertical position.
8 . Place an edge of a 3 -inch rule against the
6° surface of the reamer tooth. Move the
saddle until the edge of the 3 -inch rule that is
contacting the cutter tooth is aligned with the
point of the footstock center.
9. To eliminate backlash, move the saddle
in the same direction it will be moved when you
offset the cutter. Continue feeding the saddle until
you get the desired amount of offset; then lock
it in position.
10. Move the table until the cutter clears the
end of the reamer blank.
1 1 . Remount the blank between the centers.
12. Calculate the indexing required to space
the flutes unequally.
13. Set the table feed trip dogs so the
minimum length of the full depth of flute is equal
to the length of the reamer teeth.
14. Rough machine all flutes.
NOTE: Write down the exact indexing which
you used for each of the flutes to avoid
confusion when you index for the finish cut.
Fly Cutting
You will use a fly cutter when a formed cutter
is required but is not available. Fly cutters are
high-speed steel tool blanks that have been ground
to the required shape. Any shape can be ground
on the tool if the cutting edges are given a
sufficient amount of clearance. Fly cutters are
mounted in fly cutter arbors, such as the one
shown in figure 11-45. Use a slow feed and a
shallow depth of cut to prevent breaking the tool.
It is a good idea to rough out as much excess
material as possible with ordinary cutters and to
use the fly cutter to finish shaping the surface.
DRILLING, REAMING, AND BORING
Drilling, reaming, and boring are operations
that you can do very efficiently on a milling
machine. The graduated feed screws make it
possible to accurately locate the work in relation
to the cutting tool. In each operation the cutting
tool is held and rotated by the spindle, and the
work is fed into the cutting tool.
Boring
Of the three operations, the only one that
warrants special treatment is boring. On a milling
machine you usually bore holes with an offset
boring head. Figure 1 1-78 shows several views of
an offset boring head and several boring tools.
Note that the chuck jaws, which grip the boring
bar, can be adjusted at a right angle to the
spindle axis. This feature lets you accurately
position the boring cutter to bore holes of varying
diameters. This adjustment is more convenient
than adjusting the cutter in the boring bar holder
or by changing boring bars.
Although the boring bars are the same on a
milling machine as on a lathe or drill press, the
manner in which they are held is different. Note
in figure 11-79 that a boring bar holder is not
used. The boring bar is inserted into an adapter
and the adapter is fastened in the hole in the
adjustable slide. Power for driving the boring bar
is transmitted directly through the shank. The
elimination of the boring bar holder results in a
more rigid boring operation, but the size of the
hole that can be bored is more limited than in
boring on a lathe or a drill press.
Fly cutters, which we discussed previously, can
also be used for boring, as shown in figure 11-79.
A fly cutter is especially useful for boring
relatively shallow holes. The cutting tool must be
adjusted for each depth of cut.
The speeds and feeds you should use in boring
on a milling machine are comparable to those you
would use in boring on a lathe or drill press and
depend on the same factors: hardness of the
Drilling and Reaming
You use the same drills and reamers that you
use for drilling and reaming in the lathe and the
drill press. Drills and reamers are held in the
spindle by the same methods that you use to hold
straight and taper-shanked end mills. The work
may be held in a vise, clamped to the table, held
in fixtures or between centers, and in index head
chucks, as is done for milling. You determine the
speeds used for drilling and reaming in the same
manner as for drilling and reaming in the lathe
or the drill press. The work is fed into the drill
or reamer by either hand or power feed. If you
mount the cutting tool in a horizontal position,
use the transverse or saddle feed. If you mount
a drill or reamer in a vertical position, as in a
vertical type machine, use the vertical feed.
WORK
Figure 11-79. — Boring with a fly cutter.
metal, kind of metal in the cutting tool, and depth
of cut. Because the boring bar is a single-point
cutting tool, the diameter of the arc through which
the tool moves is also a factor. For all of these
reasons you must guard against operating at too
great a speed, or vibration will occur.
MILLING MACHINE
ATTACHMENTS
Many attachments have been developed that
increase the number of jobs a milling machine can
do, or which make such jobs easier to do.
VERTICAL MILLING ATTACHMENT
For instance, by using a vertical milling attach-
ment (fig. 1 1-80) you can convert the horizontal
spindle machine to a vertical spindle machine and
can swivel the cutter to any position in the
vertical plane. By using a universal milling attach-
ment, you can swivel the cutter to any position
in both the vertical and horizontal planes. These
attachments will enable you to more easily do jobs
that would otherwise be very complex.
HIGH-SPEED UNIVERSAL
ATTACHMENT
By using a high-speed universal attachment,
you can perform milling operations at higher
speeds than those for which the machine was
designed. This attachment is clamped to the
DRAWBOLT
DEGREE
GRADUATIONS
machine and is driven by the milling machine
spindle, as you can see in figure 11-81. You can
swivel the attachment spindle head and cutter 360 °
in both planes. The attachment spindle is driven
at a higher speed than the machine spindle. You
must consider the ratio between the rpm of the
two spindles when you calculate cutter speed.
Small cutters, end mills, and drills should be
driven at a high rate of speed to maintain an
efficient cutting action.
CIRCULAR MILLING ATTACHMENT
This attachment (fig. 11-82) is a circular table
that is mounted on the milling machine table. The
circumference of the table is graduated in degrees.
Smaller attachments are usually equipped for
hand feed only, and larger ones are equipped for
both hand and power feed. This attachment may
be used for milling circles, arcs, segments, circular
T-slots, and internal and external gears. It may
also be used for irregular form milling.
RACK MILLING ATTACHMENT
The rack milling attachment, shown in
figure 11-83, is used primarily for cutting teeth
on racks, although it can be used for other
operations. The cutter is mounted on a spindle
that extends through the attachment parallel to
the table T-slots. An indexing arrangement is used
to space the rack teeth quickly and accurately.
DEGREE GRADUATION
SPINDLE
Figure 11-80. — Vertical milling attachment.
Figure 11-81. — High-speed universal milling attachment.
DEGREE GRADUATIONS
ROTARY TABLE
DRIVE SHAFT
HAND WHEEL
END GEARING HOUSING
Figure ll-82.-CircuIar milling attachment with power feed.
Figure ll-83.-Rack milling attachment.
11-53
28.423
28.424X
RIGHT-ANGLE PLATE
The right-angle plate (fig. 11-84) is attached
to the table. The right-angle slot permits mounting
the index head so the axis of the head is parallel
to the milling machine spindle. With this attach-
ment you can make work setups that are off center
or at a right angle to the table T-slots. The
standard size plate T-slots make it convenient to
change from one setting to another for milling a
surface at a right angle.
RAISING BLOCK
Raising blocks (fig. 11-85) are heavy-duty
parallels that usually come in matched pairs. They
are mounted on the table, and the index head is
mounted on the blocks. This arrangement raises
the index head and makes it possible to swing the
head through a greater range to mill larger work.
TOOLMAKER'S KNEE
The toolmaker's knee (fig. 11-86) is a simple
but useful attachment for setting up angular work,
not only for milling but also for shaper, drill press,
and grinder operations. You mount a toolmaker's
Figure 11-84.— Right-angle plate.
knee, which may have either a stationary or
rotatable base, to the table of the milling machine.
The base of the rotatable type is graduated in
degrees. This feature enables you to machine
compound angles. The toolmaker's knee has a
tilting surface with either a built-in protractor
head graduated in degrees for setting the table or
a vernier scale for more accurate settings.
FEEDS, SPEEDS, AND COOLANTS
Milling machines usually have a spindle speed
range from 25 to 2,000 rpm and a feed range from
1/4 inch to 30 inches per minute (ipm). The feed
is independent of the spindle speed; thus, a
workpiece can be fed at any rate available in the
feed range regardless of the spindle speed being
used. Some of the factors concerning the selection
of appropriate feeds and speeds for milling are
discussed in the following paragraphs.
TILTING SURFACE
T-SLOTS
GRADUATIONS
BASE
BASE \-GRADUATIONS
Figure 11-86. — Toolmaker's knees.
Table 11-5.— Surface Cutting Speeds
Figure 11-85.— Raising blocks.
Carbon steel
High Speed
cutters (ft.
steel cutters
per min. )
(ft. per min. )
Rough
Finish
Rough
Finish
Cast iron:
Malleable
60
75
90
100
Hard
castings
10
12
15
20
Annealed tool
steel
25
35
40
50
Low carbon
steel
40
50
60
70
Brass
75
95
110
150
Aluminum
460
550
700
900
SPEEDS
Heat generated by friction between the cutter
and the work may be regulated by the use of
proper speed, feed, and cutting coolant. Regula-
tion of this heat is very important because the
cutter will be dulled or even made useless by
overheating. It is almost impossible to provide any
fixed rules that will govern cutting speeds because
of varying conditions from job to job. Generally
speaking, you should select a cutting speed that
will give the best compromise between maximum
production and longest life of the cutter. In any
particular operation, consider the following
factors in determining the proper cutting speed.
• Hardness of the Material Being Cut: The
harder and tougher the metal being cut, the
slower should be the cutting speed.
• Depth of Cut and Desired Finish: The
amount of friction heat produced is
directly proportional to the amount of
material being removed. Finishing cuts,
therefore, often may be made at a speed
40% to 80% higher than that used in
roughing.
9 Cutter Material: High-speed steel cutters
may be operated from 50% to 100% faster
than carbon steel cutters -because high-
speed steel cutters have better heat resistant
properties than carbon steel cutters.
• Type of Cutter Teeth: Cutters that have
undercut teeth cut more freely than those
that have a radial face; therefore, cutters
with undercut teeth may run at higher
speeds.
• Sharpness of the Cutter: A sharp cutter
may be run at much higher speed than a
dull cutter.
• Use of Coolant: Sufficient coolant will
usually cool the cutter so that it will not
overheat even at relatively high speeds.
Use the approximate values in table 11-5 as
a guide when you are selecting the proper cutting
speed. If you find that the machine, the cutter,
or the work cannot be suitably operated at
the suggested speed, make an immediate readjust-
ment.
By referring to table 11-6, you can determine
the cutter revolutions per minute for cutters
Table 11-6. — Cutter Speeds in Revolutions Per Minute
Surface speed (ft. per min. )
Diameter
of cutter
(in-)
25
30
35
40
50
55
60
70
75
80
90
100
120
140
160
180
200
Cutter revolutions per minute
1/4
382
458
535
611
764
851
917
1,070
1,147
1,222
1,376
1,528
1,834
2,139
2,445
2,750
3,056
5/16
306
367
428
489
611
672
733
856
917
978
1,100
1,222
1,466
1,711
1,955
2,200
2,444
3/8
255
306
357
408
509
560
611
713
764
815
916
1,018
1,222
1,425
1,629
1,832
2,036
7/16
218
262
306
349
437
481
524
611
656
699
786
874
1,049
1,224
1,398
1,573
1,748
1/2
191
229
268
306
382
420
459
535
573
611
688
764
917
1,070
1,222
1,375
1,528
5/8
153
184
214
245
306
337
367
428
459
489
552
612
736
857
979
1,102
1,224
3/4
127
153
178
203
254
279
306
357
381
408
458
508
610
711
813
914
1,016
7/8
109
131
153
175
219
241
262
306
329
349
392
438
526
613
701
788
876
1
95.5
115
134
153
191
210
229
267
287
306
344
382
458
535
611
688
764
1 1/4
76.3
91.8
107
123
153
168
183
214
230
245
274
306
367
428
490
551
612
1 1/2
63.7
76.3
89.2
102
127
140
153
178
191
204
230
254
305
356
406
457
508
1 3/4
54.5
65.5
76.4
87.3
109
120 .
131
153
164
175
196
218
262
305
34,9
392
436
2
47.8
57.3
66.9
76.4
95.5
105
115
134
143
153
172
191
229
267
306
344
382
2 1/2
38.2
45.8
53.5
61.2
76.3
84.2
91.7
107
114
122
138
153
184
213
245
275
306
3
31.8
38.2
44.6
51
63.7
69.9
76.4
89.1
95.3
102
114
127
152
178
208
228
254
3 1/2
27.3
32.7
38.2
44.6
54.5
60
65.5
76.4
81.8
87.4
98.1
109
131
153
174
196
21CI
4
23.9
28.7
33.4
38.2
47.8
52.6
57.3
66.9
71.7
76.4
86
95.6
115
134
153
172
191
5
19.1
22.9
26.7
30.6
38.2
42
45.9
53.5
57.3
61.1
68.8
76.4
91.7
107
122
138
153
11-55
varying in diameter from 1/4 inch to 5 inches. For
example: You are cutting with a 7/16-inch cutter.
If a surface speed of 160 feet per minute is
required, the cutter revolutions per minute will
be 1,398.
If the cutter diameter you are using is
not shown in table 11-6, determine the proper
revolutions per minute of the cutter by using the
formula:
(*\ mm - Cutting speed x 12
W rpm " 3.1416 x Diameter
or rpm * 0.26?^ D
where
rpm = revolutions per minute of the cutter
fpm = required surface speed in feed per
minute
D = diameter of the cutter in inches
0.2618 = constant = j^
EXAMPLE: What is the spindle speed for a
1/2-inch cutter running at 45 fpm?
rpm -
45
0.2618 x 0.5
rpm = 343.7
To determine cutting speed when you know
the spindle speed and cutter diameter, use the
following formula:
fpm x 12 = rpm x 3.1416 x D
- 3.1416 x Diameter x rpm
fpm- - n - : - K-
fpm = 0.2618 x D x rpm
EXAMPLE: What is the cutting speed of a
2 1/4-inch end mill running at 204 rpm?
fpm = 0.2618 x D x rpm
rpm = 0.2618 x 2.25 x 204
fpm= 120.1
FEEDS
The rate of feed is the rate of speed at
which the workpiece travels past the cut. When
selecting the feed, you should consider the follow-
ing factors:
• Forces are exerted against the work, the
cutter, and their holding devices during the
cutting process. The force exerted varies
directly with the amount of metal being
removed and can be regulated by adjusting
the feed and the depth of cut. The feed and
depth of cut are, therefore, interrelated,
and depend on the rigidity and power of
the machine. Machines are limited by the
power they can develop to turn the cutter
and by the amount of vibration they can
withstand when coarse feeds and deep cuts
are being used.
• The feed and depth of cut also depend on
the type of cutter being used. For example,
deep cuts or coarse feeds should not be
attempted with a small diameter end mill;
such an attempt would spring or break the
cutter. Coarse cutters with strong cutting
teeth can be fed at a relatively high rate
of feed because the chips will be washed
out easily by the cutting lubricant.
• Coarse feeds and deep cuts should not be
used on a frail piece of work or on work
mounted in such a way that the holding
device will spring or bend.
• The desired degree of finish affects the
amount of feed. When a fast feed is used,
metal is removed rapidly and the finish will
not be very smooth. However, a slow feed
rate and a high cutter speed will produce
a finer finish. For roughing, it is advisable
to use a comparatively low speed and a
coarse feed. More mistakes are made by
overspeeding the cutter than by
overfeeding the work. Overspeeding is
indicated by a squeaking, scraping sound.
If chattering occurs in the milling machine
during the cutting process, reduce the
speed and increase the feed. Excessive
cutter clearance, poorly supported work,
or a badly worn machine gear are also
common causes of chattering.
One procedure for selecting an appropriate
feed for a milling operation is to consider the chip
11-56
load of each cutter tooth. The chip load is the
thickness of the chip that a single tooth removes
from the work as it passes over the surface. For
example, with a cutter turning at 60 rpm, having
12 cutting teeth, and a feed rate of 1 ipm, the chip
load of a single tooth of the cutter will be 0.0014
inch. A cutter speed increase to 120 rpm reduces
the chip load to 0.0007 inch; a feed increase to
2 ipm increases chip load to 0.0028 inch. The
formula for calculating chip load is:
Chip load =
feed rate (ipm)
cutter speed (rpm) x number
of teeth in the cutter
Table 11-7 provides recommended chip loads
for milling various materials with various types
of cutters.
COOLANTS
The purpose of a cutting coolant is to reduce
frictional heat and thereby extend the life of the
cutter's edge. Coolant also lubricates the cutter
face and flushes away the chips, reducing the
possibility of damage to the finish.
If a commercial cutting coolant is not
available, you can make a good substitute by
thoroughly mixing 1 ounce of sal soda and 1 quart
Table 11-7. — Recommended Chip Loads
Material
Face
Mills
Helical
Mills
Slotting &
Side Mills
End
Mills
Form
Relieved
Cutters
Circular
Saws
Plastic
.013
.010
.008
.007'
.004
.003
Magnesium and alloys
Aluminum and alloys
Free cutting brasses
& bronzes
.022
.022
.022
.018
.018
.018
.013
.013
.013
.011
.011
.011
.007
.007
.007
.005
.005
.005
Medium brasses &
.014
.011
.008
.007
.004
.003
Hard brasses &
bronzes
.009
.007
.006
.005
.003
.002
.013
.010
.007
.006
.004
.003
Cast iron, soft (ISO-
ISO BH)#
.016
.013
.009
.008
.005
.004
Cast iron, med. (180-
220 BH)
.013
.010
.007
.007
.004
.003
Cast iron, hard (220-
300 BH)
.011
.008
.006
.006
.003
.003
Malleable iron .....
.012
.010
.007
.006
.004
.003
Cast steel .
.012
.010
.007
.006
.004
.003
Low carbon steel,
free mach
.012
.010
.007
.006
.004
.003
Low carbon steel . . .
Medium carbon steel
Alloy steel, annealed
(180-220 BH)
.010
.010
.008
.008
.008
.007
.006
.006
.005
.005
.005
.004
.003
.003
.003
.003
.003
.002
Alloy steel, tough
(220-300 BH)
.006
.005
.004
.003
.002
.002
Alloy steel, hard
(300-400 BH)
.004
.003
.003
.002
.002
.001
Stainless steel, free
mach
.010
.008
.006
.005
.003
.002
Stainless steels ....
Monel metals
.006
.008
.005
.007
.004
.005
.003
.004
.002
.003
.002
.002
proportionally. This emulsion is suitable for
machining most metals.
In machining aluminum, you should use
kerosene as a cutting coolant. Machine cast iron
dry, although you can use a blast of compressed
air to cool the work and the cutter. If you use
compressed air, be extremely careful to prevent
possible injury to personnel and machinery.
When using a periphery milling cutter, apply
the coolant to the point at which the tooth leaves
the work. This will allow the tooth to cool before
you begin the next cut. Allow the coolant to flow
freely on the work and cutter.
The horizontal boring mill is used for many
kinds of shop work, such as facing, boring,
drilling, and milling. In horizontal boring mill
milling machine work; therefore, a detailed
discussion of these operations will not be
necessary in this section.
The horizontal boring mill (fig. 1 1-87) consists
of four major elements.
BASE AND COLUMN— The base contains
all the drive mechanisms for the machine and
provides a platform that has precision ways
machined lengthwise for the saddle. The column
provides support for the head and has two rails
machined the height of the column for full
vertical travel of the head.
HEAD — The head contains the horizontal
spindle, the auxiliary spindle, and the mechanism
for controlling them. The head also provides a
station for mounting various attachments. The
spindle feed and spindle hand feed controls are
contained in the head, along with the quick
COLUMN \
MANUAL SPINDLE
FEED HANDWHEEL
SPINDLE
CLAMP LEVER
FEED CHANGE
LEVERS
BACKREST
TABLE FEED
DIRECTIONAL LEVER
SADDLE
BED
SPINDLE SPEED
CHANGE LEVER
FEED AND RAPID
TRAVERSE LEVER
HEAD FEED
DIRECTIONAL LEVER
SADDLE FEED
DIRECTIONAL LEVER
28.426
Figure 11-87. — Horizontal boring mill.
11-58
SADDLE AND TABLE— A large rectangular
slotted table is mounted on a saddle that can be
traversed the length of the ways. T-slots are
machined the entire length of the table for holding
down work and various attachments, such as
rotary table angle plates, etc.
BACKREST OR END SUPPORT— The
backrest is mounted on the back end of the ways.
It is used to support arbors and boring bars as
they rotate and travel lengthwise through the
work, such as in-line boring of a pump casing or
large bearing. The backrest blocks have an
antifriction bearing, which the boring bar passes
through and rotates within. The back rest blocks
travel vertically with the head.
The two types of horizontal boring mill usually
found in Navy machine shops and shore repair
activities are the table type, used for small work,
and the floor type, used for large work. The floor
type is the most common of the two types found
in shops. You will find this machine well-suited
for repair work where machining of large irregular
jobs is commonplace.
The reference to size of horizontal boring mills
differs with the manufacturer. Some use spindle
size. For example, Giddings and Lewis model
SOOT has a 3 -inch spindle. Other manufacturers
refer to the largest size boring bar the machine
will accept. In planning a job, consider both of
these factors along with the table size and the
height that the spindle can be raised. Always refer
to the technical manual for your machine.
Setting up the work correctly is most
important. Failure to set the work up properly
can prove costly in man-hours and material.
Oftentimes you will find that it is not advisable
to set up a casting to a rough surface and that
it will be preferable to set it up to the layout lines,
since these lines will always be used as a reference.
It is important that holding clamps used to
secure a piece of work be tight. If you use braces,
place them so that they cannot come loose. Fasten
blocks, stops, and shims securely. If a workpiece
is not properly secured, there is always the
possibility of ruining the material or the machine
and the risk of causing injury to machine shop
personnel.
Different jobs to be done on the boring mill
may require different types of attachments.
Such attachments include angular milling heads,
available in a variety of diameters. These boring
heads prove particularly useful in boring large
diameter holes and facing large castings. Locally
made collars may be used also. Stub arbors are
used to increase desired diameters.
COMBINATION BORING
AND FACING HEAD
The boring and facing head (fig. 1 1-88) is used
for facing and boring large diameters. This attach-
ment is mounted and bolted directly to the spindle
sleeve and has a slide with automatic feed that
holds the boring or facing tools. (This attachment
can be fed automatically or positioned manually.)
Although there are various sizes, each is made and
used similarly. The heads are balanced to permit
high-speed operation with the tool slide centered.
Whenever you use tools off center, be careful to
counterbalance the head, or use it at lower speeds.
Generally, the boring and facing head will
come equipped with several toolholders for single-
point tools, a right angle arm, a boring bar, and
a boring bar holder that mounts on the slide.
To set up and operate the boring and facing
head:
1 . Retract the spindle of the machine into the
sleeve. Engage the spindle ram clamp lever.
Figure 11-88.— Combination boring and facing head.
11-59
2. Disengage the overrunning spindle feed
clutch to prevent inadvertent engagement of the
spindle power feed while you mount the combina-
tion head on the machine. (If the slide is centered
and locked, you may run the spindle through it
for use in other operations without removing the
attachment, but be sure to disengage the spindle
overrunning clutch again before you resume use
of the slide.
3. Set the spindle for the speed to be used.
4. Before you shift the spindle back-gear to
neutral or make any spindle back-gear change
when the combination head is mounted on the
sleeve, rotate the sleeve by jogging it until the
heavy end of the head is down. This is a safety
precaution to prevent injury to you or damage to
the work. Any spindle back-gear change requires
a momentary shift to neutral, allowing free
turning of the sleeve. The sleeve may then
unexpectedly rotate until the heavy end of the
facing head is down, hitting you or the work.
5 . Lift the head into position on the machine
at the sleeve by inserting an eyebolt into the tapped
hole in the top of the head.
6. To line up the bolt holes in the sleeve with
those in the head, jog the spindle into position.
7. After you have tightened the mounting
bolts, rotate the feed adjusting arm on the back-
ing plate until the arm points directly toward the
front.
8. Mount the restraining block on the head.
9. Set the slide manually by inserting the tee-
handled wrench into the slot in the slide adjusting
dial and turning the wrench until the slide is
positioned. The dial is graduated in thousandths
of an inch with one complete turn equaling a
0.125-inch movement of the slide.
After the slide is clamped in place, a spring-
loaded safety clutch prevents movement of the
slide or damage to the feed mechanism if the feed
is inadvertently engaged. You must remember that
this is not provided to allow continuous opera-
tion of the head when the slide is clamped and
the feed is engaged. It is a jamming protection
only. A distinct and continuous ratcheting of the
safety clutch warns you to unlock the slide or to
disengage the feed. Do not confuse this warning
with the intermittent ratcheting of the feed
driving clutches as the head rotates. The same
safety clutch stops the feed at the end of travel
of the slide, thus preventing jamming of the slide
or the mechanism through overtravel.
The slide directional lever is located on the
backing plate beneath the feed adjusting arm. The
arrows on the face of the selector indicate which
way it should be turned for feeding the slide in
either direction. There are also two positions of
the selector for disengaging the slide feed. The
direction of the spindle rotation has no effect on
the direction of the slide feed.
The slide feed rate adjusting arm scale is
graduated in 0.010-inch increments from 0.000 to
0.050 inch, except that the first two increments
are each 0.005 inch. Set the feed rate by turning
the knurled adjusting arm to the desired feed in
thousandths per revolution.
When you mount the single point toolholders,
be sure the tool point is on center or slightly below
center so the cutting edge has proper clearance
at the small diameters. The feed mechanism may
be damaged if you operate the head with the tool
above center.
After you mount the facing head, perform the
machining operation using the instructions found
in the operator's manual for your boring machine.
RIGHT ANGLE MILLING
ATTACHMENT
The right angle milling attachment is mounted
over the spindle sleeve and is bolted directly to
the face of the head. It is driven by a drive dog
inserted between the attachment and the spindle
sleeve. This attachment lets you perform milling
operations at any angle setting through a full 360°.
You can perform boring operations at right angles
to the spindle axis using either the head or the
table feed depending on the position of the hole
to be bored. You may use standard milling
machine tooling, held in the spindle by a drawbolt
that extends through the spindle. A right angle
milling attachment is shown in figure 11-89.
BORING MILL OPERATIONS
You should be able to perform drilling, ream-
ing, and boring operations in a boring mill. In
addition, you may be required to use a boring mill
to face valve flanges, bore split bearings, and bore
pump cylindrical liners.
Drilling, Reaming, and Boring
Drilling and reaming operations are performed
in the horizontal boring mill as they are in a radial
11-60
Figure 11-89. — Angular milling head.
ui LJUC iiui izuiuai ooring iniii me
is held in the horizontal position (fig. 1 1-90), while
in the radial drill the tool is held in the vertical
position.
In Line Boring
To set the horizontal boring machine for a line
boring operation, insert a boring bar into the
spindle and pass it through the work. The boring
bar is supported on the foot end by the back rest
assembly. Depending on the size of the bore
required, you can use either standard or locally
manufactured tooling. The head provides the
rotary motion for the tools mounted in the boring
bar. Align the work with the axis of the boring
bar, and bolt and/or clamp it to the table. The
cutting operation is usually performed by having
the spindle move while the work is held stationary.
However, you may, from time to time, find an
operation in which you need to hold the bar in
126.30
Figure 11-90.— Drilling in the horizontal boring mill.
11-61
a fixed position and move the table lengthwise to
complete the operation. (See fig. 11-91.)
The table can be power driven to provide
travel perpendicular to the spindle, making it
possible to bore, elongated and slotted when used
in conjunction with vertical movement of the
head.
Some boring mills have a single spindle in the
head while others have a secondary or auxiliary
spindle that can be fitted with a precision
head and used in some boring operations. This
secondary spindle may also be used on light work
such as drilling accurately spaced small holes.
Reconditioning Split-Sleeve Bearings
Practically all of the high-speed bearings the
Navy uses on turbines are the babbitt-lined split-
sleeve type. Once a bearing of this type has wiped,
it must be reconditioned at the first opportunity.
Wiped means that the bearing has been damaged
by being run under an abnormal condition, such
as without sufficient lubrication. If it has wiped
only slightly, it can probably be scraped to a good
bearing surface and restored to service. If it is
badly wiped, it will have to be rebabbitted and
rebored, or possibly replaced.
When you receive a wiped bearing for repair,
follow the procedure listed below as closely as
possible:
1. Check the extent of damage and wear
marks.
2. Take photos of the bearing to indicate the
actual condition of the bearing and for future
reference in the machining steps and reassembly.
3. Check the shell halves for markings. A
letter or number should be on each half for proper
identification and assembly. (If the shell halves
are not marked, mark them before you dis-
assemble the bearing.)
4. Inspect the outer shell for burrs, worn ends
and the condition of alignment pins and holes.
5. Check the blueprint and job order to ensure
that required information has been provided to
you.
6. Ensure that the actual shaft size has not
been modified from the blueprint.
28.280
Figure 11-91. — Boring bar driven by the spindle and supported in the backrest block.
uuw.il IAJ unv* uciav^
nit ouvn.
the bearing shell with special cleaning solutions
and rebabbitt them after plugging all oil holes with
suitable material.
After relining the shell, remove the excess bab-
bitt extending above the horizontal flanges by
rough machining on a shaper. Take extreme care
to see that the base metal of the horizontal flanges
is not damaged during this machining operation.
After rough machining, blue the remaining excess
babbitt and scrape it until no more excess bab-
bitt extends above the horizontal flanges.
Next, assemble the two half-shells and set
them up on the horizontal boring mill. Check the
spherical diameter of the bearing to ensure that
it is not distorted beyond blueprint specifications
according to NAVSHIPS 9411.813.2. Generally,
the words "BORE TRUE TO THIS SURFACE"
are inscribed on the front face of the bearing shell.
When dialing in the bearing, be sure to dial in on
this surface.
Once you have properly aligned the bearing
in the boring mill, you can complete practically
all the other operations without changing the
setup. Bore the bearing to the finished diameter
and machine the oil grooves as required by
blueprint specifications.
Oil is distributed through the bearing by oil
grooves. These grooves may be of several forms;
the two simplest are axial and circumferential.
Sometimes circumferential grooves are placed at
the ends of the bearings as a controlling device
to prevent side leakage, but this type of grooving
does not affect the distribution of lubricant.
When you machine grooves into a bearing,
you must be careful in beveling the groove out
into the bearing leads to prevent excess babbitt
from clogging the oil passage. The type of grooves
used in a bearing should not be changed from the
original design, unless the change is warranted
by continuous trouble traceable to improper
lubricant distribution within the bearing.
On completion of all machining operations,
it is the responsibility of both the repair activity
and the ship's force to determine that the bearing
meets blueprint specifications and that a good
bond exists between the shell and the babbitt
metal.
Threading
Threads may be cut using the horizontal
boring mill on machines that are equipped with
is available.
To cut threads with these machines, use a
system of change gear combinations to obtain the
different leads. Secure a single point tool in a
suitable toolholder and mount the toolholder in
the spindle of the machine. While you cut threads,
keep the spindle locked in place. The saddle,
carrying the workpiece, advances at a rate
determined by the change gear combination.
Feeding, in conjunction with the spindle rotation
in the low back gear range, produces the threads.
Cut the thread a little at a time in successive
passes. The thread profile depends on how the
cutting tool is ground. When you have completed
the first pass, back the cutting tool off a few
thousandths of an inch to avoid touching the
workpiece on the return movement. Then reverse
the spindle driving motor. This causes the saddle
direction to reverse while the direction selection
lever position remains unchanged. Allow the
machine to run in this direction until the cutting
tool has returned to its starting point. Advance
the cutter to take out a little more stock, and after
setting the spindle motor to run in forward, make
another cutting pass. Follow this procedure until
the thread is completed. A boring bar with a
micro-adjustable tool bit or a small precision head
is ideal for this operation. It allows fast, easy
adjustment of the tool depth, plus accuracy and
control of the depth setting.
To set up for cutting threads, remove the
thread lead access covers and set up the correct
gear train combination as prescribed by- the
manufacturer's technical manual. After you have
set up the gear train, lock the sliding arm by
tightening the nuts on the arm clamp. Be sure to
replace the retaining washers on all the studs and
lock them with the screws provided with the
machine. Refer to the manufacturer's technical
manual for the machine you are using for the
correct gear arrangement.
Some of the gear combinations use only one
gear on the B stud. When this occurs, take up the
additional space on the stud by adding spacers to
the stud. The following check-off list will be of
assistance to you in threading in a horizontal
boring mill:
1 . Be sure the correct change gears are on the
proper centers.
2. Position the head back-gear in the low
range.
11-63
3 . Place the feed change lever in the correct
position to release the standard feed.
4. Engage the thread lead engaging lever.
5. Shift the driving gear lever to the thread
lead position.
6. Start the spindle rotation forward.
7. Place the saddle directional lever in the left
position. It will remain in this position until the
thread is completed.
8. Place the feed/rapid traverse selector lever
in the feed position. This will lock in the feed
clutch until the threading operation is completed.
9. To disengage the feed, place the thread lead
driving gear lever in the standard position. The
feed clutch will disengage. Do NOT do this during
the threading operation or the thread lead timing
will be lost.
MILLING MACHINE
SAFETY PRECAUTIONS
Your first consideration as a Machinery
Repairman should be your own safety.
CARELESSNESS and IGNORANCE are the two
great menaces to personal safety. Milling
machines are not playthings and must be given
the full respect that is due any machine tool.
ft NEVER attempt to operate a machine
unless you are sure that you understand it
thoroughly.
ft Do NOT throw an operating lever without
knowing in advance what is going to take
place.
• Do NOT play with the control levers or
idly turn the handles of a milling machine,
even if it is stopped.
ft NEVER lean against or rest your hands on
a moving table. If it is necessary to touch
a moving part, know in advance the
direction in which it is moving.
ft Do NOT take a cut without making sure
that the work is held securely in the vise
or fixture and that the holding member is
rigidly fastened to the machine table.
• Always remove chips with a brush or other
suitable tool; NEVER use fingers or hands.
• Before attempting to operate any milling
machine, study it thoroughly. Then if an
emergency arises, you can stop the
machine immediately. Knowing how to
stop a machine is just as important, if not
more important, as knowing how to start
it.
ft You must above all KEEP CLEAR OF
THE CUTTERS. Do NOT touch a cutter,
even when it is stationary, unless there is
good reason to do so, and then be very
careful.
The milling machine is not dangerous to
operate, but if you do not follow certain safety
practices you are likely to find it dangerous. There
is always the danger of getting caught in the
cutter. Never attempt to remove chips with your
fingers at the point of contact of the cutter and
the work. There is danger to your eyes from flying
chips, so always protect your eyes with goggles
and keep your eyes out of the line of cutting
action.
SHAPERS, PLANERS, AND ENGRAVERS
In this chapter we will discuss the major types
of shapers, planers, and pantographs (engravers),
and their individual components, cutters, and
operating principles and procedures. A shaper has
a reciprocating single-edged cutting tool that
removes metal from the work as the work is fed
into the tool. A planer operates on a similar
principle except that the work reciprocates, and
the tool is fed into the work. A pantograph is used
primarily for engraving letters and designs on any
type of material. A pantograph can be used to
engrave concave, convex, and spherical surfaces
as well as flat surfaces.
SHAPERS
A shaper has a reciprocating ram that carries
a cutting tool. The tool cuts only on the
forward stroke of the ram. The work is held in
a vise or on the worktable, which moves at
a right angle to the line of motion of the
ram, permitting the cuts to progress across
the surface being machined. A shaper is
identified by the maximum size of a cube it can
machine; thus, a 24-inch shaper will machine a
24-inch cube.
TYPES OF SHAPERS
There are three distinct types of shapers —
crank, geared, and hydraulic. The type depends
on how the ram receives motion to produce its
own reciprocating motion. In a crank shaper the
ram is moved by a rocker arm, which is driven
by an adjustable crankpin secured to the main
driving gear. Quick return of the ram is a feature
of a crank shaper. In a geared shaper, the ram
is moved by a spur gear, which meshes with a rack
secured to the bottom of the ram. In a hydraulic
shaper, the ram is moved by a hydraulic cylinder
whose piston rod is attached to the bottom of the
ram. Uniform tool pressure, smooth drive, and
smooth work are features of the hydraulic-type
shaper.
There are many different makes of shapers,
but the essential parts and controls are the same
on all. When you learn how to operate one make
of shaper, you should not have too much trouble
in learning to operate another make. Figure 12-1
is an illustration of a crank shaper found in shops
in some Navy ships.
SHAPER ASSEMBLIES
To perform the variety of jobs you will be
required to do using the shaper, you must know
the construction and operation of the main
components. Those components are the main
frame assembly, drive assembly, crossrail
assembly, toolhead assembly, and table feed
mechanism. (See fig. 12-2.)
Main Frame Assembly
The main frame assembly consists of the base
and the column. The base houses the lubricating
pump and sump, which provide forced lubrica-
tion to the machine. The column contains
the drive and feed actuating mechanisms. A
dovetail slide is machined on top of the column
to receive the ram. Vertical flat ways are machined
on the front of the column to receive the cross-
rail.
Drive Assembly
The drive assembly consists of the ram and
the crank assembly. These parts convert the rotary
motion of the drive pinion to the reciprocating
12-1
BASE
28.219X
Figure 12-1. — Standard shaper.
motion of the ram. By using the adjustments
provided, you can increase or decrease the length
of stroke of the ram, and can also position the
ram so that the stroke is in the proper area in
relation to the work.
You can adjust the CRANKPIN, which is
mounted on the crank gear, from the center of
the crank gear outward. The sliding block fits over
the crankpin and has a freesliding fit in the rocker
arm. If you center the crankpin (and therefore the
sliding block) on the axis of the crank gear, the
rocker arm will not move when the crank gear
turns. But if you set the crankpin off center (by
turning the stroke adjusting screw), any motion
of the crank gear will cause the rocker arm
to move. This motion is transferred to the
ram through the ram linkage and starts the
reciprocating motion of the ram. The distance the
crankpin is set off center determines the length
of stroke of the tool.
To position the ram, turn the ram position-
ing screw until the ram is placed properly with
respect to the work. Specific procedures for
positioning the ram and setting the stroke are in
the manufacturer's technical manual for the
specific machines you are using.
12-2
TOOLHEAD
CLAPPER BOX
TOOLPOST
WORKTABLE
RAM LINKAGE
UPPER ROCKER
PIVOT
CRANK GEAR
DRIVING PINION
ROCKER ARM
LOWER ROCKER
PIVOT
Figure 12-2. — Cross-sectional view of a crank type shaper.
Crossrail Assembly
The crossrail assembly includes the crossrail,
the crossfeed screw, the table, and the table
support bracket (foot). (See fig. 12-1.) The
crossrail slides on the vertical ways on the front
of the shaper column. The crossrail apron
(to which the worktable is secured) slides on
horizontal ways on the crossrail. The crossfeed
screw engages in a mating nut, which is secured
to the back of the apron. The screw can be turned
either manually or by power to move the table
horizontally.
The worktable may be plain or universal as
shown in figure 12-3. Some universal tables can
be swiveled only right or left, away from the
perpendicular; others may be tilted fore or aft at
small angles to the ram. T-slots on the worktables
are for mounting the work or work-holding
devices. A table support bracket (foot) holds the
worktable and can be adjusted to the height
required. The bracket slides along a flat surface on
the base as the table moves horizontally. The table
can be adjusted vertically by the table elevating
screw (fig. 12-2).
28.221X
Figure 12-3.— Swiveled and tilted table.
12-3
Table Feed Mechanism
The table feed mechanism (fig. 12-4) consists
of a ratchet wheel and pawl, a rocker, and a feed
drive wheel. The feed drive wheel (driven by the
main crank), which operates similarly to the ram
drive mechanism, converts rotary motion to
reciprocating motion. As the feed drive wheel
rotates, the crankpin (which can be adjusted off
center) causes the rocker to oscillate. The straight
face of the pawl pushes on the back side of a tooth
on the ratchet wheel, turning the ratchet wheel
and the feed screw. The back face of the pawl is
cut at an angle to ride over one or more teeth as
it is rocked in the opposite direction. To change
the direction of feed, lift the pawl and rotate it
one-half turn. To increase the rate of feed,
increase the distance between the feed drive wheel
crankpin and the center of the feed drive wheel.
The ratchet wheel and pawl method of feeding
crank-type shapers has been used for many years.
Relatively late model machines still use similar
principles. As specific procedures for operating
feed mechanisms may vary, you should consult
manufacturers' technical manuals for explicit
instructions.
Toolhead Assembly
The toolhead assembly consists of the
toolslide, the downfeed mechanism, the clapper
box, the clapper head, and the toolpost at the
forward end of the ram. The entire assembly can
be swiveled and set at any angle not exceeding 50 °
on either side of the vertical. The toolhead is
raised or lowered by hand feed to make vertical
cuts on the work. In making vertical or angular
cuts, the clapper box must be swiveled away from
the surface to be machined (fig. 12-5); otherwise,
the tool will dig into the work on the return stroke.
SHAPER VISE
The shaper vise is a sturdy mechanism secured
to the table by T-bolts. The vise has two jaws,
one stationary, the other movable, that can be
DOWNFEED MECHANISM
TOOLPOST
CLAPPER HEAD
CLAPPER BOX
•TOOLSLIDE
POSITION FOR HORIZONTAL CUTTING
POSITIONS FOR DOWN CUTTING
Figure 12-5. — Toolhead assembly in various positions.
WORK
PAWL,
RATCHET,
WHEEL
FEED-
SCREW
-CONTROL KNOB
ROCKER (OSCILLATES
ON FEED SCREW)
FEED DRIVE WHEEL
CONNECTING CRANKPIN (ADJUSTABLE
LINKAGE TOWARD OR AWAY FROM
CENTER OF WHEEL)
FEED DRIVE
WHEEL
C-CLAMPS
PARALLEL
ANGLE PLATE
TABLE
deeper and will open to accommodate large work.
Most such vises have hardened steel jaws ground
in place. The universal vise may be swiveled in
a horizontal plane from 0° to 180°. The usual
positions have the jaws set either parallel with the
stroke of the ram or at a right angle to the stroke.
See that the vise is free from any obstruction that
might keep the work from seating properly.
Remove burrs and rough edges on the vise and
chips left from previous machining before
starting to work.
Work can be set on parallels so the surface
to be cut is above the top of the vise. Shaper hold-
downs can be used in holding the work between
the jaws of the vise (fig. 12-6). Work larger than
the vise will hold can be clamped directly to the
top or side of the machine table. When work too
large or awkward for a swivel vise must be
also used in mounting work on shaper tables.
TOOLHOLDERS
Various types of toolholders, made to hold
interchangeable tool bits, are used to a great
extent in planer and shaper work. Tool bits are
available in different sizes and are hardened and
cut to standard lengths to fit the toolholders. The
toolholders that you will most commonly use are
(fig. 12-7):
1. Right-hand, straight, and left-hand
toolholders, which may be used for the majority
of common shaper and planer operations.
2. Gang toolholders, which are especially
adapted for surfacing large castings. With a gang
toolholder you make multiple cuts with each
LEFT-HAND, STRAIGHT, AND RIGHT-HAND TOOLHOLDERS GANG TOOLHOLDER AND MULTIPLE CHIP PRODUCED
SWIVEL HEAD TOOLHOLDER
SPRING TOOLHOLDER
EXTENSION TOOLHOLDER
Figure 12-7.— Toolholders.
12-5
forward stroke of the shaper. Each tool takes a
light cut and there is less tendency to ' 'break out' '
at the end of a cut.
3. Swivel head toolholders, which are univer-
sal, patented holders that may be adjusted to place
the tool in various radial positions. This feature
allows the swivel head toolholder to be converted
into a straight, right-hand, or left-hand holder at
will.
4. Spring toolholders, which have a rigid
U-shaped spring that lets the holder cap absorb
a considerable amount of vibration. A spring
toolholder is particularly good for use with
formed cutters, which have a tendency to chatter
and dig into the work.
5. Extension toolholders, which are adapted
for cutting internal keyways, splines, and grooves
on the shaper. The extension arm of the holder
can be adjusted to change the exposed length and
the radial position of the tool.
Procedures for grinding shaper and planer tool
bits for various operations are discussed in
Chapter 6 of this training manual.
SHAPER SAFETY PRECAUTIONS
The shaper, like all machines in the machine
shop, is not a dangerous piece of equipment if
you observe good safety practices. You should
read and understand the safety precautions and
operating instructions posted on or near a shaper
prior to operating it. Some good safety practices
are listed here but are intended only to supple-
ment those posted on the machine.
9 Always wear goggles or a face shield.
9 Ensure that the workpiece, vise, and setup
fixture are properly secured.
• Ensure that the work area is clear of tools.
• Inform other personnel in the area to
prevent possible injury to them from flying
chips.
9 Ensure that the travel of the ram is clear
to both the front and the rear of the
machine.
• Never stand in front of the shaper while
it is in operation.
• Avoid touching the tool, the clapper box,
or the workpiece while the machine is in
operation.
• Never remove chips with your bare hand;
always use a brush or a piece of wood.
• Keep the area around the machine clear of
chips to help prevent anyone from slipping
and falling into the machine.
9 Remember: SAFETY FIRST, ACCU-
RACY SECOND, SPEED LAST.
SHAPER OPERATIONS
Before beginning any job on the shaper, you
should thoroughly study and understand the
blueprint or drawing from which you are to work.
In addition, you should take the following
precautions:
• Make certain that the shaper is well oiled.
© Clean away ALL chips from previous
work.
9 Be sure that the cutting tool is set
properly; otherwise the tool bit will
chatter. Set the toolholder so the tool bit
does not extend more than about 2 inches
below the clapper box.
© Be sure the piece of work is held rigidly
in the vise to prevent chatter. You can seat
the work by tapping it with a babbitt
hammer.
9 Test the table to see if it is level and square.
Make these tests with a dial indicator and
a machinist's square as shown in figure
12-8. If either the table or the vise is off
parallel, check for dirt under the vise or
improper adjustment of the table support
bracket.
• Adjust the ram for length of stroke and
position. The cutting tool should travel 1/8
to 1/4 inch past the edge of the work on
the forward stroke and 3/4 to 7/8 inch
behind the rear edge of the work on the
return stroke.
12-6
JOINT
Figure 12-8. — Squaring the table and the vise.
28.226
Speeds and Feeds
Setting up the shaper to cut a certain material
is similar to setting up other machine tools, such
as drill presses and lathes. First, you have to
determine the approximate required cutting speed
and then you have to determine and set the
necessary machine speed to produce your desired
cutting speed. On all of the machine tools we
discussed in the previous chapters, cutting speed
was directly related to the speed (rpm) of the
machine's spindle. You could determine what
spindle rpm to set by using one formula for all
brands of a particular type of machine. Setting
up a shaper is slightly different. You still relate
cutting speed to machine speed through a
formula, but the formula that you use depends
on the brand of machine that you operate. This
is because some manufacturers use a slightly
different formula for computing cutting speed
than others. To determine what specific formula
to use for your machine, consult the operator's
manual provided by the manufacturer.
The following discussion explains basically
how the operation of a shaper differs from the
operations of other machine tools. It also explains
how to determine the cutting speeds and related
machine speeds for a Cincinnati shaper.
Whenever you determine the speed of the
shaper required to produce a particular cutting
speed, you must account for the shaper's
reciprocating action. This is because the tool only
cuts on the forward stroke of the ram. In most
shapers the time required for the cutting stroke
is 1 1/2 times that required for the return stroke.
This means that in any one cycle of ram action
the cutting stroke consumes 3/5 of the time and
the return stroke consumes 2/5 of the time. The
formula for determining required machine strokes
12-7
contains a constant that accounts for this partial
time consumption by the cutting stroke.
To determine a cutting stroke value to set
on the shaper speed indicator, first select a
recommended cutting speed for the material you
plan to shape from a chart such as the one shown
in table 12-1.
After you have selected the recommended
cutting speed, determine the ram stroke speed by
using the formula shown below (remember, your
machine may require a slightly different formula):
SPM =
CS
0.14 x LOS
Where: SPM = strokes of the ram per minute
CS = cutting speed in feet per
minute
LOS = length of stroke in inches
0.14 = constant that accounts for
partial ram cycle time and that
converts inches to feet
When you have determined the number of
strokes per minute, set it on the shaper by using
the gear shift lever. A speed (strokes) indicator
plate shows the positions of the lever for a variety
of speeds. Take a few trial cuts and adjust the ram
speed slightly, as necessary, until you obtain the
desired cut on the work.
If after you have adjusted the ram speed, you
want to know the exact cutting speed of the tool,
use the formula:
CS = SPM x LOS x 0.14
The speed of the shaper is regulated by the
gear shift lever. The change gear box, located on
the operator's side of the shaper, lets you change
the speed of the ram and cutting tool according
to the length of the work and the hardness of the
metal. When the driving gear is at a constant
speed, the ram will make the same number of
strokes per minute regardless of whether the
stroke is 4 inches or 12 inches. Therefore, to main-
tain the same cutting speed, the cutting tool must
make three times as many strokes for the 4-inch
cut as it does for the 12-inch cut.
Horizontal feed rates of up to approximately
0.170 inch per stroke are available on most
shapers. There are no hard and fast rules for
selecting a specific feed rate in shaping. Therefore,
when you select feeds, you must rely on past
experience and common sense. Generally, for
making roughing cuts on rigidly held work, set
the feed as heavy as the machine will allow. For
less rigid setups and for finishing, use light feeds
and small depths of cut. The best procedure is to
start with a relatively light feed and increase the
feed until you reach a desirable feed rate.
Shaping a Rectangular Block
An accurately machined rectangular block has
square corners and opposite surfaces that are
parallel to each other. In this discussion, faces are
the surfaces of the block that have the largest
surface area; the ends are the surfaces that limit
the length of the block; and the sides are the
surfaces that limit the width of the block.
The rectangular block can be machined in four
setups when a shaper vise is used. One face and
an end are machined in the first setup. The
opposite face and end are machined in the second
setup. The sides are machined in two similar but
separate setups. For both setups, the vise jaws are
aligned at a right angle to the ram.
To machine a rectangular block from a rough
casting, proceed as follows:
1 . Clamp the casting in the vise so a face is
horizontally level and slightly above the top of
the vise jaws. Allow one end to extend out of the
side of the vise jaws enough so you can take a
cut on the end without unclamping the casting.
Now feed the cutting tool down to the required
depth and take a horizontal cut across the face.
After you have machined the face, readjust the
cutting tool so it will cut across the surface of the
end that extends from the vise. Use the horizontal
motion of the ram and the vertical adjustment of
the toolhead to move the tool across and down
the surface of the end. When you have machined
the end, check to be sure that it is square with
the machined face. If it is not square, adjust the
toolhead swivel to correct the inaccuracy and take
another light finishing cut down the end.
2. To machine the second face and end, turn
the block over and set the previously machined
face on parallels (similar to the method used in
step 1). Insert small strips of paper between each
corner of the block and the parallels. Clamp the
block in the vise and use a soft-face mallet to tap
the block down solidly on the parallels. When the
block is held securely in the vise, machine the
second face and end to the correct thickness and
length dimensions of the block.
12-8
ijrpc u* uictcxi.
\stni uuu sicei LUUI&
niga- speeu sieei LOUIS
Roughing
Finishing
Roughing
Finishing
30
25
20
} »
75
20
40
30
100
100
60
50
40
150
150
40
80
60
200
200
Milri cstpipl --
Tnrvl cfAol „_____..__..___
3. To machine a side, open the vise jaws so
the jaws can be clamped on the ends of the block.
Now set the block on parallels in the vise with the
side extending out of the jaws enough to permit
a cut using the downfeed mechanism. Adjust the
ram for length of stroke and for position to
machine the side and make the cut.
4. Set up and machine the other side as
described in step 3.
Shaping Angular Surfaces
Two methods are used for machining angular
surfaces. For steep angles, such as on V-blocks,
the work is mounted horizontally level and the
toolhead is swiveled to the desired angle. For small
angles of taper, such as on wedges, the work is
mounted on the table at the desired angle from
the horizontal, or the table may be tilted if the
shaper is equipped with a universal table.
To machine a steep angle using the toolhead
swiveled to the proper angle:
1 . Set up the work as you would to machine
a flat surface parallel with the table.
2. Swivel the toolhead (fig. 12-5) to the
required angle. (Swivel the clapper box in the
opposite direction.)
3. Start the machine and, using the manual
feed wheel on the toolhead, feed the tool down
across the workpiece. Use the horizontal feed
control to feed the work into the tool and to
control the depth of cut (thickness of the chip).
(Because the tool is fed manually, be careful to
feed the tool toward the work only during the
return stroke.)
4. Set up and machine the other side as
described in step 3.
Shaping Key ways in Shafts
Occasionally, you may have to cut a key way
in a shaft by using the shaper. Normally, you will
lay out the length and width of the keyway on the
circumference of the shaft. A center line laid out
along the length of the shaft and across the end
of the shaft will make the setup easier (fig. 12-9,
view A). Figure 12-9 also shows holes of the same
diameter as the keyway width and slightly deeper
than the key drilled into the shaft. These holes
are required to provide tool clearance at the
/""""""'1"-"">m"""l' ""Y""""'
j J^ j
I'")""
Figure 12-9. — Cutting a keyway in the middle of a shaft.
12-9
beginning and end of the cutting stroke. The holes
shown in figure 12-9 are located for cutting a blind
key way (not ending at the end of a shaft). If the
key way extends to the end of the shaft, only one
hole is necessary.
To cut a keyway in a shaft, proceed as follows:
1 . Lay out the centerline, the keyway width,
and the clearance hole centers as illustrated in part
A of figure 12-9. Drill the clearance holes.
2. Position the shaft in the shaper vise or on
the worktable so that it is parallel to the ram.
Use a machinist's square to check the centerline
on the end of the shaft to ensure that it is
perpendicular to the surface of the worktable.
This ensures that the keyway layout is exactly
centered at the uppermost height of the shaft, to
provide a keyway that is centered on the
centerlines of the shaft.
3. Adjust the stroke and the position of the
ram, so the forward stroke of the cutting tool ends
at the center of the clearance hole. (If a blind
keyway is being cut, ensure that the cutting tool
has enough clearance at the end of the return
stroke so the tool will remain in the keyway slot.)
(See view B of fig. 12-9.)
4. Position the work under the cutting tool
so that the tool's center is aligned with the
centerline of the keyway. (If the keyway is
over 1/2 inch wide, cut a slot down the center and
shave each side of the slot until you obtain the
proper width.
5. Start the shaper and, using the toolhead
slide, feed the tool down to the depth required,
as indicated by the graduated collar.
Shaping an Internal Keyway
To cut an internal keyway in a gear, you will
have to use extension tools. These tools lack the
rigidity of external tools, and the cutting point
will tend to spring away from the work unless you
take steps to compensate for this condition. The
keyway MUST be in line with the axis of the gear.
Test the alignment with a dial indicator by taking
a reading across the face of the gear; swivel the
vise slightly, if necessary, to correct the alignment.
The bar of the square-nose toolholder should
not extend any farther than necessary from the
shank; otherwise the bar will have too much
"spring" and will allow the tool to be forced out
of the cut.
The extension toolholder should extend as far
as practical below the clapper block, rather than
in the position shown by the dotted lines in view
A of figure 12-10. The pressure angle associated
with the toolholder in the upper position may
cause the pressure of the cut to open the clapper
block slightly and allow the tool to leave the cut.
PRESSURE ANGLE OF
TOOL IN UPPER AND
LOWER POSITIONS
SQUARE NOSE TOOL
X (CROWN)
B
opening. Another method for preventing the
clapper block from opening is to mount the tool
in an inverted position.
With the cutting tool set up as in view A of
figure 12-10, center the tool within the layout lines
in the usual manner, and make the cut to the
proper depth while feeding the toolhead down by
hand. Within the setup in an inverted position,
center the tool within the layout lines at the top
of the hole, and make the cut by feeding the
toolhead upward.
The relative depths to which external and
internal keyways are cut to produce the greatest
strength are illustrated by view B of figure 12-10.
In cutting a key way in the gear, the downfeed
micrometer collar is set to zero at the point where
the cutting tool first touches the edge of the hole.
The crown, X, is first removed from the shaft to
produce a flat whose width is equal to the width
of the key. Then the cut is made in the shaft to
depth Z. The distance of "Y" plus "Z" is equal
to the height of the key that is to lock the two
parts together. (See fig. 12-10.).
Shaping Irregular Surfaces
You can machine irregular surfaces by using
form ground tools and by hand feeding the
cutting tool vertically while using power feed to
move the work horizontally. An example of work
that you might shape by using form tools is a gear
rack. You can shape work such as concave and
convex surfaces by using the toolhead feed. When
you machine irregular surfaces, you have to pay
close close attention because you control the
cutting tool manually. Also in this work you
should lay out the job before you machine it to
provide reference lines. You should also take
roughing cuts to remove excess material to within
1/16 inch of the layout lines.
You can cut RACK TEETH on a shaper as
well as on a planer or a milling machine. During
the machining operation, you may either hold
the work in the vise or clamp it directly to
the worktable. After you have mounted and
positioned the work, rough out the tooth space
in the form of a plain rectangular groove with a
roughing tool, then finish it with a tool ground
to the tooth's finished contour and size.
1 . Clamp the work in the vise or to the table.
2. Position a squaring tool, which is
narrower than the required tooth space, so the
tool is centered on the first tooth space to be cut.
3. Set the graduated dial on the crossfeed
screw to zero, and use it as a guide for spacing
the teeth.
4. Move the toolslide down until the tool just
touches the work and lock the graduated collar
on the toolslide feed screw.
5. Start the machine and feed the toolslide
down slightly less than the whole depth of the
tooth, using the graduated collar as a guide, and
rough out the first tooth space.
6. Raise the tool to clear the work and move
the crossfeed a distance equal to the linear pitch
of the rack tooth by turning the crossfeed lever.
Rough out the second tooth space and repeat this
operation until all spaces are roughed out.
7. Replace the roughing tool with a tool
ground to size for the tooth form desired, and
align the tool.
8. Adjust the work so the tool is properly
aligned with the first tooth space that you rough
cut.
9. Set the graduated dial on the crossfeed
screw at zero and use it as a guide for spacing the
teeth.
10. Move the toolslide down until the tool just
touches the work and lock the graduated collar
on the toolslide feed screw.
1 1 . Feed the toolslide down the whole depth
of the tooth, using the graduated collar as a guide,
and finish the first tooth space.
12. Raise the tool to clear the work and move
the crossfeed a distance equal to the linear pitch
of the rack tooth by turning the crossfeed lever.
13. Finish the second tooth space, then
measure the thickness of the tooth with the gear
tooth vernier caliper. Adjust the toolslide to
compensate for any variation indicated by this
measurement.
14. Repeat the process of indexing and cutting
until you have finished all of the teeth.
Irregular surfaces commonly machined on
the shaper have both CONVEX and CON-
CAVE radii. On one end of the work, lay
out the contour of the finished job. When you
shape to a scribed line, as illustrated in
12-11
figure 12-11, it is good practice to rough cut to
within 1/16 inch of the line. You can do this by
making a series of horizontal cuts using automatic
feed and removing excess stock. Use a left-hand
cutting tool to remove stock on the right side of
the work and a right-hand cutting tool to remove
stock on the left side of the work. When 1/16 inch
of metal remains above the scribed line, take a
file and bevel the edge to the line. This will
eliminate tearing of the line by the breaking of
the chip. Starting at the right-hand side of the
work, set the automatic feed so the horizontal
travel is rather slow and, feeding the tool vertically
by hand, take the finishing cuts to produce a
smooth contoured surface.
VERTICAL SHAPERS
The vertical shaper (slotter) shown in figure
12-12 is especially adapted for slotting internal
holes or key ways with angles up to 10°. Angular
slotting is done by tilting the vertical ram
(fig. 12-12), which reciprocates up and down, to
the required angle. Although different models of
machines will have their control levers in different
locations, all of them will have the same basic
functions and capabilities. The speed of the ram
is adjustable to allow for the various materials and
machining requirements and is expressed in either
strokes per minute or feet per minute, depending
on the particular model. The length and the
position of the ram stroke may also be adjusted.
Automatic feed for the cross and longitudinal
movements, and on some models the rotary move-
ment, is provided by a ratchet mechanism, gear
box, or variable speed hydraulic system, again,
depending on the model. Work may be held in
a vise mounted on the rotary table, clamped
directly to the rotary table, or held by special
fixtures. The square hole in the center of a valve
handwheel is an example of work that can be done
on a machine of this type. The sides of the hole
are cut on a slight angle to match the angled sides
of the square on the valve stem. If this hole were
cut by using a broach or an angular (square) hole
drill, the square would wear prematurely due to
the reduced area of contact between the straight
and angular surfaces.
PLANERS
Planers are rigidly constructed machines,
particularly suitable for machining large and
heavy work where long cuts are required. In
general, planers and shapers can be used for
similar operations. However, the reciprocating
motion of planers is provided by the worktable
(platen), while the cutting tool is fed at a right
Figure 12-ll.~Shaping irregular surfaces.
28.227
VERTICAL
RAM
TOOLHEAD
CUTTING TOOL
ROTARY
TABLE
TRANSVERSE
FEED
HANDWHEEL
LEVER
FEEDING
MECHANISM
COLUMN
BASE
LONGITUDINAL FEED
HANDWHEEL
Figure 12-12. — Vertical shaper.
table makes a quick return to bring the work
into position for the next cut. The size of a planer
is determined by the size of the largest work that
can be clamped and machined on its table; thus
a 30 inch by 30 inch by 6 foot planer is one that
can accommodate work up to these dimensions.
TYPES OF PLANERS
Planers are divided into two general classes,
the OPEN side type and the DOUBLE HOUS-
ING type.
Planers of the open side type (fig. 12-13)
have a single vertical housing to which the
crossrail is attached. The advantage of this
design is that work that is too wide to pass
0W CONTROL IE.VW
CSPESD COHTROO
28.230X
Figure 12-13.— Open side planer.
12-13
between the uprights of a double housing machine
may be planed.
In the double housing planer, the worktable
moves between two vertical housings to which a
crossrail and toolhead are attached. The larger ma-
chines are usually equipped with the cutting heads
mounted to the crossrail as well as a side head
mounted on each housing. With this setup, it is
possible to simultaneously machine both the side
and the top surfaces of work mounted on the table.
CONSTRUCTION AND
MAINTENANCE
All planers consist of five principal parts: the
bed, table, columns, crossrail, and the toolhead.
The bed is a heavy, rigid casting that supports
the entire piece of machinery. On the upper
surface of the bed are the ways on which the
planer table rides.
The table is a cast iron flat surface to which
the work is mounted. The planer table has T-slots
and reamed holes for fastening work to the table.
On the underside of the table there is usually a
gear train or a hydraulic mechanism, which gives
the table its reciprocating motion.
The columns of a double housing planer are
attached to either side of the bed and at one end
of the planer. On the open side planer there is only
one column or housing attached on one side of
the bed. The columns support and carry the
crossrail.
The crossrail serves as the rigid support for
the toolheads. The vertical and horizontal feed
screws on the crossrail enable you to adjust the
machine for various size pieces of work.
The toolhead is similar to that of the shaper
in construction and operation.
All sliding surfaces subject to wear are
provided with adjustments. Keep the gibes
adjusted to take up any looseness due to wear.
OPERATING THE PLANER
Before you operate a planer, be sure you know
where the various controls are and what function
each controls. Once you have mastered the opera-
tion of one model or type of planer you will have
little difficulty in operating others. You should,
however, refer to the manufacturer's technical
manual for the machine you are using for specific
operating instructions. The following sections
contain general information on planer operation.
Table Speeds
The table speeds are controlled by the start-
stop lever and the flow control lever (fig. 12-13).
Two ranges of speeds and a variation of speeds
within each range are available. The speed range
(LOW-MAXIMUM CUT or HIGH-MINIMUM
CUT) is selected by using the start-stop lever, and
the speeds within each range are varied by using
the flow control lever. As the flow control lever
is moved toward the right, the table speed will
gradually increase until it reaches the highest
possible speed.
The LOW speed range is for shaping hard
materials, which require high cutting force at low
speeds. The HIGH range is for softer materials,
which require less cutting force but higher cut-
ting speeds.
The RETURN speed control provides two
return speed ranges (NORMAL and FAST).
When NORMAL is selected, the return speed
varies in ratio with the cutting speed selected. In
FAST, the return speed remains constant (full
speed), independent of the cutting speed setting.
Feeds
Feed adjustment is made by turning the hand-
wheel, which controls the amount of toolhead
feed. Turning the handwheel counterclockwise
increases the feed. The amount of feed can be read
on the graduated dials at the operator's end of
the crossrail feed box. Each graduation indicates
a movement of 0.001 inch.
The direction of feed (right or left, up or
down) of the toolhead is controlled by the lever
on the rear of the feed box. The vertical feed is
engaged or disengaged by the upper of the two
levers on the front of the feed box. Shifting the
rear, or directional, lever to the down position and
engaging the clutch lever by pressing it downward
gives a downward feed to the toolhead. Shifting
the directional lever to the up position gives an
upward feed.
The lower clutch lever on the front of the feed
box engages the horizontal feed of the toolhead.
When the directional lever on the rear of the box
is in the down position, the head is fed toward
the left. When the directional lever is in the up
position, the head is fed toward the right. Shifting
the directional lever to the up position gives an
upward feed.
The ball crank on top of the vertical slide
(toolhead feed) is used to hand feed the toolslide
up or down. A graduated dial directly below the
crank indicates the amount of travel.
The two square-ended shafts at the end of the
crossrail are used to move the toolhead by hand.
03 ill Lilt
neutral, position, and then turn the shaft. The
upper shaft controls vertical movement. The lower
shaft controls horizontal movement.
Lock screws on both the cross-slide saddle and
the vertical slide enable these slides to be locked
in position after the desired tool setting is made.
The planer side head has power vertical feed
and hand horizontal feed. The vertical feed, both
engagement and direction, is controlled by a lever
on the rear of the side head feed box. Vertical
traverse is done by turning the square shaft that
projects from the end of the feed box. Horizontal
movement, both feed and traverse, is done by
using the bellcrank on the end of the toolhead
slide.
Rail Elevation
The crossrail is raised or lowered by a hand-
crank on the squared shaft projecting form the
rear of the rail brace. To move the rail, first loosen
the two clamp nuts at the rear of the column and
the two clamp nuts at the front; then with the
handcrank move the rail to the desired height. Be
sure to tighten the clamp nuts before you do any
machining.
On machines that have power rail elevation,
a motor is mounted within the rail brace and
connected to the elevating mechanism. Operation
of the motor, forward or reverse, is controlled by
pushbuttons. The clamp nuts have the same use
on all machines whether manual or power eleva-
tion is used.
Holding the Work
The various accessories used in planer or
shaper work may make the difference between a
superior job and a poor job. There are no set rules
on the use of planer accessories for clamping
down a piece of work — results will depend on
your ingenuity and experience.
One way to hold down work on the worktable
is by using clamps. The clamps are attached to
the worktable by bolts inserted in the T-slots.
Figure 12-14 illustrates a step block used with the
clamps shown in figure 5-30. At some time you
may have to clamp an irregularly shaped piece of
work to the planer table. One way to do this is
illustrated in figure 12-15; here an accurately
machined step block is used with a gooseneck
clamp. Figure 12-16 illustrates correct and
incorrect ways to apply clamps.
Figure 12-14.— Step block.
-STEP BLOCK GOOSENECK WORK
CLAMP
I
MACHINE TABLE
Figure 12-15. — Application of step block and clamp.
^
.OCK ^ ^BLOCK ^
SS
WORK ^ >
|
WORK /
CORRECT
INCORRECT
CORRECT
INCORRECT
BLOCK
STRIP
BLOCK
WORK
IWORK!
CORRECT
INCORRECT
^
,OCK inl ^-BLOCK iTTl
1 ' ' " . — i x r ' ^i
i
r~ui
i
\ ^
CORRECT INCORRECT
CORRECT
INCORRECT
Figure 12-16. — Correct and incorrect clamp applications.
12-15
For leveling and supporting work on the
planer table, jacks of different sizes are used. The
conical point screw (fig. 12-17) replaces the swivel
pad type screw for use in a corner. Extension bases
(fig. 12-17, C, D, E, and F) are used for increasing
the effective height of the jack.
planer, unlike the surface grinder, has no built-in
protection against the grinding particles left by
the grinding operation.
Observe the same safety precautions for the
shaper as you do for the planer. Always observe
standard machine shop practices.
SURFACE GRINDING
ON THE PLANER
While it is not a recommended practice, it is
possible, with the use of a toolpost grinder, to use
the planer as a surface grinder. Most of the large
tender and repair type ships of the Navy have
surface grinders on board, but due to space
limitations this machine may not always have a
large enough capacity to accommodate large work
pieces. It sometimes may become necessary to use
the planer as a surface grinder. Basically speak-
ing, it is a matter of replacing the toolbit with the
toolpost grinder and computing feeds and speeds
for grinding instead of planing. Prior to
attempting surface grinding on the planer, be sure
you have a thorough understanding of the
material presented in chapter 13 of this manual.
When you have completed the grinding job,
you must clean the planer extensively, both
inside and out. Filter or change the oil in the
hydraulic system prior to further operation. The
PANTOGRAPHS
The pantograph (engraving machine) is
essentially a reproduction machine. It is used in
the Navy for work such as engraving letters and
numbers on label plates, engraving and graduating
dials and collars, and in other work that requires
the exact reproduction of a flat pattern on the
workpiece. The pantograph may be used for
engraving flat and uniformly curved surfaces.
There are several different models of en-
graving machines that you may have to operate.
Figure 12-18 shows one model that mounts on a
bench or a table top and is used primarily for
engraving small items. This particular machine is
manufactured by the New Hermes Engraving
Machine Corporation. It is capable of reproduc-
ing work at ratios ranging from 1:1 to 7:1. A 1
to 1 ratio will result in the work being 1/7 the size
of the pattern.
B. CONICAL POINT;
SCREW
C,D,E, AND F EXTENSION BASES
28.332
Figure 12-18. — Engraving machine.
12-17
The Gorton 3-U pantograph (figure 12-19) is
another engraving machine commonly used by the
Navy. The principles of operation and setup
procedures for the 3-U machine are similar to
those for other models of pantograph type engrav-
ing machines. Because of the similarity in
operating principles and setup procedures, you
should have no difficulty in applying the
information contained in this section to the
operation of any model of pantograph engraver.
PANTOGRAPH ENGRAVER UNITS
The pantograph engraving machine, shown in
figure 12-19, consists of five principal parts: the
supporting base, pantograph assembly, cutterhead
assembly, worktable, and copyholder.
Supporting Base
The supporting base is a heavy, rigid casting,
which supports the entire piece of machinery. If
CONNECTING
LINK
COPY-
HOLDER
TRACER ARM
I
END BOSS
LOWER BAR
FORMING BAR
FORMING GUIDE
CUTTERHEAD
ASSEMBLY
WORKTABLE
CROSSFEED
CONTROL
TRANSVERSE
FEED
VERTICAL FEED
CONTROL
<\
Gorton Pantographs made by FAMCO Machine since 1988
1 UUJ.VJ V CU. 1J.V7JL11 Lilt
on rubber or cork pads.
Pantograph Assembly
The pantograph assembly has four connecting
arms: a tracer arm, an upper bar, a lower bar,
and a connecting link between the tracer arm and
the lower bar. It also has a cutterhead link which
supports the cutterhead. The relationship between
movement of the stylus point and movement of
the cutter is governed by the relative positions of
the sliding blocks on the upper bar and the lower
bar. The pantograph assembly can be set for a
given reduction by loosening the sliding block
bolts and setting the blocks at a desired distance
from the datum lines. This will give the desired
reduction ratio. The upper and lower bar are
inscribed with marks (for whole number and
standard reductions from 2:1 to 16: 1) to indicate
the position for setting the slider blocks for
commonly used reductions.
Cutterhead Assembly
The cutterhead assembly houses the precision
cutter spindle. Pulley drives between the motor
and the spindle enable you to adjust the spindle
speeds. Figure 12-20 gives the spindle speeds and
the arrangement of the drive belts for varying
spindle speeds. At the head of the cutter there is
a vertical feed lever, which provides a range of
limited vertical movement from 1/16 inch to 1/4
inch to prevent the cutter from breaking when it
feeds into work. A plunger locks the spindle for
flat surface engraving or releases it for floating
MOTOR DRIVE SPINDLE
2 l
HJ BS:^^
2-3-A-C 3800 rpm
2-3-A-D 5300 rpm
1-3-A-C 5300 rpm
1-3-A-D 7400 rpm
2-3 -B-C 8100
2-3-B-D 11,000
1-3-B-C 11,000
1-3-B-D I5POO
rpm
rpm
rpm
rpm
Gorton Pantographs made by FAMCO Machine since 1988
28.235X
Figure 12-20.— Spindle speeds.
. . . . . . ,
making it unnecessary to disturb any work by
lowering the table.
Worktable
The cast iron worktable of the 3-U pantograph
engraver measures 8 inches by 12 inches and is
flat and highly polished. It has four 3/8-inch
T-slots cut parallel to its front edge for mounting
a vise or table dogs to hold down a piece of work.
Longitudinal feed can move the worktable 10
inches, while the cross feed can move the table
1 1 inches. Vertical feed of the worktable is 9 3/4
inches.
Copyholder
The copyholder is a steel casting with beveled
grooves or T-slots machined from the solid plate
holder. Standard copyholders for the 3-U
pantograph engravers have four or six grooves.
Two stops are supplied for each groove in the
copyholder.
SETTING COPY
Lettering used with an engraver is known by
various terms — however, the Navy uses the term
copy to designate the characters used as sample
guides. Copy applies specifically to the standard
brass letters, or type, which are set in the
copyholder of the machine and which guide
the pantograph in reproducing. Shapes, as
distinguished from characters, are called templates
or masters.
Copy is not self-spacing; therefore, you should
adjust the spaces between the characters by
inserting suitable blank spacers, which are
furnished with each set of copy. Each line, when
set in the copyholder, should be held firmly
between the clamps.
After setting up the copy in the holder, and
before engraving, be sure that the holder is firmly
set against the stop screws in the copyholder base.
This ensures that the holder is square with the
table. Do not disturb these stops; they were
properly adjusted at the factory, and any change
will throw the copyholder out of square with the
table. The worktable T-slots are parallel with the
table's front edge, making it easy to set the work
and the copy parallel to each other.
12-19
In addition to copy, circular copy plates are
sometimes used for engraving work. A copy plate
is a flat disk with letters, numbers, and other
characters inscribed on the face of the disk near
the rim. The rim of the plate is notched beside
each character so a spring-loaded indexing pawl
can be used to hold the disk in the proper position
during the engraving procedure. The plate is
set on a pivot on the copyholder and may be
rotated 360° so that any character on the
plate may be placed in the required position for
engraving.
SETTING THE PANTOGRAPH
The correct setting of the pantograph is
determined from the ratio of (1) the size of the
\ 20.0390' .
\5Od . 990 ^
'
\J23 .
CONSTANT
?54 .495/rr r>
Upper 3ar Consent -,
,
Centers.
U^7Lj/*<^^
7450" + 3 fir*/, teuton +j). Loner for Cans f art? =^eJ .039 o'+
EXAMPLE: REQUIRED THE SETTINGS IN INCHES FOR REDUCING 4 TO I.
For
4. 0)2O.O39O'
/* 5.0097'
Tracer drm. ..
Centers.
D/srance fo set Me* £cfye or? Lowes'
S/der Bar .leatf from
See
S//der ffar.
first d/^e Me Upper S/tfer Sar Ce/ifer d/s -
torrce /Z.7450' ty tic Deduction
fas <y cor, >s ;/£?/?/ of /.
Upper S//cfer Bar Centers.
.4.O ^
Upper
2.5489'
Subfract /rom^4.2'483'-
"~"
Distance - «- / .6994'
h je/ /ndtx Edye or/ Upper Steer Bar
from (5r<x7t/fff/or/ <?. 5ee~
PANTOGRAPH
SET TO THE
REDUCTION.
4.0
To
for ar/f/ desired
Spec /a/ Sc&Se a/ tfe-
as per <?6ove
or as per" Sd?edu/e o/
Ptece Me 3eve//ed /rttfex
of Me <5Aderj awfft/ /ro/n
fhe L/sies morAec/ J? or/ Me
Bars, She O/s forces
4.O
fike Lower Sti^tf
be se/ es a/ & 5.O/O'
from She U'rre ^ asx? Sfte
i/pper 5//der ff/ocA as a/
1.699' from its Line 2.
Gorton Pantographs made by FAMCO Machine since 1988
work to the size of the copy layout, or (2) the
desired size of engraved characters to the size of
the copy characters. This ratio is called a
reduction. A 1:1 reduction results in an engraved
layout equal in size to the copy layout; a 16:1
reduction results in an engraved layout 1/16 the
size of the copy layout.
If a length of copy is 10 inches and the length
of the finished job is to be 2 inches, divide the
length of the job into the length of the copy:
10 •*- 2 = 5 inches
For this job, set the slider blocks at 5 inches.
If the length of the copy is 1 1 inches and the
length of the finished job is to be 4 inches, the
reduction is:
11 -*• 4 = 2.75 inches
You will note that reduction 2.75 is not marked
on the pantograph bars. To find the correct slider
blocks settings, use the reduction formula in
figure 12-21.
All settings are measured from the first
reduction marking on the upper and lower arms.
On the model 3-U pantograph, reductions are
measured from the line marked 2 on the upper
arm, and NOT the line marked 1. To accurately
set special reductions use a hundredth-inch
scale.
After you have set a special reduction, check
the pantograph. First, place a point into the
spindle, then raise the table until the point barely
clears the table. Next, trace along an edge of a
copy slot in the copyholder with the tracing stylus.
If the cutter point follows parallel to the T-slots,
the reduction is proper. If the point forms an arc
or an angle, recalculate the setting and reset the
sliding blocks. If the point still runs off, loosen
either of the slider blocks and tap it one way or
the other, until the path of the point is parallel
to the T-slots.
For 1:1 reduction, transfer the stylus collet
from the end boss of the tracer arm to the second
boss on the arm. Set the lower slider block on the
graduation marked "1 and 2," and the upper bar
slider block on graduation 1.
Table 12-2 provides dimensions for setting the
slider blocks on the upper and lower bars for
reductions 2 through 16. After setting the
reduction, lock the upper and lower bars in the
slider blocks by tightening the capscrews in each
block.
NOTE: For special reductions between
1 and 2, follow the sample solution in
fig. 12-22.
TRACER ARM
10.0195"
v
EXAMPLE
REQUIRED: THE SETTING IN INCHES FOR REDUCING
1.5 TO I
FOR LOWER SLIDER BAR
STEP1, DIVIDE TRACER ARM CENTERS BY THE
REQUIRED REDUCTION THUS!
TRACER ARM CENTERS 10.0195"
REQUIRED REDUCTION 1.5 = 6'679
STEP2. SUBTRACT THE QUOTIENT FROM THE LOWER
BAR CONSTANT. 10.0195"
- 6.679"
STEP3.
3.340"
THE RESULT IS THE DISTANCE TO SET INDEX
EDGE ON LOWER SLIDER BAR HEAD FROM
GRADUATION 182.
FOR UPPER SLIDER BAR
DIVIDE UPPER SLIDER BAR CENTER
DISTANCE BY THE REDUCTION REQUIRED
PLUS A CONSTANT OF ONE.
REQUIRED REDUCTION 1.5
CONSTANT 1,0
2.5
UPPERSLIDERBAR CENTERS 12.745",
2.5
•• 5.098
STEP2. SUBTRACT THE QUOTIENT FROM THE
UPPER BAR CONSTANT €.3725"
STEP3. THE RESULT IS THE - 5.098 "
DISTANCE TO SET 1.2745"
INDEX EDGE ON UPPER
SLIOER 8A.RHEA.D FROM GRADUATION I.
SCHEDULE OF VARIOUS REDUCTIONS
BETWEEN l:l AND 2:1 ON MOD. 3U
PANTOGRAPH WITH TRACING STYLUS
IN NEAREST HOLE OF ARM.
MEASUREMENTS IN INCHES
REDUCTION
DISTANCE TO SET
INDEX EDGE ON
LOWER SLIDER BAR
HEAD FROM GRAD.
MARKS 1 & Z
DISTANCE TO SET
INDEX EDGE ON
UPPER SLIDER BAR
HEAD FROM GRAD.
MARK 1
.0
. 1
,2
.3
,4
.5
.6
.7
.8
.9
0
.911"
1.670"
2.3 1 2"
2.863"
3.340"
3.757"
4. 1 2 6"
4.453"
4.746"
0
,303"
.579"
.83 1 '
,062"
• 275"
,471 "
,651"
.82 l"
1.978
FOR OTHER REDUCTIONS USE FORMULA
FOR GREATER REDUCTIONS USE SCHEDULE
AS PER NSTRUCTION BOOK WITH TRACING
STYLUS ATEXTREME END OF PANTOGRAPH ARM
Gorton Pantographs made by FAMCO Machine since 1988
Engraving Machine No. 3U
Engraving Machine No. 3U
Reduction
Lower Bar
Inches
Upper Bar
Inches
Reduction
Lower Bar
Millimeters
Upper Bar
Millimeters
2.0
0.000
0.000
2.0
00.00
0.00
2.1
0.477
0.137
2.1
12.12
3.48
2.2
0,911
0.265
2.2
23.14
6.74
2.3
1.307
0.386
2.3
33.19
9.81
2.4
1.670
0.500
2.4
42.42
12.69
2.5
2.004
0.607
2.5
50.90
15.41
2.6
2.312
0.708
2.6
58.73
17.98
2.7
2.598
0.804
2.7
65.98
20.41
2.8
2.863
0.894
2.8
72.71
22.72
2.9
3.109
0.980
2.9
78.98
24.90
3.0
3.340
1.062
3.0
84.83
26.98
3.1
3.555
1.140
3.1
90.30
28.95
3.2
3.757
1.214
3.2
95.44
30.83
3.3
3.947
1.284
3.3
100.26
32.62
3.4
4.126
1.352
3.4
104.79
34.33
3.5
4.294
1.416
3.5
109.07
35.97
3.6
4.453
1.478
3.6
113.11
37.53
3.7
4.604
1.537
3.7
116.93
39.03
3.8
4.746
1.593
3.8
120.55
40.46
3.9
4.881
1.647
3.9
123.98
41.84
4.0
5.010
1.699
4.0
127.25
43.16
4.1
5.132
1.749
4.1
130.35
44.43
4.2
5.248
1.797
4.2
133.31
45.65
4.3
5.359
1.844
4.3
136.13
46.83
4.4
5.465
1.88,8
4.4
138.82
47.96
4.5
5.566
1.931
4.5
141.39
49.05
4.6
5.663
1.972
4.6
143.84
50,10
4.7
5.756
2.012
4.7
146.20
51.11
4.8
5.845
2.051
4.8
148.46
52.09
4.9
5.930
2.088
4.9
150.62
53.04
5.0
6.012
2.124
5.0
152.70
53.95
5.1
6.090
2.159
5.1
154.69
54.84
5.2
6.166
2.193
5.2
156.61
55.69
5.3
6.239
2.225
5.3
158.46
56.52
5.4
6.309
2.257
5.4
160.24
57.33
Gorton Pantographs made by FAMCO Machine since 1988
28.236.01X
12-22
Table 12-2.— Reduction Schedules in Inches and Millimeters — Continued
Schedule of Reductions for
Engraving Machine No. 3U
Schedule of Reductions for
Engraving Machine No. 3U
Reduction
Lower Bar
Inches
Upper Bar
Inches
Reduction
Lower Bar
Millimeters
Upper Bar
Millimeters
5.5
6.376
2.288
5.5
161.95
58.10
5.6
6.441
2.317
5.6
163.60
58.86
5.7
6.504
2.346
5.7
165.20
59.59
5.8
6.564
2.374
5.8
166.74
60.30
5.9
6.623
2.401
5.9
168.23
60.99
6.0
6.680
2.428
6.0
169.66
61.66
6.1
6.734
2.453
6.1
171.05
62.31
6.2
6.787
2.478
6.2
172.40
62.95
6.3
6.839
2.502
6.3
173.70
63.56
6.4
6.888
2.526
6.4
174.97
64.16
6.5
6.937
2.549
6.5
176.19
64.74
6.6
6.983
2.571
6.6
177.38
65.31
6.7
7.029
2.593
6.7
178.53
65.87
6.8
7.073
2.614
6.8
179.64
66.40
6.9
7.115
2.635
6.9
180.73
66.93
7.0
7.157
2.655
7.0
181.78
67.44
7.1
7.197
2.673
7.1
182.81
67.94
7.2
7.236
2.694
7.2
183.80
68.43
7.3
7.274
2.713
7.3
184.77
68.90
7.4
7.312
2.731
7.4
185.71
69.37
7.5
7.348
2.749
7.5
186.63
69.82
7.6
7.383
2.766
7.6
. 187.32
70.26
7.7
7.417
2.783
7.7
188.39
70.70
7.8
7.450
2.800
7.8
189.24
71.12
7.9
7.483
2.816
7.9
190.07
71.53
8.0
7.515
2.832
8.0
190.87
71.94.
9.0
7.793
2.974
9.0
197.94
75.53
10.0
8.016
3.090
10.0
203.60
78.48
11.0
8.198
3.186
11.0
208.22
80.93
12.0
8.350
3.268
12.0
212.08
83.01
13.00
8.478
3.338
13.0
215.34
84.78
14.00
8.588
3.399
14.0
218.13
86.32
15.00
8.683
3.452
15.0
220.56
87.67
16.00
8.767
3.499
16.0
222.68
88.86
Gorton Pantographs made by FAMCO Machine since 1988
28.236.01X
CUTTER SPEEDS
GRINDING CUTTERS
The speeds listed in table 12-3 represent typical
speeds for given materials. In using the table, keep
in mind that the speeds recommended will vary
greatly, depending on the depth of cut, and
particularly the rate at which you feed the cutter
through the work. Since the 3-U engravers are fed
manually, the rate of feed is subject to a wide
variation by individual operations; this will affect
the spindle speeds used.
Run the cutters at highest speeds possible
without burning them, and remove stock with
several light, fast cuts rather than one heavy cut
at slower spindle speeds. When you cut steel and
other hard materials, start with a slow speed and
work up to the fastest speed the cutter will stand
without losing its cutting edge. Sometimes you
may have to sacrifice cutter life to obtain the
smoother finish possible at higher speeds. With
experience you will know when the cutter is
running at its maximum efficiency.
Most of the difficulties experienced in using
very small cutters on small lettering are caused by
improper grinding. The cutter point must be accu-
rately sharpened. When trouble is experienced,
usually the point is burned, or the flat is either
too high or too low. Perhaps the clearance does
not run all the way to the point. Stoning off the
flat with a small fine oilstone will make the
cutting edge keener.
You can make a cutter run almost perfectly
by sharpening it in the spindle in which it will run.
Most pantograph machines have a provision for
removing the cutter spindle from the machine and
placing it in a V-block toolhead on the cutter
grinder. This will allow you to grind the cutter
to the desired shape without removing it from the
cutter spindle.
Grinding Single-Flute Cutters
Before grinding cutters, true up the grinding
wheel with the diamond tool supplied with the
Table 12-3.— Cutter Speeds
Materials and Feeds
Cutter diameter (at cutting point)
1/32"
1/16"
1/8"
3/16"
1/4"
5/16"
3/8"
7/16"
1/2"
Speeds (rpm)
Hardwood (650-800 ft. /min. )
10,000
to
20,000
10,000
to
20,000
10,000
to
20,000
10,000
to
20,000
10,000
to
20,000
9,000
8,000
7,000
6,000
*Bakelite (170-250 ft. /min. )
10,000
8,000
6,000
4,000
3,000
2,200
1,800
1,500
1.300
**Engraver's brass and
aluminum (375-425 ft. /min. )
10,000
to
15,000
10,000
to
15,000
10,000
to
15,000
8,000
6,000
5,000
4,000
3,500
3,000
Cast iron (130-250 ft. /min. )
8,000
7,500
5,500
3,500
2,500
2,000
1,650
1.400
1,200
Hard bronze and machine steel
(80-200 ft. /min. )
7,000
6,000
3,000
2,200
1,600
1,200
975
800
700
Annealed tool steel (70-100 ft. /
min. )
5,000
4.500
2,300
1,600
1,200
1,000
850
725
600
Stainless steel, Monel (45-75
ft. /min. )
3,500
2,750
1,400
1,050
700
575
500
435
350
Very hard die and alloy steels
(30-45 ft./min.)
2.000
1,250
800
600
475
400
350
300
250
the wheel as shown in figure 12-23. Then swing
the diamond across the face of the wheel by
rocking the toolhead in much the same manner
as for grinding a cutter. In dressing the wheel,
your maximum cut should be 0.001 to 0.002 inch.
If the diamond fails to cut freely, turn it slightly
in the toolhead to present an unused portion of
the diamond to the wheel.
ROUGH AND FINISH GRINDING A
CONICAL POINT.— Set the grinder toolhead to
the desired cutting edge angle (fig. 12-24 A). This
angle usually varies from 30 ° to 45 °, depending
on the work desired. For most sunken letter or
design engraving on metal or bakelite plates, a 30 °
angle is used. Now place the cutter in the toolhead
and rough grind it to approximate size by swinging
it across the wheel's face. Do not rotate the cutter
while it is in contact with the face of the wheel
but swing it straight across, turning it slightly
BEFORE or AFTER it makes contact with the
wheel. This will produce a series of flats as in
figure 12-24B. Now, grind off the flats and
produce a smooth cone by feeding the cutter into
the wheel and rotating the cutter at the same time.
The finished cone should look like figure 12-24B,
smooth and entirely free of wheel marks.
l,v/ gJ.llJ.Vl L11V/ lldl.
SIC
Y"V"7:
JSi
Gorton Pantographs made by FAMCO Machine since 1988
28.238X
Figure 12-23. — Position of diamond for truing a grinding
wheel.
Gorton Pantographs made by FAMCO Machine since 1988
28.239X
Figure 12-24.— Grinding a conical point: (A) Cutter angle.
(B) Rough and finished conical shape.
For very small, delicate work it is absolutely
essential to grind this flat EXACTLY to center.
If the flat is oversize, you can readily see it after
grinding the cone, and the point will appear as
in figure 12-25 A. To correct this, grind the flat
to center as in figure 12-25B.
GRINDING THE CHIP CLEARANCE.—
The cutter now has the correct angle and a
cutting edge, but has no chip clearance. This must
be provided to keep the back side of the cutter
from rubbing against the work and heating
excessively, and to allow the hot chips to fly off
readily. The amount of clearance varies with the
angle of the cutter. The procedure for grinding
chip clearance is as follows.
Gently feed the cutter into the face of the
wheel. Do not rotate the cutter. Hold the back
(round side) of the conical point against the wheel.
Rock the cutter continuously across the wheel's
face, without turning it, until you grind a flat that
runs out exactly at the cutter point (fig. 12-26).
Check this very carefully, with a magnifying glass
\
Gorton Pantographs made by FAMCO Machine since 1988
28.240X
Figure 12-25.— Grinding the flat. (A) Flat not ground to
center. (B) Flat ground to center.
CUTTING EDGE
BACK SIDE
OF CUTTER
Gorton Pantographs made by FAMCO Machine since 1988
28.241X
Figure 12-26. — First operation in grinding clearance.
12-25
if necessary, to be sure you have reached the point
with this flat. Be extremely careful not to go
beyond the point.
The next step is to grind away the rest of the
stock on the back of the conical side to the angle
of the flat, up to the cutting edge. Rotate the
conical side against the face of the wheel and
remove the stock as shown in figure 12-24B. Be
extremely careful not to turn the cutter too far
and grind away part of the cutting edge. Clean
up all chatter marks. Be careful of the point; this
is where the cutting is done. If this point is
incorrectly ground, the cutter will not work.
TIPPING OFF THE CUTTER POINT.— For
engraving hairline letters up to 0.0005 inch in
depth, the cutter point is not flattened, or
TIPPED OFF. For all ordinary work, however,
it is best to flatten this point as much as the work
will permit. Otherwise, it is very difficult to
retain a keen edge with such a fine point, and
Table 12-4.— Rake Angles for Single-Flute Cutters
Material to be cut
Angle B (See figs.
12-27).andl2-28j
- 5-10 degrees
10-15 degrees
15-20 degrees
20-25 degrees
20-25 degrees
Table 12-5.— Chip Clearance Table for Square-Nose Cutters
Cutter diameter
Clearance
Cutter diameter
Clearance
Inches
Inches
Inches
Inches
1/10
.004
1/4
.010
1/8
.006
5/16
.012
5/32
.006
3/8
.015
3/16
.008
7/16
.015
1/2
.020
Table 12-6.— Clearance Angles for 3- and 4-Sided Cutters
Degrees of cutting .......
45°
40°
35°
30°
25°
20°
15°
10°
5°
Angle of clearance: (Degrees)
3 sides
26 1/2
23
19 1/2
16
13
10 1/2
7 1/2
5
21/2
35 1/2
23
25 1/2
22 1/2
18 1/2
14 1/2
10
7
3 1/2
when the point wears down, the cutter will
immediately fail to cut cleanly. Tipping off is
usually done by holding the cutter in the hands
at the proper inclination from the grinding wheel
face and touching the cutter very lightly
against the wheel, or by dressing with an oilstone.
Angle A (fig. 12-27) should be approximately 3 °;
this angle causes the cutter to bite into the work
like a drill when it is fed down. Angle B (fig.
12-27) varies, depending on the material to be
engraved. Use table 12-4 as a guide in determining
angle B.
Grinding Square-Nose
Single-Flute Cutters
A properly ground square-nose single-flute
cutter should be similar to the illustration in
WIDE AS POSSIBLE
•af
SEE
TABLE
12-4
figure 12-28. When square-nose cutters are
ground, they should be tipped off in the
same manner as described in connection with
figure 12-27. All square-nose cutters have
peripheral clearance ground back of the cutting
edge. After grinding the flat to center (easily
checked with a micrometer), grind the clearance
by feeding the cutter in the required amount
toward the wheel and turning the cutter until you
have removed all stock from the back (round
side), up to the cutting edge. Table 12-5 provides
information on chip clearance for various sized
cutters.
Grinding Three- and
Four-Sided Cutters
Three- and four-sided cutters (see fig. 12-29)
are used for cutting small steel stamps and for
small engraving where a very smooth finish is
desired. The index plate on the toolhead collet
spindle has numbered index holes for indexing to
grind three-and four-sided cutters.
Set the toolhead for the desired angle. Plug
the pin in the index hole for the desired number
of divisions and grind the flats. Now, without
loosening the cutter in the toolhead collet, reset
the toolhead to the proper clearance angle.
Clearance angles are listed in table 12-6.
Gorton Pantographs made by FAMCO Machine since 1988
28.242X
Figure 12-27. — A tipped off cutter.
SEE TABLE 12-4
Gorton Pantographs made by FAMCO Machine since 1988
28.243X
Figure 12-28.— Square-nose cutter with a properly ground
tip.
PANTOGRAPH ATTACHMENTS
Some attachments commonly used with the
pantograph engraving machine are: copy dial
holders, indexing attachments, forming guides
and rotary tables. The use of these attachments
extends the capabilities of the pantograph
engraving machine from flat, straight line
engraving to include circular work, cylindrical
work, and indexing.
Gorton Pantographs made by FAMCO Machine since 1988
28.244X
Figure 12-29. — Three-sided cutter.
Gorton Pantographs made by FAMCO Machine since 1988
28.245X
Figure 12-30.— Copy dial bolder and plate.
The copy dial holder shown in figure
12-30 is used instead of the regular copy-
holder when a circular copy plate is used.
This holder has a spring-loaded indexing
pawl, which is aligned with the center pivot
hole. This pawl engages in the notches in
a circular copy plate to hold the plate in
the required position for engraving the character
concerned.
An indexing attachment such as that shown
in figure 12-31 may be used for holding cylindrical
work to be graduated. In some cases, the dividing
head (used on the milling machine) is used
for this purpose. The work to be engraved
Gorton Pantographs made by FAMCO Machine since 1988
18
for any number of divisions available on
the plate. Figure 12-31 shows a micrometer
collar being held for graduation and engrav-
ing.
A forming guide (sometimes called a radius
plate) is used to engrave cylindrical surfaces. The
contour of the guide must be the exact opposite
of the work; if the work is concave the guide must
be convex and vice versa. The forming guide is
mounted on the forming bar. (See fig. 12-32.)
When the spindle floating mechanism is released,
the spindle follows the contour of the forming
guide.
The rotary table shown in figure 12-32
is used for holding work such as face dials.
It is similar to the rotary table used on
milling machines. The rotary table is mounted
directly on the worktable and provides a
means of rapid graduation and of engraving the
faces of disks.
USING A CIRCULAR
COPY PLATE
The circular copy plate might be efficiently
used in engraving a number of similar workpieces
with single characters used consecutively. For
example, the following setup can be used to
engrave 26 similar workpieces with a single
letter.
1. Set the workpiece conveniently on the
worktable and clamp two aligning stops in place.
These stops will not be moved until the entire job
is completed.
2. Set the circular plate on the copyholder so
that the plate can be rotated by hand. Check to
ensure that the indexing pawl engages the notch
on the rim so the plate will be steady while you
trace each character.
3 . Set the machine for the required reduction
and speed, and adjust the worktable so the spindle
is in position over the workpiece.
4. Clamp the first workpiece in place on the
worktable. (The aligning stops, step 1, ensure
accurate positioning.)
5. Rotate the circular plate until the letter A
is under the tracing stylus and the index pawl is
engaged in the notch.
6. Engrave the first piece with the letter A.
Check the operation for required adjustments of
the machine.
7. After you have finished the first piece,
remove it from the machine. Do not change the
alignment of the aligning stops (step 1), the
worktable, or the copyholder. Place the second
workpiece in the machine. Index the circular plate
to the next letter and proceed as previously
described.
8. Continue loading the workpieces, indexing
the plate to the next character, engraving, and
removing the work, until you have finished the
job.
ENGRAVING A GRADUATED
COLLAR
To engrave a graduated collar, as shown in
figure 12-31, use a forming guide and indexing
attachment. You can also use the circular copy
plate to speed up the numbering process. After
you have engraved each graduation, index the
work to the next division until you have finished
the graduating. When you engrave numbers with
more than one digit, offset the work angularly by
rotating the work so the numbers are centered on
the required graduation marks.
Gorton Pantographs made by FAMCO Machine since 1988
28.247X
Figure 12-32.— A rotary table.
ENGRAVING A DIAL FACE
Use a rotary table and a circular copy plate
to engrave a dial face, such as the one shown in
12-29
figure 12-33. Note that the figures on the right
side of the dial are oriented differently from
those on the left side; this illustrates the usual
method of positioning characters on dials. The
graduations are radially extended from the center
of the face. The graduations also divide the dial
into eight equal divisions.
To set up and engrave a dial face, proceed as
follows:
1 . Set the reduction required. The size of the
copy on the circular copy plate and the desired
size of numerals on the work are the basis for
computing the reduction.
2. Set the copy plate on the copyholder,
ensuring that it is free to rotate when the ratchet
is disengaged.
3 . Mount a rotary table on the worktable of
the engraver. Position the dial blank on the rotary
table so the center of the dial coincides with the
center of the rotary table. Clamp the dial blank
to the rotary table.
4. Place the tracing stylus in the center of the
circular copy plate and adjust the worktable so
the center of the dial is directly under the point
of the cutter.
Figure 12-33.— A dial face.
5. Rotate the copy plate until the copy
character for making graduation marks is aligned
with the center of the copy plate and the center
of the work. Set the stylus in this mark. Now, by
feeding the worktable straight in toward the back
of the engraver, adjust the table so the cutter will
cut the graduation to the desired length.
6. Start the machine and adjust the engraver
worktable vertically for the proper depth of cut.
Then clamp the table to prevent misalignment of
the work. Any further movement of the work will
be made by the rotary table feed mechanism.
7. Engrave the first graduation mark.
8. Using the rotary table feed wheel, rotate
the dial to the proper position for the next
graduation. As there are eight graduations, rotate
the table 45 °; engrave this mark and continue until
the circle is graduated. You will now be back to
the starting point.
NOTE: Do not move the circular copy plate
during the graduating process.
9. To engrave numbers positioned as shown
on the right side of the dial in figure 12-33, move
the worktable so the cutter is in position for
engraving the numbers. Rotate the circular copy
plate to the numeral 1 and engrave it. Rotate the
rotary table 45 ° and the circular copy plate to 2,
and engrave. Continue this process until you have
engraved all the numbers. If two (or more) digit
numbers are required, offset the dial as previously
described.
10. To engrave the numbers shown on the left
side of the dial in figure 12-33, rotate the copy
plate to the required number and then, using the
cross feed and longitudinal feed of the engraver
table, position the cutter over the work at the
point where the number is required. This method
requires that the worktable be repositioned for
each individual number. As previously stated,
movement of the engraver worktable in two
directions results in angular misalignment of the
character with the radius of the face; in this
example, angular misalignment is required.
PRECISION GRINDING MACHINES
Modern grinding machines are versatile and
are used to perform work of extreme accuracy.
These machines are used primarily for finishing
surfaces that have been machined in other
machine tool operations. Surface grinders,
cylindrical grinders, and tool and cutter grinders,
installed in most repair ships, can perform
practically all of the grinding operations required
in Navy repair work.
A Machinery Repairman must demonstrate an
ability to: (1) mount, dress, and true grind
machine wheels; (2) perform precision grinding
operations using a magnetic chuck; (3) grind cutter
tool bits on a surface grinder for Acme and square
threading; and (4) set up and grind milling cutters
using a tool and cutter grinder.
To perform these jobs, you must have a
knowledge of the construction and principles of
operation of commonly used grinding machines.
You gain proficiency in grinding through
practical experience. Therefore, you should take
every available opportunity to watch or perform
grinding operations from setup to completion.
There are several classes of each type of
grinder. The SURFACE grinder may have either
a rotary or a reciprocating table, and either a
horizontal or vertical spindle. Cylindrical grinders
may be classified as plain, centerless, or internal
grinders. The tool and cutter grinder is basically
a cylindrical grinder. Grinders generally found in
the shipboard machine shop are the reciprocating
table, horizontal spindle (planer type), surface
grinder; the plain cylindrical grinder; the tool and
cutter grinder; and sometimes a universal grinder.
The universal grinder is similar to a tool and
cutter grinder except that it is designed for heavier
work and usually has a power feed system and
a coolant system.
Before operating a grinding machine, you
must understand the underlying principles of
grinding and the purpose and operation of the
various controls and parts of the machine. You
must also know how to set up the work in the
machine. The setup procedures will vary with the
different models and types of machines.
Therefore, you must study the manufacturer's
technical manual to learn specific procedures for
using a particular model of machine.
SPEEDS, FEEDS, AND COOLANTS
As with other machine tools, the selection of
the proper speed, feed, and depth of cut is an
important factor in successful grinding. Also, the
use of coolants may be necessary for some
operations. The definitions of the terms speed,
feed, and depth of cut, as applied to grinding, are
basically the same as for other machining
operations.
INFEED is the depth of cut that the wheel
takes in each pass across the work. TRAVERSE
(longitudinal or cross) is the rate that the work
is moved across the working face of the grinding
wheel. WHEEL SPEED, unless otherwise
defined, means the surface speed in fpm of the
grinding wheel.
WHEEL SPEEDS
Grinding wheel speeds commonly used in
precision grinding vary from 5,500 to 9,500 fpm.
You can change wheel speed by changing the
spindle speed or by using a larger or smaller wheel.
To find the wheel speed in fpm, multiply the
spindle speed (rpm) by the wheel circumference
(inches) and divide the product by 12.
fpm - (cir- *2rpm)
fpm =
rpm
The maximum speed listed on grinding wheels
is not necessarily the speed at which the wheel will
cut best. The maximum speed is based on the
13-1
strength of the wheel and provides a margin of
safety. Usually, the wheel will have better cutting
action at a lower speed than that listed by the
manufacturer as a maximum speed.
One method of determining the proper wheel
speed is to set the wheel speed between the
minimum and maximum speeds recommended by
the wheel's manufacturer. Take a trial cut. If the
wheel acts too soft (wears away too fast), increase
the speed. If the wheel acts too hard (slides over
the work or overheats the work), decrease the
speed.
TRAVERSE (WORK SPEED)
During the surface grinding process, the work
moves in two directions. As a flat workpiece is
being ground (fig. 13-1), it moves under the
grinding wheel from left to right (longitudinal
traverse). The speed at which the work moves
longitudinally is called work speed. The work also
moves gradually from front to rear (cross
traverse), but this movement occurs at the end of
each stroke and does not affect the work speed.
The method for setting cross traverse is discussed
later in this chapter.
A cylindrical workpiece is ground in a manner
similar to the finishing process used on a lathe
(fig. 13-2). As the surface of the cylinder rotates
under the grinding wheel (longitudinal traverse)
the work moves from left to right (cross traverse).
To select the proper work speed, take a cut
with the work speed set at 50 feet per minute. If
the wheel acts too soft, decrease the work speed.
If the wheel acts too hard, increase the work
speed.
Wheel speed and work speed are closely
related. Usually by adjusting one or both, you can
obtain the most suitable combination for efficient
grinding.
GRINDING
wo
1ST. PASS
v i y
2ND. PASS
U
3RD PASS
4RO PASS
M- ~ mm 1
> k
CROSS
TRAVERSE
DEPTH OF CUT
The depth of cut depends on such factors as
the material of which the work is made, heat treat-
ment, wheel and work speed, and condition of
the machine. Roughing cuts should be as heavy
as the machine can take; finishing cuts are usually
0.0005 inch or less. For rough grinding, you might
use a 0.003-inch depth of cut and then, after a
trial cut, adjust the machine until you obtain the
best cutting action.
COOLANTS
The cutting fluids used in grinding operations
are the same fluids used in other machine tool
operations. They are water, water and soluble oil,
water solutions of soda compounds, mineral oils,
paste compounds, and synthetic compounds.
They also serve the same purposes as in other
machine tool operations plus some additional
purposes. As in most machining operations, the
coolant helps to maintain a uniform temperature
between the tool and the work, thus preventing
extreme localized heating. In grinding work,
excessive heat will damage the edges of cutters,
cause warpage, or possibly cause inaccurate
measurements.
In other machine tool operations, the chips
will fall aside and present no great problem; this
is not true in grinding work. If no means is
provided for removing grinding chips, they can
become embedded in the face of the wheel. This
embedding, or loading, will cause unsatisfactory
grinding. and you will need to dress the wheel
LATERAL
TRAVERSE
LONGITUDINAL TRAVERSE
^ CROSS TRAVERSE ^
Figure 13-1.— Surface grinding a flat workpiece.
Figure 13-2. — Surface grinding a cylindrical workpiece.
cutting fluid are to reduce friction between the
wheel and the work and to help produce a good
finish.
In most other machining operations, the
primary property of a cutting fluid is its
lubricating ability. In grinding, however, the
primary property is the cooling ability, with the
lubricating ability second in importance. For this
reason, water is the best possible grinding coolant,
but if used alone, it will rust the machine parts
and the work. Generally, when you use water, you
must add a rust inhibitor. The rust inhibitor has
very little effect on the cooling properties of the
water.
A water and soluble oil mixture gives very
satisfactory cooling results and also improves the
lubricating properties of the cutting fluid. The
addition of the soluble oil to water will alter the
grinding effect to a certain extent. Soluble oil
decreases the tendency of the machine and the
work to rust, thereby eliminating the need for a
rust inhibitor. When you prepare a mixture of
soluble oil and water as a grinding coolant, use
a ratio of three parts of water to one part of oil.
This mixture will generally be satisfactory.
The paste compounds are made of soaps of
either soda or potash, mixed with a light mineral
oil and water to form an emulsion. As a coolant,
these solutions are satisfactory. However, they
have a tendency to retain the grinding chips
and abrasive particles, which may cause un-
satisfactory finishes on the work.
Mineral oils are used primarily for work where
tolerances are extremely small or in such work as
thread grinding, gear grinding, and crush form
grinding. The mineral oils do not have as great
a cooling capacity as water. However, the wheel
face will not load as readily with mineral oils as
with most of the other coolants. Therefore, using
mineral oil allows you to select a finer grit wheel
and requires fewer wheel dressings.
When you select a cutting fluid for a grinding
operation, consider the following characteristics:
9 It should have a high cooling capacity to
reduce cutting temperature.
work
It should prevent chips from sticking to the
personnel.
• It should not cause rust or corrosion.
• It should have a low viscosity to permit
gravity separation of impurities and chips as it is
circulated in the cooling system.
• It should not oxidize or form gummy
deposits which will clog the circulating system.
• It should be transparent, allowing a clear
view of the work.
• It should be safe, particularly in regard to
fire and accident hazards.
• It should not cause skin irritation.
The principles discussed above are basic to
precision grinding machines. You should keep
these principles in mind as you study about the
machines in the remainder of this chapter.
SURFACE GRINDER
Most of the features of the surface grinder
shown in figure 13-3 are common to all planer
IDOWN-FEED HANDWHEELl
• It should be suitable for a variety of
machine operations on different materials,
reducing the number of cutting fluids needed in
the shop.
28.249X
Figure 13-3. — Surface grinder (planer type).
13-3
*V r Wl*!. J.UVV £}*• XA.1XIVA. • A. AS* ISfcbOJ. frf
this machine are a base, a cross traverse table, a
sliding worktable, and a wheelhead. Various
controls and handwheels are used for controlling
the movement of the machine during the grinding
operation.
The base is heavy casting which houses the
wheelhead motor, the hydraulic power feed unit,
and the coolant system. Ways on top of the base
are for mounting the cross traverse table; vertical
ways on the back of the base are for mounting
the wheelhead unit.
The hydraulic power unit includes a motor,
a pump, and piping to provide hydraulic pressure
to the power feed mechanisms on the cross
traverse and sliding tables. The smooth, direct
power provided by the hydraulic unit is very
advantageous in grinding. The piping from this
unit is usually connected to power cylinders under
the traverse table. When the machine is operating
automatically, control valves divert pressurized
hydraulic fluid to the proper cylinder, causing the
table to move in the desired direction. Suitable
bypass and control valves in the hydraulic system
let you stop the traverse table in any position and
regulate the speed of movement of the table within
limits. These valves provide a constant pressure
in the hydraulic system, allowing you to stop the
feed without securing the system.
CROSS TRAVERSE TABLE
The ways on which the cross traverse table are
mounted are parallel to the spindle of the
wheelhead unit. This allows the entire width of
the workpiece to be traversed under the grinding
wheel.
Power feed is provided by a piston in a power
cylinder fastened to the cross traverse table.
Manual feed (by means of a handwheel attached
to a feed screw) is also available. The amount of
cross traverse feed per stroke of the reciprocating
sliding table is determined by the thickness (width)
of the grinding wheel. During roughing cuts, the
work should traverse slightly less than the
thickness of the wheel each time it passes under
the wheel. For finish cuts, decrease the rate until
you obtain the desired finish. When the power
feed mechanism is engaged, the cross traverse
table feeds only at each end of the stroke of the
sliding table (discussed below); the grinding wheel
clears the ends of the workpiece before crossfeed
is made, thereby decreasing side thrust on the
grinding wheel and preventing a poor surface
finish on the ends of the workpiece.
grinding machines in shipboard machine shops is
usually 12 inches or less. It is not necessary to
traverse the full limit for each job. To limit the
cross traverse to the width of the work being
ground, use the adjustable cross traverse stop dogs
which actuate the power cross traverse control
valves.
SLIDING TABLE
The sliding table is mounted on ways on the
top of the cross traverse table. Recall that the
sliding table moves from left to right, carrying the
workpiece under the grinding wheel.
The top of the sliding table has T-slots
machined in it so work or workholding devices
(such as magnetic chucks or vises) can be clamped
onto the table. The sliding table may be traversed
manually or by power.
The power feed of the table is similar to that
of the cross traverse table. During manual
traverse, a pinion turned by a handwheel engages
a rack attached to the bottom of the sliding table.
During manual operation of the sliding table,
table stop dogs limit the length of stroke. When
power feed is used, table reverse dogs reverse the
direction of movement of the table at each end
of the stroke. The reverse dogs actuate the
control valve to shift the hydraulic feed pressure
from one end of the power cylinder to the other.
The rate of speed of the sliding table, given
in feet per minute (fpm), can usually be adjusted
within a wide range to give the most suitable speed
for grinding.
WHEELHEAD
The wheelhead carries the motor-driven
grinding wheel spindle. You can adjust the
wheelhead vertically to feed the grinding wheel
into the work by turning a lead screw type of
mechanism similar to that used on the cross
traverse table. A graduated collar on the hand-
wheel lets you keep track of the depth of cut.
The wheelhead movement is not usually power
fed because the depth of cut is quite small and
any large movement is needed only in setting up
the machine. The adjusting mechanism is quite
sensitive; the depth of cut can be adjusted in
amounts as small as 0.0001 inch.
WORKHOLDING DEVICES
Since surface grinding is usually done on flat
workpieces, most surface grinders have magnetic
13-4
chucks. These chucks are simple to use; the work
can be mounted directly on the chuck or on angle
plates, parallels, or other devices mounted on the
chuck. Nonmagnetic materials cannot be held in
the magnetic chuck unless special setups are used.
The universal vise is usually used when
complex angles must be ground on a workpiece.
The vise may be mounted directly on the
worktable of the grinder or on the magnetic
chuck.
Magnetic Chucks
The top of a magnetic chuck (see fig. 13-4)
is a series of magnetic poles separated by non-
magnetic materials. The magnetism of the chuck
may be induced by permanent magnets or by
electricity. In a permanent type magnetic chuck,
the chuck control lever positions a series of small
magnets inside the chuck to hold the work. In an
electromagnetic chuck, electric current induces
magnetism in the chuck; the control lever is an
electric switch. For either chuck, work will not
remain in place unless it contacts at least two poles
of the chuck.
Work held in a magnetic chuck may become
magnetized during the grinding operation. This
is not usually desirable and the work should be
demagnetized. Most modern magnetic chucks are
equipped with demagnetizers.
A magnetic chuck will become worn and
scratched after repeated use and will not produce
the accurate results normally required of a
grinder. You can remove small burrs by hand
stoning with a fine grade oilstone. But you must
regrind the chuck to remove deep scratches and
low spots caused by wear. If you remove the
chuck from the grinder, be sure to regrind the
chuck table when you replace the chuck to ensure
that the table is parallel with the grinder table.
To grind the table, use a soft grade wheel with
a grit size of about 46. Feed the chuck slowly with
Figure 13-4. — Magnetic chuck used for holding a tool grinding jig.
13-5
a depth of cut that does not exceed 0.002 inch.
Use ample coolant to help reduce heat and flush
away the grinding chips.
Universal Vise
The universal vise (fig. 13-5) can be used for
setting up work, such as lathe tools, so the
surface to be ground can be positioned at any
angle. The swivels can be rotated through 360°.
The base swivel (A of fig. 13-5) can be rotated
in a horizontal plane; the intermediate swivel (B
of fig. 13-5) can be rotated in a vertical plane; the
vise swivel (C of fig. 13-5) can be rotated in either
a vertical or a horizontal plane depending on the
position of the intermediate swivel.
USING THE SURFACE GRINDER
To grind a hardened steel spacer similar to the
one mounted on the magnetic chuck in figure
13-6, proceed as follows:
1 . Place the workpiece on the magnetic chuck.
Move the chuck lever to the position that energizes
the magnetic field.
28.251
Figure 13-5. — Universal vise (mounted on a tool and cutter
grinder). (A) Base swivel; (B) Intermediate swivel; (C)
Vise swivel.
Figure 13-6. — Grinding a spacer on a surface grinder.
2. Select and mount an appropriate grinding
wheel. This job requires a straight type wheel with
a designation similar to A60F12V.
3 . Set the table stop dogs so the sliding table
will move the work clear of the wheel at each end
of the stroke. If you will be using power traverse,
set the table reverse dogs.
4. Set the longitudinal traverse speed of the
worktable. For rough grinding hardened steel, use
a speed of about 25 fpm; for finishing, use 40
fpm.
5. Set the cross traverse mechanism so the
table moves under the wheel a distance slightly
less than the width of the wheel after each pass.
(Refer to the manufacturer's technical manual for
specific procedures for steps 4 and 5.)
6. Start the spindle motor; let the machine run
for a few minutes and then dress the wheel.
7. Feed the moving wheel down until it just
touches the work surface; then move the work
clear of the wheel, using the manual cross traverse
handwheel. Set the graduated feed collar on zero
to keep track of how much you feed the wheel
into the work.
8. Feed the wheel down about 0.002 inch and
engage the longitudinal power traverse. Using the
cross traverse handwheel, bring the grinding wheel
into contact with the edge of the workpiece.
9. Engage the power cross traverse and let the
wheel grind across the surface of the workpiece.
Carefully note the cutting action to determine if
you need to adjust the wheel speed or the work
sneed .
10. Stop the longitudinal and cross traverses
and check the workpiece.
Figure 13-5 shows a universal vise being used
on a tool and cutter grinder in grinding a lathe
tool bit. For this job, the base swivel (A) is set
to the required side cutting edge angle, the
intermediate swivel (B) is set to the side clearance
angle, and the vise swivel (C) is set so the vise jaws
are parallel to the table. A cup type wheel is then
used to grind the side of the tool. The universal
vise is reset to cut the end and top of the tool after
the side is ground.
The universal vise can be used on a surface
grinder for very accurate grinding of lathe
cutting tools such as threading tools. For example,
to grind an Acme threading tool, set the vise
swivel at 14 1/2° from parallel to the table. Set
the intermediate swivel to the clearance angle. Set
the base swivel so the tool blank (held in the vise
jaws) is parallel to the spindle of the grinder.
Remember to leave the tool blank extending far
enough out of the end of the vise jaws to prevent
the grinding wheel from hitting the vise. After
grinding one side of the tool bit, turn it one-half
turn in the vise and set the intermediate swivel to
an equal but opposite angle to the angle set for
the first side. This setting will result in a clearance
equal to the clearance of the first side.
Another method for grinding single point tools
is to hold the tool in a special jig as illustrated
in figure 13-4. The jig surfaces are cut at the angles
necessary to hold the tool so the angles of the tool
bit are formed properly.
When you use either method for grinding tool
bits, check the tool bit occasionally with an
appropriate gauge until you have obtained the
correct dimensions. To save time, rough grind the
tool bit to approximate size on a bench grinder
before you set the tool bit in the jig.
CYLINDRICAL GRINDER
The cylindrical grinder is used for grinding
work such as round shafts. Although many of the
construction features of the cylindrical grinder are
similar to those of the surface grinder, there is
a considerable difference in the functions of the
components. Cylindrical grinders have no cross
traverse table. An additional piece of equipment
(the workhead) is mounted on the sliding table,
and the wheelhead spindle is parallel to the sliding
table. See figure 13-7.
IWORKHEADl
[WHEELHEADI
JFOOTSTOGKl
TAPER TABLE
ADJUSTING DEVICE
28.252
Figure 13-7. — Cylindrical grinder (with workhead and footstock mounted).
As in the surface grinder, the base of this
machine contains a hydraulic power unit and a
coolant system. Longitudinal ways support the
sliding table. Horizontal ways (at right angles to
the longitudinal ways) permit the wheelhead to
move toward or away from the workpiece. This
horizontal movement is used for feeding the
grinding wheel into the work for a depth of cut.
SLIDING TABLE
The sliding table of the cylindrical grinder is
mounted directly on the longitudinal ways. This
table moves back and forth to traverse the work
longitudinally along the width of the grinding
wheel.
An adjustable taper table, located on top of
the sliding table, is used for grinding long (small
angle) tapers on the workpiece. The taper table
is adjusted like the taper attachment on a lathe.
Workholding devices are clamped on top of the
taper table.
The motor-driven workhead is mounted on the
taper table. This component holds and rotates the
work during the grinding cut. Variable speed drive
motors or step pulleys are provided for changing
the rate of rotating speed for the workpiece to
meet the requirements of the job.
A chuck, a center, or a faceplate can be used
to mount work on the workhead. Center rests and
steady rests are also used in conjunction with
the workhead for mounting long workpieces for
cylindrical grinding.
On most cylindrical grinders used by the Navy,
the workhead is mounted on a swivel base to
provide a way to set the work for grinding
relatively large taper angles.
WHEELHEAD
The wheelhead of a cylindrical grinder moves
on the horizontal ways (platen). Since cylindrical
grinding is done with the axis of the spindle level
with the center of the work, no vertical movement
of the wheelhead is necessary. Some wheelheads
are mounted on swivel bases to provide versatility
in taper and angle grinding setups.
USING THE CYLINDRICAL GRINDER
The methods used for setting up stock in a
cylindrical grinder are similar to the methods used
for lathe setups. Work to be ground between
centers is usually machined to approximate size
between centers on a lathe. The same center holes
are then used for the grinding setup. Center rests
or steady rests (as applicable) are used to support
long work or overhanging ends. Short workpieces
can be held in chucks. For internal grinding (on
machines that have an internal grinding spindle),
the work is held in a chuck; steady rests are used,
if necessary, for support.
To set up a workpiece for grinding between
centers proceed as follows:
1 . Ensure that the centers in the workhead
and the footstock and the center holes in the
workpiece are in good condition.
2. Clamp a driving dog onto the workpiece.
3. Position the workhead and footstock and
set the traverse stop dogs so that when the
workpiece is in place, the table will traverse
(longitudinally) the proper distance to grind the
surface.
4. Ensure that the workhead swivel, the
taper table attachment, and the wheelhead swivel
are set properly for straight cylindrical grinding
(or for the taper or angle required if you plan to
grind an angle or a taper.)
5. Adjust the workhead speed mechanism to
get the proper rotational speed. A slow speed is
usually used for roughing, while a high speed is
used for finishing.
6. Set the longitudinal traverse speed so the
work advances from 2/3 to 3/4 the thickness of
the wheel during each revolution of the workpiece.
Fast traverse feed is used for roughing and a slow
feed is used for finishing.
7. Set the workpiece in place and clamp the
footstock spindle after ensuring that both centers
are seated properly and that the driving dog is not
binding.
8. Select and mount the grinding wheel.
9. Start the spindle motor, hydraulic power
pump, and coolant pump. After the machine has
run for a few minutes, start the coolant flow and
dress the wheel.
10. Using the cross traverse mechanism, bring
the wheel up to the workpiece and traverse the
table longitudinally by hand to see that the wheel
will travel through the cycle without hitting any
projections. (About one-half of the wheel width
should remain on the work at each end of the
longitudinal traverse stroke.) Clamp the table dogs
in the correct positions to limit longitudinal
traverse.
1 1 . Start the workhead motor and feed the
grinding wheel in sufficiently to make a cleanup
cut (a light cut the entire length of the surface to
be ground).
workhead motor and wheelhead rotation, and
check the workpiece for taper. Make any changes
required. (If you are using the taper table attach-
ment and an adjustment is necessary at this point,
dress the wheel again).
We have not provided specific information on
how to set the various controls and speeds because
there is a variation for each machine. Check the
manufacturer's technical manual for your
machine for this information.
TOOL AND CUTTER GRINDER
The tool and cutter grinder (fig. 3-8) has a
combination of the features of the plain
cylindrical grinder and the planer type surface
grinder. A tool and cutter grinder is used primarily
for grinding multi-edged cutting tools such as
milling cutters, reamers, and taps. The worktable
has the same basic construction features as the
surface grinder, but a taper table is mounted on
the sliding table so you can grind tools that have
small tapers such as tapered reamers.
WHEELHEAD
The wheelhead is adjustable in two directions.
It can be moved vertically on its support column
grinding wheel, simply rotate the wheelhead
180°. Additionally, the spindle is double ended,
allowing you to mount two wheels on the
wheelhead.
WORKHEAD
The basic workholding devices used on the
tool and cutter grinder are the workhead and the
footstock (fig. 13-8). When a workhead is not
provided, you can use a left-hand footstock
similar to the right-hand footstock shown
mounted on the table in figure 13-8. Also, a
variety of tooth rests (for supporting and guiding
the teeth of a cutter being sharpened) are usually
provided.
A distinctive feature of most tool and cutter
grinders is that there are control handwheels at
both the back and the front of the machine. The
dual controls permit you to stand in the most
convenient position to view the work and still
operate the machine. You can usually disengage
the sliding table hand wheel to push the table back
and forth by hand. Graduated collars on the
handwheels are a quick visible guide to indicate
the amount of movement of the various feed
components.
WORK HEAD
WHEEL HEAD FOOTSTOCK
Figure 13-8. — Tool and cutter grinder (workhead and footstock).
13-9
CUTTER SHARPENING
The working efficiency of a cutter is largely
determined by the keenness of its cutting edge.
Consequently, a cutter must be sharpened at the
first sign of dullness. A dull cutter not only leaves
a poorly finished surface, but also may be
damaged beyond repair if you continue to use it
in this condition. A good rule for determining
when to sharpen a cutter is to sharpen it when the
wear land on the cutting edge is between 0.010
and 0.035 inch. Sharpening cutters at the first sign
of dullness is both economical and a sign of good
workmanship.
Cutters to be sharpened may be divided into
two groups: (1) those that are sharpened on the
relief and (2) those that are sharpened on the face.
Figure 13-9.— Tool grinding setups on a tool and cutter
grinder. (A) Straight wheel grinding a milling cutter.
(B) Cup wheel grinding a reamer.
In the first group are such cutters as plain milling,
side milling, stagger tooth, angle cutters, and end
mills. In the second group are the various form
cutters such as involute gear cutters and taps. The
relief on the second type of cutter is provided
when it is manufactured; the faces of the teeth
are ground to sharpen them.
Figure 13-9 shows two methods for grinding
cylindrical cutting tools on a tool and cutter
grinder. Part A of figure 13-9 shows a setup for
grinding a staggered tooth cutter using a straight
wheel. Part B of figure 13-9 shows a setup for
grinding a reamer using a cup type wheel. Either
type of wheel can be used; the cup type wheel
produces a straight clearance angle; the straight
wheel produces a hollow ground clearance angle.
When you use the straight wheel, set the
spindle parallel to the table. When you use a
flaring cup wheel, turn the spindle at an angle of
89° to the table. This provides the necessary
clearance for the trailing edge of the grinding
wheel as it is traversed along the cutter.
When you grind a cutter, you should have the
grinding wheel rotating as shown in B of figure
13-10. This method tends to keep the tooth of the
cutter firmly against the tooth rest, ensuring a
correct cutting edge. If this method causes too
much burring on the cutting edge, you may reverse
the direction of wheel rotation as shown in A of
figure 13-10. If you use the latter method, ensure
B
28.257X
Figure 13-10. — Direction of wheel rotation. (A) Toward the
cutting edge. (B) Away from the cutting edge.
126.46X
Figure 13-11. — Typical tooth rest blades.
that the tooth being ground rests firmly on the
tooth rest during the cut.
Dressing and Truing
Sharpening a high-speed steel cutter or reamer
generally requires a soft grade wheel. A soft grade
wheel breaks down easily and is therefore less
likely to burn the cutter. You should true and
dress the wheel prior to starting the sharpening
operation and then re-dress as necessary,
depending on the amount of wheel wear. As you
grind each cutter tooth, the grinding wheel
diameter decreases because of wear. As a result,
succeeding teeth have less metal removed and the
teeth gradually increase in size.
To compensate for wheel wear and to ensure
that all the teeth are the same size, rotate the
cutter 180° and grind all the teeth again. Be
careful not to grind the cutter under size.
126.47X
Figure 13-12. — L-shaped tooth rest blade.
To ensure a good cutting edge on the cutter,
there must be a good finish on the clearance angle;
therefore, you will occasionally need to dress the
grinding wheel. Use the wheel truing attachment
for this operation and for the initial truing and
dressing operation on the wheel.
Tooth Rest Blades and Holders
Tooth rest blades are not carried in stock, so
they must be made in the shop. Once you under-
stand the requirements for the blades, you will
be able to readily fabricate various shapes to suit
the types of cutters you will sharpen. It is normally
recommended that these blades be made of spring
steel.
The plain (straight) tooth rest blade (A in fig.
13-11) is used for sharpening side milling cutters,
end mills, straight-fluted reamers, or any straight-
fluted cutter. The rounded tooth rest blade (B in
fig. 13-1 1) is used for helix cutters, shell end mills,
and small end mills. The offset tooth rest blade
(C in fig. 13-11) is a universal blade that can be
used for most applications. The L-shaped tooth
rest blade for sharpening metal slitting saws and
straight tooth plain milling cutters with closely
spaced teeth is shown in figure 13-12. You can
make other shapes of tooth rest blades to fit the
specific type of cutter or the cutter grinder you
are using.
Holders for the tooth rest blades may be either
plain or universal. Figure 13-13A shows a tooth
126.48X
I /Th\ T1 A* j. » i i_ •__ • . I 1. ^
rest blade in a plain holder and figure 13-13B
shows a tooth rest blade mounted in a universal
type holder. The universal tooth rest holder has
a micrometer adjustment at its bottom to enable
you to make precise up and down movements in
the final positioning of the blade.
SETTING THE
CLEARANCE ANGLE
Correct clearance back of the cutting edge of
any tool is essential. With insufficient clearance,
the teeth will drag, producing friction and slow
cutting. Too much clearance produces chatter and
dulls the teeth rapidly. The cutting edge must have
strength, and the correct clearance will provide
this strength. Figure 13-14 shows a typical cutter
tooth and the angles produced by grinding.
The primary clearance angle is the angle
ground when a cutter requires sharpening. The
number of degrees in the primary clearance angle
varies according to the diameter of the cutter and
the material being cut. A large diameter cutter
requires less clearance than a small cutter. Cutters
used to cut hard materials such as alloy and tool
steels require less clearance than cutters used to
cut softer materials such as brass and aluminum.
The primary clearance angles range from 4 °
for a large cutter to 13 ° for a smaller cutter. Some
manufacturers of tool and cutter grinders have
charts that can assist you in determining the
correct clearance angle. The width of the primary
land (the surface created when the primary
clearance angle is ground) varies according to the
size of the cutter. Primary land widths range
•PRIMARY
LAND
PRIMARY
CLEARANCE
ANGLE
SECONDARY
CLEARANCE
ANGLE
from 0.0005-0.015 inch for a small cutter to
0.030-0.062 inch for a large cutter. You should
grind the lands very carefully. A land that is too
narrow will allow the cutting edge to chip or wear
rapidly. A land that is too wide will cause the
trailing side (heel) of the land to rub the work.
When the width of the primary land becomes
excessive due to repeated grindings, you must
grind the secondary clearance angle to reduce it.
The secondary clearance angle is normally 3 ° to
5 ° greater than the primary clearance angle.
You obtain the desired clearance angle by the
positioning of the grinding wheel, the cutter, and
the tooth rest. The general procedure is to
position the center of the wheel, the center of the
work, and the tooth rest all in the same plane and
to then raise or lower the wheel head the proper
distance to give the desired clearance angle.
When you use the straight wheel, bring the
center of the wheel and the center of the work into
the same plane by using the centering gauge
(fig. 13-15) or by using a height gauge. Then,
fasten the tooth rest to the machine table and
adjust the tooth rest to the same height as the
center of the work. Raise or lower the wheelhead
a predetermined amount to give the correct
clearance angle. To determine the amount to raise
or lower the wheelhead, multiply the clearance
angle (in degrees) by the diameter of the wheel
(inches) and then multiply this product by the
constant 0.0087.
V/IX
126.49X
the clearance angle (in degrees) by the diameter
of the cutter (in inches) and then multiply this
product by the constant 0.0087.
Some tool and cutter grinders have a tilting
wheelhead or a clearance setting device. Where
a tilting wheelhead is provided, simply tilt the
wheelhead to the desired clearance angle. If you
use a clearance setting device, follow the steps
listed below.
1 . Clamp a dog to the mandrel on which the
cutter is mounted.
2. Insert the pin on the side of the dog into
the hole in the clearance setting plate that is
mounted on the footstock.
3 . Loosen the setscrew in the clearance setting
plate and rotate the cutter to the desired setting
(graduations found on the clearance setting plate).
4. Tighten the setscrew.
5. Remove the dog.
When you grind the teeth of end mills, side
milling cutters, or stagger tooth cutters, use the
graduated dials on the workhead to set the
clearance angle.
CUTTER SHARPENING SETUPS
Tool and cutter grinders vary in design and
in the type of accessory equipment; however, most
tool and cutter grinders operate in the same way.
By using only the standard workhead, footstocks,
and tooth rest blade holders, you can sharpen
practically any cutter. In fact, you can sharpen
most cutters by using essentially the same method.
A thorough study of the following sections, along
with a little ingenuity and forethought, will enable
you to sharpen any cutter that may be sent to your
shop for sharpening.
PLAIN MILLING CUTTERS
(HELICAL TEETH)
The following is a somewhat detailed explana-
tion of how to sharpen a plain milling cutter with
helical teeth. We have provided the detail because
ine laoie ana me oouoms 01 me
footstocks.
3. Mount the footstocks on the table,
allowing just enough space between them to
accommodate the mandrel with a slight amount
of tension on the spring-loaded center.
4. Swivel the wheelhead to 89°. (This allows
the end of the cutter to clear the opposite cutting
face when you use a cup type wheel.)
5. Mount the wheel and the wheel guard.
6. Use a dressing stick to thin the cutting face
of the wheel to not more than 1/8 inch. True the
wheel, using a diamond truing device.
7. Using the centering gauge, bring the
wheelhead axis into the same horizontal plane as
the axis of the footstock centers.
8. Mount the cutter on a mandrel. (A
knurled sleeve on the end of the mandrel will help
the mandrel maintain an even, effective grip while
the cutter is being ground.
9. Mount the mandrel between the footstock
centers, preferably in such a position that the
grinding wheel cuts onto the cutting edge of the
teeth.
10. Mount the plain tooth rest holder (with
a rounded tooth rest blade) on the wheelhead.
1 1 . With the centering gauge on top of the
wheelhead and the tip of the gauge directly in
front of the cutting face of the wheel, adjust the
tooth rest blade to gauge height. (This brings the
blade into the same horizontal plane as the
footstock centers.)
12. Traverse the saddle toward the wheelhead
until one tooth rests on the tooth rest blade; then
lock the table into position.
13. With a cutter tooth resting on the tooth
rest, lower the wheelhead until the desired
clearance is indicated on the clearance setting
plate. If no clearance setting device is available,
calculate the distance to lower the wheelhead using
the method previously described.
Before starting the sharpening operation, run
through it without the machine running. This will
let you get the feel of the machine and also ensure
that there is nothing to obstruct the grinding
operation. Traverse the table with one hand while
the other hand holds the cutter against the tooth
rest blade. On the return movement, the tooth rest
13-13
Figure 13-16.— Grinding the side teeth of side-milling
cutter.
Figure 13-17. — Changing clearance angle by swiveling the
cutter in a vertical plane.
blade will cause the mandrel to turn in your hand,
thereby eliminating the necessity of moving the
table away from the wheel on the return traverse.
In sharpening the teeth of any milling cutter,
grind one tooth, then rotate the cutter 180° and
grind another tooth. Check the teeth with a
micrometer to ensure that there is no taper being
ground. If there is taper, you must remove it by
swiveling the swivel table of the machine.
As the width of the land increases with
repeated sharpenings, you will need to grind a
secondary land on the cutter. Never allow the
primary land to become greater than 1/16 inch
wide because the heel of the tooth may drag on
the work. To control the width of the primary
land, double the clearance angle and grind a
secondary land.
SIDE MILLING CUTTERS
The peripheral teeth of a side milling cutter
are ground in exactly the same manner as the teeth
of a plain milling cutter, with the exception that
a plain tooth rest blade is used.
To sharpen the side teeth, mount the cutter
on a stub arbor and clamp the arbor in a universal
workhead. Then mount a universal tooth rest
holder onto the workhead so that when the
workhead is tilted the tooth rest holder moves with
it (fig. 13-16).
The procedure for grinding clearance angles
varies, depending on the type of grinding wheel
used. If you are using a cup wheel, swivel the
workhead vertically to move the tooth toward or
away from the wheel. The clearance angle
•iiU"^"*
Figure 13-18. — Changing the clearance angle by raising the grinding wheel.
increases as the tooth is swivelled away from the
wheel (fig. 13-17). If you use a straight wheel, set
the cutter arbor horizontally and raise or lower
the wheel to change the clearance angle. The
clearance angle increases as the wheel is raised
(fig. 13-18).
STAGGERED TOOTH CUTTERS
Staggered tooth milling cutters (fig. 13-19)
may be sharpened in exactly the same manner as
plain milling cutters wij:h helical teeth (fig. 13-20).
If you use this method, grind all of the teeth on
Figure 13-19.— Staggered-tooth side milling cutter.
BROWN & SHARPS Manufacturing Company, North Kingstown, RI
28.434X
Figure 13-20. — Tooth rest mounted on the wheelhead in
grinding a helical-tooth cutter.
one side of the cutter. Then turn the cutter over
and grind all of the teeth on the other side.
There is, however, a method for sharpening
all of the cutter's teeth in one setting (see setup,
fig. 13-9A).
1. Mount the cutter on a mandrel held
between centers.
2. Fasten the tooth rest holder to the
wheelhead.
3 . Grind the tool rest blade to the helix angle
of the cutter teeth on each side of the blade
(fig. 13-21).
4. Position the high point of the tooth rest
blade in the center of the cutting face of the wheel.
5. Align the wheelhead shaft centerline, the
footstock centers, and the high point of the tooth
rest blade in the same horizontal plane.
6. Raise or lower the wheelhead to give the
desired clearance angle.
7. Rest the face of a tooth on its corre-
sponding side of the tooth rest blade (fig. 13-22).
Figure 13-21. — Tooth rest blades for staggered tooth cutters.
TOOTH
TOOTH
REST
BLADE
Figure 13-22.— Resting the face of a tooth on its
corresponding side of the tooth rest blade.
8. Move the cutting edge of the tooth across
the face of the wheel. On the return cut, rest the
next tooth on the opposite angle of the tooth rest.
Continue alternating teeth on each pass until you
have sharpened all the teeth.
ANGULAR CUTTERS
To sharpen an angular cutter, mount the
cutter on a stub arbor and mount the arbor in a
universal workhead. Then swivel the workhead
on its base to the angle of the cutter. If the cutter
has helical teeth, mount the tooth rest on the
wheelhead. But if the cutter has straight teeth,
mount the tooth rest on the table or on the
workhead. To set the clearance angle for both
types of teeth, tilt the workhead the required
number of degrees toward or away from the
grinding wheel. Then use a centering gauge to
align the cutting edge of one tooth parallel
with the cutting face of the wheel. Take a
light cut to check your settings and make fine
adjustments until you obtain the desired clearance
angle.
END MILLS
You may salvage a damaged end mill by
cutting off the damaged portion with a cylindrical
grinding attachment, as shown in figure 13-23.
When you salvage an end mill in this manner, use
a coolant if possible to avoid removing the temper
at the end of the cutter. Be sure to relieve the
center of the end in the same way as on the
original cutter.
Generally, it will not be necessary to sharpen
the peripheral teeth. If, however, the peripheral
teeth must be ground, use the same procedure that
you would use to sharpen a plain milling cutter
except for the method of mounting the cutter.
Mount the end mill in a universal workhead
(fig. 13-24) instead of between centers. You must
remember that whenever you grind the peripheral
teeth of an end mill you change the size (diameter)
126.51X
Figure 13-23. — Cutting off the damaged end of a helical end mill.
Figure 13-24.— Grinding the peripheral teeth of an end mill.
126.52X
of the cutter. You must, therefore, indicate that
the cutter size has been changed. Either mark the
new size on the cutter or grind off the old size
and leave the cutter unmarked.
Use the following steps to sharpen the end
teeth:
1. Mount the end mill in a universal
workhead.
2. Swivel the wheelhead to 89 °.
3. Bring the cutting edge of a tooth into the
same horizontal plane as the wheelhead spindle
axis by using a centering gauge. Place the gauge
on top of the wheelhead and raise or lower the
wheelhead sufficiently to place the blade of the
gauge on the tooth's cutting edge. This will at the
same time align the cutting edge with the centerline
of the wheel.
4. Lock the workhead spindle in place to
prevent the cutter from moving.
5. Clamp the tooth rest blade onto the
workhead so that its supporting edge rests against
the underside of the tooth to be ground.
6. Swivel the workhead downward to the
desired clearance angle and clamp it in position.
At this point, make sure that the tooth next to
the one being ground will clear the wheel. If it
does not, raise or lower the wheelhead until the
tooth does clear the wheel.
7. Unclamp the workhead spindle and begin
grinding the mill.
8. After you have ground all of the primary
lands, tilt the workhead to the secondary clearance
angle and grind all the secondary lands.
On large diameter wheel end mills, it is often
a good idea to back off the faces of the teeth
toward the center of the cutter, similar to the teeth
of a face mill. An angle of about 3 ° is sufficient,
allowing a land of 3/16 to 5/16 inch long.
It is important that you use as much care
when you grind the corners of the teeth as
when you grind the faces of the peripheral
teeth; otherwise, the cutting edges will dull
rapidly, and a poor finish will result. The corners
of the teeth are usually chamfered 45° by
swiveling the workhead or table and are left 1/6
to 1/8 inch wide.
13-17
To sharpen the end teeth of a shell end mill
(fig. 13-25), mount the cutter on an arbor set
in a taper shank mill bushing. Then insert
the bushing into the taper shank mill bushing
sleeve held in the universal workhead. To
obtain the desired clearance angle, swivel
the workhead in the vertical plane and swivel
it slightly in the horizontal plane to grind
the teeth low in the center of the cutter.
Turn the cutter until one of the teeth is
horizontal; then raise the wheel until that
tooth can be ground without interference.
FORMED CUTTERS
There are two methods commonly used to
sharpen formed milling cutters. The first method,
using a formed cutter sharpening attachment, is
by far the most convenient. The second method
consists of setting up the cutter on a mandrel,
grinding the backs of the teeth and then reversing
the cutter to sharpen the cutting faces.
The involute cutter (fig. 13-26) will serve as
an example. Since the teeth of these cutters have
a specific shape, the only correct way to sharpen
them is to grind their faces. An important part
of grinding the teeth is ensuring that the teeth are
uniform, that is, that they all have the same
thickness from the back face to the cutting face.
You can provide this uniformity by grinding the
back faces of all new cutters before you use them.
Grind only the back faces, since the cutting faces
are already sharp and ready to use. Once the teeth
are uniform, they should remain uniform through
repeated sharpenings because you will be taking
identical cuts on the cutting faces whenever you
sharpen the cutter.
To sharpen a formed cutter using the formed
cutter sharpening attachment, attach the
wheelhead shaft extension to the shaft and mount
a dish-shaped wheel on the extension. With the
wheelhead swiveled to 90°, clamp the attachment
to the table with the pawl side of the attachment
away from the wheel. Place the cutter on a stud
and line up the cutting face of a tooth with the
attachment centering gauge. Loosen the pawl
locking knob and adjust the pawl to the back of
the tooth. Then adjust the saddle to bring the face
of the tooth in line with the face of the grinding
126.53X
Figure 13-25.— Grinding the end teeth of a shell end mill.
KEYWAY
U 1. UU.ICIJ.
Figure 13-26. — Involute gear cutter.
wheel. Once you have made this adjustment, do
not readjust the saddle except to compensate for
wheel wear. After grinding one tooth, move the
saddle away from the wheel, index to the next
tooth, and grind. If, after you have ground all
of the teeth once, the teeth have not been ground
enough, rotate the tooth face toward the wheel
and make a second cut on each tooth.
If a cutter has been initially provided
with a radial rake angle, this angle must be
retained or the cutter will not cut the correct
form. To sharpen this type of cutter, line up
the point of one cutter tooth with the attach-
ment gauge, swivel the table to the degree
of undercut, adjust the saddle to bring the face
of the tooth in line with the face of the wheel,
and grind.
If a formed cutter sharpening attachment is
not available, you may sharpen formed cutters by
tooth formed milling cutter and for grinding a tap
are essentially the same. We will use a tap in this
example.
Grinding a Tap
To grind a tap, take the following steps:
1 . Mount the wheelhead shaft extension and
the dish wheel on the machine.
2. True the wheel with the diamond truing
device.
3. Line up the face of the wheel with the
footstock centers. Place a straightedge across the
face of the wheel and adjust the saddle toward
the wheelhead until the wheel face is centered.
4. Place the tap between centers.
5. Fasten the tooth rest to the table, with the
blade against the back of the blade to be ground.
6. Adjust the tap to the wheel with the
micrometer adjustment on the tooth rest.
7. Grind the tap.
To produce accurate results in grinding taps,
grind the backs of the teeth before you grind the
faces.
HONES AND HONING
In honing, the cutting is done by abrasive
action. Honing may be used to remove stock from
a drilled, bored, reamed, or ground hole to
correct taper, out-of-roundness, or bow (bell
mouthed barrel shape or misalignment). Honing
is also used to develop a highly smooth finish
while accurately controlling the size of the hole.
You may do cylindrical honing on a honing
machine or on some other machine tool by
attaching the honing device to the machine
spindle, or you may do it by hand. Regardless of
the method you use, either the hone or the work
must rotate, and the honing tool must move back
and forth along the axis of rotation.
13-19
PORTABLE HONING EQUIPMENT
The portable hone shown in figure 13-27 is
similar to the type used in most Navy machine
shops. It is normally available in sizes ranging
from 1 3/4 to 36 inches with each hone set being
adjustable to cover a certain range within those
sizes. The hone illustrated has two honing stones
and two soft metal guides. The stones and the
guides advance outward together to maintain a
firm cutting action during honing. An adjusting
nut just above the stone and guide assembly is
used to regulate the size of the honed bore.
Accuracy to within 0.0005 inch is possible when
the proper operating procedures are observed.
To use the portable hone, follow these basic
steps:
1. Clamp the hone shaft in the drill press
chuck.
2. Clamp the workpiece to the drill press
table.
3. Put the hone into the hole to be polished.
Use honing compound as required.
4. Turn on the drill press and use the drill
press feed handle to move the rotating hone up
and down in the hole.
When a lathe (vertical or horizontal) is used
to hone, the work can be mounted in a chuck or
on a faceplate and rotated. The honing tool is held
in the tailstock with a chuck and moved back and
forth in the workpiece bore by the tailstock
spindle.
On a milling machine or a horizontal boring
mill the workpiece is mounted on the table and
the honing tool is mounted in the spindle. The
hone is passed back and forth in the workpiece
bore by moving the machine table.
Another method is to use a hand held power
drill to rotate the hone in the workpiece. Move
the rotating hone in and out of the hole by hand.
Each of these methods requires that the hone
be allowed to self- align with the workpiece bore.
To assist in this, place one or two universals
between the hone shaft and the device or spindle
which will hold or drive the hone. These univer-
sals and shaft extensions are usually available
from the hone manufacturer.
When honing large bores, use a device that
attaches to the hone and lends support to the
stones and guides to ensure a rigid setup.
STATIONARY HONING
EQUIPMENT
Stationary honing equipment is not used as
often in the machine shop as the portable hone.
Consequently, it is not often found in too many
shops. These machines are usually self-contained
hones with a built-in honing oil pump and
reservoir, a workholding device, and a spindle to
rotate and stroke the honing stones. Controls to
adjust the rpm, the rate of stroke, and the pressure
feeding the stones to the desired size are usually
standard. Some models have a zero setting dial
indicator that lets you know when the desired bore
GUIDE
ADJUSTING NUT
STONE
Figure 13-27.— Portable hone.
of the bore.
STONE SELECTION
The honing stone is made somewhat like a
grinding wheel, with grit, a bond, and air voids.
The grit is the cutting edge of the tool. It must
be tough enough to withstand the pressure needed
to make it penetrate the surface, but not so tough
that it cannot fracture and sharpen itself. The
bond must be strong enough to hold the grit, but
not so strong that it rubs on the bore and
interferes with the cutting action of the grit. Air
voids in the structure of the stone aid the coolant
or honing oil in clearing chips and dissipating
heat.
Honing stones are available with either
aluminum oxide grit for ferrous metals or silicon
carbide grit for nonferrous metals and glass. Grit
sizes from 150 to 400 are available. If a large
amount of metal must be removed, use a coarse
grit stone such as a 150-grit to bring the base to
within 0.0002 to 0.001 inch of the finish size. Then
use a finer grit stone to obtain a smooth finish.
Specific recommendations for stone selection
are available from the hone manufacturer.
STONE REMOVAL
Honing does not change the axial location of
a hole. The center line of the honing tool aligns
itself with the center line of the bore. Either the
tool or the part floats to ensure that the tool and
the base align. Floating enables the tool to exert
equal pressure on all sides of the bore.
Thus all taper and out-of-roundness are taken out
before any stock is removed from the larger
selection of the bore. Also any bow is taken out.
Since the honing stones are rigid throughout their
length, they cannot follow a bow— they bridge the
low spots and cut deeper on the high spots,
tending to straighten out a bow.
After you have honed out the inaccuracies,
you must abrade every section of the bore equally.
To ensure that this happens, maintain both the
rotating and reciprocating motions so that every
part of the bore is covered before any grit repeats
its path of travel.
If a bore will require honing to correct taper
or out-of-roundness, leave about twice as much
stock for honing as there is error in the bore. It
is sometimes practical and economical to perform
two honing operations: (1) rough honing to
remove stock and (2) finish honing to develop the
desired finish. As previously mentioned, you
should leave from 0.0002 to 0.001 inch for finish
honing. If a machined bore must be heat treated,
rough hone it before heat treating to produce an
accurately sized, round, and straight bore. After
heat treating the workpiece, finish hone to cor-
rect any minor distortion and to produce the
desired finish.
Honing produces a Crosshatch finish. The
depth of cut depends on the abrasive, speed,
pressure, and coolant or honing oil used. To
produce a finer finish, you can do one or all of
the following:
1. Use a finer grit stone.
2. Increase the rotating speed.
3. Decrease the stroking speed.
4. Decrease the feed pressure.
5. Increase the coolant flow.
13-21
METAL BUILDUP
Metal buildup is a rapid and effective method
of applying practically any metal to a base
material. This is used to restore worn mechanical
equipment, to salvage mismachined or otherwise
defective parts, and to protect metals against
corrosion. As compared to original component
replacement costs, metal buildup is a low cost,
high quality method of restoration.
As you advance in the MR rating you must
know how to prepare a surface for metal buildup
and be able to set up and operate the equipment
used in the thermal spray systems and the
contact electroplating process. In this chapter, we
will discuss the thermal spray systems and the
contact electroplating process.
Additional information on metalizing is
contained in Mil Std 1687(SH) Thermal Spray
Process and in NAVSHIPS 0919-000-6010,
Instructions for Metalizing Shafts or Similar
Objects.
Additional information on electroplating
is contained in MIL-STD-2197(SH), Brush
Electroplating on Marine Machinery and in NAV-
SHIPS 0900-LP-038-6010, Deposition of Metals
by Contact (Brush-on Method) Electroplating.
THERMAL SPRAY SYSTEMS
There are four different thermal spray
processes: wire oxygen-fuel spray, wire-
consumable electrode spray, plasma-arc spray,
and powder oxygen-fuel gas spray. In general, all
four processes perform the same basic function:
They heat the wire or powder to its melting point,
atomize the molten material with either high
velocity gas or air, and propel it onto a previously
prepared surface.
The rapid rate at which metal coatings can be
sprayed and the portability of the equipment have
increased the use of thermal spray processes.
Metal coatings are especially useful in rebuilding
worn shafts and other machine parts not subject
to tensile stress, in hard surfacing where resistance
to wear and erosion are desired, and in protecting
metal surfaces against heat and corrosion. Navy
shipyards, Intermediate Maintenance Activity
(IMA), and repair ships use thermal spray
processes to coat metallic and nonmetallic surfaces
with practically any metal, metal alloy, ceramic,
or cermet that can be made in wire or powder
form. (Cermet is a strong alloy of a heat
resistant compound and a metal used especially
for turbine blades.)
NOTE: The thermal spray process is NOT
authorized in the repair of submarine
components (MIL-STD-1687A(SH)).
In this chapter we will discuss the wire oxygen-
fuel spray process and the powder oxygen-fuel gas
spray process with emphasis on the latter. These
are the two thermal spray processes you will most
likely use as an MRS or MR2.
APPROVED APPLICATIONS
Thermal spray coatings have been approved
by NAVSEA for several applications. Case by
case approval is not needed for the use of
thermal spraying in the applications listed below,
but the procedures used for these applications are
limited to those which have been approved by
NAVSEA.
1. Repair of seal (packing) areas of shafts
used in oil and freshwater systems to obtain
original dimensions and finish.
2. Repair of bearings' interference fit areas
of shafts to restore original dimensions and finish
(except for motors and generators where chrome
plating is permissible).
3. Buildup of pump shaft wear ring sleeves
to original dimensions.
4. Repair of miscellaneous static fit areas,
such as those on electric motor end bells, to restore
original dimensions, finish, and alignment.
14-1
flame and atomizes it by a jet of compressed air
into a fine spray. The metal particles may be
inhaled easily by anyone present. Personnel using
metalizing equipment must wear respirators that
have been approved for this kind of work.
Operators and personnel in the immediate vicinity
must wear ear muffs and properly fitted soft
rubber ear plugs.
• You must wear safety glasses or face shield
and proper protective clothing at all times during
thermal spraying operations.
• Cleaning solvents are toxic and hazardous
to your health. Use them only in a well-ventilated
area.
• Warning signs must be posted near the
operation to warn personnel.
• Adhere strictly to the safety precautions
noted in the Welding Handbook, Sixth Edition,
Section 1 Chapter 9, published by the American
Welding Society, and the manufacturer's
handbook.
QUALIFICATION OF PERSONNEL
Thermal spray operations are performed only
by qualified personnel. Potential operators who
each process, the operator must prepare test
specimens for visual, microscopic, bend, and
bond tests using qualified procedures developed
for that particular coating and thermal spray
process. In addition, the operator is responsible
for setting up the spraying equipment (gun-to-
work distance, air, fuel gas, and so on) as required
by the spraying procedure.
A potential operator who fails one or more
initial qualification test may be permitted one
retest for each type of test that he or she failed.
Certified operators retain their certification as
long as they do not let 6 months or more time pass
between their uses of the thermal spray process.
Operators who let their certification lapse may re-
qualify by satisfactorily completing the qualifica-
tion tests. Complete information regarding
certification is contained in MIL-STD-1687.
TYPES OF THERMAL SPRAY
The two types of thermal spray discussed in
this chapter are wire-oxygen-fuel spray and
powder-oxygen-fuel spray.
Wire-Oxygen-Fuel Spray
The wire-oxygen-fuel spray process is suitable
for all purpose use. It offers variable, controlled
ALSO SUITABLE FOR GAS
COMBUSTION POWER
SPRAYING GUN
AIR LINE
GAS
COMBUSTION
WIRE SPRAYING
LINE PRESSURE GAUGE
DRYING
UNIT
AIR
RECEIVER
AIR ACETYLENE OXYGEN
FILTER
MAIN AIR
PRESSURE CONTROL
Figure 14-1.— Typical installation for combustion gas spraying.
14-2
installation.
The type 12E Flame Spray Gun (fig. 14-2) can
spray metalizing wires, such as aluminum, zinc,
copper, Monel, nickel, and so forth, in wire sizes
ranging from 3/16-inch down to 20 gauge using
acetylene, propane, natural gas, manufactured
gas, or MPS as the fuel gas. The wire is drawn
through the gun and the nozzle by a pair of wire
feed drive rollers, powered by a self-contained
compressed air turbine. At the nozzle, the wire
is continually melted in an oxygen-fuel gas flame.
Then, a controlled stream of compressed air blasts
the molten tip of the wire, producing a fine metal
spray. Systems of this type are commonly used
to spray aluminum wire coatings for shipboard
corrosion control, such as on steam valves,
stanchions, exhaust manifolds, deck machinery,
and equipment foundations.
Powder-Oxygen-Fuel Spray
Figure 14-3 shows a powder spray gun. The
powder feeds by gravity through a metering valve
and is drawn at a reduced pressure into an
aspirator chamber. From the chamber the powder
is propelled through the flame where it melts and
then deposits on the work in the form of a coating.
The Type 5P Thermal Spray Gun will spray metal,
ceramic, cement and exothermic powders.
Exothermic coating composites are materials
that produce an exothermic (heat evolved)
INTERNAL
METERING VALVE
POWDER FLOW
^CONTROL VALVE
OXYGEN
AIR CAP BODY
TRIGGER
GAS VALVE
HANDLE
Figure 14-3.
*~*r
-Type 5P gravity feed oxygen-fuel powder
spray gun.
Figure 14-2.— Type 12E spray gun.
reaction from their chemical creation. These
coating materials include METCO 402 and 405
wires and 442, 444, 445, 447, 450 powders. When
the composites reach a certain temperature in the
spray gun flame, they react to form nickel
aluminide and produce a great deal of heat. Nickel
and aluminum, for example, combine to produce
nickel aluminite and heat. The extra heat provided
to the molten particles by the exothermic reaction,
coupled with the high particle velocity of the
thermal spray process, accounts for the self-
bonding characteristics of the coating and its
exceptional strength.
Exothermic materials are often referred to as
one-step coatings. They produce self-bonding,
one-step buildup coatings that combine metal-
lurgical bonding with good wear resistance. They
also eliminate the need for separate bond and
buildup coatings.
The gravity feed oxygen fuel powder spray gun
must be used in a horizontal position. Deposit
efficiencies are very high, almost as high as 100%
in some cases. Only a minute amount of the
powder is lost by being blown away or consumed
in the flame.
PREPARING THE SURFACES
We cannot overemphasize the importance of
proper surface preparation. An improperly
14-3
viii.iv/cu. p«iu ui uiiv jw, it
is frequently given the least attention. Quite often,
preparation is inadequate simply either because
proper preparation is inconvenient or because the
necessary equipment is not available. Great
emphasis is placed on preparation because even
the best and most elaborate surface preparation
is still the cheapest part of the job. To help ensure
a quality job, be sure to use the required equip-
ment and prepare the surface carefully and
thoroughly.
Preparing the surface involves three distinct
operations: (1) cleaning, (2) undercutting, and (3)
surface roughening.
Cleaning
To ensure a good bond between the sprayed
coating and the base material to which it is
applied, be sure the areas to be coated and the
adjacent areas are free from oil, grease, water,
paint, and other foreign matter which may
contaminate the coating.
SOLVENT CLEANING.--Prior to blasting
or spraying, clean with solvent all surfaces that
have come in contact with any oil or grease.
(Vapor degreasing is preferred, but you may use
solvent washing.) When using solvent, be very
careful that it is not so strong that it attacks the
base material; do NOT leave any residue film on
the base surfaces. METCO-Solvent Trichloro-
ethane O-T-620 and Toluene TT-548 are suitable
solvent cleaners. Because of the flammable and
may be attacked by the solvents.
J-'M.l IO LlldL
ABRASIVE CLEANING.— You can use
abrasive blasting to remove heavy or insoluble
deposits. Do not use for surface roughening
operations the abrasive blasting equipment that
you use for general cleaning operations.
HEAT CLEANING.— Clean porous mate-
rials that have been contaminated with grease
or oil with a solvent and then heat them for
4 hours to char and drive out the foreign materials
from the pores. Heat steel castings at 550 °F
(288 °C) maximum; heat aluminum castings,
except age hardening alloys, at 300 °F (149°C)
maximum. In thin sections, use lower
temperatures to minimize warpage.
Undercutting
To obtain a satisfactory thickness of metalized
deposit on the finished job, usually you need to
undercut the surface to be built up. (See fig. 14-4.)
Undercutting must be a dry machining operation,
as any cutting lubricants or coolants used will
contaminate the surface of the workpiece. When
building up shafts, be extremely careful to ensure
that the undercut section is concentric to the
original axis of the shaft. The length of the under-
cut should extend beyond both ends of the sleeve
or bearing or the limits of the carbon or labyrinth
ring, or the packing gland in which the shaft will
operate. However, you must be careful not to
UNDERCUT =MINIMUM COAT THICKNESS
PLUS WEAR ALLOWANCE
THICKNESS OF COAT
EQUALS UNDERCUT
PLUS FINISHING
ALLOWANCE
FINISHING
ALLOWANCE
ORIGINAL
DIAMETER
UNDERCUT
*»TTT r» i
SURFACE
PREPARATION
ofe B i
BUILD UP
a T er r> n
WffWWJnSfflWWM
t
FINISHED
TO
ORIGINAL
DIAMETER
OTCO A
Figure 14-4. — Major steps in restoration of dimensions with thermal spray.
14-4
l/Ul 31J.UU1U UC
CSUCUgill \JL
to the base metal.
The depth to which a shaft should be under-
cut is determined by a number of factors. Some
of these factors include the severity of service, the
amount of wear expected in service, the depth of
metal loss, the remaining thickness of the load
carrying member, and the limits of the particular
coating. In general, the minimum specified depth
of undercutting should be at least equal to
the recommended minimum thickness for the
particular coating, plus the wear or corrosion
tolerance for the application. Undercutting and
surface roughening reduce the effective structural
cross section of the part to be metalized. Also,
sharp grooves and shoulders without a fillet or
radius may produce stress risers. A stress riser is
a spot on a part where stresses have been set up
that may cause the part to fail. When you prepare
for thermal spraying, carefully examine from a
design standpoint all parts subjected in service to
high stresses, shock loads, or critical applications
to determine that adequate strength is maintained
in the structure. Metal spray deposits cannot be
depended upon to restore such qualities as tensile
strength or resistance to fatigue stress.
NOTE: Shot peening may be used in
applications that require high fatigue resistance
of the coating system.
Shot peening is done by shooting a high-velocity
stream of metal or glass particles suspended in
compressed air onto the metal substrate. Shot
peening is normally performed by dry blasting
with cast steel shot with a hardness of Rockwell
C 40 to 50. Steel shot must not be used on
aluminum or stainless steel; glass beads should be
used for aluminum or stainless steel alloys. When
required, shot peening is performed following
machining and before abrasive blasting.
Surface Roughening
After undercutting the shaft, you must
roughen the undercut section to provide a bond
for the metal spray. During undercutting and
roughening, do NOT use a lubricant or coolant.
Keep the surface clean and dry. Even touching
the surface with your hands will contaminate
it. If, for any reason, the surface becomes
contaminated, you must thoroughly clean and
degrease it. The cleanliness and roughness greatly
^J.caiumc&s> tu cii&uic aucqucuc
bond strength for the service to which the part
will be subjected. Two methods of surface
roughening are (1) abrasive blasting and (2)
macroroughening, for restoring dimensions
greater than 1/2 inch where exothermic materials
cannot be used.
ABRASIVE BLASTING.— Prior to thermal
spraying, condition the surfaces to be coated by
abrasive blasting. Blasting pressure is normally
60 to 80 pounds per square inch (psi) for suction
type equipment and the nozzle-to-work distance
is about 3 to 6 inches. Blasting must not be so
severe as to distort the part. The required amount
of surface roughness is related to the configura-
tion (size and shape) of the part. Where part
configuration permits, a roughness of 200-300
microinches is desired. When distortion can
occur, such as with thin walled sheet metal parts,
reduce the roughening as necessary to a minimum
surface roughness of 63 microinches and regulate
the blasting pressure as necessary.
Abrasive blasting particles used for surface
preparation may be either angular nonmetallic grit
(e.g. aluminum oxide) or angular chilled iron grit.
To prevent rusting, the abrasive particles cannot
contain any feldspar or other mineral constituents
which tend to break down and remain on the
surface in visible quantities. Keep chilled iron grit
dry during storage and use. Do not use grit
designated for coating preparation for any other
purpose. Use the following ranges of grit size as
a guide in selecting the desired grit.
GRIT
SIZE
Coarse
GRIT SIZE
MESH
USE
( - 10 to + 30) Use where the coating thickness
will be greater than 0.010", and
where the roughest blasted sur-
face is required
Medium ( - 14 to H- 40) Use where the coating thickness
will be less than 0.010", and
where the roughest basted sur-
face is not required or cannot be
tolerated
Fine ( - 30 to + 80) Use under thin coatings which
will be used as sprayed or fin-
ished lightly by brush blasting
GENERAL NOTES ON BLASTING.—
Clean, dry air is essential. Traces of oil in the air
which cannot be readily detected can seriously
14-5
on the blasted surface. A distinct dark ring after
the solvent dries usually indicates oil in the air.
Keep the blast angle within 10° or 15° from
the perpendicular. Where access to the surface is
difficult and you must blast from a steeper angle,
apply the spray from the same approximate angle.
If you blast at an angle from one direction and
spray from an angle in the other direction, the
bond strength may be close to zero.
Thorough blasting is important. It is good
practice to blast until the surface appears fully
blasted, and then to blast further for a short
period.
MASKING FOR GRIT BLASTING.— All
areas of a component that are not to be grit
blasted must be covered and masked to prevent
damage or contamination by the abrasive blasting
medium and debris. Rebound grit from the walls
of the blast room or blast cabinet may scratch and
damage areas of the work which are not to be
blasted unless they are adequately covered.
Masking for blasting may be an expensive part
of the operation and this should be taken into
account when selecting the masking method.
Following abrasive blasting, remove any masking
material that is unsuitable for use as a masking
material for the thermal spray process and replace
it with masking material suitable for thermal
spraying.
Metal masks and blasting jigs are commonly
developed for this purpose. You can sometimes
fit the work into a jig so that the part to be blasted
is the only part exposed. Where necessary, you
must use additional covers or metal masks. One
great disadvantage in using metal for masking in
blasting, however, is that the metal mask blasts
away rapidly and must be replaced frequently.
Rubber has proved to be much more
successful in masking for blasting purposes, and
you should use it wherever possible. Sometimes
it is quite practical to construct whole jigs from
blocks of rubber rather than from metal. Rubber
or aluminum masking tape is very satisfactory for
all operations where hand masking can be done
economically. Since rubber is not cut by the
blasting operation, you can use rubber jigs almost
indefinitely. You can use thin rubber tape for
heavy blasting protection.
MACROROUGHENING.— Macroroughen-
ing is a lathe operation performed on bearing
areas of shafts or similar surfaces. It consists of
APPLYING THE COATING
Applying the coating consists of three distinct
procedures: Masking, spraying the coating, and
applying a sealant to the coating.
Masking for Spraying
You can use tapes, liquid-masking com-
pounds, silicon rubber, or metal shielding as
thermal-spraying masking materials. Tapes used
for spray masking must be designed for high-
temperature use. Masking materials must not
cause corrosion or contamination of the sprayed
coatings.
More generally, however, masking tape and
masking compound are used for masking
materials to be sprayed. Use a pressure sensitive
masking tape which is designed to withstand the
usual spray temperatures.
Masking compound (METCO or equivalent)
is designed for masking where a liquid masking
material is more convenient. It is a water soluble
material which can be brushed onto any surface
to prevent the adhesion of sprayed material.
Approved masking compound will not run or
bleed at the edges.
You may also use masking compound to pro-
tect the spray booths and other equipment which
is subject to over spray, such as rotating spindles,
chucks, lathes, and the like. When you use mask-
ing compound for this purpose, be sure to clean
the surfaces on a regular schedule and reapply the
compound since it will eventually dry out and the
sprayed material will then stick to the substrate.
For instances when you cannot protect holes,
slots, keyways, or other types of recesses by tapes
or shields, use inserts of carbon, metal, or rubber.
Install these inserts before you begin abrasive
blasting and spraying, and leave them in place
throughout the thermal spray operation. Remove
them after you complete the surface finishing but
before you begin applying the final sealer.
Spraying the Coating
Spray the component using the specifications
(gun-to-work distance, rotational or linear speed
of the gun to the work piece, air, fuel, gas,
primary and secondary pressures, and power out-
put) contained in the approved procedure for the
material being sprayed.
14-6
you expect more than 15 minutes, but not over
2 hours to elapse from the time that you finish
preparing the surface until you begin the spraying
operation, or if the part must be removed to
another location, you must protect the prepared
surface from oxidation, contamination, and finger
marks. Clean paper (free of newsprint) will usually
provide adequate protection.
Whenever possible (or practical) preheat the
work to 200 °-225 °F to eliminate surface moisture.
Take temperature readings with a contact
pyrometer. Do NOT use temperature sticks or
similar devices in the thermal spray area. If you
preheat with a gas flame, do not apply the flame
directly onto the area to be sprayed to avoid
possible surface oxidation and contamination
from carbon deposits.
To safeguard against the possibility of cracks
that may occur in the sprayed deposit due to a
difference in the expansion rates of the substrate
and the sprayed metal, do not spray on substrates
with a temperature below 60 °F.
Interrupt the spraying operation only to
measure thickness or temperature, to change
spraying material from bond or undercoat to
finish coat, or to permit cooling to prevent
overheating. During spraying, do not allow the
temperature of the work to exceed 350 °F or the
tempering/aging temperature of the substrate,
whichever is lower. For cooling use a blast of
clean air, carbon dioxide, or other suitable gas
introduced near but not directly on the area being
sprayed.
In general, keep the direction of the metal
spray as close as possible to a 90° angle
to the surface being coated and never less than
45°. Apply the coating in multiple passes
of 0.005 ± 0.001 inch for wire spray and
0.003 ± 0.001 inch for powder spray. Cover the
entire prepared surface with a pass of spray before
proceeding to the next pass.
When you use the macroroughening method
of surface preparation, apply at least the first four
layers of deposited metal in each direction with
the spraying stream directed at 45 ° to the perpen-
dicular, alternately from left to right, in order to
deposit metal onto each face of the thread. Then
complete the work by spraying at a right angle
to the surface.
For cylindrical parts, direct the spray stream
at the axis at all times. Coat the part at a
rotational speed of 40 to 100 surface feet per
minute or as otherwise specified.
J. * -
in excess of that required for finished dimensions
on the surface to provide for machining or
grinding. To help ensure a proper buildup, follow
the coating manufacturer's recommendations.
Allow the work to cool normally to room
temperature after spraying. If it is necessary to
cool the work more quickly, direct an air blast
against it. Do not quench the work with a spray
of water or other liquid.
Applying the Sealant
To prevent corrosive attack or fluid leakage,
sprayed coatings must be treated with a sealant.
The particular sealant selected will depend on the
maximum use temperature of the component and
the purpose of sealing the coatings. Apply
the sealant after spraying and before finish
machining. For severe applications, apply a
sealant again, following finish machining.
Sealants used in thermal spray processes may
be of the following types:
1. Paraffin wax
2. Resins
a. Air dried
b. Baked (heat cured)
c. Pressurized
d. Vacuum impregnated
3. Inorganic
FINISHING THE SURFACE
The structure of sprayed metal deposits is
granular rather than homogeneous. In spraying,
the minute particles of metal strike the surface at
high velocity, flatten out, and built up on each
other. This structure, which by its relatively low
coefficient of friction and high oil-retaining
qualities makes sprayed metal ideal for all
bearing surfaces, creates a problem in finishing.
Experimentation and research indicate that if you
understand and appreciate the characteristics of
sprayed metals, you can machine and grind them
in the toolroom or on the production line with
less trouble than you have with many alloy
materials in solid or wrought form.
A machinist unfamiliar with sprayed metal will
grind the tool bit and set it according to past
experience with a similar metal in its solid or
wrought form. As a result, crumbly chips similar
to those from cast iron will occur regardless of
14-7
porous.
A grinding wheel operator will tend to use the
grain and grade of wheel he or she uses on the
same material in wrought form. Regardless of the
manner in which the operator dresses the wheel,
it will load up immediately and produce a spiralled
and discolored surface. If the operator continues
and attempts to remove stock with a loaded or
glazed wheel, surface checks that cannot be
removed will appear. Sufficient working data for
both machining and grinding are available to
permit production finishing of all of the
commercially used metals that have been
developed for thermal spraying. Naturally, some
finish better than others, but commercial finishes
within commercial tolerances can and are being
obtained on all thermal spray alloys.
Because of the possibility of plucking out
individual particles during the finishing operation,
the finishing specifications are more important
with sprayed coatings than with solid materials.
With many sprayed materials, maintaining
grinding wheel sharpness, for instance, and
adhering to proper feeds and speeds may be quite
critical. Most applications for sprayed materials
consist of fairly thin coatings sprayed over a
substrate. Grinding and finishing operations
should take this into account and avoid
overheating the coatings or seriously deflecting
them. For instance, if the coating material is a
refractory material with low heat conductivity,
there is some danger of developing hot spots
during grinding. Machinists who are accustomed
to grinding metals are cautioned to grind slowly
enough and apply sufficient coolant to avoid local
overheating of such materials. Where a thin
coating has been applied over a relatively soft
substrate, the finishing operations must be done
in a way to avoid loads on the coating that could
seriously deflect it.
Requirements
Thermal sprayed coatings differ enough
from the same materials in wrought form that
different grinding wheel and finishing tool
recommendations are almost always required.
Therefore, the choice of tools and wheels should
NOT be based on experience with the parent
material in wrought or cast form. Selection of the
Softer coatings are often finished by machining
with a carbide tool, using speeds and feeds for
cast iron. Harder coating materials are generally
finished by grinding.
Wheels with coarse grain and low bond
strength are used to grind sprayed coatings to
prevent loading the wheel. Wet grinding is usually
recommended over dry grinding if the proper
wheel is used. When a coolant is used, it should
contain a rust inhibitor, and it must be kept clean
and free of foreign matter. The grinding wheel
must not remain immersed in the coolant because
it will become unbalanced due to the absorption
of moisture.
Always consult and follow the coating
manufacturer's finishing recommendations when
you select the finishing technique, including the
proper tool, feeds and speeds.
Remove masking materials before you begin
surface finishing, and finish the part to the
dimensions required by the specification or
drawing.
Where finishing difficulties do arise even
though you have followed proper finishing
techniques, review the spraying operation it-
self. It is quite obvious that if, for instance,
particles pluck out, the fault may not be in
the grinding but rather in substandard coatings.
Excessive moisture or oil in the air supply
during the spraying operation can cause this
trouble. Using the wrong gun-to-work distance
and spraying at the wrong angle to the substrate
surface are typical faults which may affect the
structure of the coating adversely and cause
finishing difficulties.
Machining
The sprayed coating stream has an appreciable
area (approximately 3/8 to 1/2 inch in diameter).
Therefore, the sprayed coating cannot be
terminated sharply at the end of the undercut
section. At the end of the undercut section (at the
shoulders in the case of a shaft), the coating will
build up on top of the surface adjacent to the
undercut just as thick as in the undercut. If the
undercut is 1/8 inch, then something over 1/8 inch
of sprayed material will be built up at the
14-8
because it requires special attention during
machining.
The buildup at the shoulder usually has a
ragged edge and, if the tool is set to "hog it off",
the sprayed material will crack off in chunks,
possibly starting a crack which will penetrate the
main section of the coating. To avoid this trouble,
it is good practice to remove the ragged edge by
machining it separately, with a series of fairly thin
cuts, until the surface is nearly down to the
shoulder before proceeding to take the full cut
across the entire surface. (See figure 14-5.)
A general guide to finishing is to avoid apply-
ing pressure in directions that tend to lift the
coating from the workpiece. In many cases, a
uiau LI is in service, me pio-
cedures described above minimize the machining
stresses.
Machining sprayed metal is not difficult.
Carbide tools are necessary for the harder
materials. A tungsten carbide tool bit, sharpened
for cast iron, will be satisfactory. Since the
sprayed coating contains hard oxides, even
the softer sprayed metals which can easily be
cut with high-speed steel tools, have an abrasive
action on the tool tip. High work speed, slow
traverse and light infeed are required. When
it is necessary to hold a dimension to a tight
tolerance, you must take tool bit wear into
account. Carbide tools have been found to be
more satisfactory than softer tools for machining
most sprayed metals.
For Steps } and 2, use *am« RPM as for preheof, with ilow feed and light infeed.
Use tungsten carbide tool bit.
ENDS Of COATING TEND TO
LIFT FROM MASKED AREA.
CROSS SECTION OF SPRAYED COATING.
1. FIND HIGH SPOT OF COATING.
DIRECTION OF FEED.
2. HANOFEED TOOL TO CUT CONTINUOUS
OR STEPPED CHAMFER, BOTH ENDS
FLASH WILL BREAK OFF.
COATING AFTER STEP 2.
777777777
COATING AFTER STEP 3.
7777777777
3. MACHINE OFF AREAS MARKED "A". A. MACHINE TO REQUIRED DIAMETER. USE
FEED TOOL FROM CENTER TO OUTSIDE. SPEEDS AND FEEDS FOR CAST IRON.
INFEED NOT TO EXCEED .010" PER PASS KEEP TOOL BIT SHARP.
5. MACHINE DRY.
6. LEAVE THE PIECE IN THE LATHE UNTIL. EDGES OF COATING ARE FINISHED.
Figure 14-5.— Finishing machining of a thermal spray coating.
14-9
Figure 14-6 illustrates proper tool configura-
tion for machining sprayed materials. Do not
follow the usual rules that apply to the use of
carbide tools for heavy machining work since they
do not apply to machining sprayed materials. For
instance, when you machine sprayed materials,
it is never necessary to take a cut deeper than
about 0.025". The side cutting angle (see
figure 14-6) is not important since the cutting is
done by the tool on the radius at, the nose of the
tool. No back rake is required, but it may be as
much as 8°.
Grinding
Wherever the ground surface is to be used
for a journal or bearing surface it is most
important that the final surface is clean and not
contaminated with grinding abrasive. While such
surfaces can be cleaned by scrubbing after
grinding, it is often much more satisfactory to seal
the surface prior to grinding. Sealers, such as
METCO-SEAL AP and METCO 185 Sealer, have
been developed for this purpose. The use of
sealants before grinding prevents contamination
of the pores of the sprayed coating and also helps
to provide a cleanly ground surface instead of a
surface with the particles smeared or drawn into
feathers.
Always use heavy grinding equipment with
carefully trued concentric wheels. (See fig. 14-7.)
Pounding from an eccentric wheel or vibration
Figure 14-7. — Lathe grinder for dry grinding of thermal
spray coating.
due to the use of equipment that is too light for
the job will damage the coatings or produce a poor
finish.
Wet-grinding is recommended whenever
suitable equipment is available. When proper
equipment is used, no special difficulties arise in
grinding sprayed materials as compared to
grinding these same materials in other forms. Of
course, you must pay attention to the special
problems resulting from the structure of sprayed
materials as discussed earlier. Remember that
NO SIDE
RAKE ANGLE
7°SIDE RELIEF
' ANGLE
BACK RAKE
ANGLE 8° MAX.
B
0° BACK RAKE ANGLE
7
NOSE RADIUS
SIDE CUTTING
EDGE ANGLE
END COATING
EDGE ANGLE
\\\\\V\\VA\
15°
NOSE RADIUS
END CUTTING
EDGE ANGLE
Figure 14-6.— Cutting tool angle for machining a thermal spray metal coating.
need to use the different wheels, feeds, speeds,
and so on suggested in the coating manufacturer's
recommendations .
The softer sprayed materials, particularly the
sprayed metals, tend to "load" a wheel. The use
of wheels with relatively coarse grain and low
bond strength is necessary for such materials so
that the wheel will break down before loading.
Thoroughly clean ground surfaces after you
grind them whenever the surface is to be used as
a journal surface or a surface that will mate to
another machined part. This procedure is
emphasized because the porous structure of most
sprayed coatings are more inclined to retain
ensure clean final surfaces.
Figures 14-8, 14-9, and 14-10 illustrate the
proper techniques for finishing key ways, holes
and other openings, and the ends of coatings.
CONTACT ELECTROPLATING
Contact electroplating (brush-on) is a method
of depositing metal from concentrated electrolyte
solutions without the use of immersion tanks. The
solution is held in an absorbent material attached
to the anode lead of a d.c. power pack. The
cathode lead of the power pack is connected to
1. FINISH COATING TO REQUIRED DIAMETER.
2. FILE OR GRIND CHAMFER ON KEYWAY THROUGH EDGE OF COATING TO BASE METAL.
COATING
When filing or grinding,
always work in direction
which pushes the coating
against the part.
COATING
3. FINISH CHAMFER AS SHOWN BELOW.
BREAK SHARP
CORNERS
ABOUT 60°
4. REMOVE SPRAYED METAL FROM SIDES
AND BOTTOM OF KEYWAY WITH CHISEL.
OR SCREWDRIVER.
Sprayed metal is brittle. It is important to relieve the edges of the coating
around a keyway so that when the part is put back in service, the key cannot
bear on the coating edge and break pieces out of it.
Figure 14-8. — Finishing key ways.
14-11
1. FINISH COATING TO REQUIRED DIMENSION.
2. FILE OR GRIND CHAMFER THROUGH EDGE OF COATING TO BASE METAL.
GRINDING FILING
PRESSURE ?\ - PRESSURE
SHAFT WITH BORE
USE BALL POINT
3. FINISH CHAMFER.
BREAK SHARP
CORNERS
COATING
4. CLEAN ALL LOOSELY ATTACHED
PARTICLES OUT OF BORE.
Base
When ground with ball point,
this surface will not be flat.
This is satisfactory.
BREAK SHARP
CORNERS
REMOVE OVERSPRAY
WITH SCRAPER OR
SCREWDRIVER
The edges of the coating must be relieved around oil holes, slots or other openings
in the part, so that there is no possibility of pieces of sprayed metal breaking off
and getting between mating surfaces.
CAUTION: Clean the metallized piece thoroughly before putting it back in service.
Any loose particles of sprayed metal might cause trouble.
Figure 14-9. — Finishing holes and other openings.
the workplace to provide the ground, completing
the plating circuit. Electroplating deposits metal
by contact of the anode with the work area.
Constant motion between the anode and the work
is required to produce high quality uniform
deposits.
Contact electroplating (also referred to as
contact plating) can be used effectively on small
to medium size areas to perform the same
functions as bath plating; for example, corrosion
protection, wear resistance, lower electrical
contact resistance, repair of worn or damaged
machine parts, and so forth. This process is not
recommended to replace bath plating. However,
there are some advantages which make contact
electroplating superior to bath plating in some
situations:
© The equipment is portable; plating can
often be done at the job site.
© It can reduce the amount of masking and
disassembly required.
* It permits plating of small areas of large
assembled components or parts too large for
available plating tanks.
• By plating to the required thickness, it can
often eliminate finish machining or grinding of
the plated surface.
14-12
A. COATING IN MIDDLE OP SHAFT OR BORE
1. IF COATING FINISHES FLUSH AND SMOOTH, NO FURTHER WORK IS REQUIRED.
2. IF COATING FINISHES ABOVE SURFACE OF PART, CHAMFER EACH END AT ABOUT
45°
RIGHT WRONG
B. COATING AT END OF SHAFT OR BORE
1. IF COATING FINISHES FLUSH AND SMOOTH. NO FURTHER WORK IS REQUIRED.
2. IF COATING FINISHES ABOVE SURFACE OF PART, CHAMFER END AT ABOUT 45°
BREAK SHARP
CORNERS
CHAMFER
RIGHT
3. IF NO SHOULDER. CHAMFER AT ABOUT 45°.
BREAK SHARP
/CORNERS
WRONG
RIGHT
WRONG
The ends of the coating must be finished off so that there is no load on any edge
of the sprayed coating when the part is put back in service.
Figure 14-10.— Finishing the ends of coating.
• Damaged or defective areas of existing
plating can be touched up, instead of complete
stripping and replating of the entire part.
Although the contact electroplating
equipment— power pack, plating tools, solutions,
plating tool coverings — are discussed in detail
throughout this chapter, the following sections
contain brief descriptions which you need at this
point.
INTRODUCTORY INFORMATION
The following paragraphis provide an over-
view of the electroplating process before we begin
more detailed discussions.
Power Pack
Contact plating power packs are available in
direct current output ranges of 0-15 amperes at
0-20 volts to 0-150 amperes at 0-40 volts. These
power packs operate on 115- or 230-volt 60-Hz
single- or three-phase a.c. input.
The intermediate sizes, 25 to 100 ampere
maximum output, are most commonly used. The
units in this range are portable, weighing less than
150 Ibs, yet can provide the required power for
most shipboard and shop work. A unit in the
60- to 100-ampere range is recommended as basic
contact plating shop equipment. Even though
subsequent workload demand may require
14-13
supplementing it with smaller or larger units, a
unit of this size will always remain useful.
Plating Tools
Contact plating tools consist of a stylus handle
with a conductive core, which is insulated for
operator safety, and an insoluble anode normally
of high quality graphite. Since considerable heat
is generated during plating operations there must
be a means of cooling the plating tool. The
handles of plating tools have cooling fins to
dissipate heat. In some cases, large tools may
require the use of plating solution or water as a
cooling medium. Graphite anodes are brittle and
are not practical for use in locations where a very
small diameter anode is required. For plating holes
less than 1/2 inch in diameter, or narrow slots and
keyways, anodes made of 90% platinum and 10%
iridium material are recommended.
The removable anodes are available from the
equipment manufacturers in a wide range of
standard sizes and three basic shapes: cylindrical
or convex — for plating inside diameters;
concave — for outside diameters; and, flat or
spatula shaped.
Graphite material may also be purchased for
manufacturing special tools.
Solutions
The solutions used in contact plating include
preparatory solutions for cleaning and activating
the surface to be plated, plating solutions for
depositing pure or alloy metals, and stripping
solutions for removing defective plating. These
solutions are manufactured and sold by the
process equipment manufacturers. Solutions of
any trade name can be used if the deposits meet
the applicable plating specification and if they are
certified by procedure tests. However, plating and
preparatory solutions of different manufacturers
must not be used for the same plating job.
For plating operations, solution is either
poured into shallow glass or plastic dishes or
beakers for dipping or into a pump for dispensing
through solution-fed tools.
Plating Tool Coverings
Cotton batting of surgical grade U.S. P. long
fiber, sterile cotton is the most common tool
covering. It is fastened to the anode to hold and
distribute the solution uniformly. Cotton batting
alone can be used for jobs involving a few short
preparing and plating operations or to ensure
maximum tool to workpiece contact for plating
in corners or on irregularly shaped areas. When
longer tool cover life is desired, cotton, Dacron
or cotton-Dacron tubegauze sleeving should be
used over the cotton batting. In addition to cotton
batting and tubegauze, Dacron batting, Pellon
and treated "Scotchbrite" may also be used as
plating tool coverings.
Operator Qualification
Only qualified operators are permitted to
perform production plating. The plating shop and
the quality control department maintain a list of
qualified operators. Qualification of operators is
the responsibility of the performing activity and
is based on the operator's ability to:
1 . Successfully complete a process equipment
manufacturer's training course, in-house training
course, or other approved training course. To
qualify the operator must show proficiency in the
contact plating process which includes the
following:
a. Preparation of a metal surface for
contact plating
b. Selection of the proper power settings,
tools and solution
c. Proper masking technique
d. Proper plating technique
e. Calculation of plating thickness
f. Proper surface finishing technique
2. Successfully plate mock-ups, simulating
typical plating work required at the facility, to the
specified quality requirements and thickness range
indicated in MIL-STD-2197(SH).
Completion of an approved training course
and certification will not always assure that the
operator is skilled enough to do all jobs that he
or she may encounter. Much of the required skill
can be gained only from actual plating experience.
Newly trained and certified operators should
generally work under the guidance of an
experienced operator for a minimum of 30 days.
If there are no experienced operators at the
facility, experience can be gained by limiting the
plating work to simple applications at first,
avoiding jobs requiring heavy plating buildup,
especially for critical and rubbing contact applica-
tions, and gradually progressing to more difficult
tasks. In either event, the plating vendor or
distributor should be consulted whenever plating
VCUUUJL aci vices amjiuu uc u&cu
to assist with the actual plating and to provide
on-the-job training.
Health and Safety Precautions
The plating solutions may be poisonous and
may produce fumes which are irritating to the
eyes. For these reasons, you must take the follow-
ing precautions.
• You MUST wear safety glasses or a face
shield, rubber gloves and a rubber apron or
laboratory clothing at all times when
electroplating.
• NEVER let your skin come in contact with
the solutions. If you do contact a solution, wash
your skin thoroughly with soap and water.
• When electroplating in air conditioned
compartments, nonventilated compartments,
confined areas of ventilated compartments, or in
compartments with only minimal ventilation, be
sure that portable ventilation exhaust blowers are
installed and operating BEFORE you begin.
Direct the exhaust hose from these blowers to an
adequately sized exhaust terminal or discharge
directly to the weather where practical.
• Ensure that warning signs are posted near
the operation to warn personnel that toxic and
poisonous chemicals are being used.
• Adhere strictly to the safety precautions
noted in the caution plate on the equipment or
specified in the manufacturer's operation
procedures.
© Wear resperators of the proper type dur-
ing all plating operations.
Terminology
Contact electroplating is highly technical and
introduces many terms of which you probably
have little knowledge. The next few pages
contain definitions which you will need as you
study the process of contact electroplating. Read
them carefully and then refer to them as you
progress through the remainder of the chapter.
ACTIVATE: Removing passive film which is
normally present or which forms quickly on
follow.
improves aunesion 01 ine piaung 10
ADHESION: The degree to which an
electroplate is bonded or "sticks" to the base
material.
ANODIZED COATING: An oxide coating
formed on aluminum by making it the anode in
an appropriate solution. Thickness varies from
0.000020 to 0.001 inch depending upon the
application.
ALLOY: Metallic combination of two or more
elements.
ALTERNATING CURRENT (a.c.): Elec-
trical current that changes direction of current
flow, usually 60 times per second.
AMPERE-HOURS (also AMP-HR or Ah): A
measure of a total quantity of electrical current.
Comparable to a quantity or volume of water.
AMPS, AMPERES, or AMPERAGE: A
measure of the quantity of electrical current
flowing through a conductor such as wire or a
conductive solution. Comparable to the rate (gal
per minute) at which water flows through a pipe.
ANODE: Positive terminal in a conductive
solution. Metal ions in the solution flow away
from the positive terminal. In the reverse
direction, the workpiece is positive and there is
a tendency to remove material or "etch" the
workpiece. In the forward direction, the
workpiece is negative and metal ions flow to the
part; that is, the workpiece is plated.
ANODE-TO-CATHODE SPEED: The rate
of movement of the plating tool relative to the
surface being plated. The relative movement can
be obtained by moving the tool, by moving the
workpiece, or by moving both.
ANODIC CORROSION PROTECTION:
Corrosion protection offered by a deposit more
reactive than the base material. The deposit
corrodes, rather than the base material. The
coating therefore, does not have to be pore-free.
BAKE: Heating a part for several hours at
approximately 400 °F, usually to remove en-
trapped gases such hydrogen.
14-15
BATH PLATING: Electroplating by im-
mersing the workpiece in a tank of plating
solution.
BHN: Brinell Hardness Number.
BURNED DEPOSIT: A loose, powdery,
defective deposit applied by improper plating.
Burned deposits tend to occur first at high
current density areas, such as masked edges and
sharp external corners, and can be recognized by
being distinctly darker in color. A burned deposit
can be covered, but additional layers will not
adhere well to the burned layer and the final
surface will be rougher. Moderate, localized
burning can be tolerated in most applications.
Severe, overall burning requires that the plating
operation be stopped to allow for chemical or
mechanical removal of the burned layer. Plating
then can be resumed after the surface is properly
prepared.
CARBURIZED: Case hardened by impreg-
nating carbon in the surface of a part and then
heat treating the part.
CASE HARDEN: Hardening an iron base
alloy, such as steel or cast iron, so that the
surface layer or case is substantially harder than
the interior.
CATHODE: Negative terminal in an electro-
lyte. Metal in an electrolyte flows to the negative
terminal. In the "forward" or plating direction,
the workpiece is negative and metal flows to it.
CATHODE EFFICIENCY: The percentage
of current flow (amperes) or quantity of current
(ampere-hours) used to electroplate metal. (See
NOBLE METALS.)
CATHODIC CORROSION PROTECTION:
Corrosion protection offered by a deposit more
reactive than the base material. The deposit must
be pore-free, to prevent the base material from
corroding in preference to the coating.
CHROMATE COATING: A coating applied
on many metals, often zinc and cadmium. The
color of the coating varies from almost
transparent to yellow or brown. It is applied for
additional corrosion protection, for decorative
reasons, or as a base for paints.
COHERENT: Holds firmly together as one
piece; has high resistance to breaking apart in
pieces.
CONSTANT FACTOR: The factor (see
factor) is constant and is not affected by plating
conditions, such as current density, temperature,
etc. A certain number of amp-hr, therefore,
always deposits a certain volume of metal from
the solution.
CONTACT AREA: The area of contact made
by a plating tool on the workpiece; measured in
square inches.
CURRENT DENSITY: The plating current
being passed per square inch of contact area. The
value is determined by dividing the plating
current by the contact area. When 10 amps are
drawn with a tool making 5 square inches of
contact with a part, the current density is 2 amps
per square inch.
DENSE: Has no voids, cracks, or pores.
DESMUT: To remove a loose, powdery,
darker surface film formed by a previous etching
operation.
DIFFUSION: The movement of atoms in a
solid, liquid, or gas; usually tends to make the
system uniform in composition.
DIRECT CURRENT (d.c.): Electrical current
that flows in only one direction.
DPH or DIAMOND PYRAMID HARD-
NESS: A microhardness test that is suitable for
testing the hardness of thin or small areas,
such as an electrodeposit. It develops square
impressions. DPH hardnesses are converted
to more familiar Brinell or Re values using
conversion charts.
DRAG-OFF: The solution left on the
workpiece when plating is completed. This
solution will be lost in the following rinse
operation.
DUCTILITY: The property of a material that
permits it to be stretched permanently without
fracture. The opposite of brittleness.
ELECTROLYTE: A solution that will
conduct electricity.
ELECTROPOLISH: To polish a surface
while electrochemically etching it in a special
solution.
ETCH: To electrochemically remove material
from a surface. Conducted with an appropriate
solution and reverse current.
"F" or FACTOR: The ampere-hours required
to deposit the volume of metal equivalent to a
0.0001-inch thickness on 1 square inch of area.
FORWARD CURRENT: Direction of d.c.
current flow in which metal ions tend to flow away
from the anode and toward the workpiece. The
anode is positively charged and the workpiece is
negatively charged.
FRETTING: Wear that occurs between two
adjacent surfaces caused by a minute back and
forth rubbing movement or vibration.
FRETTING CORROSION: The formation of
oxides in an area undergoing fretting. The oxides
cause additional wear to the mating surfaces.
GALLING: The damaging of one or both
metallic surfaces by the removal of particles
during sliding friction.
GASSING: Development of hydrogen gas
bubbles on the workpiece, either by activating or
plating, or by chemical attack of the activator on .
chromium.
GRAIN STRUCTURE: The physical arrange-
ment (appearance) of the grains of a metal. Grain
size varies from invisible to the naked eye to
perhaps 1/8 inch in diameter.
HARDCOAT: An oxide coating formed on
aluminum by making the aluminum the anode in
an appropriate solution. Thickness varies from
0.001 to 0.005 inch. The coating is used primarily
for wear resistance.
HARDNESS: The ability of a material to
resist indentation. Brinell and Re are common
hardness tests.
HYDROGEN EMBRITTLEMENT: A con-
dition in which a material is easier to break than
usual because of its absorption of hydrogen.
Occurs only with certain materials such as steel
over 40 Re, titanium, and certain harder stainless
steels.
IMMERSION DEPOSIT: A metallic deposit
which forms on more reactive metals by chemical
reaction with certain plating solutions. No flow
IONS: electrically charged atoms or groups of
atoms in a solution. Metal atoms are charged
positive and migrate toward the cathode.
KNOOP: A microhardness test which is
suitable for testing thin or small areas such as an
electrodeposit for hardness. Knoop hardness
values are converted to more familiar Brinell or
Re hardness values by using conversion charts.
LITER: A volume equal to 1.0567 quarts.
MATTE: A dull, satiny appearance resulting
from a fine microroughness.
MICROCRACKED: A type of deposit
structure in which there are numerous fine
surf ace-to-base metal cracks. Cracks are so
numerous and fine that they can be seen only at
high magnifications.
MICROPOROUS: A type of deposit structure
in which numerous fine pores exist. The pores are
so numerous and fine that they can be seen only
at high magnification.
MICROSTRUCTURE: The structure of
deposit when viewed at SOX magnification or
greater.
MILKY: A type of deposit appearance that
is almost bright but has a cloudy appearance due
to a very fine microroughness.
NITRIDED: Case hardened surface on certain
steels formed by heating in nitrogen containing
material. Nitrogen defuses into the surface,
causing a hard case.
NOBLE METALS: Metals may be classified
according to their tendency to be corroded or
chemically attacked. The noble metals are less
easily corroded or chemically attacked. They
include metals such as copper, nickel, and gold.
NODULAR: Type of electrodeposit that has
rounded projections on the surface, visible to the
naked eye upon close examination.
OHMS or SYMBOL £: A unit of measure of
resistance to the flow of electrical current.
PASSIVATE: The formation of a thin,
invisible oxide film on certain metals which
impairs adhesion of an electroplate.
pH: A measurement value on a scale of 0 to
14 of the acidity or alkalinity of a solution.
0 indicates strongly acidic, 4 less acidic, 7 neutral,
10 mildly alkaline, and 14 strongly alkaline.
PLATING RATE: The rate at which a deposit
builds up. In this manual it is expressed in inches
per hour.
PORES: Small random holes in a deposit just
barely visible to the naked eye.
POROUS: A type of deposit that contains
pores.
PREPLATE: A thin preliminary plating
applied using a plating solution other than the
desired solution. Preplates are used to improve
adhesion.
PREWET: Applying plating solution to the
surface before applying current. The operation
improves the adhesion of deposits from certain
solutions by ensuring that plating begins on a
surface covered all over with full strength
solution.
Re: Rockwell C hardness.
REACTIVE METALS: Metals that are more
easily corroded or chemically attacked. They
include metals such as aluminum, steel, and zinc.
REVERSE CURRENT: Direction of d.c.
current flow in which metal ions tend to flow away
from the workpiece and toward the anode. The
anode is negatively charged and the workpiece is
positively charged.
SACRIFICIAL CORROSION PROTEC-
TION: Cathodic corrosion protection.
SCALE: Surface oxidation on a metal caused
by heating in air or in an oxidizing atmosphere.
SEIZING: When two surfaces have fused
together due to friction.
SMEARED METAL: Deformed metal near
the surface caused by machining, grinding, or
wear.
STRESS: Pressure (force per unit area)
existing in a deposit. Tensile stress is a "pulling
apart" type of stress. Compressive stress is a
"pushing together" type of stress.
STRESS CRACK LIFTING: The type of
deposit structure caused by the development of
surface-to-base metal cracks which then curl up
on the edges because of poor adhesion. Can be
seen visually or at low magnification. Similar in
appearance to a dried up clay lake bed.
STRESS CRACKS: Cracks running from the
plated surface to the base material. Can be seen
visually or at low magnification. Normally
detrimental only when corrosion protection is
desired of the plating.
STRIPPING: Removing an electroplate from
a workpiece by chemical or electrochemical
means.
TANK PLATING: Same as BATH
PLATING.
THROWING POWER: The ability of a
plating solution to provide a uniform deposit on
a part that has surface irregularities readily
visible to the naked eye. A solution with good
throwing power is particularly useful for pit filling
since relatively more plating is applied at the bot-
tom of the pit.
VARIABLE FACTOR: A factor that is not
constant but which varies depending on plating
conditions such as current density and
temperature. A given number of amp-hr,
therefore, will deposit different amounts of
metal, depending on plating conditions. Plating
conditions, therefore, must be controlled to get
desired thickness of deposit.
VOLTS: A measure of the electrical force
applied. Comparable to water pressure.
WATER BREAKS: The breaking of a water
film into beads. Beading indicates contaminates
on the surface.
Applications
The contact plating process is a rapidly
expanding field. When used for depositing a
corrosion resistant coating, electroplating has
shown sufficient success to permit almost
14-18
macnmery is limited only oy the knowledge and
skills of the operator in areas where plating is
allowed. Requirements for contact plating are
specified in Table 14-1 which defines the area of
permissible use of contact plating. For simplifica-
tion, applications are classified as follows:
Class I: Plating used for decorative or
corrosion prevention functions only.
Class II: Plating on parts that remain in static
contact with other plated or unplated
parts.
Class III: Plating on parts that make rubbing
contact with other plated or unplated
parts, excluding those in Class IV.
Class IV: Plating on rubbing contact parts in
elements of turbine/reduction gearing,
turbo or diesel electric power gener-
ating units, and main propulsion
shafting.
Class V: Plating on parts under the cognizance
of the Nuclear Power Division.
• Bearing beats, baddies, and Supports
Ball Bearings: Plating of shafts and bores
to reestablish close tolerance fits. The use of an
outer layer of tin (0.002 to 0.003 inch thick) has
produced significant results in reducing fretting
of bearing bores in electric motor end bells and
also contributes to noise reduction.
Sleeve Bearings: Plating of seats, saddles,
and supports to correct for oversize machining
and out-of-roundness caused by distortion.
• Flanges and Flat Surfaces
Steam turbine casing joint flanges: Repair
of steam cuts and erosion damage.
Diesel engine cylinder blocks: Restoration
of mating surfaces damaged by fretting.
Wave guide plumbing: Plating of flange
seal areas to provide corrosion resistant metallic
gaskets.
• O-Ring Grooves and Sealing Surfaces
Repair of pits, scratches, and gouges on parts
used for air, oil, saltwater and freshwater service.
Table 14-1. — Requirements For Production Contact Plating
Class
Allowable
Thickness (Max)
Restrictions
Qualification Requirements
I
No limit1
None
See Operator Qualifications
II
0.030"2
None
III
0.020"2
Excluding Class IV
and V
Original qualification plus plating of a mock-up
simulating the production plating. The plated
mock-up must be approved by the Quality Control
Department of the performing facility.
IV
V
NAVSEA Approval
required on a case
basis.
limitations to be governed by practical and economical use of the metals deposited. The material
manufacturer's recommendations should not be exceeded.
2Thickness limit does not apply to filling-in pits, scores, dents, etc. where the total surface area comprises
10% or less of the area to be plated. The maximum allowable plating thickness shall not exceed that
recommended by the material manufacturer.
14-19
• Close Tolerance Mating Parts
Pump impellers: Repair of worn bores and
keyways to restore design size and fit on a shaft.
• Hydraulic Equipment
Scored, scratched pitted or gouged
surfaces of cylinder walls, tailrods, steering gear
rams, spool valves, and O-ring seal grooves.
• Masts, Periscopes, Antennas, and
Associated Hull Fittings
• Shafting
Areas worn by contact with seals and
packing.
• Steam Valves
Repair of a turbine nozzle control valve
seat's hard facing by plating 0.003-0.005 inch
thickness of cobalt over copper and nickel
substrates. The thickness is as required to repair
steam cutting and erosion damage and restore
valve seat geometry.
• Applications Approved by NAVSEA on
a Case Basis
Repair of steam turbine rotor bearing
journals.
Repair of diesel engine crankshaft main
bearing journals.
Limitations
• Cracks: Plating cannot be made over areas
containing cracks. Cracks must be completely
removed by grinding or other mechanical means.
Fill shallow grooves by copper plating and then
plate the area with the specified material. Repair
deep grooves by welding.
• Chromium plating on existing bath
chromium deposits: Brushing chromium plating
on existing bath chromium deposits has not been
consistently successful, due to poor bonding. For
this reason, you should not contact plate
chromium on an existing bath chromium deposit
on engine parts that make rubbing contacts. To
plate such parts, completely remove previous
chromium deposits prior to contact plating. As
an alternate, apply a nickel flash over the existing
bath plated chromium and follow with contact
chromium or other plating material.
• Brush electroplating of lead and lead alloys
is restricted. Use it only to repair plating on
battery terminals and busing components where
its use has been previously authorized.
• Deposition of chromium: Contact plating
solutions can produce deposits with mechanical
properties which will satisfy the requirements for
most plating work. Therefore, brush on plating
coatings can normally be used for repairs or
as a substitute for bath plated coatings. The
exception to this is the use of chromium to
refurbish worn parts. Deposition of chromium by
contact electroplating is not recommended
because the deposit is much softer than chromium
deposited by bath electroplating, the thickness of
the buildup is limited, and the process is tedious
and slow. As an alternate, you can use other
metals such as cobalt or nickel. These will provide
wear resistance and hardness properties which are
suitable for most applications where chromium
would normally be used. For areas that require
extensive buildup, deposit copper up to about
0.020 inch of the final dimension, and then
deposit an outer layer of cobalt, nickel-tungsten
or cobalt tungsten for greater wear resistance and
surface hardness.
PROCESSING INSTRUCTIONS
The equipment and solution manufacturers
have prepared comprehensive instructions cover-
ing the use of their products. You should follow
these instructions closely especially those con-
cerning procedures for preparing base metals for
plating and the use of individual plating solutions,
to ensure satisfactory plating results. A list
of vendors' literature is shown in table 14-2.
Detailed, step by step contact plating procedures
for the most commonly used metals are also found
in Engineered Uniform Method and Standard
No. 3426-801. (Copies may be obtained from
Commander, Mare Island Naval Shipyard,
Vallejo, California 94592). Another Government
document on this subject is MIL-STD-865
(USAF). (Copies may be obtained from Com-
mander, Hill Air Force Base, OOAMA/OONEO,
Utah 84401.)
Refer questions arising from difficulty with
equipment or solutions to the manufacturer or his
nearest local sales representative and send a
report, identifying the problem and its resolution,
to NAVSEC (Code 6101D) for information.
i A in
The major vendors of contact plating equipment and material are listed below. These vendors also
provide consultant and operator training services.
VENDORS
PUBLICATIONS*
Dalic Process
SIFCO Metachemical Division of Steel
Improvement and Forge Company
5708 Schaaf Road
Independence, Ohio 44131
Piddington & Associates Ltd.
3221 E. Foothill Boulevard
Pasadena, Calif. 91107
Operating Instruction Manual
Containing Technical Bulletins:
IM-1, 2, 3, 10 and 11 through 20
IM-200, 202 through 210
IM-302, 303, 305, 307, and 308
Equipment and Material price list
Selectron Process
Selectrons Ltd.
116 E. 16th Street
New York, N.Y. 10003
Vanguard Pacific Inc.
1655 Ninth Street
Santa Monica, Calif. 90406
Technical Instruction Manuals SI-115 and SI-130
Technical Bulletins SL-81, SL-82, SP-1023 and
Navy-Fact File
Selectron " Plating Guide" slide rule
Equipment and Material price list
* Publications may be obtained on request.
Quality Control
Quality control is composed of several factors:
documentation, process control, general (all
plating) inspection, and liquid penetrant inspec-
tion of plating for rubbing contact service.
DOCUMENTATION.— The quality control
department ensures that each plating job meets
the requirements of the applicable specifications
listed below:
Deposit
Cadmium
Chromium
Copper
Gold
Nickel
Silver
Tin
Tin-lead
Zinc
Specification
QQ-P-416
QQ-C-320
Mil-C-14550
Mil-G-45204
QQ-N-290
QQ-S-365
Mil-T-10727
Mil-P-81728
QQ-Z-325
PROCESS CONTROL.— All parts to be
plated should be handled according to written
Process Control Procedures approved by the
individual activity. Plating work should be set up
to ensure a smooth flow of work from initial
engineering approval through final inspection.
Adequate records must be kept of work
performed by the plating shop. Processing
information recorded should include the
following:
1. Name of the ship, the date, and the job
order number when applicable.
2. Description of the part to be plated by
proper name and piece number on the
blueprint.
3. A sketch of the area requiring plating.
4. Identification of the base metal.
5. Final required thickness of the deposit.
6. Plating material(s) to be used.
7. Step by step processing procedure.
8. Method of surface finishing (grinding,
honing, etc.)
9. Final inspection, including method and
dimensional checks when applicable.
14-21
Items 1 through 6 above should be engineer-
ing and job planning functions and represent the
minimum information required by the plating
shop.
Process control records of completed work are
a ready reference for handling repeat jobs and for
assessing the capability of the plating shop.
GENERAL INSPECTION PROCEDURE
(ALL PLATING).— Prior to declaring the plating
job complete, ensure that the finish satisfies the
following inspection requirements:
• Visual Inspection: All platings must be
smooth and free of blisters, pits, nodules,
porosity, excessive edge buildup, and other defects
which will affect the functional use of the plated
part. The finished plating must conform to the
required design surface finish for the part
and must be free of burnings and stress
concentrations. Burning is defined as rough,
coarse grained, or dull plates caused by localized
high current density or arcing. Highly stressed
deposits are normally indicated by cracks or
crazing.
• Adhesion Test: Perform an adhesion test
with Scotch #250 tape or an equivalent high tack
strength pressure sensitive tape as follows:
1. Thoroughly clean and dry the plated
surface.
2. Cut a piece of 1 inch wide unused tape
approximately 6 inches longer than the width of
the plated area.
3. Stick the tape across the width of the
plated area. Continue taping so that approxi-
mately 1 1/2 inches of the base metal on each side
of the plated area is also taped. Tamp the tape
down to ensure that it sticks thoroughly.
4. Grip the loose end of the tape and rip
rapidly upward (at a right angle to the plating),
removing the tape with a single jerk.
5. Inspect the tape. If any plating is stuck
to the tape, reject the plating job.
Platings for Rubbing Contact Service
In addition to the general inspection, plating
for rubbing contact service must meet the liquid
penetrant inspection.
• Liquid Penetrant Inspection: Use Group I
liquid penetrant in according to the requirements
of MIL-STD-271. Indications must not be greater
than 1/16 inch and the concentration of indica-
tions must not exceed 3 in any square inch area.
For chromium plating only, because of the
inherent crazying characteristic of the material,
you may use water washable penetrant material
(Group III or IV of MIL-STD-271) for liquid
penetrant inspection.
POWER PACK COMPONENTS
The equipment must contain the safety
features required by MIL-STD 454. Operations
that could create personnel hazards or result in
damage to the equipment or work must be noted
on a caution plate permanently attached to the
front of the equipment.
The parts of the power pack-ammeter, d.c.
circuit breakers, voltmeter, ampere-hour meter,
start and stop buttons, output terminals, forward-
reverse switch, output leads-are discussed below
and labelled in figure 14-11, using a DALIC
machine as an example.
Ammeter
There is at least one ammeter on the power
pack. The ammeter measures the rate of current
flow through the plating tool. Since the rate at
which metal is being applied is exactly or nearly
proportional to the rate of current flow, the
ammeter gives you a second-to-second of how fast
you are plating.
D.c. Circuit Breakers
All power packs have at least one d.c. circuit
breaker. Its purposes are to prevent overloading
the power pack and to minimize damage to the
workpiece in case there is an accidental direct
shorting of a lead or a tool on the workpiece.
Voltmeter
The voltmeter measures the voltage (electrical
pressure) applied across the d.c. circuit or through
the solution. Different voltage ranges are used
with different solutions. The "volts" control knob
makes the adjustments for applied voltage, which
is the initial step in obtaining the proper plating
conditions.
Ampere-Hour Meter
The ampere-hour meter measures the quantity
(amps x time) of current passed through the d.c.
D.C. C1RCUITBREAKER -START
D.C. CIRCUITBREAKER-STOP
'AMBER (FORWARD POLARITY)
OUTPUT POLARITY ,' *
INDICATOR LAMP
RED (REVERSE POLARITY)
AMPERE/HOUR
H&IT&, READOUT (LED) „<, ,
WITH RESET BUTTON
OUTPUT POLARITY 'SWITCH,
PORWARO/R|VERSE
' ' , >
VARIABLE AUTO -TRANSFORMER
ADJUSTMENT KNOB
A,C, LINE FUSE HOLDER
D,C. OUTPUT TERMINAL,
I BLACK (NEGATIVE)
D.C. OUTPUT TERMINALS,
2 RED (POSITIVES
Figure 14-11.— DALIC power pack.
28.449X
circuit and allows control of the thickness
of deposits. The formula for determining
ampere-hours will be discussed later in this
chapter. The meter also has a zero reset. The
reset button is pushed after cleaning, etching,
and so on are finished. When the computed
amp-hours are passed, the plating operation
has been completed. The white dot below the
numbers indicates the decimal point; example
0012.61 means 12.61 amp-hours have been
passed.
Start Button
The start button energizes the circuit breaker
and makes the d.c. circuit operative.
Stop Button
The stop button deenergizes the d.c. circuit
and makes it inoperative.
Output Terminals
Each power pack has at least one black and
one red output terminal. Larger power packs have
a number of black and red terminals, sometimes
of various sizes. Plating tool leads, usually color
coded red, are always connected to a red terminal.
The alligator clamp lead, usually color coded
black, is always connected to a black terminal.
A lead can be connected to any terminal if the
color and size are compatible.
14-23
Forward-Reverse Switch
The forward-reverse switch changes the
direction of current flow in the d.c. circuit.
Output Leads
Larger power packs have a number of wire
leads of different sizes. Small leads are used with
small terminals for small tools where low
amperages will be drawn. Larger size wire leads
are used with large terminals for large tools where
high currents will be drawn.
SELECTING THE POWER PACK
The power pack size is determined by the
solution used and the plating tool contact area.
Use Table 14-3 in selecting the size. It lists (1) the
plating tool contact area desirable with a given
solution and power pack and (2) the power pack
size required for a given solution and plating tool
contact area.
EXAMPLES IN USING TABLE 14-3:
a. You are to use a 60-35 power pack and
code 2050 solution on a given job. If possible, you
should use a plating tool that gives 20 square
inches of contact area.
b. You are to use code 2080 solution on a job
where the contact area is up to 5 square inches.
Use a 30-25 power pack or larger on this job.
OPERATING THE POWER PACK
Prior to Plating
Perform the following steps on the power pack
you will use:
1 . If the power pack has an external ground
post, connect the post with sufficient size wire to
a suitable ground.
2. Turn the "volts" control to the extreme
"low" position.
3. Connect the appropriate size output leads
for the plating tools you will use to the appropriate
terminals on the power pack. (Black alligator
clamp lead to black terminal; red plating tool lead
to red terminal.)
During the Plating Operation
• Press the "start" button to energize the
d.c. circuit.
• Adjust the ' 'volts ' ' control and the ' ' forward-
reverse" switch as necessary for various
preparatory and plating steps.
• Press the amp-hour meter button to reset
the indicator to zero just prior to plating.
• When the plating is completed, press the
"stop" button to deenergize the d.c. circuit.
SELECTING AND PREPARING
PLATING TOOLS
Selection and preparation of the proper
preparatory and plating tools is a VERY
IMPORTANT factor in determining how rapidly
and effectively you carry out a particular job. In
plating operations (preparation of the surface or
plating), work is done only where and when the
tool meets the part. Rapid, proper, and uniform
processing of a part largely depends on:
1. Whether the tool you select covers a
sufficient or optimum contact area on the part.
2. Whether the tool covers the full length of
an inside diameter, outside diameter, or flat area.
3. How you pump the solution through the
plating tool when you plate higher thicknesses on
larger areas.
The preparatory steps (cleaning, deoxidizing,
etching, etc.) are relatively short steps, compared
to those of the plating operation. Selection of the
preparatory tools, therefore, is not as critical as
for the plating tool. The preparatory tools,
however, should contact approximately 10% or
more of the area to be plated, and should, if
possible, cover the full length of the area to be
plated to assure uniform preparation.
You can get sufficient solution on the tool by
dipping for solution. In most cases, a standard
plating tool will meet the above requirements and
you will not need to make special preparatory
tools.
Proper Plating Tools
The plating step generally represents the major
part of a complete plating operation. Therefore,
the selection of the proper plating tool is more
critical than the selection of the preparatory tools.
The higher the thickness of plating to be applied,
the larger the area to be plated and the larger
the number of parts to be plated, the more
important it is to have the proper tool. It is
14-24
Antimony
2000
2
6
12
24
40
60
80
Bismuth
2010
4
10
20
40
67
100
134
Cadmium
2020
1
3
5
10
17
25
34
Cadmium
2021
3
8
15
30
50
75
100
Cadmium
2022
2
5
9
18
29
43
57
Cadmium
2023
2
4
8
15
25
38
50
Chromium
2030
1
3
5
10
17
25
34
Chromium
2031
3
8
15
30
50
75
100
Cobalt
2043
1
2
5
9
15
22
29
Copper
2050
2
5
10
20
34
50
67
Copper
2051
2
5
9
18
29
43
57
Copper
2052
2
5
9
18
29
43
57
Copper
2054
1
4
7
14
23
34
45
Copper
2055
0.5
2
3
5
8
12
16
Iron
2061
1
3
5
10
17
25
34
Lead
2070
3
8
15
30
50
75
100
Lead
2071
3
8
15
30
50
75
100
Nickel
2080
1
3
5
10
17
25
34
Nickel
2085
1
2
5
9
15
22
29
Nickel
2086
1
3
6
12
20
30
40
Nickel
2088
1
3
5
10
17
25
34
Tin
2090
3
8
15
30
50
75
100
Tin
2092
3
8
15
30
50
75
100
Zinc
2100
2
5
10
20
34
50
67
Zinc
2101
1
2
5
9
15
22
29
Zinc
2102
1
2
5
9
15
22
29
Zinc
2103
1
2
5
9
15
22
29
Gallium
3011
4
10
20
40
67
100
134
Gold
3020
4
10
20
40
67
100
134
Gold
3021
4
10
20
40
67
100
134
Gold
3022
4
10
20
40
67
100
134
Gold
3023
20
60
120
240
400
600
800
Indium
3030
3
8
15
30
50
75
100
Palladium
3040
2
5
10
20
34
50
67
Platinum
3052
1
3
5
10
17
25
34
Rhenium
3060
2
5
10
20
34
50
67
Rhodium
3072
2
5
10
20
34
50
67
Rhodium
3074
3
8
15
30
50
75
100
Silver
3080
2
4
8
15
25
38
50
Silver
3081
5
15
30
60
100
150
200
Silver
3082
2
6
12
24
40
60
80
Silver
3083
2
6
12
24
40
60
80
Nickel-Cobalt
4002
1
3
5
10
17
25
34
Tin-Indium
4003
3
8
15
30
50
75
100
Tin-Lead-Nickel
4005
4
10
20
40
67
100
134
Cobalt-Tungsten
4007
1
3
5
10
17
25
34
Nickel-Tungsten
4008
1
3
5
10
17
25
34
Babbitt-SAE 11
4009
5
15
30
60
100
150
200
Babbitt-Soft
4010
5
15
30
60
100
150
200
Babbitt-Navy #2
4011
5
15
30
60
100
150
200
28.X
14-25
also important to have the proper tool when
uniformity of deposit thickness is necessary.
Optimum Contact Area
for the Plating Tool
A tool that gives the optimum contact area on
the area to be plated lets you plate a good deposit
as fast as possible. The optimum contact area
depends on the power pack to be used, the
solution to be used, and the size and shape of the
area to be plated.
In determining the optimum contact area,
refer to table 14-3 which gives the maximum
contact area required for a given solution to be
plated and the power pack to be used.
If, for example, Code 2080 solution is to be
used with a 60-amp power pack, the maximum
contact area required is 10 square inches.
Seven formulas that are useful with the Dalic
plating process are discussed at the end of this
chapter, beginning on page 14-59. You can use
formula 3 to determine the optimum contact area
mathematically. The optimum contact area is
required on very large areas. On very small areas
the contact area is the maximum contact area that
you can obtain; that is, full contact for flat areas
and 50% of the total area for outside diameters
(O.D.) and inside diameters (I.D.). In other
words, the optimum contact area for a flat
surface is full contact up to an area the size given
in table 14-7. For larger areas it remains that size.
On O.D.'s and I.D.'s where it is usually
difficult to get a tool that contacts more than 50%
of the total area, the optimum contact area is 50%
contact area up to a contact area of the size given
in table 14-3; for larger O.D.'s and I.D.'s it
remains that size.
Covering the Full Length
Covering the full length of an O.D. , I.D., or
flat surface with a tool makes it relatively easy
to get a uniform thickness. When the tool does
not cover the full length, problems arise. For
example, take the case of trying to plate an O.D.
3 inches long with a tool that will cover only
2 inches. If you move the tool as shown in figure
14-12A, the center 1 inch is always covered, but
in moving the tool to the ends there is less
coverage time. The plate distribution you will get
is shown at the bottom (plating). The alternative
to this is to move the tool as shown in figure
14-12B. You get an even plate distribution, but
now you waste some time with the tool off of the
part. This motion, also, may not be practical if
there is a shoulder at one side. The same situation
' Tool
Part
Part
Plating
Tool
B
28.450X
Figure 14-12.— Plating— covering the full length.
applies to I.D.'s and flat surfaces. Summarizing,
always try to have the tool cover the full length
of the O.D. or I.D. or the full length or width
of a flat surface.
Solution-Feed Tool
Solution-fed tools are used for plating high
thicknesses on large areas of a large number of
parts. It is, of course, not worthwhile to use a
solution-fed tool when a small thickness of deposit
is required on a small area of one part. Solution-
fed tools are not used with precious metals, since
a higher volume of a high cost solution is required.
Solution-fed tools usually double plating speed
and improve the quality and reliability of the
deposit because the flowing solution (1) cools the
anode, allowing higher currents to be passed; (2)
ensures that sufficient fresh solution is maintained
in the work area; and (3) eliminates time wasted
in dipping for solution.
Use the following procedure to determine if
it is worthwhile to use a solution-fed tool.
1. Use Formula 1 (page 14-59) to determine
amp-hours required for one part and then
multiply by the number of parts.
2. Determine the type of tool to be used and
also its contact area. Then use formula 4
(page 14-60) to determine the total plating time
if the solution is pumped through the tool.
Since dipping for solution usually doubles
plating time, the value you determine in step 2
above also represents the extra time you will spend
dipping for solution. This possible savings in time
can help you determine if it is worthwhile to set
up to pump the solution.
Standard Tools
Standard tools (figures 14-13 and 14-14) are
available for preparing and plating a wide variety
14-26
AC -SERIES
WC -SERIES
TOOL COMPONENTS
Cat. No. Handle Anode Adapter
AIR-COOLED (for small areas and I.D.'s)
Solution Dip
AC
-0
AC 1-3
AC-0*
.09 0 x 2"
AC
- 1
AC 1-3
AC-1
.180 0x 2.25"
AC
-2
AC 1-3
AC-2
.25" 0x2.25"
AC
-3
AC 1-3
AC-3
.31" 0x2.25"
AC
-4
AC 4-7
AC-4
.375" 0 x 3"
AC
-5
AC 4-7
AC-5
.5"0x 3"
AC
-6
AC 4-7
AC-6
AC
.75" 0x 3.5"
AC
-7
AC 4-7
AC-7
AC
1.0" eJx 1"
AC
-8
AC 4-7
AC-8
AC
2.25" x 1.5" x. 75"
AC
-9
AC 4-7
AC-9
AC
2" x3" x .75"
*AC - 0 ANODE is platinum clad titanium
WATER-COOLED (for larger I.D.'s)
Solution Dip
WC - 25 WC - 25 WC-25
1.125" 0x 3.75"
WC - 40 WC - 40 WC-40
1.625" 0x3.75"
WC - 55 WC - 75 WC-55
2.125" 0x 3.75"
WC - 70 WC - 75 WC-70
3" 0x3.75"
WC - 75 WC-75 WC-75
3.125"0x 2.11V'
SOLUTION FED (for larger I.D.'s)
FG
FG
FG
FG
FG
RF
- 15
F
RF-15
FG
1.5" 0
x3.75"
RF
-20
F
RF-20
FG
2"p x
3.75"
RF
-25
F
RF-25
FG
2.5" 0
x3.75"
RF
-30
F
RF-30
FG
3"0x
3.75"
Figure 14-13.— Standard plating tools.
28.451X
14-27
V f
SCC - SERIES / SCG - SERIES
TOOL COMPONENTS
Cat. No. Handle Anode Adapte
SOLUTION FED (for O.D.'s)
SCC-10 AC 4-7 SCC-10 A
1" I.D. x 1" wide
SCC-15 AC 4-7 SCC-15 A
1.5" I.D. x 1" wide
SCC-20 A
2" I.D. x 1" wide
SCC-25
2.5" I.D. x 1" wide
SCG-25
2.5" I.D. x 2" wide
SCG-30
3" I.D. x 2" wide
SCG-35
3.5" I.D. x 2" wide
SCG-40
4" I.D. x 2" wide
SCC-20
AC
4-7
SCC-25
AC
4-7
SCG-25
G
SCG-30
G
SCG-35
G
SCG-40
G
FG -SERIES / FF- SERIES
FLAT & MULTI-PURPOSE TOOLS
Solution Dip
FG 1
2.5" x 2.5"x 1"
FG 2
3.5" x 3.5" x 1"
FG 3
4.5" x 4.5"x 1"
FF 1
2.5" x 2.5" x 1'
FF 2
3.5" x 3.5" x V
FF3
4.5" x 4.5" x 1'
FF4
4"x 3"x 2"
FF-5
6" x 4" x 2"
NOTE: All anodes except AC-0 are made of special grades of
graphite. Anodes of any size, shape or material can be
made on short order, please inquire.
Figure 14-14.— Standard plating tools.
28.452]
of sizes and shapes of parts. These are described
on the following pages. You can use standard
tools if they meet the following requirements.
Preparatory Tools:
1 . Cover approximately 10% or more of the
area to be plated.
2. Cover the full length.
Plating Tools:
1. Provide the optimum contact area.
2. Cover the full length.
3. Allow for pumping the solution when
required.
NOTE: You must allow 1/8 to 1/4 inch on
the radius for the tool cover when considering
standard tools for O.D.'s and I.D.'s.
Special Tools
You should use special plating tools when
standard plating tools will not effectively
accommodate a particular area to be plated. The
greater the thickness of plate desired and/or the
larger the number of pieces to be plated, the more
desirable it is to use special tools, since there is
more opportunity to offset the extra cost by
savings in plating time.
1. Obtain required information for the job:
a. Amperage output of the power pack to
be used.
b. Plating solution to be used.
c. Shape and size of the area to be plated.
2. Determine the optimum contact area using
either table 14-3 or formula 3 (see page 14-60).
3. Determine the maximum practical contact
area:
a. On flat surfaces it is the total area
b. On O.D.'s it is 50% of the total area
since you can always cover the full
length but only 50% of the
circumference.
c. On I.D.'s it is 50% of the total area
since you can always cover the full
length, but practically only 50% of the
circumference. Attempts to get more
than 50% contact on an I.D. are
generally defeated by compression of
the tool cover during plating.
4. When the maximum practical contact area
(3 above) is less than optimum contact area (1
above) the special tools should be as follows:
a. On flat areas the tool should be 1 or 2
inches wider than the area to be plated.
This allows for moving the tool while
plating.
b. On I.D.'s and O.D.'s the tool should
cover the full length and one-half of the
circumference.
5. When the optimum contact area is less than
the maximum practical contact area, the special
tools should be designed to give the optimum
contact area.
In the interest of getting a uniform thickness,
the full length of an I.D. or O.D. and the smaller
dimension of a rectangle is covered. This
establishes one contact dimension. To get the
second, divide the optimum contact area by the
first dimension.
The height of the anode is not critical. It
should be high enough to accommodate the
handle hole and solution flow lines. If the anode
is too high, it just adds to tool weight. Heights
of 1 to 2 inches are generally used.
6. Select handles, solution inlet fittings, and
so on based on design plating amperage. When
dimensions of anodes are based on the optimum
contact area, the plating amperage should be the
amperage rating of the power pack. When the
anode dimensions are based on maximum
practical contact area, compute the expected
plating amperage using formula 4 (page 14-60).
At this point you will find a ruler and a
compass helpful in sketching in the anode. Keep
the following rules in mind:
• On radii for I.D. and O.D. tools, allow for
the anode cover, usually 1/4 inch thick.
• Space the solution outlet holes coming out
of the working face of the anode at intervals of
at least every 1 inch in the direction of the length
of an I.D. or O.D. tool and perpendicular to the
direction of tool movement on a flat surface tool.
This eliminates the possibility of plating tapers
through uneven solution distribution. In the other
direction, they should be spaced at least every 2
inches to ensure reasonably complete wetting of
the cover and to permit passage of current
throughout the cover. The outlet holes are usually
3/32 inch in diameter.
• Make the main distribution hole in the
anode next to the inlet fitting at least 1/4 inch in
diameter when you use a small submersible pump
and 1/2 inch in diameter when you use a large
submersible pump. This helps ensure that all
outlet holes are reasonably well fed.
The following examples will help you under-
stand how to make the special tools you may need
in contact electroplating.
EXAMPLE #1
Plate a 16-inch length of a 13 inch O.D. tubing
with .006 inch of nickel Code 2080. Use a 200-amp
power pack. You can rotate the part in a lathe.
The optimum contact area is 34 sq in. which
is less than 50% of the total area to be plated.
Covering the full length of 16 inches gives one
contact dimension. The contact width around the
surface then is
CS = II = 2 1/8 inches
foV
DRILL AND TAP TO
V->*
RECEIVE £•£" INLET
un t; F FtrriMK
-*•-,
**#"*
HANDLES-?
'i,rlj
^ ,
'!
/
] | '"]
} S'6< DIA-
r
/
I1
\ OUTLET
L'
jl ""'
HOLES
;'^;
'L..J
\ t
ii
-T l
* •?»•
M
\ l" TYP.
•"*•" " ' I1
M
1 1
f
i i
I F---
\S--t- OIA.
v^jiv^.
| pi---
} OUTLET
J HOLES
"T~
| 1
1 1
1 Ur:.-J
u
1 1
1 1
If
1 t ---.d
LI
| F- --H
ll
' l.N
II... -J
If*
s- ^ niA
'JX'
1 1
5 61 ° A'
l^
" w
OUTLET
1 1
II""1
HOLES
ii
j- SCALE
".....
1 1
1 f "••
Pi
u
V
1
28.453X
Figure 14-15. — Desicn of a soecial tool.
Allowing for a cover thickness of 1/4 inch,
put a 6 3/4-inch radius in the 16 inch x 2 1/8-inch
face. To help keep the rather long tool squarely
on the part, use two G-handles. Make the solution
outlet holes slightly larger as their distance from
the solution inlet port increases. (See figure 14-15.)
EXAMPLE #2:
A 12-inch I.D., 3 inches long requires 0.0035
inch of nickel, Code 2085. The part is very large
and cannot be rotated. Therefore, you must move
the tool by hand. Use a 100-amp power pack. The
amp-hours required for the job are
Amp-hr= .015x35 x 113 =59
A tool such as the Rf-30 will give a small
contact area, draw only approximately 30 amps,
and result in a plating time of 2 hours. A better
tool would be a pie wedge-shaped tool which has
the
a. disadvantage of having to be rotated in
addition to being moved around the I.D.
b. advantage of being able to draw 100 amps
which reduces the plating time to 0.6 hours.
In view of the difficulty in moving the tool,
make the tool 33/4 inches long to ensure full
contact along the length. The bore being 3 inches
long, the contact length remains 3 inches. (See
fig. 14-16.) The optimum contact area is 15 sq in.
The contact width then is
CS = y = 5 inches
EXAMPLE #3:
Ten bearings must be plated on a 20 inch long,
26 inch I.D. with .002 inch of babbitt, Code 4009,
per side. The part will be rotated in a barrel
rotator, leaving the I.D. accessible from both
ends. Use a 100-amp power pack.
The optimum contact area is 100 sq in. Since
the contact length is 20 inches, the contact width
is 100/20 or 5 inches. Solution will be pumped in
from both ends to obtain more uniform solution
distribution, since thickness control is critical. Use
two G-handles to help keep the tool properly
located on the part. Mill a channel into the
anode face around the outlet hole to get better
distribution along the length of the anode.
(See fig. 14-17.)
.------= ^
------1)
T~~~ —3 — 1! ~Z£>
ir-
ii
ji
^r? DIA. TYP
DRILL AND TAP
FOR "F" HANDLE
28.454X
Figure 14-16.— Design of a special tool.
Plating Tool Anode Materials
A grade of graphite with maximum resistance
to breakage and anodic corrosion is used on most
standard tools and in the fabrication of special
tools from block form. Other materials, however,
have been used and are recommended. Check the
manufacturer's instruction manual for particular
applications.
Use sandpaper or other similar abrasive
materials to remove loose graphite from the
working area of graphite anodes used as part
of the recovering operations. This helps keep
subsequently used solutions clean. Then,
thoroughly soak the anodes in clean water and
wipe off the abraded area.
Thorough cleaning of the anode is particularly
important when the tool will be used later with
a different solution. Thorough cleaning of the
anode (or use of one tool for one operation) is
of maximum importance in forward "cleaning
and deoxidizing" and "activating" operations.
,-j RECEIVE -^ INLET
HOSE FITTING
2 PLACES
ll"
If"
ii
i /*
iE:
i
i
IL!
r*
i
IL,
j
J 1
i
II1'1
if"
If"
If"
If
If"
ir.::
IL!
iL,..
IM -
f ~\
'
OUTLET
HOLES
± TYP
-* 5 fc.
~~\
l' f
{
J
•i
(
l 1
J -- t
I
(
3 - .
1
I
J t
J
1
J
1
1
J
i
I
J !
2*
i l
1
2"
J f
i f
1
1
:
1 t
J
;
j I
J
t
J I
1
1
f:
1 t
J
' f
i F
1 f
( P
b
(.-. t
i i
n
L
\
1
I
J
-* — T Y P
28.455X
Figure 14-17. — Design of a special tool.
Since you may not always be able to clean a tool
thoroughly, your best action is to identify it for
and use it with only one preparatory or plating
solution.
Plating Tool Covers
The plating tool cover performs several
important functions:
1 . It insulates the anode from the part and
thereby (a) prevents damage to the part by direct
shorting and (b) forces current to pass through
the solution which allows electrocleaning, plating,
and so forth to occur.
2. It mechanically scrubs the surface being
plated which permits sound deposits to be applied
rapidly.
3. It holds and uniformly distributes the solu-
tion where it is needed.
14-31
Several covering materials are used with the plating process. They may be categorized
as follows:
INITIAL COVER: Holds and distributes solution, but requires a final cover since it
is not wear resistant.
FINAL COVER: Overlay cover on an initial cover to provide wear resistance.
COMBINATION COVER: Can be used by itself since it holds and distributes the
solution uniformly and has satisfactory wear resistance.
SPECIAL COVERS: Used for special effects such as described below.
COVER TYPE
ADVANTAGES, DISADVANTAGES,
AND USES
Cotton Batting Initial
Dacron Batting Initial
Cotton Tubegauze Final
Dacron Tubegauze Final
White Scotch-Brite Combination
Dacron Felt
Combination
Gray Scotch-Brite Special Purpose
Widely used because of its very low cost and
excellent absorbency and purity. Cannot be used
with chromium, Code 2031, and copper, Code
2055. Requires a final cover for wear resistance.
Used very little because of its high cost
compared to cotton batting. Used as a replace-
ment for cotton batting with very corrosive
solutions such as chromium 2031 and copper
2055.
Used to a moderate degree as a final cover. Very
low cost and high purity and absorbency. Has
less wear resistance than Dacron tubegauze.
Used as a final cover for preparatory tools and
for rhodium plating.
Widely used as a final cover especially for
plating tools where its superior wear resistance
compared to cotton tubegauze is important.
Low cost, moderate purity and absorbency.
Used frequently for plating tools because of its
moderate cost and high purity and wear
resistance. Absorbency is poor and therefore
satisfactory only when solution-fed tools are
used with the workpiece under the tool.
Used frequently for plating tools because of its
excellent wear resistance, absorbency, and
moderate cost and purity.
Used occasionally when a higher than normal
thickness, such as 0.005 to 0.015 inch, is
required in a certain deposit. Keeps the deposite
smoother than normal since it has an abrasive
which polishes as plating is proceeding. One
problem in using this material is that an effect
called "Plating in Cover" usually starts in
approximately 10 minutes. It is the actual
plating of metal in the form of a fine powder
in the cover rather than the material being
applied on the workpiece. This is indicated by
brightening of the surface being plated and a
considerable rise in amperage at a given voltage.
Gray Scotch-Brite
(Continued)
Special Purpose
(Continued)
Bonnet Material
Combination
Carbon Felt
Special Purpose
This in turn requires that the voltage be
decreased to maintain a constant amperage. As
this continues, more and more plating occurs
in the cover and less occurs on the part,
requiring at some point replacement of the
cover, sometimes several times. Replacement of
the cover is usually done when the voltage has
been reduced to half of the starting voltage.
Replacement of the cover is ordinarily done by
quickly taking off the old Scotchbrite and
applying new material, pre-soaked with plating
solution. This eliminates the need to prepare
(clean, etch, and so forth) the surface for
additional plating. Cost is moderate and wear
resistance is good.
Used moderately for preparatory and plating
tools. Moderate in cost, wearability, and
purity. High in absorbency. Not recommended
with certain preparatory and plating solutions.
Refer to the plating equipment instruction
manual.
Applied directly on the anode and then covered
with a thin final insulating cover. The carbon
felt serves as the outside surface of the anode.
The felt is conductive enough to carry plating
current, but not conductive enough to damage
the part of shorting if the thin final cover is
worn through. Two important advantages are
thereby gained using the combination carbon
felt and thin final cover.
(1) Better throwing power into internal corners
such as in O-ring grooves.
(2) Less tool overheating with solutions plated
at high voltages and, therefore, lower possible
plating times.
Cost is high and absorbency and purity are
excellent.
Used for low thickness deposits (9.001 inch or
less) where an as plated surface is desired that
will be brighter than one started with. There is
some sacrifice of quality of deposite and
adhesion.
Special Purpose Very thin wear resistant cover useful for plating
Combination small I.D.'s, grooves, and so forth where
Cover conventional covers cannot be used. Absorb-
ency is poor.
Plating tools with clean and unworn covers, which will be used the next day, may be
tightly wrapped in a clean plastic sheet or bag. Plating tools that will not be used for several
days should be re-covered. Plating solution remaining in the covers can be squeezed out
and filtered for reuse.
Orion
Special Purpose
Final Cover
Pellon
14-33
PREPARATION OF ANODES FOR
THE ELECTROPLATING PROCESS
The following paragraphs contain step-by-step
procedures for you to use in preparing various
types of anodes for use in plating.
SCC AND SCG SERIES ANODES
To prepare SCC and SCG anodes for plating
outside diameters, take the following steps:
PREPARE THE COTTON BATTING— Cut
a piece of cotton batting large enough to cover
the concave side of the anode to be wrapped. It
is important that the cotton fibers run along the
longest dimension of the pad. This pad can be
split into two layers for use on smaller anodes
(picture 1). The thickness of the cotton used may
vary, according to the application. Experience has
shown that a 3/16" thickness works well for the
average application.
28.457X
MOLD THE COTTON TO THE ANODE—
Mold the cotton to the concave side of the anode
(picture 2).
28.457X
FASTEN THE TUBEGAUZE— Cut a
suitable size of tubegauze (at least twice the length
of the anode) and slip half of the tubegauze over
the anode and its cover (picture 3). Twist the
remaining half of the tubegauze (picture 4) and
slip it back over the anode. You then have two
layers of tubegauze cover, you should secure the
ends with rubber bands or tubegauze ties around
the base of the Dalic Plating Solution flow
tube (picture 5). Cut a hole in the tubegauze for
the Dalic tool handle and insert the handle
(pictures 6 and 7). The finished tool should have
a smooth concave surface (picture 8).
28.457X
AC, WC, AND RF SERIES ANODES-
GENERAL PURPOSE
Take the following steps to prepare AC, WC,
and RF series anodes for plating inside diameters
and flat surfaces.
PREPARE THE COTTON BATTING— Cut
a piece of long-fiber cotton batting about one inch
wider than the length of the Dalic anode and six
to eight times longer than the diameter. Split the
cotton to about a 3/32" thickness so that the final
cover thickness after rolling will be 3/16". Lay the
cotton on a table and wet the anode with water
14-34
no bulges or thin spots (picture 13).
28.548X
12
FOLD THE ENDS EVENLY— Fold the
protruding end of the cotton evenly over the tip
of the anode (picture 10).
28.548X
WRAP THE COTTON TIGHTLY— Wrap
the cotton around the anode tightly by rolling
from one end to the other. Feather the ends of
the cotton so that the long fibers can be inter-
twined (picture 11).
28.548X
FG AND FF SERIES ANODES-
GENERAL PURPOSE
Take the following steps to prepare FG and
FF series anodes for plating flat and other
surfaces.
FOLD THE COTTON AROUND THE
ANODE— Cut the long-fiber cotton pad for the
FG and FF anodes to provide a 1/2" overlap
around the anode. Place the anode on the cotton
making sure that the length of the cotton fibers
run in the direction of the long side of the anode
(picture 14). Fold the cotton evenly around the
anode and keep the bottom surface smooth
(picture 15).
28.548X
15
28.548X
SECURE THE COTTON WRAP WITH
TUBEGAUZE— The application of tubegauze
provides maximum wear resistance and prevents
cutting through on sharp edges. Apply the
INSERT THE ANODE INTO THE TUBE-
GAUZE — Holding the wrapped anode by
the bottom to keep the cotton smooth, insert
it into a piece of tubegauze of appropriate
14-35
size (picture 16). Secure the ends of the tube-
gauze tightly by twisting them and binding
them with rubber bands or tubegauze ties
(picture 17).
anode and partway up the end. Punch holes for
tubegauze ties (Picture 20).
20
28.549X
28.548X
CUT A HOLE FOR THE HANDLE— Cut
a hole in the tubegauze large enough to
screw the Dalic tool handle into the anode
(picture 18). The fully wrapped FG or FF
anode should have a smooth even pad of cotton
on the bottom, secured tightly by the tubegauze
(picture 19).
MAKE TIES— Cut the tubegauze ties (#56
Dacron is best) as shown (Pictures 21, 22).
19
28.548X
28.549X
TIE THE COVER TO THE TOOL— Secure
the cover to the tool with ties (Picture 23). It may
be necessary to make a cover with "ears" in some
applications where a more secure cover is
required.
SCC AND SCG ANODES-SPECIAL
PURPOSE
Take the following steps to prepare SCC and
SCG anodes with Scotchbrite, Dacron felt, and
similar materials.
PREPARE THE SCOTCHBRITE— Cut a
piece of Scotchbrite 1/4-1/2" wider than the anode
and long enough to cover the concave side of the
23
28.549X
and other special anodes with Scotchbrite, Dacron
felt, and similar materials for plating flat and
other surfaces.
PREPARE THE SCOTCHBRITE AND
THE TIES— Cut a piece of Scotchbrite 1/4-1/2"
wider than the anode and long enough to
cover the working surface and extend onto the
top of the tool. Punch the necessary holes in
the Scotchbrite and make the tubegauze ties
(Picture 24).
28.460X
TIE THE COVER TO THE TOOL— Secure
the cover to the tool with the ties (Picture 25).
28.460X
unlimited. Each manufacturer can provide you
specific information. As a general rule, solutions
should be stored at room temperature away from
light. Excess cold, in storage or in transit, may
lead to "salting out," that is, formation of solid
crystals at the bottom of the container. You may
restore these solutions to full effectiveness by
heating them to approximately 140°F and
stirring them until all salted out material is
redissolved.
Return used plating solution to used plating
solution bottles along with a log of the ampere-
hours passed through the solution. This will
provide some idea of how heavily the solution has
been used. The used solution is best used on less
critical applications requiring lower thicknesses
of deposits.
As a solution is used and collected for reuse
it tends to become diluted by water used to rinse
the parts that are plated. A minor dilution will
not cause a plating problem. However, when
dilution reaches 25% the solution should be
discarded.
MASKING
Masking serves several purposes in the
electroplating process: It prevents plating from
being applied on areas where it is not wanted. It
provides a definite area to be plated, which
permits more accurate thickness control. It
reduces waste of metal from the plating solution.
It reduces the possibility of contaminating the
solution.
Masking tapes are generally used to mask off
areas immediately adjacent to the area being
plated. The materials tapes may be made of vinyl,
polyester, aluminum, and copper tape. Do not use
absorbent tapes, such as painter's masking tape,
since they can cause small amounts of one
solution to contaminate another solution.
Although you should mask all parts carefully,
you must mask more carefully when you plan to
use a corrosive solution on a reactive base material
or when your plating process will develop
considerable heat.
14-37
Careful masking includes:
1. Careful cleaning of the surface before you
apply the tape.
2. Pressing down the tape where a second
layer of tape rises to cover a preceding layer
of tape.
3. Applying vinyl tape on surfaces such as
I.D.'s with no tension, since vinyl tape
tends to spring back.
Vinyl tapes are ordinarily used for most
solutions. However, there are exceptions listed by
individual vendors. Consult your instruction
manual for particular solutions for which vinyl
tape cannot be used.
Use aluminum tape on demanding masking
jobs such as when you use corrosive solutions,
when you plate with solutions that develop heat,
and when you mask difficult areas such as I.D.'s.
Aluminum tape has an excellent adhesive and is
strong and ductile. It will stay when carefully
pressed down. You may then apply vinyl tape over
the aluminum tape and it will stay better since it
is on a fresh, clean surface.
A masking technique that offers a number of
advantages is to mask with aluminum tape and
then mask off a larger area with a nonconductive
tape such as vinyl, leaving a 1/8 to 1/4-inch band
of aluminum tape exposed. The aluminum tape,
being conductive, will in a minute or so start
taking plating. The first traces of burning and high
buildup will then occur at the vinyl masked edge
on the aluminum tape. The area of interest,
therefore, will have no buildup and is less likely
to be burned at the edges.
You may occasionally have to mask off large
areas to prevent corrosive solutions from
attacking the part and to prevent solution
contamination. In these cases, apply tape to the
immediately adjacent areas; mask areas farther
away with (1) "Contact Paper" which comes in
18-inch wide rolls, (2) quick drying acrylic spray
paints, (3) vinyl drop cloth, or (4) "Orange Paint"
which is a tough adherent, heat resistant brush-
on type of paint.
SETTING UP THE JOB— LONGER
RANGE PREPARATIONS
This section deals with how to properly make
the longer range preparations to carry out a job.
It includes recommendations on selecting and
assuring that the proper solutions, power pack,
preparatory tools, plating tools, and so on are
available. The material is arranged in a step by
step manner developed from past practical
experience.
We assume that a basic installation is available
including a power pack. You can, however, use
steps 1 through 7 to select an appropriate installa-
tion including a power pack or to assure that an
appropriate installation has been purchased.
Step #1 Obtain the necessary information on
the job including:
a. The number of parts to be done.
b. The material on which deposit will be
applied. In most cases, it will be the material from
which the part is made. If the part, however, has
had a surface treatment such as an electroplate
or carburizing, the plating will be applied on the
surface material and not on what is underneath.
c. The area to be plated; that is, have a
concrete idea of size and shape of the area to be
plated.
d. The purpose and requirements of the
deposit; that is, why the coating is being applied
and what it is expected to do.
e. A general idea of what is adjacent to the
area to be plated.
f. The required thickness of the deposit.
Step #2 Selecting the plating solution to use.
This is, in most cases, an extremely important
step. Proper selection assures that you will get the
desired results with maximum ease and minimum
cost. In many cases, the pure metal or alloy will
have already been chosen either by a specification
or blueprint; in other cases, the metal or alloy will
be obvious, such as cadmium for touching up a
defective cadmium deposit. In these cases, if there
is a choice of solutions, only the selection of the
proper specific solution remains. There are other
cases where a particular metal or alloy is not
specified or obvious such as in salvage or repair.
Tables 14-4, 14-5, 14-6, 14-7 and 14-8 have been
prepared to assist you in both instances. Review
these tables carefully before you make a selection.
Step #3 Calculate the amp-hours using for-
mula 1, page 14-59.
Step #4 Decide on the general approach to the
plating job:
a. Whether you will rotate the part or move
the tool by hand.
b. Whether you will pump or dip the
solution.
Plating
Solution
Code
Normal
Maximum
Thickness
In One
Layer (In.)
Ease in
Using
Solution
Ease in
Reactivating
Deposit
Corrosion
Tendency
in Base
Materials
Special
Toxicity
Problems
Antimony
2000
—
Very Difficult
Low
Toxic Metal
Bismuth
2010
—
Very Difficult
Low
None
Cadmium
2020
.007
Easy
Very Easy
Some
Toxic Metal
Cadmium
2021
.005
Easy
Very Easy
Low
Toxic Metal
Cadmium
2022
.007
Very Easy
Very Easy
Low
Toxic Metal
Cadmium
2023
.005
Easy
Very Easy
Low
Toxic Metal
Chromium
2030
.002
Difficult
Very Difficult
Low
Toxic Metal
Chromium
2031
.0005
Very Difficult
Very Difficult
Some
Toxic Metal
Cobalt
2043
.008
Easy
Average
Low
None
Copper
2050
.015
Very Easy
Very Easy
High
Very Acidic
Copper
2051
.006
Average
Difficult
Low
None
Copper
2052
.004
Easy
Difficult
Low
None
Copper
2054
.015
Easy
Easy
High
Very Acidic
Copper
2055
.012
Easy
Easy
High
Very Acidic
Iron
2061
.007
Average
Average
Low
None
Lead
2070
.007
Very Easy
Easy
Low
Toxic Metal
Lead
2071
.007
Very Easy
Easy
Low
Toxic Metal
Nickel
2080
.007
Average
Average
Low
None
Nickel
2085
.015
Easy
Easy
Low
None
Nickel
2086
.007
Average
Average
Low
None
Nickel
2088
.007
Average
Average
Low
None
Tin
2090
.007
Very Easy
Easy
Low
None
Tin
2092
.007
Very Easy
Easy
Low
None
Zinc
2100
.003
Easy
Easy
Low
Toxic Metal
Zinc
2101
.008
Very Easy
Very Easy
Low
Toxic Metal
Zinc
2102
.006
Very Easy
Very Easy
Low
Toxic Metal
Zinc
2103
.012
Very Easy
Very Easy
Low
Toxic Metal
Gallium
3011
Average
Low
None
Gold
3020
.007
Easy
Very Easy
Low
Has Cyanide
Gold
3021
.007
Easy
Very Easy
Low
Has Cyanide
Gold
3022
.007
Easy
Very Easy
Low
Has Cyanide
Gold
3023
.001
Easy
Very Easy
Low
Has Cyanide
Indium
3030
.010
'Very Easy
Very Easy
Low
None
Palladium
3040
.005
Easy
Average
Low
None
Platinum
3052
.005
Average
Easy
Low
Very Acidic
Rhenium
3060
.0001
Very Difficult
Low
Very Acidic
Rhodium
3072
.002
Difficult
Average
High
Very Acidic
Rhodium
3074
.001
Difficult
Average
High
Very Acidic
Silver
3080
.005
Average
Easy
Some
Has Cyanide
Silver
3081
.007
Average
Easy
Some
Has Cyanide
Silver
3082
.010
Very Easy
Easy
Low
Has Cyanide
Silver
3083
.010
Very Easy
Easy
Low
Has Cyanide
Nickel-Cobalt
4002
.007
Average
Average
Low
Toxic Metal
Tin-Indium
4003
.007
Very Easy
Very Easy
Low
Toxic Metal
Tin-Lead-Nickel
4005
.015
Very Easy
Very Easy
Low
Toxic Metal
Cobalt-Tungsten
4007
.005
Difficult
Difficult
Low
Toxic Metal
Nickel-Tungsten
4008
.005
Difficult
Difficult
Low
Toxic Metal
Babbitt-SAE 11
4009
.010
Very Easy
Very Easy
Low
Toxic Metal
Babbitt-Soft
4010
.010
Very Easy
Very Easy
Low
Toxic Metal
Babbitt-Navy #2
4011
.010
Very Easy
Very Easy
Low
Toxic Metal
28.X
14-39
Solution
Code
G/L
Factor
Max.
Max.
Yield %
Lit.
Gal.
Price
Antimony
2000
80
.008
5
2.5
.062
.031
50
2.7
.72
128
Bismuth
2010
70
.008
3
1.5
.038
.019
50
4.6
1.21
287
Cadmium
2020
160
.007
12
6
.172
.086
40
2.2
.56
109
Cadmium
2021
70
.007
4
2
.057
.029
50
4.1
1.07
216
Cadmium
2022
110
.007
7
3.5
.100
.050
50
2.6
.68
139
Cadmium
2023
100
.007
8
4.0
.114
.057
50
2.8
.75
150
Chromium
2030
30
.137
12
6
.009
.005
7
56.0
14.8
2,974
Chromium
2031
150
.120
4
2
.003
.002
5
15.7
4.15
874
Cobalt
2043
80
.020
14
7
.070
.035
33
5.4
1.44
242
Copper
2050
60
.013
6
3
.046
.023
50
4.9
1.29
94
Copper
2051
60
.013
7
3.5
.054
.027
66
3.7
.97
98
Copper
2052
60
.013
7
3.5
.054
.027
66
3.7
.97
102
Copper
2054
60
.013
9
4.5
.069
.035
50
4.9
1.29
Copper
2055
145
.013
25
12.5
.192
.096
25
4.1
1.07
116
Iron
2061
50
.018
12
6
.067
.033
12.5
20.6
5.45
864
Lead
2070
100
.006
4
2
.067
.033
50
3.7
.98
98
Lead
2071
100
.006
4
2
.067
.033
50
3.7
.98
106
Nickel
2080
110
.021
12
6
.057
.029
16.6
8.0
2.1
338
Nickel
2085
50
.015
14
7
.093
.047
50
5.8
1.54
160
Nickel
2086
40
.025
10
5
.040
.020
37.5
9.7
2.57
445
Nickel
2088
55
.021
12
6
.057
.029
30
8.8
2.34
Tin
2090
80
.007
4
2
.057
.029
50
3.0
.79
172
Tin
2092
80
.007
4
2
.057
.029
50
3.0
.79
166
Zinc
2100
100
.011
6
3
.055
.027
50
2.3
.62
56
Zinc
2101
75
.011
14
7
.127
.064
50
3.1
.82
75
Zinc
2102
100
.011
14
7
.127
.064
40
2.9
.77
75
Zinc
2103
80
.011
14
7
.127
.064
50
2.9
.77
84
Gallium
3011
30
.015
3
1.5
.020
.010
50
6.5
1.71
Gold
3020
100
.006
3
1.5
.050
.025
50
6.3
1.67
Gold
3021
98
.006
3
1.5
.050
.025
50
6.5
1.71
Gold
3022
90
.006
3
1.5
.050
.025
50
7.0
1.86
Gold
3023
25
.007
.5
.25
.007
.004
50
25.3
6.7
Indium
3030
60
.009
4
2
.044
.022
50
4.0
1.05
Palladium
3040
30
.017
6
3
.035
.018
50
13.1
3.47
Platinum
3052
50
.150
12
6
.008
.004
20
35.2
9.3
Rhenium
3060
20
.750
6
3
.001
.0005
33
52.2
13.8
Rhodium
3072
50
.030
6
3
.020
.010
60
6.8
1.80
Rhodium
3074
20
.030
4
2
.013
.007
50
20.4
5.4
Silver
3080
190
.005
8
4
.160
.080
33
2.7
.72
Silver
3081
100
.005
2
1
.040
.020
50
3.4
.91
Silver
3082
100
.005
5
2.5
.100
.050
50
3.4
.91
Silver
3083
100
.005
5
2.5
.100
.050
50
3.4
.91
Nickel-Cobalt
4002
84.2
.030
12
6
.040
.020
16.6
10.4
2.75
361
Tin-Indium
4003
73.4
.008
4
2
.050
.025
50
3.3
.86
265
Tin-Lead-Nickel
4005
84
.006
3
1.5
.050
.025
40
3.8
1.01
158
Cobalt-Tungsten
4007
80
.020
12
6
.060
.030
12.5
14.5
3.83
640
Nickel-Tungsten
4008
123
.025
12
6
.048
.024
10
11.9
3.13
487
Babbitt-SAE 11
4009
80
.006
1
1
.017
.017
33
4.5
1.19
245
Babbitt-Soft
4010
80
.006
1
1
.017
.017
33
4.5
1.19
245
Babbitt-Navy #2
4011
80
.006
1
1
.017
.017
33
4.5
1.19
231
28.X
14-40
1U|1C1UC3 Ul
Hardness
Structure
Properly Plated
Ductility
Adhesion
Deposit
Code
Knoop
DPH
BHN
Re
Antimony
2000
47
40
38
—
Very Poor
Poor
Bismuth
2010
19
16
15
—
Very Poor
Poor
Cadmium
2020
25
21
20
—
No Defects
Good
Excellent
Cadmium
2021
23
20
19
—
Micro Porous
Fair
Fair
Cadmium
2022
30
26
25
—
No Defects
Good
Excellent
Cadmium
2023
27
23
22
—
Micro Porous
Fair
Fair
Chromium
2030
681
584
553
54
Micro Cracked
Not Coherent
Fair
Chromium
2031
908
778
709
63
Some Stress Cracks
Very Poor
Fair
Cobalt
2043
514
441
418
45
No Defects
Fair
Excellent
Copper
2050
165
141
134
—
No Defects
Excellent
Excellent
Copper
2051
249
213
202
(14)
No Defects
Poor
Fair
Copper
2052
244
209
198
(13)
No Defects
Poor
Fair
Copper
2054
206
177
168
( 5)
No Defects
Good
Good
Copper
2055
260
223
211
(16)
No Defects
Fair
Good
Iron
2061
595
510
483
50
Some Stress Cracks
Very Poor
Excellent
Lead
2070
7
6
6
—
No Defects
Excellent
Good
Lead
2071
7
6
6
—
No Defects
Fair
Good
Nickel
2080
530
454
430
46
No Defects
Very Poor
Excellent
Nickel
2085
683
585
554
54
Micro Cracked
Very Poor
Fair
Nickel
2086
326
279
264
27
No Defects
Excellent
Excellent
Nickel
2088
400
343
325
35
No Defects
Fair
Excellent
Tin
2090
8
7
7
—
No Defects
Excellent
Good
Tin
2092
9
8
8
—
No Defects
Excellent
Good
Zinc
2100
48
41
39
—
Micro Porous
Fair
Good
Zinc
2101
61
52
49
—
No Defects
Good
Excellent
Zinc
2102
63
54
51
—
No Defects
Excellent
Excellent
Zinc
2103
•3A1 1
55
47
45
—
No Defects
Excellent
Excellent
Gallium
Gold
jUl 1
3020
148
127
120
No Defects
Fair
Excellent
Gold
3021
140
120
114
—
No Defects
Fair
Excellent
Gold
3022
143
123
117
—
No Defects
Fair
Excellent
Gold
3023
140
120
114
—
No Defects
Fair
Excellent
Indium
3030
2
2
2
—
No Defects
Excellent
Excellent
Palladium
3040
436
374
354
38
Micro Cracked
Not Coherent
Fair
Platinum
3052
•3 r\£ f\
550
471
446
47
No Defects
Fair
Good
Rhenium
Rhodium
oUOU
3072
927
795
718
64
Some Stress Cracks
Very Poor
Fair
Rhodium
3074
950
814
729
64
Some Stress Cracks
Very Poor
Fair
Silver
3080
110
94
89
—
No Defects
Very Poor
Fair
Silver
3081
163
140
133
—
No Defects
Poor
Good
Silver
3082
80
69
65
—
No Defects
Poor
Excellent
Silver
3083
142
122
116
—
No Defects
Poor
Excellent
Nickel-Cobalt
4002
543
465
441
47
No Defects
Very Poor
Excellent
Tin-Indium
4003
11
10
9
—
No Defects
Excellent
Good
Tin-Lead-Nickel
4005
9
8
8
—
No Defects
Excellent
Excellent
Cobalt-Tungsten
4007
630
540
512
52
Micro Cracked
Very Poor
Good
Nickel-Tungsten
4008
620
531
503
51
Some Stress Cracks
Very Poor
Good
Babbitt-SAE 11
4009
25
21
20
—
No Defects
Fair
Good
Babbitt-Soft
4010
22
19
18
—
No Defects
Fair
Good
Babbitt-Navy #2
4011
23
20
19
—
No Defects
Fair
Good
28.X
14-41
T3 H .
0> D -H
VO C)
T-H' VO
r-l VO
?H ^ fli CO
.d S M HH
^H
M O &l •
ON r-'
04 ^
o^ d'O
'•S '§ S3 ^
-3 cr ex 3
O D O •
04 I-H
r^ 03
r- vo
p™"l >IBII|I
H-I
04' TJ-'
00
04 1-H
2'| rS ^
r ^ Q <3 t S
W M O ™
*S
•o m
7. — Commonly Used Data
Voltages
imum Procedures
; Tools on
Areas New Jobs*
i i
i i
00 O
4 60 ed °°T3
rt d "5 J3 d
<u • rj P< «9 d
« S
Si— H ^
O «J
3 O 0
a^«j
.§ ^ T3
5 d c
f( ^
. N
rH
O
"o
oo oo
8^?
^5
£
(U
13
O
U
§o
r-H
o
04 04
H
Antimony
Bismuth
vo n-
00 rt
rf 0
<N m
o o «n
"*
T-H T-H
ON en
en ON
vo vo
ON «o
T-H VO
gr^
tS ON
O\ 00
ON O
m O
Tf rf O
en m O
»-< en
04 en
T-H T— (
vo vo
O\ l>
ON ON
r- o\
ON oo
oo oo
OO OO
VO en
"-< r-
T!- -^f
oo vo
rf Tf vo
»-H r-
r-H T— 1
^ r-
r~ r-
TJ- rj-
T-H O
m •— i
t-> '^i-
<N (N
rf vo
C4 (^
vo vo
en <N
U*4 »O VO
en en o4
04 oo
en
VO VO
r-H r-H
vo »o
04 04
»n en
04 04
en en
04 04
vo r-
<o o
oo wn
vo r-
u-i
OO i— i
Tf O-N
Tf- ro
r- t- O\
ON O> 04
i^ «r»
0 Tf
OO OO
ON ON
Tj-
T-H \S)
l> Tf
«n en
ON ON
r- r-
r""(
Tt- ^f
T-H
l-H i— 1
1— (
»-H V}
04 ^
04 04
04 *-H
VO 00
o r-
•n- o>
r- t^> ON
,-! VO
r- r-
O OO
r~ oo
O O
04 rf
ra ts
vo »o
»0 i— i
m ^t
en en TJ-
Tf 0
04
en en
oo »n
ON oo
en en
«o o
>n «^i m
»/•>
VO 04
m rt
VO <N
r- m
en en rf
04 VO
1— 1
04 04
vo r~-
»n vo
04 04
04 Tf
T-H
r- oo
(N -Tf
T-H
Tf vo
i— i
r- r- ON
m 04
04 "i
•<± -«*
04 "*
r-H r-H
O 04
r— ( r-H
Tfr Tt
r-
i— i fn
oo
rn
r-
r-H
en ^^
ON O
'"I ^
en en
1 1
r—{ T-H.
VO »O
1 1
i— i »— <
+ +
r- vo
1 ^o
*? u
+ <u
00 C/5
vo |
<u "71
(U +
c/3 m
JH i i
+ + +
r-- -^t «o
1 1
1— 1 T-H
+ +
VO VO
1 1
r—{ r-H
+ +
vo oo
vo |
<u V
<u +
CO vo
vo vo
(L> <D
0) <U
00 OO
1 1
r—H r-H
v> vo
o o
04 04
<N 0
r4 <s
in o
«N '-H
»n r4
04 »-H
O 00 10
04 T-H ^H
00 0
r-H (S
0 0
04 04
»o o
04 04
»r> »o
04 04
O in
04 04
vo »o
o vo
oo -^j-
o m
r— (
r- TT w-»
vo vo
vo oo
oo vo
r- oo
10 VO
££
r-- r-
Of— \
r- o
O co
en en en
en oo
VO VO
r-H »0
IO r-H
r- r-
00
o o
»— ( r-H
O 0
O O O
O O
o o
O 0
0 0
^j
04 04
o o
04 04
«N en
ss
fS (S
O '-H
m m
O O
<S <N
en O
Tf »O
0 0
04 04
<-! 04 Tt
m «o «r>
o o o
04 04 04
>O r-H
S 8
04 04
0 r-H
r- r-
O O
04 04
O <O
oo oo
0 0
04 04
VO 00
oo oo
o o
04 04
O 04
ON ON
O O
04 04
admium
admium
admium
admium
tiromium
hromium
•3 ^
Cd OH
X) PH
0 0
Ui U. t-
(U <U <U
CX CX CU
i CX CX
o o o
t-4
0)
g c
o o
-a -a
<tf «j
<D <U
'u "c3
* ^
0 O
"a> *S
^ -^
O CJ
a a
UU
UU
UU
U U
JUU
1 -H
'w' hH
J J
22
^x
H H
<
00
d
-»->
o
T^H
"3
oo
O
in
00
O
a
o
U
o
U
r~
-4
rH
0)
3 o3
>
>*'
1— 1 T-H T-H
r-H
T-H
in T-H
T-H
S CD
g
CD
W
CO
lH
'3 s
D
ffi
•2 o
ft
T-H rn vo
^OrN
v> m
in oo
10 ON t*~
•n T-H
(~- Tj-
«n «/^ in
ON *r\
VO t~~ T-H
co co
ro
s §
t-- «o t-
t^-m
ON ON
oo ro
co co co
CO ^j-
^t OO
^t Tt Tf
oo •<*
*o m T-H
m m
m
<LJ
*"TJ
. i
^1" m rn
n cO
CO T«H ^"
*n ^*
T-H T-H
T-H T-H T-H
OA C^
T-H T-H CO
T-H T-H
r-H
^
^
T-H
fN co r--
">• T-H
r- ^H
VO
in t • m
•* o
CN
T-H T-H T-H
»n vo
I-H m m
ON ON
ON
13
vo oo t->
-- (~*
vo t~-
oo r-
O ^ m
00 OO
•^f r*-
ON ON ON
l> 00
O OO T-H
T-H f-H
•2.8
^
d
r— 1
0
*^
T-H T-H
r-H VO
I-H m ON
m I-H
T-H
10
co
T-H rn m
T— 1 T-H
^
-2 &
ft
•
*O CD
OO Qfi
u
.
m T-I ON
o»o
m «n
O rn
O T— i CO
CO OO
-* t^-
n- rj- rr
•«t m
oo «n ON
«n »n
«n
\f * H^
T
co m co
(NVO
vo vo
t~- »/-)
Tf m >n
CO VO
O CO
m m m
o m
m ^ T-H
•^f Tf
THJ-
r- 1
CO
T-H m
T-H
T-H 1-H
ob
^
•nun
"j8.
^ ^
in
S3 £*
<<
m r- r-
T-H
T-H T-H
*"•
co m vo
m m
<N Tf
T-H co ro
VO CO
T-H' VO VO
T-H T-H
1—1
£'55
a
^
C C3
\
.
So
^
0
c3
in
^7
~j>
vo ^~ 'Tf
Tt m
m m
m
xf vo CO
VO vo
•^t oo
cO *r\ *o
CO "*
m co CO
T— 1 r—(
T-H
T-H T-H
'~H
T-H
T-H
T-H T-H
CO
#
r- r-
oo ON
O CO
ON
T-H CO
m m
m
l_l
CO
CO CO
m m
rn
"*<• ^Hf
^1" Tt
Tf
IT-J
O
rn rn
rn rn
m T_( m
T-H
r-H r— H
T— (
rn
,_, m m
m m
m
•fcj
O
h~5
1 1 1
1
vd vd
vd vo
vd | vd
1
1 1
in 1 1
vd
| vo vo
vo vo
vo
o
CD
T-H T-H T-H
T-H
CD CD
CD CD
CD CD
0) *£ CD
T-H
U? 4^
+ + +
CD
T1 CD CD
+ CD CD
O CD
([} flj
CO
CO
£
oo ON ON
"s~
00 00
00 00
00 Tj- OO
^
m oo
00
»r> 00 00
OO 00
00
CD
00
1
CO
i— (
O
8
in
o
CD
0
1
H
CD
43
O O O
co co co
T-H T-H
0 O
CO CO
*n O
T-H T-H
«n TJ- o
CO T-H rH
T— (
co O
T-H CO
O vo vo
T— 1 T-H T-H
<o in
in in i/^
T-I CO CO
in i/~>
T-H T-H
£
00
erf
00 T3
c
M
H
a
r-1
aJ
PH
CO
a
"o
CO
0
CD
1
H
^
oo ON ON
r>Tt
"* "*
Tfr ^
oo rf m
"*
m oo
-<t ir» m
oo oo
«n o oo
m m
m
;a
l3
T3
S
S
§
00
O
T-H T-H T-H
T-H in
vo vo
VO f-
ON l> O
^^ ,.. -i) |/^
0 0
O «n
^^ «n
O 00
vo O «^>
VO vo
vo
000
oo
o o
o S
O O T-H
l> O
O O
O O O
o o
O O O
O O
O
CD
m T-H
O T-I
CO m
o o co
o co
^ O
T-I cO m
co m
in r- oo
ON O
T—H
O
o o o
T-H T-H T-H
23
o o
O O
m rh »n
O O O
vo r-
O 0
r- oo
O 0
oo oo oo
o o o
8 8
8 8 §
O T-H
T-H
O
co co (S
m m
m m
m m m
m m
m m
m m m
Plating
Solution
o o o
age
N N R
Zinc
Gallium
r-H T-H
O O
OO
"o "o
OO
Indium
Palladium
Platinum
Rhenium
Rhodium
Rhodium
Silver
rH lH rH
CD 1) CD
bo bo bo
Nickel-Cobalt
Tin-Indium
_O g, "to
1 "73 ^
»-H
i?
oo oo
1 1
-t-J +-*
.tn .tJ
rD rO
•§•8
PQ «
1
I
• rH
,0
•8
ffi
14-43
Table 14-8.— Solutions Used for Salvage
Solution
Code
BHN
Normal Maximum
Maximum Plating Solution
Build Up One Ease in Speed Cost $
Ductility Layer-Inches Plating In./Hr. Per In.3
Chromium
2031
709
Very Poor
.0005
Very Difficult
.003
874.00
Nickel
2085
554
Very Poor
.015
Easy
.093
160.00
Chromium
2030
553
Not Coherent
.002
Difficult
.009
2,974.00
Cobalt-
Tungsten
4007
512
Very Poor
.005
Difficult
.060
640.00
Nickel-
Tungsten
4008
503
Very Poor
.005
Difficult
.048
487.00
Nickel
2080
430
Very Poor
.007
Average
.057
338.00
Cobalt
2043
418
Fair
.008
Easy
.070
242.00
Nickel
2088
325
Fair
.007
Average
.057
—
Nickel
2086
264
Excellent
.007
Average
.040
445.00
Copper
2055
211
Fair
.012
Easy
.192
116.00
Copper
2052
198
Poor
.004
Easy
.054
102.00
Copper
2050
134
Excellent
.015
Very Easy
.046
94.00
Silver
3083
116
Poor
.010
Very Easy
.100
391.00
Zinc
2102
51
Excellent
.006
Very Easy
.127
75.00
Note: Code 2085, 4007, and 4008 deposits should be ground if machining is required after plating.
Code 2080, 2043, 2088, and 2086 deposits should be ground, but can be machined but with difficulty
and high tool wear. Code 2055, 2052, 2050, 2102 and 3083 deposits are easily machined.
28.X
Step #5 Decide on what type of plating tool
you will use, whether a standard tool
or a special tool. If you plan to use a
special tool, determine its design. (See
figures 14-15, 14-16, and 14-17.)
Step #6 Based on the plating tool you will use,
determine the contact area if you did
not determined it in Step #5.
Step #7 Based on the contact area, determine
the plating current if you did not
determine it in Step #5. Use formula
4, page 14-60.
Step #8 Determine the plating time using
formula 5, page 14-60. If you plan to
dip for the solution, double the plating
time.
Step #9 Determine the amount of plating
solution necessary, using formula 6,
page 14-60. Multiply by a factor given
4. (bee figure 14-18.)
Step #10 Determine the preparatory and
preplate solutions required using table
14-9. Determine the type of tools to be
used with these solutions using figures
14-13 and 14-14.
Step #11 Determine the covers to use on all
preparatory and plating tools.
Step #12 Determine the masking required.
Two examples of the planning procedure used
on actual jobs follow below. This information is
you begin any plating operation.
EXAMPLE #1
Step #1 Information on the job.
a. No. of parts— 1
b. Base Material— Steel
c. Area to be plated— 1" long x 3.500
+ 0.000 bore in a turbine wheel.
d . Purpose of the deposit — To repair a worn
I.D. Color match is important. Good hardness,
adhesion and cohesion are required.
COPPER
(Ull)
rums $9ii?!ia
CODE 20!!
28.456X
Figure 14-18.— Plating Solutions.
14-45
aoiuiicm aim iseposu rruperucs
Solution
Code
Applications
Chromium 2031
Nickel
2085
Chromium
Cobalt-
Tungsten
Nickel
Cobalt
Nickel
Copper
Copper
Copper
Silver
2030
4007
2080
2043
2088 &
2086
2055
2052
2050
3083
Zinc
2102
Used occasionally as an overlay a few ten-thousandths
inches thick on nickel or cobalt where a little more wear
resistance is desired, such as on hydraulic piston rods.
Never used alone for salvage.
Used extensively for salvage and repair of aluminum, cast
iron, and steel parts. Works well under roller bearings,
riding against babbitt bearings, etc. Not used in cases
where there is extreme shock such as on cutting ends of
punches, etc.
Very seldom used for salvage.
Used occasionally for high wear applications, particularly
at high temperature, i.e., up to approximately 1000 °F.
Maximum thickness approximately .005 inches.
Used often where a good combination of wear resistance,
corrosion resistance, and toughness is desired. Used
primarily on steel, stainless steel, nickel, etc.
Used often where a good combination of wear resistance,
and toughness is desired. Used primarily on steel, stainless
steel, nickel, etc. Excellent color match with steel and
stainless steel.
Used often where maximum ductility and corrosion
protection are desired along with some hardness.
Used occasionally for high-buildups on smaller areas
where maximum plating speed is important. Adhesion and
coherence not quite as good as Code 2050.
Used occasionally for buildups up to .004 inches on
alumimum, steel, cast iron, and zinc, particularly where
it is difficult to mask and prevent attack by other
solutions.
Used extensively on steel, copper, cast iron, nickel, and
stainless steel particularly in high buildups. Often overlaid
with nickel or cobalt for extra wear or corrosion
resistance.
Used occasionally on worn surfaces where the plating must
be hand-worked to meet final dimensional requirements.
It is hard enough for most applications, but is soft enough
to be easily scraped or sanded.
Used extensively on aluminum and zinc particularly in
high buildups.
28.X
14-46
thickness of about 1 inch. Numberous turbine
blades are at the O.D.
f. Thickness of deposit required— The
diameter after truing up the I. D. by grinding must
be 3.5015. A plating thickness of 0.001 inch will
bring the bore to the middle of the desired
tolerance.
Step #2 Select plating solution to be used.
Cobalt 2043 meets all requirements.
Step #3 Amp-hr required.
A = 3.14 DL = 3.14 x 3.50 x 1.00 = 11.0
Amp hr = FxAxT = 0.020 x 11 x 10 = 2.2
Step #4 General approach.
The small area, amp-hr, and thickness involved
suggest that (1) a special tool is not required and
(2) that the solution need not be pumped. This
will be justified in the following steps. The part
will be cleaned, etched, rinsed, and so on over a
drain and then, being light enough, will be placed
over a 14" x 17" collecting pan. A hole in the
collecting pan will direct the solution back to the
solution container. The solution container is large
enough to hold all the solution, but small enough
to have enough depth of solution to thoroughly
wet all of the plating tool.
Step #5 Plating tool to be used.
An RF-30 tool with a 1/4" thick cover will just
match the I.D.
Step #6 Plating tool contact area.
Although the tool with its cover just matches the
I.D., pressure on the tool cover will compact it
and lead to perhaps a 50% contact area, or 5.5
square inches.
Step #7 Plating amperage.
Plating Amps = CA x ACD = 5.5 x 7 = 38.5
Step #8 Plating time
- AmP"hr - — = 0 057 hr
- - - u.w / nr
Double the plating time because the solution will
be dipped for. The total plating time, therefore,
pumping the solution is not necessary and the tool
will be moved by hand.
Step #9 Plating solution required.
Liters = Q(L) x T(I) x A = 5.4 x 0.0010 x H = 0.059
This obviously is not enough to thoroughly wet
the cover. It is estimated that 1 liter will be
sufficient for the purpose.
Step #10 Preparatory and preplate solutions and
tools.
a. Code 1010, 1022, and 1023, and 2080.
b. Tools: AC-5. These, although relatively
small, give a 1/2" x 1" contact area and should
be satisfactory.
c. Quantity of solution required: Approx-
imately 0.1 liter for each tool. This amount, when
a small beaker is used, should thoroughly wet the
cover.
Step #11 Covers to be used.
Preparatory tools: Cotton batting and cotton
tubegauze.
Plating tool: Cotton batting and cotton
tubegauze, since the cover is pure and in-
expensive. Although cotton tubegauze is not wear
resistant, it should easily 1st for the 15-minute
plating time.
Step #12 Masking.
Use aluminum tape and contact paper to prevent
the part from contaminating the solution.
EXAMPLE #2
Step #1 Information on the job.
a. Number of parts — 1
b. Base material— Steel with loose metal
spray from a previous repair.
c. Area to be plated— 7" long area on a
2.436 OD
+ 0.001
- 0.000
d. Purpose and requirements of deposit-
To repair a loose fit on the inner race of a roller
bearing.
14-47
e. Although the part is a large recirculating
fan about 5 feet long with a maximum O.D. of
3 feet, the area being plated is a simple O.D. on
a shaft.
f. Thickness required — It was decided to
machine off the metal spray coating which was
obviously very loose, leaving a gentle taper at the
edges. After machining, the diameter was 2.285".
The thickness required, therefore, is 0.152" in
diameter or 0.076" on radius. Since plating will
have to be stopped one or two times for machining
to remove the buildup at the edges and to improve
the surface, a total of approximately 0. 100 of inch
plating should be planned on.
Step #2 Select the plating solution to be used.
Copper 2050 will be used because of the high
thickness required. Copper 2050 stays smooth to
high thicknesses and is easy to reactivate for more
plating. Machining will be required because of the
high thickness of deposit to be applied. The
deposit, therefore, after copper plating will be
machined 0.0005 inch undersize on the diameter
and then be plated with 0.0005 inch of nickel 2085
for color match.
Step #3 Amp-hr required.
A = 3.14 DL = 3.14 x 2.436 x 7 = 53.5
Amp-hr(Cu) = F x A x T = 0.013 x 53.5 x 1000 = 696
Amp-hr(Ni) = F x A x T = 0.015 x 53.5 x 5 = 4.01
Step #4 General approach.
The part will be rotated in a lathe because a lathe
is available. The solution will be pumped through
a special tool.
Step #5 Plating tool to be used.
A special tool will be prepared for copper plating
since no standard tool is available to cover the
full 7" length. The largest power pack available
is a 60-35. Planning on drawing 55 amperes, the
Optimum Contact Area was determined:
= = 18 1
ACD - 3 ~ «.3
Since the length of the O.D. is 7", the contact
length around the circumference should be
18.3
or approximately 2.6 inches. A special anode,
therefore, will be prepared about 7 1/2" long
x 2 3/8" wide x 1 7/8" high. It will have all/2"
radius (1/4" allowance for the tool cover) placed
in the 2 3/8" x 7 1/2" face. The solution will be
fed through an F-handle to a 1/2" hole in the
anode, running in the 7" direction (capped off at
the ends) and then through six 1/8" holes
distributed along the 7" direction to the face hav-
ing the radius.
Step #6 Plating tool contact area.
Copper — Not required (determined in Step #5).
Nickel — If an F-3 plating tool is used for nickel
plating, the contact area will be 3 1/2" x \" along
the circumference with a soft pad. CA = 3.5 x 1
= 3.5 sq in.
Step #7 Plating current.
Copper — Not required (determined in Step #5).
Nickel — Plating amperage
Plating Amps = CA x ACD = 3.5 x 7 = 24.5
Step #8 Plating time.
Copper PT (hr) = ,. mp"hr = 12.7
** ^ '
,. A
Plating Amps 55
Nickel PT (hr) =
v '
P1
Plating Amps 24.5
= 0.164
If the solution is dipped for total nickel plating,
the time will double, to 0.328 hour. The use of
an F-3 tool, therefore, is justified and the
solution need not be pumped through the anode.
Step #9 Plating solution required.
Copper 2050(gal) - Q(G) x T(I) x A = 1.29 x 0.100
x 53.5 = 6.90
Since almost all solution can be caught for reuse,
7 gallons of copper 2050 should be sufficient.
Nickel 2085(gal) = Q(G) x T(I) x A = 1.54 x .0005
x 53.5 = 0.041
Nickel 2085(liter) = Q(L) x T(I) x A = 5.8 x .0005
x 53.5 = 0.155
Since an F-3 tool will be used to apply the nickel,
0.155 liter will not be sufficient to wet the tool
and the area to be plated. Approximately 1/2 liter
is required.
a. To activate the base material— 1010,
1022, 1023, and 2080. To activate the copper for
more copper and the final nickel coating 1010,
1023.
b. Tools required.
4 (F-2 or F-3)
c. Amount of solution required.
1010 — 1 liter (will be used several times)
1022—1/2 liter (will be used once)
1023 — 1 liter (will be used several times)
2080—1/2 liter (will be used once)
Step #11 Covers to be used.
Preparatory tools— Cotton batting and cotton
tubegauze.
Copper plating tool — White Scotchbrite
Step #12 Masking.
Aluminum tape 2" and vinyl tape 2".
FINAL PREPARATION
Longer range planning should have assured
that appropriate equipment, materials, and
supplies are available to carry out the job. This
section deals with the final preparations you
should make just prior to plating.
Familiarization with the
Equipment and Procedures
Success in carrying out plating operations is
assured by quickly and knowledgeably carrying
out the various steps. As the operator you should
be familiar with the following:
1. The power pack and the position and
purpose of the various controls and meters.
2. How the base material should look at
various stages of preparation.
3. What a good and bad deposit look like as
the plating is being applied.
Some practice is recommended when the
equipment is new, when you encounter a new base
material, or when you plan to use a new plating
solution. In practicing on a new base material,
try shorter and longer operations until you are
very high and very low voltages until you are
certain that you know what good deposit and bad
deposits (burned or otherwise) look like. If
possible, run a plating test on a 1" x 1" area using
an AC-5 or similar size tool; you should be able
to plate a good deposit at the volts and amps given
in table 14-3 and in the "Plating Example".
Draft a Flow Chart
A very valuable tool for any operation is a
good plan. Figure 14-19 shows a recommended
plan or flow chart which will help you conduct
the operation smoothly, and remind you of all the
important elements of the operation.
Prepare the Part for Plating
1 . Inspect the area to be plated for any signs
of a foreign surface being present such as an
electroplate, paint, scale, or anodized coating.
Remove the coating by suitable means such as
vapor or dry blast, sandpaper, wire brush, and
so forth. In pit-filling applications pay particular
attention to ensure that the bottom of the pit is
clean.
2. Preclean, if necessary, the area to be plated
and the surrounding areas with a quick-drying
solvent that leaves no residue (such as
trichlorethylene or perchlorethylene). This should
assure that masking materials will still stick and
that solutions and tools will not come in contact
with dirty, oily surfaces. The area to be plated
should look clean.
3. Mask off the area to be plated.
4. If the part is to be rotated in a lathe or
turning head, set the rpm to obtain optimum
anode-to-cathode speed as given in table 14-10.
If you plant to move plating tool by hand,
visualize the proper tool movement speed.
5. When the solution plates better at
temperatures higher than room temperature,
preheat the part and the solution, as required, by
a suitable means. Methods used to preheat
solutions include:
a. Placing tightly capped bottles in a basin
or tank of hot water.
b. Pouring solutions into pyrex or stainless
steel containers and heating them on a
range.
c. Putting immersion heaters into the
solution.
14-49
t-t
-M
t-l
TJ
O
^M
1 §
^
)-H
o
O
^
<L>~
-(-•
OO
B §
'O
%
o
1— 1
'o
\
T— (
2 0
o •— "
1 OH I
oo
bo
'o
o o
^M en
bO £
fl r3
0 JB
O o
'oo
(D ••— '
V-H >
Cd s»_
3 O
following rinse.
OO
^
cd
u
>-i
X>
»-i
(L>
•S3
£
o
Z
cd
(U
ts
cd
(U
VH
cd
U
tH
^O
"o
o
^
>-i
bJQ
^4
I-H
cd
Q
cd'
<u
VH
cd
oo
•a
(U
l-t
pD
VH
CD
•(_>
cd
£
0
Z
cd
CD
t-l
cd
<u
Ix
. light gray color. Will not b
rons change their grain stri
re area. No water breaks.
0
Z
IH
^
3
0
i— <
<L>
^
0
'3
<L>
M
O
S
cd
00
^H &
cd .t!
^ *
JD
n S^
(D ?>
td cB
^
o 2
* '§
Cd "
D _,
H C
cd o
a>
UH t-<
<L>
5
U.
"1
JS «
cS ,9
•^ ^
u. -5
3 '5
cd ^
£ S
CD
n <-H
2 S
(-H
S^ '-+3
g s
<u g
VH O
00
OJ
o
CO
«4-H
t-l
C/3 r— < r \
o .5 <u
Q S W
° §
CO <U
f] Q
> £ en
H S <U
C""1 5 «1-H
Id CO
3 «J «. <
oo (L) T3
> U §
UH
a>
t;
cd
oo
•a
0)
t-l
rO
!-<
(U
4— >
cd
^
0
Z
Thorough rinse of enti
Uniform etch of entire
grain structure visible.
Thorough rinse of enti
co — i «3
0 to S
-M cd U
bo o c*^
CH O O
'§ | 8
^^ «
bO • ^
•r- 1 >— i
•— ' 0> rC
6S 3°
o.SP o
<2 a k
'3^2
£ fl ^3
^ § H
O
-*-)
o
o
cd
«H-H
V-4
S 3
(4-H CJ
0 S
ITS
ll
o£
Thorough rinse of enti
Replacement of wate
Code 2085.
Medium gray, matte si
Thorough rinse of enti
Replacement of water
3
CO
C4-I
O
bO
G
'>.
VH
-a
aj e«
4-> Q
^H '-2
"E 2
S a
o g-
U 1
S
a
2
ex
>»
T3
-a
TJ
^
i-H
.*— >
V-^
cu
O.J
j_^
UH
ln^
cd
oo
C^l
cd
cd
«S
«fr
j-j i
i
i
OJ
1
o> |
>
I |
>
i i
• i
VO
r— i 1
?"
p>.
i
j^
i i
J_,
i i
' "C
,.
O
o
(U
<u
O
o
81
C?^
OH
P4
p<
b
U
o "S
^
1— 1 hJ
O
% 1
O
o
«B
x a
. a>
CO
"*"* m
T— 1 r— 1
1— 1 T— 1
"a.
S
1 !
oo
t— i
S
^
S
0 !
J-H X
*-H Q
i i
i i
d ^"
i i
i i
i i
S ^
>-< >
i^
_c *"*
_rt ^
IB
* 0 in
en ^
4-1 OH
^ OH
9\
1 ?*
oo cd
oo cd
•4
HH E
bo
bO
a
O ffi
fN
m
.S
iZ
PH +_> i_
*N
• r— t
O
o
'.3
CO -S OH
»— <
T3
<L> O ri
HOC
< H <
13
1
fe
CJ
S3
(U
T3 »-;
o ^
^^
oo
o
,_, 00
c3 o
oo
O
S3 S
"C
Q
td
U
OS
U cd
fN
•*— * o^
cd
td Q
CD
^ CU
(U
cri "^^
>>>
f
(-i
&
r- 1 &
T)
TJ
d?i !•-•%
'O
^ •§
«^S
OH
-»->
W
OH
£ ^
w 5
o
Q. O
cd U
•M
O
U
OH S
(U
1-1
'3
cr
• r-H ""^
1— 1
F— I
«>— i T~~l
cr
(U
C"H flj
CN
CH
en c3
CO
CH ^^
<L>
C3 CH (U
Cd *rj
§
cd
cd
1-^
cd ^
P^
cd cd TJ
t-H
^
oo
£ 0
0>
o
<u
O ^
JJ
tu o
O
CO CO X
oo
CH Q
uo
0
2
U
K U
z
U Z
g
Duo
£q s
._, I 3
•+•"* F^
00 . fS .
cti ^3 ^^
fl
G
<u
O b* I
0
D
-S
2j
i '3 £»
TJ C
cd cd
VH (L>
m i
1 1
o
o
(-1
flj
+-"
3
<u
T»S
•4— >
£ |
13
S
<L> J3
"^ ^> o<
rrt OO
a 1
0 £
•4-J
8
S
oo
_c
^3
oo
,g
C &o
<S .S
Q 04
K^ Q
o a)
S •"
C D
"-H (-1
W P i
o
2
S S
04 Z
Q
J2 4) C
S s.2
(U O "5
OH
cd S "75
(U »~*
<N
m
rf
10
vo c^-
oo
ON O
»— i
ol m
^>
W H c/D
^0
i— i
i—H
»— 1 »-H
»— i
solution
Code on 1 in. Volts Amps Lit. OaJ. rt./mm. Optimum Temp.
Antimony
Bismuth
Cadmium
2000
2010
2020
.008
.008
.007
8
4
8
1.3
1
5
29.5
17.4
31.6
111.6
66.0
119.6
50
50
75
60-120
60-120
60-120
Yes
Yes
Yes
Cadmium
Cadmium
Cadmium
2021
2022
2023
.007
.007
.007
8
16
8
1
2
1.2
17.3
27.1
24.7
65.4
102.8
93.4
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Chromium
Chromium
Cobalt
2030
2031
2043
.137
.120
.020
12
6
13
6
4
5
24.4
76.4
36.8
92.4
289.0
139.2
20
50
25
60-120
105
60-150
Yes
Yes
Yes
Copper
Copper
Copper
2050
2051
2052
.013
.013
.013
4.5
10
8
2.5
3
3
26.6
35.4
35.4
100.5
134.0
134.0
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Copper
Copper
Iron
2054
2055
2061
.013
.013
.018
8
10
14
3
10
4
26.6
32.1
8.7
100.5
121.4
33.
50
50
50
60-120
60-120
60-150
Yes
Yes
Yes
Lead
Lead
Nickel
2070
2071
2080
.006
.006
.021
10
12
14
1.5
1.2
4
16.1
16.1
26.4
61.1
61.1
99.9
50
50
50
60-120
60-120
110-170
Yes
Yes
No
Nickel
Nickel
Nickel
2085
2086
2088
.015
.025
.021
8
14
14
3
4
4
25.7
25.7
23.7
97.3
97.3
89.9
75
50
50
60-150
110-170
110-170
Yes
No
No
Tin
Tin
Zinc
2090
2092
2100
.007
.007
.011
8
8
8
1.2
1.0
2
23.4
23.4
47.1
88.6
88.6
178.1
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Zinc
Zinc
Zinc
2101
2102
2103
.011
.011
.011
13
13
9
4
4
2.5
35.3
37.6
37.6
133.6
142.5
142.5
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Gallium
Gold
Gold
3011
3020
3021
.015
.006
.006
8
8
8
1.5
1.0
1.2
23.2
9.5
9.3
87.9
35.9
35.1
50
50
50
72 max.
60-120
60-120
Yes
Yes
Yes
Gold
Gold
Indium
3022
3023
3030
.006
.007
.009
8
7
10
1.0
.25
3
8.5
2.8
22.5
32.3
10.5
85.3
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Palladium
Platinum
Rhenium
3040
3052
3060
.017
.150
.750
8
5 '
12
2.0
2.5
2.5
12.9
42.7
152.5
49.0
161.5
577.3
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Rhodium
Rhodium
Silver
3072
3074
3080
.030
.030
.005
10
7
13
3.5
2
2.5
44.1
14.7
18.4
167.1
55.7
69.7
50
50
50
60-120
60-120
60-120
Yes
Yes
Yes
Silver
Silver
Silver
3081
3082
3083
.005
.005
.005
7
13
12
.8
2
2.5
14.5
14.5
14.5
55.0
55.0
55.0
50
50
50
72 min.
60-120
60-120
Yes
Yes
Yes
Nickel-Cobalt
Tin-Indium
Tin-Lead-Nickel
4002
4003
4005
.030
.008
.006
14
6
10
4
.75
1.2
28.9
24.5
15.6
109.2
92.9
59.2
50
50
50
110-170
60-120
60-120
No
Yes
Yes
Cobalt-Tungsten
Nickel-Tungsten
Babbitt-SAE 11
4007
4008
4009
.020
.025
.006
13
16
9
4
4
.5
13.7
21.1
13.2
52.2
79.8
50.0
50
50
50
110-170
110-170
60-120
No
No
Yes
Babbitt-Soft
Babbitt-Navy #2
4010
4011
.006
.006
9
9
.5
.5
13.2
13.2
50.0
50.0
50
50
60-120
60-120
Yes
Yes
14-51
Setting up the Equipment
Set up the power pack near the work so that
it is easily accessible and you can view the
instruments. Connect appropriate size output
leads to the power pack and connect the alligator
clamp lead to the part of the lathe.
Wrap the tools, making sure the covers do not
get dirty.
Pour out sufficient solution in clean con-
tainers. Set up the solution pump and test operate
it. Soak the covered tools as long as possible in
their respective solutions (at least five minutes).
Arrange the setup so that everything you will
use is handy.
General Setup
As the operator, you should be as comfortable
as possible, particularly on lengthly plating jobs.
You can then concentrate your full attention on
the job, you will not be diverted by unnecessary
distractions, and your efficiency will not decrease
from fatigue.
You should have adequate lighting so you can
see that the preparation and plating is proceeding
properly.
Refer to table 14-11 for special safety pre-
cautions such as the necessity for ventilation,
gloves, special clothing, and so on.
Have sufficient clean tap water available for
rinsing the part.
Review the setup procedure one last time to
ensure that everything necessary is available and
handy. This step is to avoid delays during plating
and in turn to produce a finer finished product.
GENERAL PREPARATION
INSTRUCTIONS
Electroplates and tank electroplates depend on
atomic attraction of the electroplate to the base
material for adhesion. Extremely thin, invisible
films of oil, grease, dirt, oxides, and passive films
are sufficient to prevent an atomic attraction, thus
preventing the adhesion of the electroplate.
A preparation cycle is used, therefore, just prior
to plating to remove, step by step, all of the last
traces of these obstacles to developing excellent
adhesion.
A preparation cycle consists of a number of
operations, each one performing a specific
function. The number and types of operations and
the solutions used depend on the base material,
not on the plating solution to be used later. You
must carry out each operation properly to ensure
maximum adhesion. You do this when:
1 . You use the proper solutions in the proper
sequence.
2. You use the solutions one after another are
used in the proper direction, in other words
forward or reverse.
3. You perform the operations one after
another as rapidly as possible without
allowing the surface to dry between
operations.
4. You obtain the desired results in each
operation.
In most operations, you can tell by the
appearance of the surface whether you have
achieved the desired results. The visual tests are
important and you should pay particular
attention to those given in this chapter.
Each operation is usually carried out within
a certain voltage range as shown in the following
pages on preparing specific base materials. When
you use a small tool on a small area, use a low
voltage in the range. When you use a large tool
on a large area, use a high voltage in the range.
The voltage used in a preparatory step, however,
is not critical and can vary by several volts.
Obtaining the desired results as determined by the
visual test is again the important part of the
operation.
The following sections discuss the various
types of operations carried out on various base
materials.
Cleaning and Deoxidizing
A cleaning and deoxidizing operation is
usually performed first on most base materials to
Plating
Solution
Code
Ave.
pH
Special Problems
Ventilation
Required
For Precautions
Against
Skin Contact
Antimony
Bismuth
Cadmium
2000
2010
2020
7.3
10.8
0.5
Poisonous Metal
Poisonous Metal
Poisonous Metal-Corrosive Solution
Seldom
Seldom
Usually
Very Strong
Moderate
Very Strong
Cadmium
Cadmium
Cadmium
2021
2022
2023
9.0
8.8
11.0
Poisonous Metal
Poisonous Metal
Poisonous Metal
Seldom
Seldom
Seldom
Very Strong
Very Strong
Very Strong
Chromium
Chromium
Cobalt
2030
2031
2043
6.3
0.5
1.5
Poisonous Metal
Poisonous Metal-Corrosive Solution
Frequently
Usually
Seldom
Very Strong
Very Strong
Moderate
Copper
Copper
Copper
2050
2051
2052
0.5
11.1
6.4
Corrosive Solution
Seldom
Seldom
Seldom
Very Strong
Moderate
Moderate
Copper
Copper
Iron
2054
2055
2061
1.7
1.0
2.8
Corrosive Solution
Corrosive Solution
Seldom
Frequently
Seldom
Very Strong
Very Strong
Moderate
Lead
Lead
Nickel
2070
2071
2080
8.0
8.0
2.4
Poisonous Metal
Poisonous Metal
Seldom
Seldom
Frequently
Very Strong
Very Strong
Moderate
Nickel
Nickel
Nickel
2085
2086
2088
7.3
3.0
3.0
Seldom
Seldom
Frequently
Moderate
Moderate
Moderate
Tin
Tin
Zinc
2090
2092
2100
7.2
7.3
7.7
Seldom
Seldom
Seldom
Moderate
Moderate
Very Strong
Poisonous Metal
Zinc
Zinc
Zinc
2101
2102
2103
5.8
4.9
2.7
Poisonous Metal
Poisonous Metal
Poisonous Metal
Seldom
Seldom
Seldom
Very Strong
Very Strong
Very Strong
Gallium
Gold
Gold
3011
3020
3021
11.0
9.9
7.5
Seldom
Usually
Usually
Very Strong
Very Strong
Very Strong
Contains Cyanide-Cyanide In Fumes
Contains Cyanide-Cyanide In Fumes
Gold
Gold
Indium
3022
3023
3030
5.1
9.7
9.3
Contains Cyanide-Cyanide In Fumes
Contains Cyanide-Cyanide In Fumes
Usually
Usually
Seldom
Very Strong
Very Strong
Moderate
Palladium
Platinum
Rhenium
3040
3052
3060
8.3
0.5
1.0
Seldom
Seldom
Seldom
Moderate
Very Strong
Very Strong
Corrosive Solution
Rhodium
Rhodium
Silver
3072
3074
3080
.6
1.1
10.6
Corrosive Solution
Corrosive Solution
Contains Cyanide
Seldom
Seldom
Seldom
Very Strong
Very Strong
Very Strong
Silver
Silver
Silver
3081
3082
3083
10.3
9.6
11.6
Contains Cyanide
Contains Cyanide-Cyanide In Fumes
Contains Cyanide
Seldom
Usually
Frequently
Very Strong
Very Strong
Very Strong
Nickel-Cobalt
Tin-Indium
Tin-Lead-Nickel
4002
4003
4005
2.5
8.7
7.3
Frequently
Seldom
Seldom
Moderate
Moderate
Very Strong
Poisonous Metal
Cobalt-Tungsten
Nickel-Tungsten
Babbitt-SAE 11
4007
4008
4009
2.0
2.5
7.5
Frequently
Frequently
Seldom
Moderate
Moderate
Very Strong
Poisonous Metal
Babbitt-Soft
Babbitt-Navy #2
4010
4011
7.5
7.5
Poisonous Metal
Poisonous Metal
Seldom
Seldom
Very Strong
Very Strong
28.X
14-53
remove the last traces of dirt, oil and grease. It
also removes the light oxide films on some metals.
Forward current (cathodic electrocleaning) is
usually used. However, reverse current (anodic
electrocleaning) must be used whenever hydrogen
contamination and embrittlement of the base
material must be avoided, such as in the cleaning
of ultra high-strength steel. The cleaning and
deoxidizing operation is performed at 8 to 20
volts, depending on the base material and the size
of the tool. Higher voltages, longer cleaning times,
and heat developed in the tool are helpful in
cleaning stubborn areas. When you clean the area
to be plated, also clean the surrounding area since
oil and grease travel on the surface of water.
Follow the cleaning with a thorough water rinse.
If water "breaks" on the surface, the cleaning and
deoxidizing time was too short and you should
repeat the operation.
Etching
An etching operation using an etching
solution and reverse current usually follows the
cleaning and deoxidizing operation. The operation
electrochemically removes oxides, corrosion
products and smeared and contaminated surface
material, all of which impair adhesion. When the
unwanted surface material is removed, the area
will develop a uniform, dull, grainy appearance,
indicating that you should stop the etching
operation. Normally, you will remove 0.000050
to 0.0002 inch of material. This requires 0.006 to
0.026 amp-hr per square inch of area.
Desmutting
The etching operation on some materials
results in the formation of a loose layer of
insoluble material on the surface. An example of
this is the carbon film left on the surface after the
etching of a carbon steel. These layers can
interfere with maximum adhesion and should be
removed by an appropriate desmutting operation.
The operation is completed when the surface is
uniform in appearance and will not become any
lighter in color.
Activating
An activating operation is used on some base
materials, such as chromium, nickel, stainless
steel, and so on to remove a "passive" film which
quickly forms on these materials. A cleaning and
deoxidizing operation on these materials does not
remove the passive film. An etching operation on
these removes material from the surface, but
simultaneously forms the passive film. Passive
films prevent maximum adhesion. Therefore, you
will need to perform an activating operation on
these materials just prior to plating, using forward
current and an appropriate solution.
Cleanliness is of extreme importance in the
activating operation since it is the last operation
before plating. Avoid contaminating the solution
from any source since this operation is in the
forward direction and contaminants may be
plated out as a nonadherent film.
With the exception of chromium, there are no
visual keys to help you determine whether or not
you have performed the operation properly. The
passive film is invisible and on most materials such
as nickel and stainless steel you cannot detect a
change when it is removed. Any change that is
apparent may indicate contamination from the
activating solution, the anode, or the plating tool.
You must, therefore, carry out the operation on
a timely basis, spending about 3 seconds on each
part of the total area. With an activating tool
covering all the area to be plated, spend about
3 seconds in the operation. With a tool covering
1/5 of the area, conduct the operation for 15
seconds, spending an equal amount of time on
all parts of the area.
Plating
Follow the final preparatory operation as
quickly as possible with the plating operation,
whether it is a preplate or the final desired plating.
This is of particular importance when your
last procedure was an activating operation.
DO NOT ALLOW THE PART TO DRY BE-
TWEEN THE ACTIVATING AND PLATING
OPERATIONS.
VERIFYING THE IDENTITY OF
THE BASE MATERIAL
Obtaining good adhesion of a deposit begins
with proper identification of the surface being
plated. You will be frequently misinformed about
the identity of the base material and whether or
not a coating is present. This, of course, can lead to adhesion problems.
However, by carefully watching the etching operation, you can frequently
detect incorrect identifications or the presence of coatings. The following
descriptions may help you make these determinations. (Also refer to table 14-3.)
Result of No. 2 or No. 4 Etching Reverse Operation
Appearance of the Color of the Solution
Surface Rusts
After Etching
Material
Etched Surface
in the Cover
When Kept Wet
Magnetic
Low Carbon Steel
Light Gray
No Color
Yes
Yes
Medium or High
Medium Gray to
Black smut in cover
Yes
Yes
Carbon Steel
Black
300 Stainless
Light Gray
400 Stainless Soft Light Gray
400 Stainless Hard Black
Monel
Chromium
Light Gray
Shiny White
Yellow at first; green
later
Blue-green
Blue-green with Black
Smut
Pale Orange
Yellow
No
No
No
No
No
No
Yes
Yes
Yes
No
PREPLATING INSTRUCTIONS
It may be necessary, in some cases, to apply
a preplate with an appropriate plating solution.
Apply the preplate immediately after you prepare
the surface. After you finish applying the preplate,
immediately rinse the surface with water and plate
with the final desired solution. The preplate
ensures maximum adhesion of the final deposit.
The base material and the final desired plating
solution determine whether a preplate is required
and, if so, what preplate is required. Table 14-12
lists the preplates required for commonly used
solutions on commonly plated base materials. A
Code 2080 preplate and then a Code 2050
preplate, for example, are required on stainless
steel before plating copper 2055. A preplate is not
required for plating Code 2103 on low carbon
steel.
The preplate thickness applied varies from
0.000010 inch on smooth surfaces to 0.000050
inch on rough surfaces. Normally, when a
uniform color change results from plating the
preplate on the base material, a satisfactory
thickness has been applied. Since new operators
often do not apply a sufficient thickness of
preplate, they should calculate and pass the
ampere-hours necessary for a thickness of at least
0.000025 inch. Examples for solutions are from
the Dalic Selective Plating Manual. Each
manufacturer has its own instruction manual and
solution guide.
The preplate voltages used are as follows:
Code Very Small Tool Very Large Tool
12
2080
2050
2051
2085
3023
3049
6
8
10
8
8
SUMMARY OF ELECTROPLATING
The ideal plating operation is carried out when
(1) the quality of deposit is the best possible;
Table 14-12.— Preplates for Base Materials for Various Solutions
Plating Solution
Code
Aluminum
and
Aluminum
Alloys
Copper
and
Copper
Base
Alloys
Iron, Steel
and
Cast Iron
Nickel
and Nickel
Base Alloys
Stainless Steel
Zinc and Zinc
Base Alloys
Antimony
Bismuth
Cadmium
2000
2010
2020
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
2051 or 2085
2051 or 2085
Cadmium
Cadmium
Cadmium
2021
2022
2023
2080
2080
2080
1032
2080
2080
2080
2080
2080
2080
2051 or 2085
2051 or 2085
2051 or 2085
Chromium
Chromium
Cobalt
2030
2031
2043
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051
Copper
Copper
Copper
2050
2051
2052
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051
2051
Copper
Copper
Iron
2054
2055
2061
2080 + 2050
2080 + 2050
2080
2080 + 2050
2080 + 2050
2080
2080 + 2050
2080 + 2050
2080
2080 + 2050
2080 + 2050
2080
2051
2051
2051
Lead
Lead
Nickel
2070
2071
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
2051 or 2085
2051
Nickel
Nickel
Nickel
2085
2086
2088
2080
2080
2080
2080
2051
2051
Tin
Tin
Zinc
2090
2092
2100
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
2051 or 2085
Zinc
Zinc
Zinc
2101
2102
2103
2080
2080
2080
2080
2080
2080
Gallium
Gold
Gold
3011
3020
3021
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
Gold
Gold
Indium
3022
3023
3030
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
Palladium
Platinum
Rhenium
3040
3052
3060
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051 or 2085
2051 or 2085
2051 or 2085
Rhodium
Rhodium
Silver
3072
3074
3080
2080
2080
2080 + 3040*
3040
2080
2080
2080 + 3040*
2080 + 3040*
2080
2080
2080 + 3040*
2051
2051
2051 + 3040*
Silver
Silver
Silver
3081
3082
3083
2080 + 3040*
2080 + 3040*
2080 + 3040*
3040
3040
3040
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2080 + 3040*
2051 + 3040*
2051 + 3040*
2051 + 3040*
Nickel-Cobalt
Tin-Indium
Tin-Lead-Nickel
4002
4003
4005
2080
2080
2080
2080
2080
2080
2080
2080
2051
2051 or 2085
2051
Cobalt-Tungsten
Nickel-Tungsten
Babbitt-SAE 11
4007
4008
4009
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051
2051
2051
Babbitt-Soft
Babbitt-Navy #2
4010
4011
2080
2080
2080
2080
2080
2080
2080
2080
2080
2080
2051
2051
*Gold Code 3023 may be used in place of Palladium Code 3040
28.X
(2) the deposit is applied in a minimum amount
of time; and (3) the deposit has a uniform desired
thickness happen simultaneously.
You should have taken a number of steps in
the initial and final preparations to ensure that
you could apply the best possible quality deposit.
Some of them include use of clean anodes, un-
contaminated solution, and proper cover material.
You, at the time of plating, however, must still
carry out the operation properly.
Guidelines for the Operator
The operator guidelines discussed in detail
throughout this chapter, are reviewed briefly in
the following sections.
• Keep the area being plated clean.
• Keep the surface wet with plating solution.
• Keep the number and length of plating
interruptions to a minimum.
• Prevent the solution from depleting in the
work area.
• Maintain proper anode-to-cathode speed.
• Plate at the proper current density.
o Plate at approximately the proper
temperature when plating temperature is
important.
The first three guidelines assure obtaining
good adhesion of the deposit to itself, the last four
assure obtaining best quality deposit.
KEEP THE AREA BEING PLATED
CLEAN. — Contamination of the area by oil,
grease, dirt, and so on can result in adhesion
problems and possibly poor deposit quality.
Careful final preparations prior to plating should
prevent contamination of the area being plated.
Watch, however, for a possibly overlooked source
of contamination such as the tool or the solution
moving over a dirty surface; correct this as soon
as possible.
KEEP THE SURFACE WET WITH
PLATING SOLUTION.— Drying of the solution
on the area being plated is obviously a significant
change in the composition of the solution. This
can affect the adhesion of the next deposit. Proper
setups will largely ensure that the surface will not
dry during plating. However, you should watch
for signs of "overheating" of the part and the
solution. If this occurs, supply more solution. If
you dip for solution, you should dip often enough
every 5 seconds or as required.
KEEP INTERRUPTIONS TO A MIN-
IMUM.—Some metals, primarily nickel, cobalt,
and chromium are subject to passivation, which
is the formation, in a short period of time, of a
thin invisible oxide film. You cannot obtain a
good bond without activation. To prevent
passivation, avoid all unnecessary interruptions
of the plating operation, minimize the length of
time of unavoidable interruptions, and ensure that
you cover all areas being plated periodically (at
least every 10 seconds) during plating.
PREVENT THE SOLUTION FROM DE-
PLETING IN THE WORK AREA.— Depletion
of the solution in the work area (where the cover
meets the part) has various effects depending on
the solution. With most plating solutions, there
is a greater tendency for depletion to produce
shiny, low thickness deposits. Other indications
are a drop-off in plating current and a change in
color of the solution in the cover. To prevent this,
provide a sufficient amount of fresh plating
solution and then pump fast enough or dip often
enough to get it into the work area.
MAINTAIN PROPER ANODE-TO-CATH-
ODE SPEED.— Ensure that the tool is always
moving relative to the part (fig. 14-12). If you set
a plating tool on a flat part then move it in a
straight back and forth motion instead of in a
rotary motion or move the tool in the direction
of rotation of a rotating part, in some spots you
momentarily have no relative movement. Burn-
ing of the deposit can result from this.
USE VISUAL CONTROL.— While you
plate, you can see what the deposit looks like as
it goes on. Its appearance gives you valuable
information on deposit quality and overall plating
efficiency. If you know the significance of
variations in the deposit and what causes them,
you can make appropriate corrections, such as
changing the voltage, the anode-to-cathode speed,
or the rate of solution supply. You should be
aware of what good and bad deposits look like,
pay attention to the plating's appearance while
plating, and be able to make appropriate
corrections.
Evaluating Deposits
The qualities to look for in all plating deposits
are good adhesion, proper thickness of the
coating, and high density of deposit. In corrosion
protection applications where you use non-
sacrificial coatings, also be sure there are no pores
or surf ace-to-base metal cracks.
Evaluating Adhesion
Some of the tests that you can use to see how
well the deposite has adhered to the base metal
are (1) the chisel, knife, and scratch tests or (2)
the grind and saw test.
CHISEL, KNIFE, AND SCRATCH
TESTS.— If the deposit is sufficiently thick to
permit the use of a chisel, test the adhesion by
forcing the chisel between the coating and the base
metal. Use a hammer to apply the force. Test
thinner coatings by substituting a knife or scalpel
for the chisel and lightly tap it with a hammer.
Test very thin coatings by scratching through the
coating to the basic metal. After these tests,
closely examine the test area for lifting or peeling
of the deposit from the base material.
GRIND AND SAW TESTS.— Another good
test for adhesion is to grind an edge of the plated
specimen with a grinding wheel with the direction
of cutting from unplated base metal to the
deposit. If adhesion is poor, the deposit will be
torn from the base. You can use a hacksaw
instead of the grinder, as long as you saw in a
direction that tend to separate the coating from
the base metal. Grinding and sawing tests
are especially effective on hard or brittle
deposits.
TROUBLESHOOTING
Poor Adhesion
Carefully inspect the plated area to determine
at which stage in the plating process the separa-
tion occured. Examine the back side of the
material coming off. Perform two etch tests using
either Code 1022 or 1024 solution. Etch part of
the area where the material came off and the base
material of the part in an area where etching will
not cause a problem. Compare the appearance of
the two areas to determine where the separation
occurred. If the two areas are identical, the failure
occurred at the base material. If they are different,
the failure occurred between two of the plated
layers.
In some cases, such as when you plate on
metal spray, tungsten carbide, electroless nickel,
and so on, the separation is in the base material,
and, therefore, the DALIC plating cannot be
faulted.
1. COMMON CAUSES FOR THE DE-
POSIT COMING OFF OF THE BASE
MATERIAL
a. The base material was not correctly
identified.
(1) Determine, for certain, the identity
of base material.
(2) Determine if the surface was etched
as it should have been
b. The surface has a foreign coating such
as metal spray, chrome plate, and so on.
(1) Determine if the plated area and
other areas on the workpiece etch
the same. Use Code 1022 or 1024
solution and reverse current.
c. The preparatory procedure was not
thoroughly, properly, and quickly
carried out.
d. Contaminated preparatory solutions
were used.
e. Contaminated preparatory or preplate
tools were used.
f . The surface was not pre-wetted before
it was plated.
h. The wrong plating solution was used,
i. An improper preplate was used.
2. COMMON CAUSES FOR THE FINAL
DEPOSIT COMING OFF OF THE PRE-
PLATE
a. The preplate was not followed quickly
by the final plating solution.
b. The surface was not pre-wetted accord-
ing to manufacturer's instructions.
c. The wrong plating solution was used.
3. COMMON CAUSES FOR THE FINAL
DEPOSIT COMING OFF OF ITSELF
a. The deposit was burned.
b. The plating operation was interrupted
for too long.
c. The solution was contaminated.
d. The anode was contaminated.
e. The wrong anode cover was used.
yu. cubing, cuiu au
causes are as follows:
miiug.
easily machined and do not require specific
recommendations .
1. The wrong solution was used.
2. The plating solution was contaminated.
3. The plating tool was contaminated.
4. The wrong cover was used or the cover was
too thick or too thin.
5. The plating method was wrong.
Low Thickness Deposit
The deposit did not achieve the desired
thickness. Common causes are as follows:
1 . The operator did not properly calculate the
area.
2. The operator did not properly calculate the
amp-hr.
3. Considerable plating went on the
aluminum tape or adjacent areas.
4. The operator overetched the base material.
5. The operator plated wrong with a "variable
factor" solution.
6. Certain solutions were overused.
7. The supply of solution to the tool was
insufficient.
8. Plated in the cover. Wash and examine the
cover to see if this actually occurred.
Nonuniform Thickness of the Deposit
1. The wrong tool was used.
2. Tool was not used correctly.
3. The solution was not distributed uniformly
in the cover.
4. The tool cover thickness varied.
Took too Long to Finish the Job
1. The wrong solution was used.
2. The plating tool was too small.
3. The power pack was too small.
4. The operator did not plate as fast as
possible with the existing tool or solution.
5. The operator did not properly preheat
certain variable factor solutions.
MACHINING AND GRINDING
The following paragraphs discuss basic
requirements for machining and grinding plated
deposits.
Cobalt, iron, and nickel deposits or their
alloys are difficult to machine. If possible, grind
rather than machine these deposits. When it is
absolutely necessary to machine, use good equip-
ment and a good technique. Recommendations
include:
1. Use new, tight machine tools.
2. Use sharp carbide bits.
3. Use plenty of coolant.
4. Take light cuts of approximately 0.005
inch.
5. Use low cutting speeds, such as approx-
imately 50 ft/min.
Grinding Nickel and Cobalt Deposits
The Norton Company, Worcester, Massa-
chusetts, makes the following recommendations
concerning the grinding of nickel or cobalt
deposits:
1 . Wet grinding recommended. Use plenty of
coolant.
2. Wheel— C36K6V.
3. Wheel and Work Speeds— Wheel 6000
surface feet per minute.
4. Depth of Cut— 0.0002 inch maximum to
ensure against overheating of the deposit
and the deposit-to-base metal interface.
FORMULAS
There are a number of formulas that prove
very useful with the DALIC Process. They, when
used, assure fast, efficient, and trouble free
DALIC plating operations.
Formula 1: Formula to control thickness of
metal deposited
Amp-Hr = F x A x T
Use this formula to determine the ampere-hours
that should pass during plating to provide the
desired thickness of deposit on the area to be
plated.
14-59
In this formula, F is the factor you obtain from
the plating solution bottle or from table 14-5.
A = area of the surface to be plated in square
inches.
T = thickness of the deposit desired measured in
ten-thousandths of an inch.
Deposit Thickness
Desired— Inches T equals
Formula 3 : Formula to determine the optimum
plating tool contact area when you
design special tools
0.010
100.0
0.002
20.0
0.001
10.0
0.0005
5.0
0.000060
0.6
0.000008
0.08
NOTE: You can determine the proper value
for T to put in the above formula by writing the
thickness desired in inches and then moving the
decimal point four (4) places to the right.
Example:
You desire a thickness of 0.001 inch. Since 0.00 1
is the same as 0.0010, move the decimal point four
places to the right to get 0.010. T, therefore, is 10.
Formula 2: Formula to determine the current
density
CD =
CA
CD = current density in amps per square inch
PA = plating amperage
C A = contact area being made by the plating tool
on the part in square inches.
This formula allows you to compute the current
density at which you are plating in a given opera-
tion. You can then make comparison with values
given in table 14-3 to determine if you are plating
at a low current density, a normal current density,
or an excessive current density. You can use this
information to make appropriate adjustments
while plating.
OCA =
MA
ACD
MA = maximum aperage output of the power
pack to be used
ACD = average current density for the solution
to be used
Use this formula when you design special tools
to develop the right size tool, neither too large
nor too small.
Formula 4: Formula to estimate the plating
amperage to draw with a given
solution and plating tool
PA = CA x ACD
ACD = average current density for the solution
Use this formula for two purposes:
1. In conjunction with Formula 5 to
estimate plating time.
2. By itself to determine if you are
plating at the right amperage.
Formula 5: Formula to estimate the plating time
PT (Hrs) =
PA = the value from Formula 4 for purpose 1 or
the average current while plating for purpose 2
Use this formula is used for two purposes:
1 . To estimate the plating time in setting
up a job
2. To control the thickness when no
ampere-hour meter is available
Formula 6: Determining amount of solution
required
Liters = Q(L) x T(I) x A
Use this formula (1) in estimating jobs and (2) to
ensure that you have the appropriate amounts of
solution to use in a given job.
T(I) = thickness of the deposit desired in inches
A = area of the surface to be plated
Formula 7: Formula to check ampere-hour
meter accuracy
Amp-Hrs = Amps x Hrs
Use this formula periodically as a maintenance
procedure to ensure that the amp-hr meter
is accurate, or in cases where you suspect its
accuracy.
Run the test by shorting the d.c. output leads and
running the power pack for a set time (hr) at a
Amps = 20
Hrs = ~ or 0.05
Placing these values in the above formula
Amp-Hr = 20 x 0.05
Amp-Hr = 1.00
The computed value (1 .00) should be close (within
a small percentage) to that passed on the amp-hr
meter when you short the d.c. output leads and
run the test for 3 minutes at 20 amps.
14-61
THE REPAIR DEPARTMENT
AND REPAIR WORK
As a Machinery Repairman you may be
assigned to almost any type of ship. Aboard many
ships, you will be a member of the engineering
department; most Machinery Repairmen, how-
ever, are assigned to repair and tender type ships.
On these ships, you will be part of the repair
department and should know something about its
functions, personnel, and shops. This chapter, will
teach you about the repair department and will
give you some examples of repair work you are
likely to encounter.
Repair ships and tenders are floating bases,
capable of performing a variety of maintenance
and repair services that are beyond the capabilities
of ships they serve. They are like small-scale Navy
yards, with the same primary mission: to provide
repair facilities and services to the forces afloat.
The most common type of repair ship,
designated AR, provides general and specific
repairs to all types of ships. Special types of repair
ships have been developed for special uses; for
example, the ARG is designed for the repair of
internal-combustion engines.
Each type of tender provides services for one
type of ship, as indicated by the designation of
the tender. The best known types of tenders are
the destroyer tender (AD) and the submarine
tender (AS). Submarine tenders are capable of
tending both conventional submarines and fleet
ballistic missile submarines; however, individual
ships specialize in either conventional submarines
or ballistic missle submarines. The organization
of the repair department of an AS that tends
conventional missile submarines differs somewhat
from that of an AS that tends fleet bassistic missile
submarines.
Since repairs and services to other ships are
the primary functions of all repair ships and
tenders, the repair department on a repair ship
or tender makes a direct and vital contribution
to fleet support. The operating forces of the
fleet depend upon the services provided by all
personnel of the repair department.
REPAIR DEPARTMENT
ORGANIZATION AND PERSONNEL
The type of repair ship to which you will
probably be assigned will be a destroyer tender
(AD), a repair ship (AR), an internal-combustion
engine repair ship (ARG), or a submarine tender
(AS).
When you report aboard ship, you will need
to learn the lines of authority and responsibility
in the repair department. You will need to find
out where your orders and assignments originate,
exactly what is expected of you, and where to go
for information, assistance, and advice. You can
start acquiring this knowledge by studying the
following material on repair department organiza-
tion and personnel.
Repair department organization varies
somewhat from one ship to another, as you can
see by comparing figures 15-1 and 15-2. Figure
15-1 shows the organization of the repair depart-
ment in a typical repair ship (AR); figure 15-2
shows the organization of the repair department
in a fleet ballistic missile (FBM) submarine tender
(AS).
In comparing the two illustrations, you will
notice several differences. For one thing, the
repair department in the AR includes an ordnance
repair division (R-5) which is not included in the
repair department of the AS. Instead, the AS has
a separate weapons repair department under a
weapons repair officer. In all types of repair ships,
you will probably be assigned to the R-2 division.
The machine shop is normally within the R-2
division organization.
The duties of personnel in the repair depart-
ment vary somewhat according to the type of ship.
However, the following description of personnel
functions will give you a general idea of the way
things are in most repair departments.
REPAIR OFFICER
In a repair ship or tender, the repair officer
is head of the repair department. The repair
15-1
REPAIR OFFICER
SHIP SUPERINTENDENTS
MAINTENANCE DATA
COLLECTION COORDINATOF
ASSISTANT REPAIR
ADMINISTRATIVE
ASSISTANT
5
OFFICER
1
R-l DIVISION
HULL REPAIR
SHIPFITTER SHOP
SHEETMETAL SHOP
PIPE SHOP
CARPENTER SHOP
DIVING
WELDING SHOP
FOUNDRY
PATTERN SHOP
R-2 DIVISION
MACHINERY REPAIR
MACHINE SHOP
OUTSIDE REPAIR SHOP
BOILER SHOP
DIESEL SHOP
ENGRAVING SHOP
VALVE SHOP
TOOL ROOM
R-3 DIVISION
ELECTRICAL REPAIR
ELECTRICAL REPAIR
SHOP
I.C. REPAIR SHOP
R-4 DIVISION
ELECTRONICS REPAIR
TYPEWRITER 8. GAGE
SHOP
WATCH & CLOCK SHOP
ELECTRONICS SHOP
TELETYPE SHOP
ELECTRONICS CALIBRA-
TION LAB
R-S DIVISION
ORDNANCE REPAIR
CANVAS SHOP
OPTICAL SHOP
PHOTO SHOP
ORDNANCE
FIRE CONTROL
DRAFTING
PRINTING
Figure 15-1. — Organization of the repair department in a typical repair ship (AR).
officer is responsible under the commanding
officer for accomplishing repairs and alterations
to the ships tended or granted availabilities. The
repair officer is also responsible for the follow-
ing actions:
% Accomplishing repairs and alterations to
the ship itself (tender or repair ship) which
are beyond the capacity of the engineer-
ing department or other departments.
@ Maintaining a well-organized and effi-
ciently operated department.
9 Issuing and enforcing repair department
orders which govern department
procedures.
© Enforcing orders of higher authority.
@ Knowing the current workload and
capacity of the ship's crew and facilities,
and keeping the staff maintenance rep-
resentative informed of their current status
so that the maintenance representative may
properly schedule and assign ships.
• Reviewing work requests received via the
staff maintenance representative from the
ships assigned for repair and for accepting
or rejecting the individual jobs according
to the capacity of the repair department.
• Reviewing and accepting any work lists or
work requests which develop after an
availability period has started.
9 Operating the department within the allot-
ment granted and initiating requests for
further funds, if required.
• Ensuring the accuracy, correctness, and
promptness of all correspondence, in-
cluding messages, prepared for the
commanding officer's signature.
• Reviewing all personnel matters arising in
all the divisions within the department,
such as training, advancement in rate,
assignment to divisions, and leave.
To acquire a thorough knowledge of depart-
mental conditions and to ensure adequate
standards, the repair officer must make frequent
inspections of the department and require the
division officers to make corrections as necessary.
Specific duties of the repair officer vary
somewhat, depending upon the type of repair ship
or tender. In general, however, a summary of the
repair officer's duties include the following:
• Planning, preparing, and carrying out
schedules for alterations and repair work
assigned to the repair department.
15-2
REPAIR OFFICER
ASSISTANT REPAIR OFFICER
DEPARTMENTAL
"3-M" COORDINATOR
RADIOLOGICAL
CONTROL OFFICER
R-5 DIVISION
RADIOLOGICAL CALIBRATION LAB
NUCLEONICS
SHIP
SUPERINTENDANTS
ADMINISTRATIVE DIVISION
R-0 DIVISION
ARRS
PRINT SHOP
PHOTO LAB
DRAFTING SHOP
DEPARTMENTAL
TRAINING OFFICER
NUCLEAR REPAIR
OFFICER
R-10 DIVISION
NUCLEAR PLANNING
NUCLEAR SHIPALTS
NUCLEAR REPAIR
PRODUCTION
MANAGEMENT ASSISTANT
HULL REPAIR
OFFICER
MACHINERY REPAIR
OFFICER
ELECTRICAL REPAIR
OFFICER
ELECTRONICS REPAIR
OFFICER
R-1 DIVISION
SHIPFITTER SHOP
SHEETMETAL SHOP
WELD SHOP
PIPE SHOP
FLEX HOSE SHOP
LAGGING SHOP
R-2 DIVISION
INSIDE MACHINE SHOP
ENGRADING SHOP
LOCKSMITH SHOP
OPTICAL SHOP
WATCH/CLOCK SHOP
MECHANICAL STANDARDS LAB
R-3 DIVISION
ELECTRICAL ISSUb
ELECTRICAL REPAIR SHOP
I/C GYRO SHOP
RUBBER/PLASTICS SHOP
SOUND ANALYSIS
R-4 DIVISION
OFFICE MACHINE REPAIR
ELECTRONIC REPAIR SHOP
ELECTRONIC CAL LAB
SONAR REPAIR SHOP
ANTENNA SHOP
REPAIR SERVICES
OFFICER
TECHNICAL DIVISION
OFFICER
QUALITY ASSURANCE
OFFICER
MECHANICAL REPAIR
OFFICER
R-6 DIVISION
RIGGING SHOP
WOODWORKING SHOP
PATTERN SHOP
DIVING LOCKER
CANVAS SHOP
FOUNDRY
R-7 DIVISION
NON-NUC PLANNING
TECH LIBRARY
ALT' S & A&I ' S
R-8 DIVISION
NOT LAB
QUALITY ASSURANCE
CHEMICAL ANALYSIS LAB
R-9 DIVISION
VALVE SHOP
HYDRAULIC SHOP
OUTSIDE MACHINE SHOP
A/C & R REPAIR SHOP
Figure 15-2. — Organization of the repair department in fleet ballistic missile submarine tender (AS).
15-3
• Establishing and operating the Planned
Maintenance System of the 3-M System.
• Coordinating repair capabilities, work
assignments, and available personnel to
ensure maximum use of manpower.
• Supervising and inspecting repairs and
service to ensure timely and satisfactory
completion of work; providing controls for
quality control.
• Preparing records, reports, forms, and
orders in connection with repair functions
and duties.
• Ensuring proper operation of all equip-
ment and material assigned to the repair
department.
• Ensuring strict compliance with safety
precautions and security measures.
• Reporting to the commanding officer the
progress of major repairs and alterations;
keeping the executive officer informed;
reporting promptly any inability to meet
scheduled completion dates.
ASSISTANT REPAIR OFFICER
In the absence of the repair officer, the
assistant repair officer assumes the responsibilities
of the repair officer. The assistant repair officer
is the personnel administrator for the repair
department, and is responsible for the assignment
of personnel, the administrative control of the
repair office, and the departmental control of
training.
Specific duties of the assistant repair officer
may vary somewhat, depending upon the type of
repair ship or tender. In general, however, the
duties of the assistant repair officer include the
following:
• Assigning personnel to divisions, schools,
shore patrol, and beach guard.
• Having a basic knowledge of courses,
schools, and rating programs necessary to
further the education of personnel and
their advancement in rate for their benefit
and that of the ship and the Navy.
• Maintaining the office stores and accounts.
• Assisting the repair officer in all matters
pertaining to general office routine,
current availabilities of ships assigned to
the repair ship or tender, and liaison
between the repair office and the ship
alongside and in shipyards.
• Reviewing all work requests as they are
received.
• Assigning work and priority ratings to the
division and its shops.
• Maintaining liaison with the supply depart-
ment for materials on order or to be
ordered for the work requested.
• Procuring the necessary blueprints,
sketches, or samples for the shops.
• Scheduling the services of tugs, cranes, and
technical services, as available, for
successful completion of an availability.
• Surveying reports from each shop to
ascertain the successful completion of all
work during the allotted time.
• Analyzing man-hour shop reports to
determine an even balance of work versus
personnel assigned.
• Coordinating the actions of the repair
office and the shops to keep the repair
facilities fully productive.
In addition to the assistant repair officer, there
are usually several other officers who assist the
repair officer in performing repair department
functions. These may include a production
engineering assistant, a repair assistant, a
radiological control officer, a department training
officer, a production management assistant, and
an administrative assistant.
DIVISION OFFICERS
Each division within the repair department is
under a division officer. The division officer may
be a commissioned officer, a warrant officer, or
a chief petty officer. The duties of the division
officer vary, according to the nature of the work
done in the division.
ENLISTED PERSONNEL
As a Machinery Repairman assigned to the
repair department of a repair shop or tender, you
will work with people in a number of other
ratings. It will be very much to your advantage
to learn who these people are and what kind of
work they do. Ratings that are often assigned
to the repair department include Opticalmen,
Electronics Technicians, Radiomen, Fire Control
Technicians, Gunner's Mates, Draftsmen, Lithog-
raphers, Hull Maintenance Technicians, Pattern-
makers, Molders, Machinist's Mates, Boiler
Technicians, Enginemen, Gas Turbine Systems
15-4
You can get some idea of the work done by
people of these ratings by looking through
the Manual of Navy Enlisted Manpower and
Personnel Classifications and Occupational
Standards, NAVPERS 18068 (revised). You can
also learn about the work of these ratings by
observing how the work is handled in the repair
department. In handling repair work, it is often
necessary for two or more shops (and two or more
ratings) to cooperate to complete corrective
maintenance actions.
When you are assigned to shore duty, you will
almost certainly be assigned to a billet in the repair
department of a shore installation. Since the
shore-based installation has the same essential
mission as the repair ship, the organization will
be similar.
REPAIR DEPARTMENT SHOPS
Each shop in the repair department is assigned
to one of the divisions. As a Machinery
useful to learn as much as you can about the other
shops. After you have gotten acquainted with
personnel in your own shop and have learned to
find your way around your own working spaces,
make an effort to find out something about the
other shops in the division and the department.
Find out where each shop is located, what kind
of work is done in each shop, and what
administrative procedures are necessary when one
shop must call on another for assistance.
MACHINE SHOP
Shop layout and arrangement vary somewhat
from one ship to another depending upon space
available, the nature and amount of equipment
installed, and the services that must be provided
by the ship. The following discussion is intended
to give a general picture of a shop layout in AR,
AS, and AD type ships. Figure 15-3 shows the
layout of a Navy machine shop in a submarine
tender.
ENGRAVING-SECTION
L A DOER
PANTOGRAPH
PAINT
STORAGE
COFFEE
MESS AND
WASH
AREA
VERTICAL
SHARER
VERTICAL
TURRET
LATHE
BALANCING
MACHINE
CUT-OFF
SAW
BAND
SAW
HEAVY-
SECTION
BENCH
LARGE
LATHE
GAP
LATHE
STOCK
RACK
STORAGE
AREA
FOAM
STATION
TRUNK
DRILL
PRESS
GRIND. LATHE
AFT. '
TOOL ROOM
SHOP OFFICE
LADDER
GRIND SECTION BENCH
TOOL MAKERS
LATHE
HEAT TREATMENT
OVEN
Figure 15-3.— Machine shop layout (submarine tender).
15-5
Most machine shops are broken down into
sections as you can see in figure 15-3. These
sections are lathe, milling, engraving, grinding,
and heavy. Also included in the layout are a
toolroom and a shop office. The toolroom should
be as centrally located as possible and be of
adequate size to store all the tools needed for the
work required of the shop.
The positioning of the machines is of great
importance. In figure 15-4, you can see that the
lathes are positioned headstock end to footstock
end. This way the operators won't interfere with
one another, and the chips from one machine will
not fly in the direction of the next operator. Good
lighting is of prime importance also. In figure 15-4
you can see good overhead lighting as well as work
lights on the machines. The problem of one
machine interfering with another is taken care of
by angular placement as illustrated in figure 15-5.
A good monorail system is another important
asset to the machine shop. You can see in figure
15-5 that the monorail system covers all machines
and work benches.
OTHER REPAIR SHOPS
As previously stated, you should become
familiar with the other shops within the repair
department. Machining is only a small portion of
a Machinery Repairman's work. You can expect
to work with every shop within the Repair Depart-
ment. An example of a job that requires coordina-
tion is the making of hatch dogs. The pattern shop
makes the pattern, the molders cast them in the
28.314
Figure 15-4.— Machine shop lathe section.
Figure 15-5. — Machine shop milling section.
28.315
foundry, the machine shop machines them, and
the outside repair shop installs them. You can see
from this example that a smooth flow of work
demands close cooperation between many shops.
REPAIR WORK
Replacement parts for most equipment are
usually available through the Navy supply system.
But occasionally, parts such as shafts and gears
must be made in the machine shop (see fig. 15-6).
A major portion of the repair work done in
shipboard machine shops involves machining
worn or damaged parts so that they can be placed
back in service. For example, the sealing surfaces
of valves and pumps must be machined if leaks
occur; broken studs must be removed, and bent
Figure 15-6. — Part made in a machine shop.
15-7
work because of alignment problems in the
machining operation.
Many of the repair jobs that you will be
assigned to do will require you to make certain
mathematical calculations such as finding the
areas of circles, rectangles, and triangles and
calculating linear dimensions. You may also have
to find the volume of cylinders and cubes. To do
this, you will have to use specific formulas, which
you can find in various machinist's handbooks
and in Mathematics, Volume 1, NAVPERS 10069
(series).
When you are making a replacement part, the
leading petty officer of the shop will usually give
you a working drawing of the part or a sample
part similar to the one required. Study the draw-
ing or sample until you are familiar with the
details and ensure that you have all pertinent
information.
Decide which machines are required for
making the part and calculate all necessary
dimensions from the information provided.
Choose the most logical sequence of machining
operations so that the part is machined in a
minimum number of setups.
GEARS
When you manufacture gears, you may need
to calculate simple gear trains or gear trains using
compound gearing. Information on this subject
is contained in Basic Machines, NAVPERS 10624
(series).
A gear is made by cutting a series of equally
spaced, specially shaped grooves on the periphery
of a wheel (see fig. 15-7). A rack is made by
cutting similar grooves in a straight surface. The
grooves and teeth of a spur gear are straight and
parallel to the axis of the wheel.
To calculate the dimensions of a spur gear,
you must know the terms used to designate the
parts of the gear. In addition, you must know the
formulas for finding the dimensions of the parts
of a spur gear. To cut the gear you must know
what cutter to use, in adition to how to index the
blank, so that the teeth are equally spaced and
have the correct profile.
Spur Gear Terminology
The following terms (see fig. 15-8) are used
to describe gears and gear teeth (symbols in
Figure 15-7.— Cutting specially shaped grooves.
parentheses are standard gear nomenclature
symbols used and taught at MR schools):
OUTSIDE CIRCLE (OC): The circle formed
by the tops of the gear teeth.
OUTSIDE DIAMETER (OD): The diameter
to turn the blank to; the overall diameter of the
gear.
PITCH CIRCLE (PC): (a) Contact point of
mating gears; the basis of all tooth dimensions,
(b) Imaginary circle one addendum distance down
the tooth.
PITCH DIAMETER (PD): (a) The diameter
of the pitch circle, (b) In parallel shaft gears, the
pitch diameter can be determined directly from
the center to center distance and the number of
teeth.
ROOT CIRCLE (RC): The circle formed by
the bottoms of the gear teeth.
ROOT DIAMETER (RD): The distance from
one side of the root circle to the opposite side
passing through the center of the gear.
ADDENDUM (ADD): The height of the part
of the tooth that extends outside the pitch circle.
CIRCULAR PITCH (CP): The distance from
a point on one tooth to a corresponding point on
the next tooth measured on the pitch circle.
CIRCULAR THICKNESS (CT): (a) One-half
of the circular pitch, (b) The length of the arc
between the two sides of a gear tooth, on the pitch
circle.
15-8
WORKING DEPTH
ADDENDUM
DEDENDUM
CLEARANCE
RIM
HUB
CT = CIRCULAR THICKNESS
CP = CIRCULAR PITCH
tc= CHORDAL THICKNESS
dc = CHORDAL ADDENDUM
ROOT CIRCLE-
Figure 15-8.— Gear terminology.
CLEARANCE (CL): The space between the
top of the tooth of one gear, and the bottom of
the tooth of its mating gear.
DEDENDUM (DED): (a) The depth of the
tooth inside of the pitch circle, (b) The radial
distance between the root circle and the pitch
circle.
WHOLE DEPTH (WD): The radial depth
between the circle that bounds the top of the gear
teeth and the circle that bounds the bottom of the
gear teeth.
WORKING DEPTH (WKD): (a) The whole
depth minus the clearance, (b) The depth of
engagement of two mating gears, the sum of their
addendums.
CHORDAL THICKNESS (tc): (a) The
thickness of the tooth measured at the pitch circle,
(b) The section of the tooth that is measured to
see if the gear is cut correctly.
CHORDAL ADDENDUM (ac): The distance
from the top of a gear tooth to the chordal
thickness line at the pitch circle (used for setting
gear tooth vernier calipers for measuring tooth
thickness).
DIAMETRAL PITCH (DP): (a) The most
important calculation, it regulates the tooth size,
(b) The number of teeth on the gear divided by
the number of inches of pitch diameter.
NUMBER OF TEETH (NT): The actual
number of teeth of the gear.
BACKLASH (B): The difference between the
tooth thickness and the tooth space of engaged
gear teeth at the pitch circle.
The symbols used by the American Gear
Manufacturers Association to describe gears and
gear teeth are different from those used by the
Navy. The following list will familiarize you with
these symbols.
Spur Gear Terms
Pitch Circle
Pitch Diameter
Center to Center
Distance
Addendum
Dedendum
Working Depth
Clearance
Whole Depth
Root Circle
Outside Diameter
Circular Thickness
Circular Pitch
Diametral Pitch
Number of Teeth
Root Diameter
Chordal Thickness
Chordal Addendum
Machinery
Repairman
School
Abbreviations
PC
PD
C-C
ADD
DED
WKD
CL
WD
RC
OD
CT
CP
DP
NT
RD
American Gear
Manufacturers
Association
Abbreviations
(none)
D
C
a
d
hk
c
ht
(none)
Do
tc
P
P
N
DR
(none)
(none)
15-9
Diametral Pitch System
The diametral pitch system was devised to
simplify gear calculations and measurements. It
is based on the diameter of the pitch circle,
rather than on the circumference. Since the
circumference of a circle is 3.1416 times it
diameter, this constant must always be taken into
consideration in calculating measurements based
on the pitch circumference. In the diametral pitch
system, however, the constant is in a sense "built
into" the system, thus simplifying computation.
When you use this system, there is no need
to calculate circular pitch. Indexing devices based
on the diametral pitch system will accurately space
the teeth, and the formed cutter associated with
the indexing device will form the teeth within the
necessary accuracy. All calculations, such as
center distance between gears and working depth
of teeth, are simplified by the diametral pitch
system.
Many formulas are used in calculating the
dimensions of gears and the gear teeth. Only the
formulas needed in this discussion are given here;
a more complete list of formulas for calculating
the dimensions of gears is provided in Appendix
II of this manual. Appendix III contains explana-
tions of how you determine the formulas to
calculate the dimensions of gear teeth.
Usually the outside diameter (OD) of a gear
and the number of teeth (NT) are available from
a blueprint or a sample gear. Using these two
known factors, you can calculate the necessary
data.
For example, to make a gear 3.250 inches in
diameter that has 24 teeth:
1. Find the pitch diameter (PD) using the
formula:
_ (ND) OD
NT + 2
pn 24 + 3.250 78 - ™ . ,
PD = 24 = 2 = 26 = 3-000 inches
2. Find the diametral pitch (DP) using the
formula:
3. Find the whole depth of tooth (WD) by
using the formula:
PD =
PD
NT
PD
24
WP =
WP =
2.157
DP
2.157
8
= 0.2696 inch
You can select the cutter for machining the
gear teeth as soon as you have computed the
diametral pitch. Formed gear cutters are made
with eight different forms (numbered from 1 to 8)
for each diametral pitch. The number of cutter
that you should use depends upon the number of
teeth the gear will have. The following chart shows
which cutter to use to cut various numbers of teeth
on a gear.
If, for example, you need a cutter for a gear
that has 24 teeth, use a number 5 cutter since as
a number 5 cutter will cut all gears containing
from 21 to 25 teeth.
Range of teeth Number of cutter
135 to a rack
55 to 134
35 to 54
26 to 34
21 to 25
17 to 20
14 to 16
12 to 13
Most cutters are stamped, showing the number
of the cutter, the diametral pitch, the range for
the number of cutter, and the depth. The involute
gear cutters usually (on-board a repair ship) run
from 1 to 48 diametral pitch and 8 cutters to each
pitch.
To check the dimensional accuracy of gear
teeth, use a gear tooth vernier caliper (see
fig. 15-9). The vertical scale is adjusted to the
CHORD AL ADDENDUM (ac) and the horizon-
tal scale is used for finding the CHORDAL
THICKNESS (tc). Before you calculate the
chordal addendum, you must determine the
addendum (ADD) and circular thickness (Ct).
To determine the addendum, use the formula:
3
= 8
ADD =
PD
NT
VERTICAL SCALE
GEAR TOOTH-— s\
Figure 15-9. — Measuring gear teeth with a vernier caliper.
Using values from the preceding example,
3.000
ADD =
24
= 0.125 inch
To determine the circular thickness, use the
formula:
CT =
1.5708
DP
Using the values from the example,
1.5708
CT
8
= 0.1964 inch
The formula used for finding the chordal
addendum is
ac = ADD +
= 0.125 +
(CT)2
4(PD)
(0.1 964)2
4x3
= 0.125 = ^^386) = 0.128 inch
The formula for finding the chordal
tooth thickness is
t-PDsin
= 3xsin3°45"
= 3 x 0.0654
= 3 x 0.1 962 inch
(Note: Mathematics, Volume //, NAVPERS
1007 1-B and various machinist's handbooks
contain information on trigonometric functions.)
Now set the vertical scale of the gear tooth
vernier caliper to 0.128 inch. Adjust the caliper
so that the jaws touch each side of the tooth as
shown in figure 15-9. If the reading on the
horizontal scale is 0.1962 inch, the tooth has
correct dimensions; if the dimension is greater,
the whole depth (WD) is too shallow; if the
reading is less, the whole depth (WD) is too deep.
Sometimes you cannot determine the outside
diameter of a gear or the number of teeth from
available information. However, if a gear
dimension and a tooth dimension can be found,
you can put these dimensions into one or more
of the formulas in Appendix II and calculate the
required dimensions.
Machining the Gear
The procedures for making a gear of the
dimensions given in the preceding example are as
follows:
1 . Select and cut a piece of stock to make the
blank. Allow at least 1/8 inch excess
material on the diameter and thickness of
the blank for cleanup cuts.
2. Mount the stock in a chuck on a lathe, and
at the center of the blank, face an area
slightly larger than the diameter of the bore
required.
3. Drill and bore to the required size (within
tolerance).
4. Remove the blank from the lathe and press
it on a mandrel.
5. Set the mandrel up between the centers of
the index head and the footstock on the
milling machine. Dial in within tolerance.
7. Select a number 5 involute gear cutter
(8-pitch) and mount and center it as
described in chapter 11.
15-11
move the table up until the cutter just
touches the gear blank. Set the
micrometer collar on the vertical feed
handwheel to zero, then hand feed the
table up toward the cutter slightly less
than the whole depth of tooth.
10. Cut one tooth groove, index the
workpiece for one division and take
another cut. Check the tooth dimensions
with a vernier gear tooth caliper as
described previously. Make the required
adjustments to provide an accurately
* 'sized" tooth.
1 1 . Continue indexing and cutting until the
teeth are cut around the circumference of
the workpiece.
When you machine a rack, space the teeth by
moving the work table an amount equal to the
circular pitch of the gear for each tooth cut.
Calculate the circular pitch by dividing 3.1416 by
the diametral pitch:
CP
3.1416
DP
You do not need to make calculations for
corrected addendum and chordal pitch for check-
ing rack teeth dimensions because on racks the
addendum is a straight line dimension and the
tooth thickness is one-half the linear pitch.
sucn as pump or rotor snatts is an important part
of machine shop work. Information provided here
will help you to see the proper method of
manufacturing a new shaft and also the proper
method of repairing a bent or damaged shaft.
Manufacturing a New Shaft
Figure 15-10 illustrates a shaft that might be
made in the machine shop. The information given
in the illustration is normally available in the
manufacturer's technical manual for the
machinery component for which the shaft is
required. The circled numbers indicate a sequence
of operations for machining the various surfaces
of the shaft.
Select and cut a piece of round stock at least
1/16 inch larger in diameter and 1/8 inch longer
than the shaft. Face and centerdrill each end of
the stock. In facing, ensure that the workpiece is
faced to the correct length for the shaft, which
in this example is 10 11/16 inches. Most of the
linear dimensions in figure 15-10 are given in the
form of mixed numbers of proper fractions
which indicate that rule measurement of these
dimensions will be sufficiently accurate. In
manufacturing a new shaft, you must take all
linear dimensions from the same reference point
to ensure the correct lengths. However, the linear
position of the grooves at numbers 1 1 and 12 are
in the form of decimal fractions and require
greater accuracy than is available by rule
measurement.
0
*^V^y>^ s?/* v«$
.rffttfX/ vf ^/Wv/"^/^ ,/
P^.tfp'
>I*H
i
+ K
•p
/
v
r
p. ,
11
r
s' v1 s
^V" N
* r, r :J ,
• v i i i
j —
f
M-'
(
^.058
1
§f-
-
.Op^J
1
\\
-
77-*
"*"
\)
u — *•
-1-
/
• V. i
V
hu'"
>i
1*.
V
V.J.R
"^1.1*1"*
""I.MI"*"
'7
2. — ^
., 1 »> ,,
«— — <
* 'p
J-i- ••
ii
_
J--^- r
^ \
- I ' >
, «
.
* st
r y f
' *• i *
"• '4 *1
1
fc,
Figure 15-10. — Steps in making a shaft.
15-12
Plain turning required on surfaces 1 through 6 is
performed in the first lathe setup; surfaces 7
through 12 are machined in the second lathe setup.
Key ways 13 and 14 are machined in the first
milling setup and then the cutter is changed for
machining the Woodruff keyway (15). To
machine the shaft, take the following steps:
1. Turn the workpiece to a 2 3/16-inch
diameter. Check the diameter for taper and make
corrections as necessary.
2. Set hermaphrodite calipers to 11 3/32
inches and lay out the shoulder between the 2 3/16
inch diameter and the 2.050 inch finish diameter.
Using the crossfeed handwheel with the
micrometer collar set on zero, feed the tool in
0.068 inch (one-half of the difference between
2.050 and 2 3/16). Make a short length of cut at
the end of the shaft and measure the diameter with
a micrometer. Adjust the crossfeed handwheel as
required to provide the 2.050 _'QQI diameter
and complete the cut to the layout line.
3 . Use procedures similar to those described
in step 2 for machining surfaces 3 through 6. Be
extremely careful to accurately measure the
diameter of the beginning of each cut to ensure
that you hold the dimensions within the range
provided in the illustration.
4. Turn the workpiece end-for-end and
machine surfaces 7, 8, and 9 as described in step 2.
5. Set a 3/16-inch parting tool in the tool-
holder, position the tool (by rule measurement)
for making groove 10, and make the groove.
6. Set the compound rest parallel to the axis
of the workpiece for laying out grooves 1 1 and
12. Place a sharp pointed tool in the toolholder
and align the point of the tool with the shoulder
between surfaces 7 and 8. Then use the compound
rest to move the tool 1 . 152 inches longitudinally
as indicated by the micrometer collar on the
compound feed screw. Feed the tool toward the
work with the crossfeed until a thin line is scribed
on the surface of the workpiece. Now swivel the
compound rest to the angle required for cutting
the chamfer and cut the chamfer. (Calculate the
angular depth from the given dimensions.) Then
using a parting tool between 0.053 and 0.058 inch
wide, make the groove.
7. With a fine cut file, remove all sharp edges
from shoulders and grooves.
to the required dimensions.
Check the dead center frequently to see that
it does not overheat and to prevent the workpiece
from becoming loose on the center. Use a center
rest as necessary, for supporting the work.
Repairing Shafts
Bent shafts 11/4 inches and less in diameter
which are used for low-speed operations can be
straightened so that they have less than 0.003- to
0.004-inch runout. Before attempting to straighten
a shaft, however, always ensure that the leading
petty officer of the shop is informed of the opera-
tion. To straighten a shaft take the following step:
1 . Mount the shaft between centers in a lathe.
If the shaft is too long for mounting between
centers, mount it in a 4-jaw chuck and a center.
2. Clamp a dial indicator on the compound
rest and locate the area of the bend and measure
how much the shaft is bent (runout). To
determine the area of the bend, run the dial
indicator along the shaft longitudinally. The
greatest variation of the pointer from zero
indicates the bend area. With the dial indicator
set at this point, rotate the shaft and note the
amount of fluctuation of the pointer. This
fluctuation is the amount of runout. Mark the
longitudinal position of the bend and the high side
of the bend with chalk or a grease pencil.
3. Remove the shaft from the lathe and place
it on a hydraulic press. Place a V-block on each
side of the bend area and turn the shaft so that
the high side is up. Move the press ram downward
until it touches the shaft. Set up a dial indicator
so that the contact point contacts the high side
of the shaft as near to the ram as possible.
4. Carefully apply pressure on the shaft with
the ram. Watch the pointer of the dial indicator
to determine how much the shaft is "sprung" in
the direction opposite the bend. When the
indicator reading is 0.002 or 0.003 inch greater
than the amount of runout, release the ram
pressure.
5. Set up the shaft between centers and check
again as explained in step 1. Repeat steps 2, 3,
and 4 until the runout is decreased to within
acceptable limits.
If little or no change in runout results from
the first straightening attempt, spring the shaft
further in the second operation to overcome the
elasticity of the shaft so that it bends in the
required direction. It is better to make several
15-13
attempts to straighten the shaft a few thousandths
of an inch at a time than to attempt to straighten
the shaft in one or two tries with the possibility
of bending the shaft too far in the opposite
direction.
Damaged ends of shafts can be repaired by
removing the bad section and replacing it with a
new "stub" end. Check to see if the type
commander allows stubbing of shafts.
Take the following steps to stub a shaft:
1. If a blueprint is not available, make a
drawing of the shaft showing all dimensions.
2. Machine a piece of scrap stock (spud), of
the same material as the shaft, in the lathe to the
diameter of the shaft at the point where the center
rest will be used. Carefully align the center rest
on this spud.
3. Mount the undamaged end of the shaft
in a 4-jaw chuck and "zero in" the shaft near the
jaws of the chuck. Use soft jaws or aluminum
shims to prevent damage to the shaft surface.
4. Position the previously set center rest
under the shaft so that the center rest is between
the chuck and the damaged end of the shaft.
5. Cut off the damaged portion of the shaft.
6. Face, centerdrill, and drill the end of the
shaft. The diameter of the hole should be about
5/8 of the diameter of the shaft; the depth of the
hole should be at least 21/2 times the hole
diameter.
7. Chamfer the end of the shaft liberally to
allow space for weld deposits.
8. Make a stub of the same material as the
shaft. The stub should be 1/4 inch larger in
diameter and 3/8 inch longer than the damaged
portion of the shaft plus the depth of the hole
drilled in the shaft. This provides ample machin-
ing allowance.
9. Machine one end of the stub to a press
fit diameter of the hole in the shaft. The length
of this portion should be slightly less than the
depth of the hole in the shaft. (A screw fit
between the shaft and stub can be used instead
of the press fit.)
10. Chamfer the shoulder of the machined
end of the stud the same amount as the shaft is
chamfered.
1 1 . Press (or screw for a threaded fitting) the
stub into the shaft and have the chamfered joint
welded and stress relieved.
12. Mount the shaft with the welded stub back
in the lathe and machine the stub to the original
shaft dimensions provided by the drawing or
blueprint.
VALVES
In repairing valves, you must have a
knowledge of the materials from which they are
made. Each material has its limitations of pressure
and temperature; therefore, the materials used in
each type of valve depend upon the temperatures
and pressures of the fluids which they control.
Valves are usually made of bronze, brass, cast
or malleable iron, or steel. Steel valves are either
cast or forged and are made of either plain steel
or alloy steel. Alloy steel valves are used in high-
pressure, high-temperature systems; the disks and
seats of these valves are usually surfaced with a
chromium-cobalt alloy known as Stellite. This
material is extremely hard.
Brass and bronze valves are never used for
temperatures exceeding 550°F. Steel valves are
used for all services above 550 °F and for lower
temperatures where conditions, either internal or
external, such as high-pressure, vibrations, or
shock, may be too severe for brass or iron. Bronze
valves are used almost exclusively in systems
carrying saltwater. The seats and disks of these
valves are usually made of Monel, an excellent
corrosion- and erosion-resistant metal.
Information on the commonly used types of
valves and their construction is provided in
Fireman, NAVEDTRA 10520 (series). The
information supplied here applies to globe, ball,
and gate valves but the procedures discussed can
usually be adapted for repairing any type of valve.
Globe Valve
Closely inspect the valve seat and disk for
erosion, cuts on the seating area, and proper fit
of the disk to its seat. Inspect all other parts of
the valve for wear and alignment and, if you find
them defective, repair or renew them. Generally,
valve repair is limited to overhaul of the seat and
disk. Overhauling of the disk and seat is usually
done by grinding-in the valve seat and disk or by
lapping the seat and machining the disk in a lathe.
Where the disk and seat surfaces cannot be recon-
ditioned by grinding or lapping, you must machine
both the valve disk and valve seat in a lathe.
If upon inspection, the disk and seat appear
to be in good condition, spot them in with
Prussian blue to find out whether they actually
are in good condition.
SPOTTING-IN.— The method used to vis-
ually determine whether or not the seat or disk
make good contact with each other is called
spotting-in. To spot-in a valve seat, first apply a
thin coating of prussian blue evenly over the entire
The prussian blue will adhere to the valve seat at
points where the disk makes contact. Figure 15-1 1
shows what a correct seat looks like upon
spotting-in, and also shows what various kinds
of imperfect seats look like upon spotting-in.
After you have noted the condition of the seat
surface, wipe all the prussian blue off of the
disk face surface and apply a thin, even coat of
prussian blue on the contact face of the seat.
Again place the disk on the valve seat and rotate
the disk a quarter turn. Examine the resulting blue
ring on the valve disk. If the ring is unbroken and
of uniform width, the disk is in good condition,
if there are not cuts, scars, or irregularities on its
face. If the ring is broken or wavy, the disk is not
making proper contact with the seat and must be
machined.
GRINDING.— Valve grinding is the method
of removing small irregularities from the contact
surfaces of the seat and disk. This process is also
used to follow up all seat or disk machining work
on a valve.
To grind-in a valve, apply a small amount of
grinding compound to the face of the disk, insert
the disk into the valve and rotate the disk back
and forth about a quarter turn. Shift the disk-seat
relation from time to time so that the disk will
be rotated gradually in increments through several
rotations. During the grinding process, the
grinding compound will gradually be displaced
from between the seat and disk surfaces, so you
must stop every minute or so to replenish the
compound. For best results when you do this,
uiai me iiicguicuiucs iiavc
been removed, spot-in the disk to the seat as
described previously.
When a machined valve seat and disk are
initially spotted-in, the seat contact will be very
narrow and located close to the edge of the bore.
Grinding-in, using finer compounds as the work
progresses, causes the seat contact to become
broader until a seat contact is produced as
illustrated in figure 15-11. The contact area should
be a perfect ring, covering approximately one-
third of the seating surface, as shown in the
correct seat in figure 15-11.
Avoid overgrinding. It will produce a groove
in the seating surface of the disk and also will tend
to round off the straight angular surface of the
seat. The effects of overgrinding can be corrected
only by machining the surfaces.
LAPPING. — Lapping is the truing of a valve
seat surface by means of a cast iron lapping tool,
shaped like and of exactly the same size as the disk
for that particular valve.
By using such a tool, you can remove slightly
larger irregularities from the seat than you can
by grinding the disk to the seat. (See fig. 15-12.)
NEVER USE THE VALVE DISK AS A LAP.
Below is a summary of the essential points you
must keep in mind while using the lapping tool.
1 . Do not bear heavily on the handle of the
lap.
2. Do not bear sideways on the handle of the
lap.
3 . Shift the lap-valve seat relation so that the
lap will gradually and slowly rotate around
the entire seat circle.
4. Check the working surface of the lap; if
a groove wears on it, have the lap refaced.
WIDE SEAT HIGH SEAT
Figure 15-11.— Examples of spotted-in valve seats.
Figure 15-12.— Lapping tools.
15-15
5. Use only clean compound.
6. Replace the compound often.
7. Spread the compound evenly and lightly.
8. Do not lap more than is necessary to
produce a smooth and even seat.
9. Always use a fine grinding compound to
finish the lapping job.
10. When you complete the lapping job, spot-
in and grind-in the disk to the seat.
Abrasive compound for grinding-in and
lapping-in valve seats and disks is available in
Navy stock in four grades. The grades and the
recommended sequence of use are as follows:
GRADE USE
Coarse For lapping-in seats that have
deep cuts and scratches or
extensive erosion.
Medium For following up the corase
grade: may be used also at the
start of the reconditioning process
where damage is not too severe.
Fine For use when the reconditioning
process nears completion.
Microscopic For finish lapping-in and for final
fine grinding-in.
REFACING.— If the seat of a valve has been
deeply cut, scored, or corroded to the extent that
lapping will not correct the condition, it must be
machined, or, in an extreme case, replaced with
a new seat.
Many valves have removable seats which are
threaded, welded, threaded and welded, or
pressed into the valve body. In A of figure 15-13,
the valve seating surface has been welded so that
it has become an integral part of the valve body.
In B of figure 15-13, the seating surface has been
welded so that it has become an integral part of
the seat ring. The seat ring is threaded into the
body and seal-welded after installation. If the
seating surface of A is damaged to the extent that
it must be renewed, you need only remove the
existing weld material by machining and then
rebuild the seating surface with successive deposits
of new weld material. After you have made a
sufficient deposit of weld material, you can
machine a new seating surface. If the seating
surface of B requires renewal, you must first
machine the seal weld from the ring and remove
the ring from the valve body. You may then either
RETAINER NUT
THRUST
WASHER
HANOWHEEL
BODY
BALL
SEAT
BALL
Figure 15-14. — Typical seawater ball valve.
SEATING SURFACE
VALVE BODY
A-WELDED INTEGRAL SEAT
HARD FACING SEATING SURFACE
SEAT RING
SEAL WELDED
VALVE BODY
B-REMOVABLE SEAT
Figure 15-13. — Valve seat construction.
described.
The actual machining operations for valve
seats and disks are described in chapter 8. After
you have completed the machining, spot-in, lightly
grind-in, and respot the seat and the disk to
ensure that the valve disk-seat contact is as it
should be.
Ball Valve
Ball valves, as the name implies, are stop
valves that use a ball to stop or start the flow of
fluid. The ball, shown in figure 15-14 performs
the same function as the disk in a globe valve.
When you turn the handwheel to open the valve,
the ball rotates to a point where the hole through
only a 90° rotation of the handwheel for
most valves, the ball rotates so that the hole is
perpendicular to the flow openings of the valve
body, and the flow stops.
Most ball valves are the quick-acting type
(requiring only a 90° turn of a simple lever or
handwheel to completely open or close the valve),
but many are operated by planetary gears. This
type of gearing requires a relatively small hand-
wheel and opening force to operate a fairly large
valve. The gearing does, however, increase the
time for opening and closing the valve. Some ball
valves have a swing-check located within the
ball to give the valve a check valve feature.
Figure 15-15 shows a ball-stop swing-check valve
INDICATOR
DISK'
INDICATOR
INDICATOR
SHAFT
BEARING
OPERATOR
BODY
BUSHINGS
RETAINING
NUT
DISK
•ECCENTRIC
SHAFT
HANDWHEEL.
GREASE. PLUG
BONNET
RING GEAR
INTERNAL GEAR
BEARING
BEARING RETAINER
VALVE STEM
VALVE
BODY
THRUST WASHERS
GASKET PIN
BUMPER
TAILPIECE
BALL
Figure 15-15. — Typical ball stop swing-check valve for seawater service.
15-17
with planetary gear operation. Ball valves are
normally found in the following systems onboard
ship: seawater, sanitary, trim and drain, air,
hydraulic and oil transfer. Repair procedures for
ball valves can be found in Portsmouth Process
Instructions, discussed below. In the case of the
smaller types, repairs consist of part replacements
rather than machining and rebuilding.
There are two basic instructions published by
Portsmouth Naval Shipyard which are guidelines
in the repair procedures of seawater ball valves
and the balls themselves. In most cases the most
common repair to the ball itself is to pit fill any
erosion and recoat the ball. The guidelines for this
process are covered in Portsmouth Process
Instruction number 4820-9 17-3 3 8D, change 1,
of 31 January 1977. The other instruction
which covers the actual valve body is the
PPI 4820-921-339B. The latter instruction applies
to the repair of seawater ball valves when the
waterway lip area has been corroded or eroded
to the extent that its function is reduced and
serviceability is affected. The repair of ball valve
waterway lips in this instruction applies only to
straight waterway valves whose stem connection
does not enter the waterway. This instruction also
applies to the repair of the stem cavity and O-ring
sealing areas and to seawater ball valves whose
back seat areas are corroded and eroded to the
extent that leakage between the valve seat and
back seat areas exceeds allowable leakage. The
detailed repair steps are in Portsmouth Process
Instruction Number 4820-921 -339B of 24 June
1977, which cancels number 4820-92 1-339A.
Gate Valve
Gate valves are used when a straight line flow
of fluid with minimum flow restriction is desired.
Gate valves are so named because the part (gate)
which either stops or allows flow through the
valve acts somewhat like the opening or closing
of a gate. The gate is usually wedge shaped. When
the valve is wide open, the gate is fully drawn up
into the valve, leaving an opening for flow
through the valve which is the same size as the
pipe in which the valve is installed. Gate valves
are not suitable for throttling purposes since
the control of flow would be difficult due to
turbulence, and fluid force against a partially open
gate causes it to vibrate, resulting in extensive
damage to the valve.
Gate valves are classified as either rising stem
(fig. 15-16) or nonrising stem valves (fig. 15-17).
On the nonrising stem gate valves, the stem is
YOKE SLEEVE
NUT
WHEEL
GUIDE RIBS
Figure 15-16. — Cutaway view of a gate stop valve (rising stem
type).
threaded on its lower end into the gate. As you
rotate the handwheel on the stem, the gate travels
up or down the stem on the threads while the stem
remains vertically stationary. This type of valve
almost always has a pointer type indicator
threaded onto the upper end of the stem to
indicate the gate's position.
The rising stem gate valve (fig. 15-16) has the
stem attached to the gate, and the gate and the
stem rise and lower together as the valve is
operated. With this basic information on the
principles of the gate valve, you are ready to learn
about repair procedures and manufacturing of
repair parts.
Defects such as light pitting or scoring and
imperfect seat contact can be corrected best by
-I4J3
LIST OF PARTS
PARTNOI _ NAME OF WRT
ill HANDWHEEL
14 "yANDWHEETWr
BONNET STUn i"_
BONNET STUD^NUf
BODY
SEAT RING
GATE
STEM
BONNET^ GASKET
BONNET
STUFFlNGlOX
PACKING
GLAND
GLAND STUD
GLAND STUD NUT
HANDWHEEL
^PLATE SCREW
STUFFING BOX
Figure 15-17.-Cross-sectiona. views of gate stop valves (nonrising stem type)
3-S 3.
a lapping t001 desiSned for the type
to be reconditioned. NEVER use the gate
.
The lapping process is the same for gate valves
as for globe valves, but you turn the lap by a
hancHe extending through the inlet or outlet end
the , o. *»
the handle into the valve so that you cover one
01 the seat rings. Then attach
*«
lap and begin the lapping work. You can lap the
wedge gate to a true surface, using the same lap
that you used on the seat rings. In some cases
when a gate is worn beyond repair and a shim
behind the seat will not give a proper seat, it is
possible to plate the gate or seat, or both, as
described m chapter 14. (Note: Shim has to be
applied behind both seats to maintain the orooer
damaged gate and then machine it to its original
specifications in either a mill or lathe, using an
angle plate or fixture. One of the advantages of
plating over the weld repair method is that no heat
is involved in the selective brush plating method.
Building up metal by welding always heats the
surfaces being repaired and can cause loss of
temper or other weaknesses in the metal.
Constant-Pressure Governor
Many turbine driven pumps are fitted with
special valves called constant-pressure governors.
A constant-pressure governor maintains a con-
stant pump discharge pressure under varying
conditions of load. The governor, which is
installed in the steam line to the pump, controls
the amount of steam admitted to the driving
turbine, thereby controlling the pump discharge
pressure.
Two types of constant-pressure pump gover-
nors are used by the Navy — the Leslie and the
Atlas. The two types of governors are very similar
in operating principles. Our discussion is based
on the Leslie governor, but most of the informa-
tion applies also to the Atlas governor.
A Leslie constant-pressure governor for a
main feed pump is shown in figure 15-18. The
governors used on fuel oil service pumps, lube oil
service pumps, fire and flushing pumps, and
various other pumps are almost identical. The
chief difference between governors used for
different services is in the size of the upper
diaphragm. A governor used for a pump that
operates with a high discharge pressure has a
smaller upper diaphragm than one used for a
pump that operates with a low discharge pressure.
Two opposing forces are involved in the
operation of a constant-pressure pump governor.
Fluid from the pump discharge, at discharge
pressure, is led through an actuating line to the
space below the upper diaphragm. The pump
discharge pressure exerts an UPWARD force on
the upper diaphragm. Opposing this, an adjusting
spring exerts a DOWNWARD force on the upper
diaphragm.
When the downward force of the adjusting
spring is greater than the upward force of the
pump discharge pressure, the spring forces both
the upper diaphragm and the upper crosshead
downward. A pair of connecting rods connects
the upper crosshead rigidly to the lower crosshead,
so the entire assembly of upper and lower
crossheads moves together. When the crosshead
assembly moves downward, it pushes the lower
mushroom and the lower diaphragm downward.
The lower diaphragm is in contact with the
controlling valve. When the lower diaphragm is
moved downward, the controlling valve is forced
down and open.
The controlling valve is supplied with a small
amount of steam through a port from the inlet
side of the governor. When the controlling valve
is open, steam passes to the top of the operating
piston. The steam pressure acts on the top of the
operating piston, forcing the piston down and
opening the main valve. The extent to which the
main valve is opened controls the amount of steam
admitted to the driving turbine. Increasing the
opening of the main valve therefore increases the
supply of steam to the turbine and so increases
the speed of the turbine.
The increased speed of the turbine is reflected
in an increased discharge pressure from the pump.
This pressure is exerted against the underside of
the upper diaphragm. When the pump discharge
pressure has increased to the point that the up-
ward force acting on the underside of the upper
diaphragm is greater than the downward force
exerted by the adjusting spring, the upper
diaphragm is moved upward. This action allows
a spring to start closing the controlling valve which
in turn allows the main valve spring to start closing
the main valve against the now-reduced pressure
on the operating piston. When the main valve
starts to close, the steam supply to the turbine is
reduced, the speed of the turbine is reduced, and
the pump discharge pressure is reduced.
At first glance, it might seem that the con-
trolling valve and the main valve would be
constantly opening and closing and the pump dis-
charge pressure would be continually varying over
a wide range. This does not happen, however,
because the governor is designed to prevent
excessive opening or closing of the controlling
valve. An intermediate diaphragm bears against
an intermediate mushroom which in turn bears
against the top of the lower crosshead. Steam is
led from the governor outlet to the bottom of the
lower diaphragm and also through a needle valve
to the top of the intermediate diaphragm. A steam
chamber provides a continuous supply of steam
at the required pressure to the top of the
intermediate diaphragm.
Any up or down movement of the crosshead
assembly is therefore opposed by the force of the
steam pressure acting on either the intermediate
diaphragm or the lower diaphragm. The whole
arrangement serves to prevent extreme reactions
15-20
HANDWHEEL
ADJUSTING SCREW
LOCK NUT
ADJUSTING SPRING
DIAPHRAGM DISK
(UPPER MUSH ROOM)
UPPER DIAPHRAGM
ACTUATING LINE FROM
DISCHARGE SIDE
OF PUMP
INTERMEDIATE DIAPHRAGM
CROSSHEAD CONNECTING ROD
DIAPHRAGM STEM CAP
(INTERMEDIATE MUSHROOM)
MAIN VALVE — iWyNVrSVte
STEAM CHAMBER
CYLINDER LINER
OPE RATING PIS TON
NEEDLE VALVE
DIAPHRAGM STEM
(LOWER MUSHROOM)
DIAPHRAGM STEM GUIDE
CONTROLLING VALVE BUSHING
CONTROLLING VALVE
CONTROLLING VALVE SPRING
STEAM OUTLET
(TO TURBINE)
MAIN VALVE SPRING
INDICATOR PLATE •JL> «i .
FTC., -j Ji
^Kra
HANDWHEEL(FORnv/nA"' ^ifcW^
"^
Figure 15-18. — Constant-pressure governor for main feed pump.
of the controlling valve in response to variations
in pump discharge pressure.
Limiting the movement of the controlling
valve in the manner just described reduces the
amount of hunting the governor must do to
find each new position. Under constant-load
conditions, the controlling valve takes a position
that causes the main valve to remain open by the
required amount. A change in load conditions
causes momentary hunting by the governor until
it finds the new position required to maintain
pump discharge pressure at the new load.
A pull-open device, consisting of a valve stem
and a handwheel, is fitted to the bottom of the
governor. Turning the handwheel to the open
position draws the main valve open and allows
full steam flow to the turbine. When the main
valve is opened by use of the handwheel, the
turbine must be controlled manually. Under all
normal operating conditions, the bypass remains
closed and the pump discharge pressure is raised
or lowered, as necessary, by increasing or decreas-
ing the tension on the adjusting spring.
CONTROL AND MAIN VALVE.— If there
is leakage in the generator through the control
valve or its bushing, steam will flow to the top
of the operating piston, opening the main valve,
and holding it open, even though there is no
tension on the adjusting spring. The main valve
must be able to close off completely or else the
governor cannot operate properly. The only
remedy is to disassemble the governor and stop
the steam leakage. In most instances, you must
renew the control valve. If the leakage is through
the bottom of the bushing and its seat, you must
lap the seat. A cast iron lap is best for this type
of work.
Rotate the lap through a small angle of
rotation, lift it from the work occasionally, and
move to a new position as the work progresses.
This will ensure that the lap will slowly and
gradually rotate around the entire seat circle. Do
not bear down heavily on the handle of the lap.
Replace the compound often, using only clean
compound. If the lap should develop a groove or
cut, redress the lap. Lapping should never be
continued longer than necessary to remove all
damaged areas.
When you are installing the control valve and
its bushing, remember that the joint between the
bottom of the bushing and its seat is a metal-to-
metal contact. Install the bushing tightly, and
when it is all the way down, tap the wrench lightly
with a hammer, to ensure a steamtight joint.
When the controlling valve is installed, you
must check the clearance between the top of the
valve stem and the diaphragm. It is absolutely
mandatory that this clearance be between .001 and
.002 inch (fig. 15-19). If the clearance is less than
.001 inch, the diaphragm will hold the control
valve open, allowing steam to flow to the main
Figure 15-19.— Critical dimensions of the Leslie top cap.
valve at any time the throttle valve is open. If the
clearance is more than .002 inch, the diaphragm
will not fully open the control valve — which
means that the main valve cannot open fully, and
the unit cannot be brought up to full speed and
capacity.
When the main valve seating area is damaged,
it must be lapped in by the same process.
ALWAYS lap in the main valve with the piston
in the cylinder liner to ensure perfect centering.
If the damage to the seating surfaces is
excessive, you must install new parts. Use only
parts supplied by the manufacturer, if they are
available.
TOP CAP.— If the top flange of the top cap
of the governor becomes damaged, you must be
extremely careful when you machine it. Consult
the manufacturer's technical manual for the
correct clearances. (See fig. 15-19.)
All seating surfaces must be square with the
axis of the control valve seat threads and must
have the smoothest possible finish. Before you
start the reassembly, be sure that all ports in the
top cap and the diaphragm chamber are free of
dirt and other foreign matter. Check to ensure
that the piston rings are free in their grooves. The
cylinder liner must be smooth and free of grooves,
pits, and rust.
When installing the cylinder liner, make
certain that the top of the liner does not extend
above the top of the valve body. The piston must
work freely in the liner; if there is binding, the
governor will not operate satisfactorily. Renew
the controlling valve spring and the main valve
spring if they are weak, broken or corroded, or
if they have taken a permanent set. If necessary,
renew all diaphragms; if you use the old
diaphragms, install them in their original position;
do not reverse them.
Follow the instructions in the manufacturer's
technical manual in reassembling the governor.
All clearances must be as designed if the
governor is to operate satisfactorily. Check each
moving part carefully to ensure freedom of
movement.
When the governor is reassembled, test it as
soon as possible so that you can make corrections,
if necessary.
Double Seated Valves
Depending on the extent of damage to the disk
of a double seated valve, you can lap or weld-
repair it and remachine it to fit the body. The
normal seat angles remain the same as for globe
valves and the spotting-in procedure will be the
same. Most valve disks can be held on a spud or
mounted on a mandrel and can be cut in the same
way as a globe valve. In this case as in the others,
it is best to consult local quality assurance
directives and local procedures in the repair of this
type of valve. Also, in most cases the blueprints
will show "ND" (no deviations) and must be
closely adhered to, as far as type of weld and
quality. In all cases shop LPO's should be able
to provide the necessary information.
Duplex Strainer Plug Valves
The cost common cause for repair to duplex
strainers is scored or chipped O-ring grooves or
scored or scratched liners. In some cases it may
be necessary to perform a weld repair and then
machine back to blueprint specifications on the
plug cock. In the case of repair to the strainer
body, you will usually hone it and in some cases
you will use an oversized O-ring. Consult local
type commander and quality assurance procedures
to find out which method is best suited for your
situation. Check with the shop's leading petty
officer before you undertake any repair
procedures.
Pressure Seal Bonnet Globe Valves
In many cases you may be required to repair
pressure seal bonnet globe valves. This type of
valve (fig. 15-20) is usually the welded bonnet
HAMMER-BLOW WHEEL
ON 3 AND 4-INCH SIZES
YOKE BRUSHING
GLAND FLANGE
BONNET LOCKING
RING
AND BONNET
SEAL RING
DISC AND DISC
STEM RING
Figure 15-20.— 1500-pound pressure seal bonnet globe valve.
type, and you will be involved in machining
the bonnet seal area to specifications provided
by either the applicable blueprint or the Hull
Technician doing the welding. This basic type
valve is used in steam systems; it is also commonly
found in the nuclear systems in submarines and
submarine tenders. This type of valve is also
referred to as canopy seal valve. In some instances
you may be required to work closely with the
radiological control division since these valves are
used in nuclear systems that must be closely
monitored for radiation levels and possible
contamination of equipment and tools used
during the repair procedure. Inn most tenders the
R-5 division has facilities to work on valves that
require special handling. In these instances you
would be required to provide the technical ability,
and R-5 division personnel would do the
monitoring.
Assembling High-Pressure Steam Valves
The bonnet joint of a high-pressure steam
valve is always made with a metallic or a flexible
gasket and high-temperature-use alloy stud bolts
and nuts. When you assemble such a valve, be
sure that you use the correct kind of gasket and
stud bolts. If you are the least bit doubtful of what
you should use in a particular valve, ask your
leading petty officer.
There are two ways to identify a high-
temperature-use alloy stud bolt: (1) the thread
runs the entire length of the body and one end
of the bolt has a small center hole recess and (2)
the bolt will have either an "H" or "A" stamped
on the crown. If you do not see such an identifica-
tion on a stud, do not use it on a high-pressure
valve.
When assembling a valve, use antiseize
compound on the stud bolt threads, and always
be sure to back the disk away from the seat before
tightening any of the bonnet nuts. In setting up
on bonnet flange nuts, alternate approximately
180° and 90° from the starting point until you
have all of them set up evenly and fairly tight.
For final all-round setup on the nuts, use a torque
wrench to measure for correct tightening tension
Figure 15-21. — Applying a hydrostatic test to a high-pressure steam valve.
28.263
or a micrometer to measure elongation of the
studs to compute the tension. Your leading petty
officer can give you practical instruction on
correct tension for different sizes of stud bolts.
Testing Valves
After a valve has been overhauled in the shop,
it is standard practice to test it under hydrostatic
pressure to prove the tightness of the seat and the
bonnet joint. Figure 15-21 shows a Machinery
Repairman in the process of applying a hydro-
static test to a high-pressure steam valve. In this
particular setup, the valve is held on a thick rubber
gasket by U-clamps and water delivered under
pressure from a hydraulic test pump will be led
into the bottom of the valve from a connection
underneath the test stand.
After you finish applying a test pressure to the
lower part of the valve, turn the valve over, with
the other flange down, and test the bonnet joint.
When you test valves hydrostatically, be sure
to use the specified test pressure. Too low a
pressure will not prove the tightness of the valve
and too high a pressure may cause damage to the
valve.
REPAIRING PUMPS
A description of the common types and uses
of pumps onboard ship is provided in Fireman,
NAVEDTRA 10520 (series). The following
discussion is limited to repair of centrifugal pumps
because these pumps are the ones that a
Machinery Repairman will usually be required to
repair.
Figure 15-22 is a sketch of the internal parts
of a centrifugal pump. Look at the arrangement
of the impeller, casing wearing rings, impeller
wearing rings, shaft, and shaft sleeves in
particular.
THRUST BEARING
CARBON PACKING
38.109
Figure 15-22.— Two-stage main feed pump.
In a centrifugal pump, the portion of the shaft
in the way of the packing gland and the casing-
impeller sealing areas are subject to wear during
operation. They must be renewed from time to
time to maintain the efficiency of the pump.
To prevent having to renew the entire shaft
solely because of wear in the packing gland area,
shafts in centrifugal pumps are often provided
with tightly fitting renewable sleeves. To offset
the need for renewing or making extensive repairs
to the casing and impeller, these two parts also
have renewable wearing surfaces, called the casing
wearing rings and impeller wearing rings. You can
see the arrangement clearly in figure 15-23.
When it is necessary to renew these parts, the
rotor assembly, consisting of the pump shaft, the
impeller and its wearing ring, and the casing rings,
is usually brought into the shop. The method of
replacing these parts is described in the follow-
ing paragraphs.
The repair parts generally are available from
the ship's allowance, but often you may need to
turn them out in the shop. Before you proceed
with these repairs, consult the manufacturer's
technical manual and the applicable blueprints to
get the correct information on vital clearances and
other data.
In some pumps, the shaft sleeve is pressed onto
the shaft with a hydraulic press, and you must
machine off the old sleeve in a lathe before you
can install a new one. On centrifugal pumps, the
shaft sleeve is a snug slip-on fit, butted up against
a shoulder on the shaft and held securely in place
with a nut. The centrifugal pump sleeve-shaft-
shoulder joint is usually made up with a hard fiber
wash to prevent liquid from leaking through the
joint and out of the pump between sleeve and the
shaft.
The impeller wearing ring is usually lightly
press fitted to the hub of the impeller and keyed
in with headless screws (also referred to as "Dutch
keyed"). To remove the worn ring, withdraw the
headless screws or drill them out and then machine
the ring off in a lathe.
The amount of diametrical running clearance
between the casing rings and the impeller rings
affects the efficiency of a centrifugal pump. Too
much clearance will let an excessive amount of
liquid leak back from the discharge side to the
suction side of the pump. Insufficient clearance
will cause the pump to "freeze." Before you
install a new wearing ring on the impeller, measure
STUFFING BOX
(INTEGRAL
WITH CASING)
RADIAL
CLEARANCE
STUFFING
BOX PACKING
GLANO LANTERN
RING
THROAT
BUSHING
IMPELLER
SHAFT
SLEEVE
IMPELLER
WEARING
RING
CASING WEARING
•RING
the outside diameter of the impeller wearing ring,
and the inside diameter of the casing ring. (See
fig. 15-24.) If the measurements do not agree with
the fit and clearance data you have on hand, ask
your leading petty officer for instructions before
you proceed any further. Sometimes it is necessary
to take a light cut on the inside diameter of the
impeller ring to get its correct press fit on the
impeller hub. The difference between the outside
diameter of the impeller wearing ring and the
inside diameter of the casing wearing ring is the
diametrical running clearance between the rings.
If this clearance is too small, correct it by taking
a cut on either the outside diameter of the impeller
ring or the inside diameter of the casing ring.
Another thing to check is the concentricity of the
two rings; if they do not run true, you must
machine their mating surfaces so that they do run
true, bearing in mind, of course, to keep the
specified diametrical clearance.
When a pump like the one shown in figure
15-22 needs repairs, usually only the shaft
assembly and casing wearing rings are brought to
the shop. To renew the wearing rings and re-
surface the packing sleeves of the pump shown
in figure 15-22, take the following steps:
1. Clamp the casing wearing ring on a
faceplate and align the circumference of the ring
concentrically with the axis of the lathe spindle.
(The casing rings may be chucked in a 4-jaw chuck
but there is danger of distorting the ring if this
is done.)
2. Take a light cut on the inside diameter of
the casing ring to clean up the surface. Do this
to all casing rings.
3. Mount the shaft assembly between centers
or in a chuck and align its axis with the lathe axis.
IMPELLER WEARING
RING
IMPELLER
WITH IMPELLER
WEARING RING
CASING WEARING-
RING
Figure 15-24.— Impeller, impeller wearing ring, and casing
wearing ring for a centrifugal pump.
4. Machine away the impeller wearing rings.
Be careful not to cut into the impeller.
5. Take a light cut on the packing sleeves to
clean up their surfaces.
6. Remove the shaft assembly from the lathe.
7. Make the impeller rings. The size of the
inside diameter of the impeller rings should
provide a press fit on the impeller; the outside
diameter should be slightly larger than the inside
diameter of the casing rings.
8. Press the impeller rings on the impeller and
lock them in place with headless screws, if so
stated on blueprint.
9. Mount the shaft assembly back in the lathe
and machine the diameter of the impeller rings
to provide the proper clearance between impeller
rings and casing rings. Blueprints and technical
manuals list the desired clearance as either
diametrical clearance or radial clearance.
Diametrical clearance is the total amount of
clearance required. Radial clearance is one-half
of the clearance required and must be doubled to
get diametrical clearance.
MACHINE SHOP MAINTENANCE
The ship in which you serve and the shop in
which you work were designed to accomplish a
particular mission or job. As an MRS or MR2,
you will be expected to assist in the proper
maintenance and preservation of the machines
and spaces you use. Generally, you can give a
workshop one good look and tell whether it is
efficient and well run. The Ship's Maintenance
and Material Management (3-M) System has been
implemented by the Navy as an answer to the ever
present problem of maintaining a high degree of
operational readiness. A thorough study of
Military Requirements for Petty Officers 3 &2,
NAVPERS 10056 (series), will give you all the
information you need on the 3-M System.
Although the 3-M System is designed to
improve the degree of readiness, its effectiveness
and reliability depend on you, the individual. The
accuracy with which you perform your work,
along with neat and complete recording of
required data on the prescribed forms is one of
the keys to the degree of readiness of your ship.
Remember PREVENTIVE MAINTENANCE
(scheduled checks) will lead to less CORRECTIVE
MAINTENANCE (repair of equipment). Control
over rust and corrosion will be a major problem.
Equipment used often is not likely to "freeze up,"
but machinery which is seldom used may fail to
operate at a crucial moment. It is a good policy
to check and operate all shop machinery
immediately after the weekly lubrication.
There will be rust film trouble in all climates,
but it will occur more frequently in the tropics
because of humidity (moisture). A rust prevention
program should be a part of your daily cleanup
routine. Keep all bare metal surfaces clean and
bright, and apply a light coat of machine oil to
protect them. Use an approved rust preventive
compound to help keep decks, bare metal
surfaces, and machinery parts from rusting.
It is sometimes said that a machine tool
operator can be judged by the condition of his
or her tools, machines, and spaces. Good
maintenance practices will save you many hours
of extra work. Some good precautions for the
maintenance of machinery are listed below:
• Before you apply power to a machine, see
that the machine is ready for starting. For
example, move the carriage of a lathe by the hand
feed to ensure that all locking devices have been
released.
• Do not lay work or handtools on the ways
of a machine.
• Avoid scoring the platen of a planer, drill-
ing holes in the table of a drill press, or gouging
the vise or footstock of a milling machine.
© Do not use the table of any machine for
a workbench.
© When you use a toolpost grinder on a
lathe, cover the ways and other finished surfaces
to protect them against grit.
• See that pneumatic power-driven hand-
tools are lubricated after each 8 hours of opera-
tion or more often if necessary.
• Before you take an electric power-driven
handtool from the toolroom, examine it carefully
for mechanical and electrical defects and ensure
that the electrical safety tag is current.
• When you secure for sea, take all pre-
cautions to ensure that machinery or components
will not sway or shift with the motion of the ship.
The precautions should include the following:
a. In securing top-heavy equipment such
as a radial drill press arm, lower it to
rest on the table or base of the machine
and then make sure that it is locked and
blocked securely.
b. Secure chain falls, trolleys, overhead
cranes, and other suspended equip-
ment, such as counterweights on boring
mills and drill presses.
c. Secure tailstocks of lathes.
d. Secure spindles of horizontal boring
mills.
e. Protect and secure tools stowed in
cabinets or drawers. Secure drawers
and cabinet doors.
REMOVING BROKEN
BOLTS AND STUDS
When you must remove a broken bolt or stud,
flood the part being worked on with plenty of
penetrating oil or oil of wintergreen. Time
permitting, soak the area for several hours or
overnight. A week's soaking may loosen a bolt
which would otherwise have to be drilled out.
If enough of the broken piece protrudes, take
hold of it with locking pliers, as shown in
Figure 15-25. — Removing a broken stud with locking pliers. Figure 15-26. — Removing a broken bolt with a prick punch.
Table 15-1.— Chart for Screw and Bolt Extractors
Extractor
Used For—
Size No.
Overall Length,
Inches
Nominal Screw
And Bolt Size,
Inches
Nominal Pipe
Size, Inches
Use Drill Size
Dia., Inches
1
2
3/16- 1/4
5/64
2
23/8
1/4 - 5/16
7/64
3
2 11/16
5/16- 7/16
5/32
4
3
7/16- 9/16
1/4
5
3 3/8
9/16- 3/4
1/4
17/64
6
3 3/4
3/4 -1
3/8
13/32
7
41/8
1 -1 3/8
1/2
17/32
8
43/8
1 3/8 -1 3/4
3/4
13/16
9
45/8
1 3/4 -2 1/8
1
1 1/16
10
5
2 1/8 -2 1/2
1 1/4
1 5/16
11
55/8
2 1/2 -3
1 1/2
1 9/16
12
6 1/4
3 -3 1/2
2
1 15/16
Figure 15-27. — Screw and bolt extractors for removing
broken studs.
figure 15-25, and carefully try to ease it out. If you
cannot turn the bolt, further soaking with
penetrating oil may help. Or try removing the
pliers and jarring the bolt with light hammer
blows on the top and around the sides. This may
loosen the threads so that you can remove the bolt
with the pliers.
If a bolt has been broken off flush with the
surface as shown in figure 15-26, it is sometimes
possible to back it out with light blows of a prick
punch or center punch. However, if the bolt was
broken due to rusting, this method will not
remove it. If you cannot remove it by carefully
punching first on one side and then the other, use
a screw and bolt extractor. (See fig. 15-27B.)
When using this extractor, file the broken
portion of the bolt to provide a smooth surface
B
Figure 15-28.— Removing a stud broken off below the
surface.
at the center for a punch mark, if possible. Then
carefully center punch the exact center of the bolt.
(See fig. 15-27A.)
Refer to table 15-1 to select the proper drill
to use according to the size of the broken bolt that
you are trying to remove. If possible, drill through
the entire length of the broken bolt. Then carefully
work some penetrating oil through the hole so that
it fills the cavity beneath the bolt and has a chance
to work its way upward from the bottom of the
bolt. The more time you let the penetrating oil
work from both ends of the broken bolt, the better
are your chances of removing it.
In drilling a hole in a stud that has broken off
below the surface of the piece which it was holding
(fig. 15-28A), use a drill guide to center the drill.
15-29
This method may be preferred rather than a center
punch mark.
After you have drilled the hole and added
penetrating oil and let it soak, put the spiral end
of the screw and bolt extractor into the hole. Set
it firmly with a few light hammer blows and secure
the tap wrench as shown in figure 15-28B.
Carefully try to back the broken bolt out of the
hole. Turn the extractor counterclockwise. (This
type of extractor is designed for right-hand
threads only.)
Sometimes you can use a screw and bolt
extractor to remove an Allen head capscrew when
the socket has been stripped by the Allen wrench.
(See fig. 15-29.) Carefully grind off the end of
the extractor so that it will not bottom before the
Figure 15-29.— Removing an Allen head capscrew with a boll
extractor.
spiral has had a chance to take hold. Figure 15-29
shows this end clearance. In doing this grinding
operation, be very careful to keep the temperature
of the extractor low enough so that you can handle
the tip with your bare hands. If the hardness is
drawn from the tip of the extractor by overheating
during the grinding, the extractor will not take
hold.
REMOVING A BROKEN BOLT
AND RETAPPING THE HOLE
To remove a broken bolt and retap the hole,
file the bolt smooth, if necessary, and centerpunch
it for drilling. Then select a twist drill which is
a little less than the tap-drill size for the particular
bolt that has been broken. As shown in figure
15-30, this drill will just about but not quite touch
the crests of the threads in the threaded hole or
the roots of the threads on the threaded bolt.
Carefully start drilling at the center punch mark,
crowding the drill one way or the other as
necessary so that the hole will be drilled in the
exact center of the bolt.
The drill in figure 15-30 has almost drilled
the remaining part of the bolt away and will
A
B
Figure 15-31.— Removing a broken bolt and retapping the
hole to a larger size.
Figure 15-30.— Removing a broken bolt and retapoine the
eventually break through the bottom of the bolt.
When this happens, all that will remain of the bolt
will be a threaded shell. With a prick punch or
other suitable tool, chip out and remove the first
two or three threads, if possible, at the top of the
shell. Then carefully start a tapered tap into these
clean threads and continue tapping until you have
cut away the shell and restored the original
threads.
In cases where the identical size of capscrew
or bolt is not necessary as a replacement, center
punch and drill out the old bolt with a drill larger
than the broken bolt, as shown in figure 15-31 A.
Tap the hole first, and then finish it with a
bottoming tap as shown in figure 15-31. Replace
the original capscrew or stud with a larger size.
REMOVING A BROKEN
TAP FROM A HOLE
To remove a broken tap from a hole,
generously apply penetrating oil to the tap, work-
ing it down through the four flutes into the hole.
Then, if possible, grasp the tap across the flats
with locking pliers. This operation is shown in
figure 15-32. Carefully ease the tap out of the
hole, adding penetrating oil as necessary.
If the tap has broken off at the surface of the
work or slightly below the surface of the work,
the tap extractor shown in figure 15-33 may
remove it. Again, apply a liberal amount of
penetrating oil to the broken tap. Place the tap
extractor over the broken tap and lower the upper
collar to insert the four sliding prongs down into
the four flutes of the tap. Then slide the bottom
collar down to the surface of the work so that it
will hold the prongs tightly against the body of
the extractor. Tighten the tap wrench on the
square shank of the extractor and carefully work
the extractor back and forth to loose the tap. You
may need to remove the extractor and strike a few
sharp blows with a small hammer and pin punch
to jar the tap loose. Then reinsert the tap remover
and carefully try to back the tap out of the hole.
Each size of tap will require its own size of
tap extractor. Tap extractors come in the follow-
ing sizes: 1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8,
3/4, 7/8 and 1 inch.
When a tap extractor will not remove a broken
tap, you may be able to do so by the following
method: Place a hex nut over the tap (fig. 15-34),
and weld the nut to the tap. Be sure to choose
a nut with a hole somewhat smaller than the tap
diameter to reduce the possibility of welding the
nut and the tap to the job itself. Allow the weld
to cool before trying to remove the tap. When the
nut, tap, and job have come to room temperature,
it is often helpful to quickly heat
the immediate area around the hole with an
oxyacetylene torch. This quick heating expands
the adjacent metal of the work, allowing you to
remove the tap more easily. If the heating is too
slow, the tap will expand with the adjacent metal
of the work and there will be no loosening effect.
MAKING PISTON RINGS
To make a cast iron piston ring, select a billet
of sufficient size to permit you to remove surface
defects. For example, in making a ring that has
a 10-inch outside diameter and a 9-inch inside
diameter, use a billet with an outside diameter of
11 inches and an inside diameter of 8 inches. A
billet this size has a wall thickness of 1 1/2 inches
and will allow you to remove 1/2 inch of metal
from the inside surface and 1/2 inch of metal from
the outside surface. To make the ring, proceed
as follows:
1. Mount the billet in a chuck on the lathe.
2. Face the end.
BROKEN
.TAP
SLIDING 100CD
PRONG UPPER
COLLAR
SQUARE
SHAN"
PLUG WELD
AREA
HEX NUT
Figure 15-33.— Removing a broken tap with a tap extractor. Figure 15-34.— Using a plug weld to remove a broken tap.
3. Rough bore and then finish bore to the in-
side diameter of the ring. Bore a sufficient
distance into the billet to make the desired width
of the ring or rings.
4. Rough turn the outside of the billet to a
diameter that is 0.010 inch larger per inch than
the bore of the cylinder into which the ring is to
be fitted. For example, for a 10-inch cylinder bore,
the rough turn diameter would be 10.100 inches.
5. Cut off the ring to the required width with
a parting tool.
6. Split the ring with a 45 ° cut, using a
hacksaw. Place a piece of chart paper in the
cut and then wrap a piece of wire around the
circumference of the ring and draw it up until the
ends butt up snugly.
7. Mount the ring on a faceplate to finish turn
it to the exact cylinder bore size. Place faceplate
clamps on the inside of the ring to prevent
interfering with the operation. Place a piece of
paper between the ring and the surface of the
faceplate to keep the ring from slipping and also
to keep the tool from cutting into the faceplate
when you turn. When you have centered the ring
on the faceplate and taken up the clamps securely,
remove the binding wire, and proceed with the
finish turning operation.
SPRING WINDING
The methods and tools used for winding or
coiling springs vary greatly in form and in
regard to productive capacity. The method used
ordinarily depends upon the number of springs
required and to some extent upon their form.
When a comparatively small number of springs
are needed in connection with repair work, and
so forth, it is common practice to wind them in
a lathe; whereas when springs are manufactured
in large quantities, special machines are used.
Springs are often made with an "initial
tension", which causes the coils to be drawn
tightly together. This tension is maintained by
twisting the wire as the spring is wound. A
common example of such a spring is the ordinary
screen door spring. When in a static condition
(before being installed on a door), these springs
will not begin to stretch as soon as the load is
applied. The load must first overcome the initial
tension already in the spring.
TABLES FOR SPRING WINDING
When springs are to be wound on a lathe
instead of a spring-coiling machine, the lathe is
geared in the same manner as for screw cutting.
Table 15-2 indicates which gearing should be used.
The figures in the body of the table give the
number of threads per inch for which the lathe
should be geared to wind coil springs of a given
wire gauge. The figures in the column headed
"A" are for closewound tension springs, while
the figures in the columns headed "B" are for
compression springs. Assume, for example, that
you must wind a compression spring of No. 10
Brown and Sharpe gauge wire. From the table,
you will note that this spring should have four
and one-half coils per inch. Gear the lathe as you
would to cut four and one-half threads per inch.
Table 15-3 gives data for winding piano wire
tension springs. Assume that you must wind three
different springs; the first to be wound from
0.035-inch wire to fit in an 11/16-inch hole, the
second to be wound from 0.040-inch wire to fit
a 3/8-inch hole, and the third to be would from
0.060-inch wire to be a sliding fit on a 1/2-inch
diameter shaft. The table shows the proper sizes
of mandrels for winding to be as follows: for the
first spring 0.562 inch; for the second spring,
0.250 inch; and for the third spring, 0.437 inch.
In the latter case, 0.011 inch is allowed for play
between the spring and the shaft. The wire sizes
given in the table conform to the English music
wire gauge.
In all cases when the mandrel diameter is
larger than 3/8 inch, the mandrel is mounted in
a lathe chuck. Mandrels less than 3/8 inch in
diameter are mounted in a drill chuck. In fasten-
ing the wire in a lathe chuck, one jaw is usually
loosened. When the mandrel is driven by a drill
chuck, place the wire between the jaws and the
mandrel. If a long spring is required, use a
mandrel of corresponding length, which is ground
to an angle of 60 ° at the end to fit into a female
dead center for support. Place the wire in a bench
lathe boring tool holder or a V-holder in the
toolpost. Place a piece of brass about 1/8 inch
by 1/2 inch by 3 inches between the wire and the
toolpost screw. File a V-shaped groove lengthwise
in the brass to hold the wire in place. Make the
groove the proper depth for the size of wire from
which the springs are being wound. Tighten this
clamping arrangement with the toolpost wrench.
Use just enough tension on the wrench to keep
the wire from slipping.
Further information and strengths of wire is
given in the Machinery's Handbook.
Tension Spring — I Compression Spring — II
Number
of Wire
Gage
Brown &
Sharpe
Birmingham
or Stub's
Washburn &
Moen Mfg. Co.
Trenton
Iron Co.
Prentiss
Old English
Brass Man-
ufacturers'
I
II
I
II
I
II
I
II
I
II
I
II
000000
00000
0000
000
00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
2
2 1/4
21/2
23/4
3
3 1/4
3 1/2
3 1/2
4
4
4 1/2
5
5 1/2
6
6 1/2
7
8
9
10
12
13
14
16
20
23
28
28
32
40
40
48
52
56
56
64
64
72
72
88
96
104
1
1 1/8
1 1/4
1 3/8
1 1/2
1 5/8
1 3/4
1 3/4
2
2
21/4
21/2
23/4
3
3 1/4
3 1/2
4
4 1/2
5
6
6 1/2
7
8
10
11 1/2
14
14
16
20
20
24
26
28
28
32
32
36
36
44
48
52
2
21/2
23/4
3
3
3 1/2
3 1/2
4
4
4 1/2
5
5 1/2
6
6 1/2
7
8
9
10
12
14
16
18
22
24
28
32
32
40
44
48
52
56
56
64
64
72
80
88
96
104
1
1 1/4
1 3/8
1 1/2
1 1/2
1 3/4
1 3/4
2
2
21/4
2 1/2
23/4
3
3 1/4
3 1/2
4
4 1/2
5
6
7
8
9
11
12
14
16
16
20
22
24
26
28
28
32
32
36
40
44
48
52
2
2 1/4
23/4
3
3 1/4
3 1/2
4
4 1/2
5 1/2
6
6 1/2
7
8
9
11
12
14
14
16
18
22
24
28
28
32
36
44
48
56
56
64
72
88
96
112
1
1 1/8
1 3/8
1 1/2
1 5/8
1 3/4
2
2 1/4
23/4
3
3 1/4
3 1/2
4
4 1/2
5 1/2
6
7
7
8
9
11
12
14
14
16
18
22
24
28
28
32
36
44
48
56
2
21/4
2 1/2
27/8
3 1/4
3 1/2
3 1/2
4
4 1/2
4 1/2
5 1/2
6
6 1/2
7
8
9
10
12
13
14
16
20
23
28
28
32
40
44
48
52
56
64
72
80
96
104
112
1
1 1/8
1 1/4
17/16
1 5/8
1 3/4
1 3/4
2
2 1/4
2 1/4
23/4
3
3 1/4
3 1/2
4
4 1/2
5
6
6 1/2
7
8
10
11 1/2
14
14
16
20
22
24
26
28
32
36
40
48
52
56
23/4
3
3 1/4
3 1/4
3 1/2
4
4
4 1/2
5
5 1/2
6
6 1/2
7
8
9
10
12
13
14
16
20
23
28
28
32
36
40
46
48
52
56
56
64
64
72
72
80
88
1 3/8
1 1/2
1 5/8
1 5/8
1 3/4
2
2
2 1/4
2 1/2
23/4
3
3 1/4
3 1/2
4
4 1/2
5
6
6 1/2
7
8
10
11 1/2
14
14
16
18
20
23
24
26
28
28
32
32
36
36
40
44
...
12
13
14
16
20
24
28
28
32
36
40
40
48
52
56
64
72
80
88
92
104
104
6
6 1/2
7
8
10
12
14
14
16
18
20
20
24
26
28
32
36
40
44
46
52
52
15-33
Table 15-3.— Data for Winding Piano Wire Tension Springs
Diam.
of
Man-
drel,
Inches
Inside
Diam.
of
Spring,
Inches
Outside
Diam.
of
Spring,
Inches
Num-
ber of
Piano
Wire
Diam.
of Piano
Wire,
Inches
Diam.
of
Man-
drel,
Inches
Inside
Diam.
of
Spring,
Inches
Outside
Diam.
of
Spring,
Inches
Num-
ber of
Piano
Wire
Diam.
of Piano
Wire,
Inches
0.125
0.130
0.150
1
0.0098
0.187
0.209
0.258
10
0.0245
0.187
0.192
0.212
1
0.0098
0.250
0.272
0.321
10
0.0245
0.250
0.255
0.275
1
0.0098
0.312
0.336
0.385
10
0.0245
0.312
0.318
0.338
1
0.0098
0.375
0.401
0.450
10
0.0245
0.375
0.382
0.402
1
0.0098
0.437
0.465
0.514
10
0.0245
0.125
0.130
0.151
2
0.0105
0.500
0.533
0.582
10
0.0245
0.187
0.192
0.213
2
0.0105
0.562
0.600
0.649
10
0.0245
0.250
0.255
0.276
2
0.0105
0.625
0.665
0.714
10
0.0245
0.312
0.318
0.339
2
0.0105
0.187
0.212
0.266
11
0.0270
0.375
0.382
0.403
2
0.0105
0.250
0.277
0.331
11
0.0270
0.125
0.130
0.152
3
0.0115
0.312
0.340
0.394
11
0.0270
0.187
0.193
0.215
3
0.0115
0.375
0.406
0.460
11
0.0270
0.250
0.256
0.278
3
0.0115
0.437
0.470
0.524
11
0.0270
0.312
0.320
0.342
3
0.0115
0.500
0.535
0.589
11
0.0270
0.375
0.382
0.404
3
0.0115
0.562
0.600
0.654
11
0.0270
0.125
0.135
0.160
4
0.0125
0.625
0.665
0.719
11
0.0270
0.187
0.197
0.222
4
0.0125
0.187
0.212
0.269
12
0.0285
0.250
0.260
0.285
4
0.0125
0.250
0.279
0.336
12
0.0285
0.312
0.322
0.347
4
0.0125
0.312
0.342
0.399
12
0.0285
0.375
0.385
0.410
4
0.0125
0.375
0.408
0.465
12
0.0285
0.125
0.135
0.164
5
0.0145
0.437
0.472
0.529
12
0.0285
0.187
0.198
0.227
5
0.0145
0.500
0.537
0.594
12
0.0285
0.250
0.261
0.290
5
0.0145
0.562
0.602
0.659
12
0.0285
0.312
0.324
0.353
5
0.0145
0.625
0.667
0.724
12
0.0285
0.375
0.389
0.418
5
0.0145
0.187
0.217
0.278
13
0.0305
0.125
0.135
0.165
6
0.0150
0.250
0.282
0.343
13
0.0305
0.187
0.198
0.228
6
0.0150
0.312
0.346
0.407
13
0.0305
0.250
0.262
0.292
6
0.0150
0.375
0.411
0.472
13
0.0305
0.312
0.325
0.355
6
0.0150
0.437
0.475
0.536
13
0.0305
0.375
0.390
0.420
6
0.0150
0.500
0.540
0.601
13
0.0305
0.125
0.137
0.172
7
0.0175
0.562
0.604
0.665
13
0.0305
0.187
0.201
0.236
7
0.0175
0.625
0.670
0.731
13
0.0305
0.250
0.266
0.301
7
0.0175
0.250
0.284
0.348
14
0.0320
0.312
0.330
0.365
7
0.0175
0.312
0.348
0.412
14
0.0320
0.375
0.395
0.430
7
0.0175
0.375
0.414
0.478
14
0.0320
0.125
0.138
0.176
8
0.0190
0.437
0.478
0.542
14
0.0320
0.187
0.202
0.240
8
0.0190
0.500
0.545
0.609
14
0.0320
0.250
0.266
0.304
8
0.0190
0.562
0.609
0.673
14
0.0320
0.312
0.330
0.368
8
0.0190
0.625
0.677
0.741
14
0.0320
0.375
0.396
0.434
8
0.0190
0.250
0.284
0.354
15
0.0350
0.125
0.145
0.189
9
0.0220
0.312
0.350
0.420
15
0.0350
0.187
0.209
0.253
9
0.0220
0.375
0.417
0.487
15
0.0350
0.250
0.271
0.315
9
0.0220
0.437
0.480
0.550
15
0.0350
0.312
t\ *\r* t*
0.335
f\ A f\f\
0.379
9
0.0220
0.500
0.547
0.617
f\ ^ r\ +
15
0.0350
Table 15-3.— Data for Winding Piano Wire Tension Springs— Continued
Diam.
of
Man-
drel,
Inches
Inside
Diam.
of
Spring,
Inches
Outside
Diam.
of
Spring,
Inches
Num-
ber of
Piano
Wire
Diam.
of Piano
Wire,
Inches
Diam.
of
Man-
drel,
Inches
Inside
Diam.
of
Spring,
Inches
Outside
Diam.
of
Spring,
Inches
Num-
ber of
Piano
Wire
Diam.
of Piano
Wire,
Inches
0.250
0.290
0.362
16
0.0360
0.312
0.369
0.467
23
0.0490
0.312
0.355
0.427
16
0.0360
0.375
0.436
0.534
23
0.0490
0.375
0.420
0.492
16
0.0360
0.437
0.500
0.598
23
0.490
0.437
0.483
0.555
16
0.0360
0.500
0.565
0.663
23
0.0490
0.500
0.550
0.622
16
0.0360
0.562
0.628
0.726
23
0.0490
0.562
0.613
0.685
16
0.0360
0.625
0.700
0.798
23
0.0490
0.625
0.683
0.755
16
0.0360
0.312
0.371
0.477
24
0.0530
0.250
0.292
0.368
17
0.0380
0.375
0.438
0.544
24
0.0530
0.312
0.358
0.434
17
0.0380
0.437
0.504
0.610
24
0.0530
0.375
0.423
0.499
17
0.0380
0.500
0.568
0.674
24
0.0530
0.437
0.486
0.562
17
0.0380
0.562
0.630
0.736
24
0.0530
0.500
0.554
0.630
17
0.0380
0.625
0.702
0.808
24
0.0530
0.562
0.615
0.691
17
0.0380
0.312
0.374
0.486
25
0.0560
0.625
0.686
0.762
17
0.0380
0.375
0.441
0.553
25
0.0560
0.250
0.294
0.374
18
0.0400
0.437
0.508
0.620
25
0.0560
0.312
0.361
0.441
18
0.0400
0.500
0.571
0.683
25
0.0560
0.375
0.426
0.506
18
0.0400
0.562
0.634
0.746
25
0.0560
0.437
0.489
0.569
18
0.0400
0.625
0.706
0.818
25
0.0560
0.500
0.557
0.637
18
0.0400
0.312
0.375
0.495
26
0.0600
0.562
0.618
0.698
18
0.0400
0.375
0.442
0.562
26
0.0600
0.625
0.690
0.770
18
0.0400
0.437
0.511
0.631
26
0.0600
0.312
0.363
0.447
19
0.0420
0.500
0.573
0.693
26
0.0600
0.375
0.427
0.511
19
0.0420
0.562
0.635
0.755
26
0.0600
0.437
0.491
0.575
19
0.0420
0.625
0.710
0.830
26
0.0600
0.500
0.558
0.642
19
0.0420
0.375
0.445
0.573
27
0.0640
0.562
0.619
0.703
19
0.0420
0.437
0.513
0.641
27
0.0640
0.625
0.691
0.775
19
0.0420
0.500
0.575
0.703
27
0.0640
0.312
0.364
0.450
20
0.0430
0.562
0.637
0.765
27
0.0640
0.375
0.429
0.515
20
0.0430
0.625
0.713
0.841
27
0.0640
0.437
0.493
0.579
20
0.0430
0.375
0.446
0.583
28
0.0685
0.500
0.560
0.646
20
0.0430
0.437
0.514
0.651
28
0.0685
0.562
0.621
0.707
20
0.0430
0.500
0.575
0.712
28
0.0685
0.625
0.693
0.779
20
0.0430
0.562
0.638
0.775
28
0.0685
0.312
0.365
0.454
21
0.0445
0.625
0.714
0.851
28
0.0685
0.375
0.431
0.520
21
0.0445
0.375
0.448
0.591
29
0.0715
0.437
0.495
0.584
21
0.0445
0.437
0.516
0.659
29
0.0715
0.500
0.561
0.650
21
0.0445
0.500
0.577
0.720
29
0.0715
0.562
0.623
0.712
21
0.0445
0.562
0.640
0.783
29
0.0715
0.625
0.695
0.784
21
0.0445
0.625
0.714
0.857
29
0.0715
0.312
0.367
0.461
22
0.0470
0.375
0.451
0.603
30
0.0760
0.375
0.433
0.527
22
0.0470
0.437
0.518
0.670
30
0.0760
0.437
0.497
0.591
22
0.0470
0.500
0.580
0.732
30
0.0760
0.500
0.563
0.657
22
0.0470
0.562
0.643
0.795
30
0.0760
0.562
0.625
0.719
22
0.0470
0.625
0.717
0.869
30
0.0760
0.625
0.698
0.792
22
0.0470
0.375
0.455
0.617
31
0.0810
15-35
Table 15-3.— Data for Winding Piano Wire Tension Springs— Continued
Diam.
Inside
Outside
Num-
Diam.
Diam.
Inside
Outside
Num-
Diam.
of
Diam.
Diam.
ber of
of Piano
of
Diam.
Diam.
ber of
of Piano
Man-
of
of
Piano
Wire,
Man-
of
of
Piano
Wire,
drel,
Spring,
Spring,
Wire
Inches
drel,
Spring,
Spring,
Wire
Inches
Inches
Inches
Inches
Inches
Inches
Inches
0.437
0.522
0.684
31
0.081
0.375
0.480
0.682
34
0.101
0.500
0.585
0.747
31
0.081
0.437
0.550
0.752
34
0.101
0.562
0.647
0.809
31
0.081
0.500
0.610
0.812
34
0.101
0.625
0.722
0.884
31
0.081
0.562
0.673
0.875
34
0.101
0.375
0.461
0.633
32
0.086
0.625
0.750
0.952
34
0.101
0.437
0.527
0.699
32
0.086
0.375
0.490
0.708
35
0.109
0.500
0.590
0.762
32
0.086
0.437
0.560
0.778
35
0.109
0.562
0.651
0.823
32
0.086
0.500
0.622
0.840
35
0.109
0.625
0.727
0.899
32
0.086
0.562
0.686
0.904
35
0.109
0.375
0.467
0.649
33
0.091
0.625
0.765
0.983
35
0.109
0.437
0.533
0.715
33
0.091
0.375
0.500
0.736
36
0.118
0.500
0.595
0.777
33
0.091
0.437
0.572
0.808
36
0.118
0.562
0.657
0.839
33
0.091
0.500
0.637
0.873
36
0.118
0.625
0.733
0.915
33
0.091
0.562
0.702
0.938
36
0.118
QUALITY ASSURANCE
Quality assurance is an inspection of man-
ufactured parts to ensure that they meet blueprint
specifications. Quality assurance is also used
to lay out procedures in assembling and
disassembling different components. Quality
assurance should be used in all steps of
manufacturing, such as checking diameters and
lengths, and so on. Basic quality assurance
guidelines are usually set by type commanders
such as SERVLANT, SUBLANT, SERVPAC,
and SUBPAC. Until it is coordinated under one
system, you will have to follow local guidelines.
In most ships and at shore installations there are
also a calibration program where all measuring
instruments are periodically checked for accuracy
against standards. Usually, this program is
coordinated by the IM shop. Before using
measuring tools from the toolroom, you as the
machine operator, should check for a current
sticker affixed to the measuring device, and then
check the instrument against the standard usually
kept in the toolroom. In most cases, upon
completion of a manufactured part, the shop
quality assurance inspector will check the part
against the blueprint for accuracy and document
the results on a Quality Assurance Form. On this
form is recorded the name of the ship, the part
manufactured, the print number used, the serial
number and calibration date of the instrument
used to check the workpiece, the name of the
person who manufactured the part, and the
person who made the final quality assurance
inspection. To determine type commander quality
assurance guidelines, your shop leading petty
officer should be able to find up-to-date
information and have access to the appropriate
directives and documents.
CALIBRATION SERVICING
LABELS AND TAGS
Standards require a sticker or equivalent
certification, showing the date and place of
calibration, before they can be used to check
operating instruments. Instruments calibrated by
Mechanical Instrument Repair and Calibration
Shops (MIRCS) require labels and tags to indicate
the status of calibration or testing. In marking
labels and tags, MIRCS personnel should write
in the DATE and DUE columns the appropriate
month, day, and year, such as 8 Dec 1980. The
Metrology Engineering Center's 3-letter code
designation of the servicing MIRCS is written or
stamped on applicable labels and tags. The
various labels and tags for calibration standards
or test and measuring equipment within MIRCS
are shown in figure 15-35 and 15-36.
15-36
CALIBRATED
CALIBRATION
PROGRAM
DATE.
DUE .
(BLACK ON WHITE)
CALIBRATION
NOT REQUIRED
NOT USED FOR
QUANTITATIVE
_ MEASUREMENT
NAVY
CALIBRATION
PROGRAM
(ORANGE ON WHITE)
CALIBRATED
NAVY
CALIBRATION
PROGRAM
DATE
DUE
(RED ON WHITE)
NAVV
CALIBRATION
FROORAM
CALIBRATED
niir
(RED ON WHITE)
*»r,
CALIBRATED
CHIIMTtOtt
MOCftAM
(BLUE ON WHITE)
NAVY
CALIBRATION
PROGRAM
CALIBRATED
DUE
(BLACK ON WHITE)
CALIBRATION
VOID IF
SEAL BROKEN
(BLACK ON WHITE)
CALIBRATED
NAVY-y MULTIPLE INTERVAL
CALIBRATION PARTIAL
PROGRAM
COMPLETE
(BLACK ON WHITE)
CALIBRATION
PROGRAM
INACTIVE
CALIBRATE
BEFOREUIE
DATE.
(GREEN ON WHITE)
Figure 15-35.— Calibration labels.
O
SPECIAL
CALIBRATION
SERVICING ACTIVITY
MANUFACTURER
DATE
MODEL
SUBMITTING ACTIVITY
SERIAL
HAW
CAUMATKM
moo HAM
SPECIAL
CALIBRATION
USE REVERSE SIDE IF REQUIRED
NAVMAT FORM NO. 4355.22
o
REJECTED
SERVICING ACTIVITY
MANUFACTURER
DATE
MODEL
SUBMITTING ACTIVITY
SERIAL
USE REVERSE SIDE IF REQUIRED
SUGGESTED CORRECTIVE ACTION
REJECTEI
Keren ro
AT1ACHCO IAC
NAVY
CALIBRATION
PROGRAM
DATE.
USE REVERSE SIDE IF REQUIRED
NAVMAT FORM NO. 4355 23
(BLACK ON YELLOW ) ( BLACK ON RED)
Figure 15-36. — Labels and tags.
Calibrated
The CALIBRATED label is placed on each
standard or piece of test and measuring equipment
that has been checked against a standard of higher
accuracy. Each check is made using approved
Navy calibration procedures and checklists and
is adjusted to meet (1) a predetermined specifica-
tion or (2) a specified value of magnitude. When
an instrument is calibrated to meet a pre-
determined specification, only the knowledge that
the instrument is within this specification is
significant, and a black on white label is used.
When an instrument is calibrated to meet an
expressed value of magnitude and uncertainty, the
actual measured value and associated uncertainty
are reported, a red on white label is used, and a
Report of Calibration is provided with the
instrument.
Special Calibration
On occasion, specific user requirements do not
involve the full instrument capability. In such
instances a calibration is not performed over the
entire range of the instrument. Only the needed
quantities and ranges are calibrated. A SPECIAL
CALIBRATION label (black and yellow) is used
to draw attention to the special conditions under
which the instrument is calibrated. In addition to
the label, a special calibration tag is attached
to the instrument. This tag is filled in by the
servicing activity to adequately describe the
conditions which are to be observed in the use of
the instrument. The label and tag remain on the
instrument until the next calibration. The 3 -inch
by 2-inch special calibration label may be used
alone in lieu of the label and tag combination
when space is available on the instrument and
reasons for special calibration can be shown on
the label itself.
Calibration Not Required — Not Used
for Quantitative Measurement
Some instruments normally fall within the
category of equipment requiring calibration, but
15-38
are not used for quantitative measurements for
various reasons. With several like instruments, for
example, only one or two are calibrated and used
for quantitative measurements; the others are used
as indicators only. Also, some instruments do not
require calibration because they receive an
operational check each time they are used, or
malfunctions and loss of accuracy are readily
apparent during their normal use. A label (orange
on white), indicating that calibration is not
required because the instrument is not used for
quantitative measurements, is placed on the
instrument.
Calibrated-In-Place
The CALIBRATED-IN-PLACE label is used
by on-site calibration teams to identify items that
are calibrated in place and should not be for-
warded to the calibration laboratory. These labels
(blue on white) alert the ships' forces that the
items should not be off-loaded when ships come
into port.
Calibration Void If Seal Broken
This label (black on white) is used to prevent
tampering with certain adjustments which would
affect the calibration.
Rejected
If an instrument fails to meet the accept-
ance criteria during calibration and cannot
be adequately serviced, a REJECTED label
(black on red) is placed on the instrument
and all other servicing labels are removed.
In addition to the REJECTED label, a
REJECTED tag is placed on the instrument.
The tag is filled in by the servicing activity
giving the reason for rejection and other
information as required. The rejected label
and tag remain on the instrument until it
is repaired and reserviced. The instrument
is not to be used while it bears a rejected
label.
Inactive
The INACTIVE label is placed on an instru-
ment of the type which normally requires calibra-
tion and is found to have no foreseeable usage
requirements. The inactive label remains on the
instrument until it is reserviced. The instrument
is not to be used while it bears the inactive
label.
APPENDIX I
TABULAR INFORMATION OF BENEFIT TO
MACHINERY REPAIRMAN
Table AI-1.— Decimal Equivalents of Fractions (inch)
frac-
tions
#
64ths
&
32ds
&
leths
•#
Bths
#
4ths
decimal
equiv.
frac-
tions
#
64ths
#
32ds
&
leths
*
Bths
#
4ths
decimal
equiv.
'/64
1
0.015625
33/64 '
33
0515625
!/32
2
1
0.03125
17/32
34
17
053125
3/64
3
0.046875
35/64
35
0 546S75
V\6
4
2
1
0.0625
9/l«
36
18
9
05625
5/64
5
0.078125
37/64
37
0 578125
3/32
6
3
0.09375
%
38
19
0 59375
7/64
7
0.109375
39/64
39
0 609375
W
8
4
2
1
0.125
5/8
40
20
10
5
0625
9/6<
9
0.140625
41/64
41
0 640625
5/32
10
5
0.15625
%
42
21
065625
U/64
11
0.171875
^
43
0.671875
3/16
12
6
3
0.1875
%
44
22
11
0.6875
13/64
13
0.203125
45/64
45
0.703125
7/32
14
7
0.21875
23/32
46
23
0.71875
15/64
15
0.234375
47/64
47
0.734375
>/4
17/64
16
17
8
4
2
1
0.250
0.265625
3/4
49/64
48
49
24
12
6
3
0.750
0.765625
9/32
18
9
0.28125
25/32
50
25
0.78125
19/64
19
0.296875
M/64
51
0.796875
5/16
20
10
5
0.3125
13/16
52
26
13
0.8125
21/64
21
0.328125
53/64
53
0.828125
U/32
22
11
0.34375
%
54
27
0.84375
a/64
23
0.359375
55/64
55
0.859375
3/8
H/64'
24
25
12
6
3
0.375
0.390625
H
57/64
56
57
28
14
7
0.875
0.890625
13/32
26
13
0.40625
W/32
58
29
0.90625
27/64
27
0.421875
59/64
59
0.921875
7/16
28
14
7
0.4375
%
60
30
15
0.9375
»/64
29
0.453125
6l/64
61
0.953125
15/32
30
15
0.46875
31/32
62
31
0.96875
31/64
31
0.484375
63/64
63
0.984375
fc
32
16
8
4
2
0.500
1 inch
64
32
16
8
4
1.000
Table AI-2.— Decimal Equivalents of Millimeters
mm
inches
mm
inches
mm
inches
mm
inches
mm
inches
0.1
0.00394
3.5
0.13779
6.9
0.27165
10.3
0.40551
13.8
0.54330
0.2
0.00787
3.6
0.14173
7.0
0.27559
10.4
0.40944
13.9
0.54724
0.3
0.01181
3.7
0.14566
7.1
0.27952
10.5
0.41388
14.0
0.55111
0.4
0.01575
3.8
0.14960
7,2
0.28346
10.6
0.41732
14.1
0.55511
0.5
0.01968
3.9
0.15354
7.3
0.28740
10.7
0.42125
14.2
0.55905
0.6
0.02362
4.0
0.15748
7.4
0.29133
10.8
0.42519
14.3
0.56299
0.7
0.02756
4.1
0.16141
7.5
0.29527
10.9
0.42913
14.4
0.56692
0.8
0.03149
4.2
0.16535
7.6
0.29921
11.0
0.43307
14:5
0.57086
0.9
0.03543
4.3
0.16929
7.7
0.30314
11.1
0.43700
14.6
0.57480
1.0
0.03937
4.4
0.17322
7.8
0.30708
11.2
0.44094
14.7
0.57873
1.1
0.04330
4.5
0.17716
7.9
0.31102
11.3
0.44488
14.8
0.58267
1.2
0.04724
4.6
0.18110
8.0
0.31496
11.4
0.44881
14.9
0.58661
1.3
0.05118
4.7
0.18503
8.1
0.31889
11.5
0.45275
15.0
0.59055
1.4
0.05512
4.8
0.18897
8.2
0.32283
11.6
0.45669
15.5
0.61023
1.5
0.05905
4.9
0.19291
8.3
0.32677
11.7
0.46062
16.0
0.62992
1.6
0.06299
5.0
0.19685
8.4
0.33070
11.8
0.46456
16.5
0.64960
1.7
0.06692
5.1
0.20078
8.5
0.33464
11.9
0.46850
17.0
0.66929
1.8
0.07086
5.2
0.20472
8.6
0.33858
12.0
0.47244
17.5
0.68897
1.9
0.07480
5.3
0.20866
8.7
0.34251
12.1
0.47637
18.0
0.70866
2.0
0.07874
5.4
0.21259
8.8
0.34645
12.2
0.48031
18.5
0.72834
2.1
0.08267
5.5
0.21653
8.9
0.35039
12.3
0.48425
19.0
0.74803
2.2
0.08661
5.6
0.22047
9.0
0.35433
12.4
0.48818
19.5
0.76771
2.3
0.09055
5.7
0.22440
9.1
0.35826
12.5
0.49212
20.0
0.78740
2.4
0.09448
5.8
0.22834
9.2
0.36220
12.6
0.49606
20.5
0.80708
2.5
0.09842
5.9
0.23228
9.3
0.36614
12.7
0.49999
21.0
0.82677
2.6
0.10236
6.0
0.23622
9.4
0.37007
12.8
0.50393
21.5
0.84645
2.7
0.10629
6.1'
0.24015
9.5
0.37401
12.9
0.50787
22.0
0.86614
2.8
0.11023
6.2
0.24409
9.6
0.37795
13.0
0.51181
22.5
0.88582
2.9
0.11417
6.3
0.24803
9.7
0.38188
13.1
0.51574
23.0
0.90551
3.0
0.11811
6.4
0.25196
9.8
0.38582
13.2
0.51968
23.5
0.92519
3.1
0.12204
6.5
0.25590
9.9
0.38976
13.3
0.52362
24.0
0.94488
3.2
0.12598
6.6
0.25984
10.0
0.39370
13.4
0.52755
24.5
0.96456
13.5
0.53149
25.0
0.98425
3.3
0.12992
6.7
0.26377
10.1
0.39763
13.6
0.53543
25.5
1.00393
3.4
0.13385
6.8
0.26771
10.2
0.40157
13.7
0.53936
26.0
1.02362
Table AI-3.— Dividing a Circle into Parts
To find the length of the chord for dividing the circumference of a circle into a required
number of equal parts, multiply the factor in the table by the diameter.
no. of
spaces
chord
length
no. of
spaces
chord
length
no. of
spaces
chord
length
3
0.866
21
0.149
39
0.0805
4
0.7071
22
0.1423
40
0.0785
5
0.5878
23
0.1362
41
0.0765
6
0.5
24
0.1305
42
0.0747
7
0.4339
25
0.1253
43
0.073
8
0.3827
26
0.1205
44
0.0713
9
0.342
27
0.1161
45
0.0698
10
0.309
28
0.112
46
0.0682
11
0.2818
29
0.1081
47
0.0668
12
0.2584
30
0.1045
48
0.0654
13
0.2393
31
0.1012
49
0.0641
14
0.2224
32
0.098
50
0.0628
15
0.2079
33
0.0951
51
0.0616
16
0.1951
34
0.0932
52
0.0604
17
0.1837
35
0.0896
53
0.0592
18
0.1736
36
0.0872
54
0.0581
19
0.1645
37
0.0848
55
0.0571
20
0.1564
38
0.0826
AI-3
Table AI-4.— Formulas for Dimension, Area, and Volume
\_y
W • WIDTH
X • 1.1547 W
Y« 1.4142 W
Z- I.0824W
BASE
HYP '/BASE * ALT1
BASE '^HYP2- ALT'
ALT « ^HYP* - BASE*
ALT
BASE
DIA • BASE t ALT - HYP
ALT '
BASE
COT A t COT 8
ALT
BASE
COT A - COT B
» . INCLUDED A P ' PLUG SIZE
X • 5 x SIN INC 4 Y • X -H 5 •» •
BASE
RAO
BASE
COT$ +COT|
PERIMETER: BASE: :ALT:R
BASE X ALT
R ' PERIMETER
ALT
1
Z CSC -4* +
X • Y - 2
Table AI-4.— Formulas for Dimension, Area, and Volume— Continued
TRIANGLE
TRAPEZOID
I 1
CIRCLE
AREA--J- (A + B)H
AREA' 3. 1416 M
FILLET
SEGMENT
RECTANGOLA'R PRISM
A»R* -•
1416 R.»
TRIANGULAR PYRAMID
VOLUME
AREA OF BASE X H
2H
FRUSTUM OF PYRAMID
VOLUME'
H(A+B+VABT
D»2R
VOLUME
CYLINDER
n
D*2R
CONE
FRUSTUM OF CONE
D*2R
VOLUME' 3. MI6 Rf XH
VOLUME'
3.1416 R»XH
VOL'0.26I8H(DI+-0I4DB)
AI-5
Table AI-5.— Formulas for Circles
Circumference of a circle
Diameter of a circle
Side of a square inscribed in a given circle
Side of a square with area of a given circle
Diameter of a circle with area of a given square
Diameter of a circle circumscribing a given square
Area of a circle
Area of the surface of a sphere or globe
Diameter multiplied by 3.1416
Diameter divided by 0.3183
Circumference multiplied by 0.3183
Circumference divided by 3.1416
Diameter multiplied by 0.7071
Circumference multiplied by 0.2251
Circumference divided by 4.4428
Diameter multiplied by 0.8862
Diameter divided by 1.1284
Circumference multiplied by 0.2821
Circumference divided by 3.545
Side multiplied by 1.128
Side multiplied by 1.4142
The square of the diameter multiplied by 0.7854
The square of the radius multiplied by 3.1416
The square of the diameter multiplied by 3.1416
Table AI-6.— Number, Letter and Fractional Identification of Drill Sizes (Letter drills are larger than number drills; they
begin where number drills end.)
no.&
letter
drills
frac-
tional
drills
dec-
imal
equiv.
r-
no.&
etter
drills
_
frac-
tional
drills
dec- 1
imal 1
equiv. 1
r
no.&
etter
drills
— r
frac-
tional
drills
dec- 11 no.&
imal letter 1
equiv. || drills
frac-
tional
drills
dec-
imal
equiv.
80
.0135
42
.0935
!%4
.2031
J%2
.4062
79
.0145
%2
.0937
6
. . .
.2040
Z
. . .
.4130
Mi 4
.0156
41
.0960
5
. . .
.2055
2%4
.4219
78
f \) t
.0160
40
* . *
.0980
4
. . .
.2090
T/1G
.4375
77
.0180
39
.0995
3
. . .
.2130 1|
2%4
.4531
76
.0200
38
.1015
7/32
.2187 1|
15/32
.4687
75
.0210
37
.1040
2
. . .
.2210
.4844
74
.0225
36
. . .
.1065
1
.2280 1|
%
.5000
73
.0240
%4
.1094
A
.234U ||
33/
'H.'M
72
71
70
.0250
.0260
.0280
35
34
33
.1100
.1110 1
.1130
B
C
A) 4
.2344
.2380
.2420
17/32
3%4
.(JXclU
.5312
.5469
SfiOer
69
.0292
32
.1160
D
. . .
.2460
716
.OQ^iO
68
.0310
31
.1200
E
y4
.2500
3%4
.5781
Voo
.0312
J/8
.1250
F
.2570
19/32
.5937
67
732
.0320
30
.
.1285
G
• . •
.2610
3%4
.6094
66
.0330
1 29
.1360
17/C4
.2656
%
.6250
65
.0350
28
.1405
H
.2660
4 17
.6406
64
.0360
%4
.1406
I
.2720
21/32
.6562
63
.0370
27
...
.1440
J
• ...
.2770
4%4
.6719
62
.0380
26
.1470
•rr
.2810
I U Ti
.6875
61
.0390
25
.1495
%2
.2812
457
7031
60
59
.0400
.0410
24
23
.1520
.1540
M
.2900
.2950
704
28/32
47/.
• 1 \J\JJL
.7187
.7344
58
.0420
5/32
.1562
1%4
.2969
704
.7500
57
.0430
22
...
.1570
N
...
.3020
56
.0465
21
:..
.1590
%6
.3125 I
*%4
.7656
%4
.0469
20
.1610
O
. • .
.3160
25/32
.7812
55
/l> Tl
.0520
19
.1660!
P
• » •
.3230
5V04
.7969
54
.0550
18
.1695
21/04
.3281 1
18/16
.8125
53
.0595
.1719
Q
. . .
.3320
8%4
.8281
Me
.0625
17
..°4
.1720
R
.33901
27/32
.8437
52
.0635
16
.1770
!%2
.3437
.8594
51
.0670
15
.1800
S
...
.3480
?/r
.8750
50
49
48
47
5/04
.0700
.0730
.0760
.0781
.07S5
14
"
Vie
.1820
.1850
.1875
.1890
.1910
T
U
V
2%4
.3580
.3594
.3680
.3750
.3770
57/G4
2%2
15/16
.8906
.9062
.9219
.9375
t\t*f\ +
46
.0810
10
.1935
W
. . .
.3860
6^4
.9531
f\r\f\*t
45
.0820
9
.1960
25/64
.3906!
8%2
.9687
44
.0860
8
.1990
X
.3970
8%4
.9844
43
.0890
1 7
.2010
Y
1 • • •
.4040
1
1.0000
Table AI-7.— Units of Weight, Volume, and Temperature
AVOIRDUPOIS WEIGHT
16 drams or 437.5 grains = 1 ounce
16 ounces or 7,000 grains = 1 pound
2,000 pounds = 1 net or short ton
2,240 pounds = 1 gross or long ton
2,204.6 pounds = 1 metric ton
BOARD MEASURE
One board foot measure is a piece of wood 12
inches square by 1 inch thick, or 144 cubic inches.
A piece of wood 2 by 4, 12 feet long contains 8 feet
board measure.
DRY MEASURE
2 pints = 1 quart
8 quarts = 1 peck
4 pecks = 1 bushel
1 standard U.S. bushel = 1.2445 cubic feet
1 British imperial bushel = 1.2837 cubic feet
LIQUID MEASURE
4 gills = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon
1 U.S. gallon = 231 cubic inches
1 British imperial gallon = 1.2 U.S. gallons
7.48 U.S. gallons = 1 cubic foot
LONG MEASURE
12 inches = 1 foot
3 feet = 1 yard
1,760 yards = 1 mile
5,280 feet = 1 mile
16.5 feet =1 rod
PAPER MEASURE
24 sheets = 1 quire
20 quires = 1 ream
2 reams =1 bundle
5 bundles = 1 bale
SHIPPING MEASURE
1 U.S. shipping ton = 40 cubic feet
1 U.S. shipping ton = 32.143 U.S. bushels
1 U.S. shipping ton = 31.16 imperial bushels
1 British shipping ton = 42 cubic feet
1 British shipping ton = 33.75 U.S. bushels
1 British shipping ton = 32.718 imperial bushels
SQUARE MEASURE
144 square inches = 1 square foot
9 square feet = 1 square yard
30.25 square yards = 1 square rod
160 square rods = 1 acre
640 acres = 1 square mile
TEMPERATURE
Freezing, Fahrenheit scale = 32 degrees
Freezing, celcius scale = 0 degrees
Boiling, Fahrenheit scale = 212 degrees
Boiling, celcius scale = 100 degrees
If any degree on the celcius scale, either
above or below zero, be multiplied by 1.8, the result
will, in either case, be the number of degrees above
or below 32 degrees Fahrenheit.
TROY WEIGHT
24 grains = 1 pennyweight
20 pennyweights = 1 ounce
12 ounces = 1 pound
WEIGHT OF WATER
1 cubic centimeter = 1 gram or 0.035 ounce
1 cubic inch = 0.5787 ounce
1 cubic foot = 62.48 pounds
1 U.S. gallon = 8.355 pounds
1 British imperial gallon = 10 pounds
32 cubic feet = 1 net ton (2,000 pounds)
35.84 cubic feet = 1 long ton (2,240 pounds)
1 net ton =,240 U.S. gallons
1 long ton = 268 U.S. gallons
ENGLISH-METRIC EQUIVALENTS
1 inch = 2.54 centimeters
1 centimeter = 0.3937 inch
1 meter = 39.37 inches
1 kilometer = 0.62 mile
1 quart = 0.946 (iter
1 U.S. gallon = 3.785 liters
1 British gallon = 4.543 liters
1 liter = 1.06 quarts
1 pound = 0.454 kilogram
1 kilogram = 2.205 pounds
1 watt = 44.24 foot-pounds per minute
1 horsepower = 33,000 foot-pounds per minute
1 kilowatt = 1.34 horsepower
Table AI-8.— Screw Thread and Tap Drill Sizes (American National)
screw
size
threads
per inch
dimensions, inches
tap drill
75%
full thread
body
drill
decimal
equiv.
NC
coarse
thread
NF
fine
thread
major
diameter
pitch
diameter
single
depth of
thread
minor
diameter
tap
drill
decimal
equiv.
0
80
0.060
0.0519
0.00812
0.0438
3/64
0.0469
52
0.0635
1
64
0.073
0.0629
0.01015
0.0527
53
0.0595
47
00785
1
72
0.073
0.0640
0.00902
0.0550
53
0.0595
47
W«U ( Qtf
0.0785
2
56
0.086
0.0744
0.01160
0.0628
50
0.0700
42
0.0935
2
64
0.086
0.0759
0.01015
0.0657
50
0.0700
42
0.0935
3
48
0.099
0.0855
0.01353
0.0719
47
0.0785
37
0.1040
3
56
0.099
0.0874
0.01160
0.0758
45
0.0820
37
0.1040
4
40
0.112
0.0958
0.01624
0.0795
43
0.0890
31
0.1200
4
48
0.112
0.0985
0.01353
0.0849
42
0.0935
31
0.1200
5
40
0.125
0.1088
0.01624
0.0925
38
0.1015
29
0.1360
5
44
0.125
0.1102
0.01476
0.0955
37
0.1040
29
0.1360
6
32
0.138
0.1177
0.02030
0.0974
36
0.1065
.27
0.1440
6
40
0.138
0.1218
0.01624
0.1055
33
0.1130
27
0.1440
8
32
0.164
0.1437
0.02030
0.1234
29
0.1360
18
0.1695
8
36
0.164
0.1460
0.01804
0.1279
29
0.1360
18
0.1695
10
24
0.190
0.1629
0.02706
0.1359
25
0.1495
9
0.1960
10
32
0.190
0.1697
0.02030
0.1494
21
0.1590
9
0.1960
12
24
0.216
0.1889
0.02706
0.1619
16
0.1770
2
0.2210
12
28
0.216
0.1928
0.02320
0.1696
14
0.1820
2
0.2210
i/4
20
0.2500
0.2175
0.03248
0.1850
7
0.2010
'/4
28
0.2500
0.2268
0.02320
0.2036
3
0.2130
5/16
18
0.3125
0.2764
0.03608
0.2403
F
0.2570
5/16
24
0.3125
0.2854
0.02706
0.2584
1
0.2720
%
16
0.3750
0.3344
0.04059
0.2938
5/16
0.3125
3/8
24
0.3750
0.3479
0.02706
0.3209
Q
0.3320
7/16
14
0.4375
0.3911
0.04639
0.3447
U
0.3680
7/16
20
0.4375
0.4050
0.03248
0.3725
25/64
0.3906
'/2
13
0.5000
0.4500
0.04996
0.4001
27/64
0.4219
!/2
20
0.5000
0.4675
0.03248
0.4350
%
0.4531
9/l6
12
0.5625
0.5084
0.05413
0.4542
31/64
0.4844
9/16
18
0.5625
0.5264
0.03608
0.4903
"764
0.5156
5/8
11
0.6250
0.5660
0.05905
0.5069
%
0.5313
5/8
18
0.6250
0.5889
0.03608
0.5528
37/64
0.5781
3/4
10
0.7500
0.6850
0.06495
0.6201
%
0.6562
3/4
16
0.7500
0.7094
0.04059
0.6688
ll/16
0.6875
ft
9
0.8750
0.8028
0.07217
0.7307
49/64
0.7656
%
14
0.8750
0.8286
0.04639
' 0.7822
13/16
0.8125
1
8
.0000
0.9188
0.08119
0.8376
y»
0.8750
1
14
.0000
0.9536
0.04639
0.9072
15/16
0.9375
1'/8
7
.1250
1.0322
0.09279
0.9394
63/64
0.9844
11/8
12
.1250
1.0709
0.05413
1.0167
13/64
1.0469
1'/4
7
.2500
1.1572
0.09279
1.0644
17/64
1.1094
1!/4
12
.2500
1.1959
0.05413
1.1417
1H44
1.1719
13/8
6
.3750
1.2667
0.10825
.1585
T/32
1.2188
13/8
12
.3750
1.3209
0.05413
.2667
1%
1.2969
tfc
6
.5000
1.3917
0.10825
.2835
IHfc
1.3438
1!/2
12
1.5000
1.4459
0.05413
.3917
1"/64
1.4219
13/4
5
1.7500
1.6201
0.12990
.4902
19/16
1.5625
2
4'/2
2.0000
1.8557
0.14434
1.7113
1%
1.7813
AI-9
Table AI-9.— Full Thread Produced in Tapped Holes (Percentage)
top
tap
drill
decimal
tap drill
usual
hole size
thread
percentage
tap
tap drill
decimal
tap drill
usual
hole size
thread
percentage
0-80
56
0.0465
0.0480
74
36
0.1065
0.1088
55
3/4
0.0469
0.0484
71
6-32 37
0.1040
0.1063
78
1-64
54
0.0550
0.0565
81
36
0.1065
0.1091
71
53
0.0595
0.0610
59
7/64
0.1094
0.1120
64
35
0.1100
0.1126
63
1-72
53
0.0595
0.0610
67
34
0.1110
0.1136
60
Me
0.0625
0.0640
50
33
0.1130
0.1156
55
2-50
51
0.0670
0.0687
74
6-40 34
0.1110
0.1136
75
50
0.0700
0.0717
62
33
0.1130
0.1156
69
49
0.0730
0.0747
49
32
0.1160
0.1186
60
2-64
50
0.0700
0.0717
70
8-32 29
0.1360
0.1389
62
49
0.0730
0.0747
56
28
0.1405
0.1434
51
3-48
48
0.0760
0.0779
78
8-36 29
0.1360
0.1389
70
%4
0.0781
0.0800
70
28
0.1405
0.1434
57
47
0.0785
0.0804
69
9/64
0.1406
0.1435
57
46
0.0810
0.0829
60
45
0.0820
0.0839
56
10-24 27
0.1440
0.1472
79
26
0.1470
0.1502
74
3-56
46
0.0810
0.0829
69
25
0.1495
0.1527
69
45
0.0820
0.0839
65
24
0.1520
0.1552
64
44
0.0860
0.0879
48
23
0.1540
0.1572
61
5/32
0.1563
0.1595
56
4-40
44
0.0860
0.0880
74
22
0.1570
0.1602
55
43
0.0890
0.0910
65
42
0.0935
0.0955
51
10-32 5/32
0.1563
0.1595
75
3/32
0.0938
0.0958.
50
22
0.1570
0.1602
73
21
0.1590
0.1622
68
4-48
42
0.0935
0.0955
61
20
0.1610
0.1642
64
3/32
0.0938
0.0958
60
19
0.1660
0.1692
51
41
0.0960
0.0980
52
12-24 ii/64
0.1719
0.1754
75
5-40
40
0.0980
0.1003
76
17
0.1730
0.1765
73
39
0.0995
0.1018
71
16
0.1770
0.1805
66
38
0.1015
0.1038
65
15
0.1800
0.1835
60
37
0.1040
0.1063
58
14
0.1820
0.1855
56
5-44
38
0.1015
0.1038
72
12-28 16
0.1770
0.1805
77
37
0.1040
0.1063
63
15
0.1800
0.1835
70
Table AI-9.— Full Thread Produced in Tapped Holes (Percentage)— Continued
tap
tap
drill
decimal
tap drill
usual
hole size
thread
percentage
tap
tap
drill
decimal
tap drill
usual
hole size
thread
percentage
12-28
14
0.1820
0.1855
66
/2-13
27/64
0.4219
0.4266
73
13
0.1850
0.1885
59
7/16
0.4375
0.4422
58
3/16
0.1875
0.1910
54
/2-20
29/64
0.4531
0.4578
65
W-20
9
0.1960
0.1998
77
8
0.1990
0.2028
73
9/i6-12
%
0.4688
0.4736
82
7
0.2010
0.2048
70
31/64
0.4844
0.4892
68
13/64
0.2031
0.2069
66
6
0.2040
0.2078
65
9/l6-18
'/2
0.5000
0.5048
80
5
0.2055
0.2093
63
33/64
0.5156
0.5204
58
4
0.2090
0.2128
57
5/8-11
17/32
0.5313
0.5362
75
M-28
3
0.2130
0.2168
72
35/64
0.5469
0.5518
62
7/32
0.2188
0.2226
59
2
0.2210
0.2248
55
5/8-18
9/16
0.5625
0.5674
80
37/64
0.5781
0.5831
58
Vie-IB
F
0.2570
0.2608
72
G
0.2610
0.2651
66
3/4'10
41/64
0.6406
0.6456
80
17/64
0.2656
0.2697
59
21/32
0.6563
0.6613
68
H
0.2660
0.2701
59
3/4-16
U/16
0.6875
0.6925
71
5/i6-24
H
0.2660
0.2701
78
1
0.2720
0.2761
67
7/8-9
<9/64
0.7656
0.7708
72
J
0.2770
0.2811
58
25/32
0.7812
0.7864
61
3/8-18
5/16
0.3125
0.3169
72
7/8-14
51/64
0.7969
0.8021
79
0
0.3160
0.3204
68
13/16
0.8125
0.8177
62
p
0.3230
0.3274
59
1-8
55/64
0.8594
0.8653
83
3/s-24
21/64
0.3281
0.3325
79
7/8
0.8750
0.8809
73
Q
0.3320
0.3364
71
57/64
0.8906
0.8965
64
R
0.3390
0.3434
58
%
0.9063
0.9122
54
7/ie-14
T
0.3580
0.3626
81
1-12
29/32
0.9063
0.9123
81
23/64
0.3594
0.3640
79
59/64
0.9219
0.9279
67
u
0.3680
0.3726
70
15/16
0.9375
0.9435
52
3/8
0.3750
0.3796
62
V
0.3770
0.3816
60
1-14
59/64
0.9219
0.9279
78
15/16
0.9375
0.9435
61
7/ie-20
w
0.3860
0.3906
72
25/64
0.3906
0.3952
65
X
0.3970
0.4016
55
Table AI-10.— American National Pipe Thread
. — L» —^ Length of
&^s \"XXXN^;s
^-- effect
ive thread
A - Pitch diameter of thread atend of pipe VN\^ IJ^
B = Pitch diameter of thread atgouging notch Engagement ^jSvv^
V~
Ineffective thread
D= Outside diameter of pipe f <222z2&
xvffiffilfc
U'MnrmnliifinnnmnAntlwhfinflhntitfnftn A
D Taoer 3/4 in. o*r fo
• nurfnu i irnyuijvniwii ujr nunu i/aiwccn **
/
on diameter
external and internal tnreoo 1 ^//AJAF/AJ
%%'%%&{
Tap Drills for
Pitch Diameter
length
Pipe
Depth
Pipe Threadi
Threadi
O.D.
of
Minor
She
P*r
D
Thread
Ota meter
Site
Inchet
Inch
A
B
LJ
Ll
Inctofl
Inches
Small End
DrW
Inchei
IfKhei
' Indict
hchei
of Pipe
i/fc
27
.36351
.37476
.2639
.180
.405
.02963
.3339
R
14
18
.47739
.48989
.4018
.200
.540
.04444
.4329
>/*
%
18
.61201
.62701
.4078
.240
.675
.04444
.5676
>%4
'/i
14
75843
.77843
.5337
.320
.840
.05714
.7013
'ft
%
14
.96768
.98887
.5457
.339
1.050
.05714
.9105
*%4
1
11V4
1.21363
1.23863
.6828
.400
1.315
.06957
1.1441
Ife
114
1114
1.55713
1.58338
.7068
.420
1.660
.06957
1.4876
1 '/I
114
11 '/i
1.79609
1.82234
.7235
.420
1.900
.06957
1.7265
14%4
2
1114
2.26902
2.29627
.7565
.436
2.375
.06957
2.1995
2&
2V4
8
2.71953
2.76216
1.1375
.682
2.875
.10000
2.6195
2%
3
8
3.34062
3.38850
1.2000
.766
3.500
.10000
3.2406
3V4
3!6
8
3.83750
3.88881
1.2500
.821
4.000
.10000
3.7375
3%
4
8
4.33438
4.38712
1.3000
.844
4.500
.10000
4.2344
4%
Table AMI.— 3-Wire Method— American National Std.
M = D — (1.5156 X P) + (3 X W)
,-«
-,
86603
| ,
* \
PD — M + .ooog.j ^ ^ ^
No. of thds.
m
per inch
M, — M,
To Chcclc Ancle
^s
W, — W,
— (?•-• — ^-
p ^i^==-
J7 ,w
M = Measurement over beat size wire.
d£=S£
VPD
-i ^
Mi = Measurement over maximum size wire
M, = Measurement over minimum size wire
D = Outside Diameter of Thread.
P.D. = Pitch Diameter.
W = Diameter Best size wire.
0.57735
X pitch
Wt = Diameter maximum size wire.
0.90
X pitch.
Wi = Diameter minimum size wire.
0.56
X pitch
No. Thds. Pitch Best Wire Size
per inch Thds. per inch .57736 x Pitch
Maximum
Wire Size
Minimum
Wire Size
4 .250000 .144337
.226000
.140000
4V4 .222222 .128300
.200000
.124444
5 .200000 .115470
.180000
.112000
5V4 .181818 .104969
.163636
.101818
6 .166666 .096224
.149999
.093333
7 .142857 .082478
.128571
.080000
7'/2 .133333 .076979
.120000
.074666
8 .125000 .072168
.112500
.070000
9 .111111 .064149
.100000
.062222
10 .100000 .057735
.090000
.050000
1 1 .090999 .052486
.081818
.050909
1 1 4 .086966 .050204
.078260
.048695
12 .083333 .048112
.075000
.046666
13 .076923 .044411
.069231
.043077
14 .071428 .041239
.064285
.040000
1 6 .062600 .036084
.056250
.035000
18 .065655 .032074
.050000
.031111
20 .050000 .028867
.045000
.028000
22 .045454 .026242
.040909
.025454
24 .041606 .024055
.037499
.023333
2G .038461 .022205
.034615
.021538
27 .037037 .021383
.033333
.022543
28 .035714 .020620
.032143
.020000
30 .o:t:(:i.'t:i .019244
.030000
.018666
32 .031250 .018042
.028125
.017500
36 .027777 .016037
.024999
.015555
40 .025000 .014433
.022500
.014000
44 .022727 .013121
.020454
.014727
48 .020833 .012027
.018750
.011666
50 .020000 .011547
.018000
.011200
56 .017857 .010309
.016071
.010000
Table AI-12. — Diagonals of Squares and Hexagons
E = 1.4142d
D-1.1547d
d
D
E
d
D
E
d
D
E
%
fe
0.28*6
0.3247
0.3608
0.3535
0.3977
0.4419
1>/4
1%2
15Ae
1.4434
1.4794
1.5155
1 .7677
1.8119
t.8561
2S4«
*%
2Vl6
2.6702
2.7424
2.8145
3.2703
3.3587
3.4471
H"
\*
0.3968
0.4329
0.4690
0.4861
0.5303
0.5745
1^2
1*%2
1,5516
1.5877
1.6238
1.9003
1.9445
1.9887
*%
29/16
2%
2.8867
2.9583
3.0311
3.5355
3.6239
3.7123
7/if
I?*
0.5051
0.5412
0.5773
0.61 87
0.6629
0.7071
17/16
1l%2
iv*
1.6598
1.6959
1.7320
2.0329
2.0771
2.1213
2'y16
«%
2'M.
3.1032
3.1754
3.2476
3.8007
3.8891
3.9794
17/»2
f/16
19/33
0.6133
0.6494
0.6855
0.7513
0.7955
0.8397
1l7/42
19/16
1J%J
1.7681
1 .8042
1.8403
2.1655
2.2097
2.2539
*%
2l5/!«
3.3197
3.3919
3.4641
4.065S
4.1542
4.2426
\,
"At
0.7216
0.7576
0.7937
0.8839
0.9281
0.9723
1%
12f/»2
1"/u
1.8764
1.9124
1.9485
2,2981
2.3423
2.3865
3Vie
3%
33/16
3.5362
3.6084
3.6806
4.3310
4.4194
4.5078
2%2
K
2%2
0.8298
0.8659
0.9020
1.0164
1.06O6
1.1048
123/3:
13/(
12S/37
1.9846
2.0207
2.0568
2.4306
2.4708
2.5190
3%
35/16
3%
3.7527
3.8249
3.8971
4.5962
4.6846
4.7729
13/16
2%2
7/8
0.9380
0.9741
1.0102
1.1490
1.1932
1.2374
1I3/1*
12%:
1%
2.0929
2.1289
2.1650
2.5632
2.6074
2.6516
3Vl6
3%
3Vi«
3.9692
4.041 4
4.1136
4.861 3
4.9497
5.0381
29/32
15/16
31/32
1.0463
1.0824
1.1184
1.2816
1.3258
1.3700
12%
1l5/i
13tt
2.2011
2.2372
2.2733
2.6958
2.7400
2.7842
3%
3»M»
33/4
4.1857
4.2579
4.3301
5.1265
5.2149
5.3033
1
1%2
1Vl6
1.1547
1.1907
1.2268
1.4142
1.4584
1.5026
2
«%2
2Vl6
2.3094
2.3453
2.3815
2.8284
2.8726
2.9168
3i3/i«
3%
3IS/16
4.4023
4.4744
4.5466
5.3917
5.4801
5.5684
13/32
1%
1%2
1 .2629
1.2990
1.335
1.546
1.591
1.635
2%2
2v£
25/32
2.4176
2.4537
2.489
2.961 0
3.0052
3.049
4
4V.
4'/4
4.6188
4.7631
4.907
5.6568
5.8336
6.0104
1V16
1%2
1.371
1.407
1.679
1.723
2Vl6
»'/4
2.5259
2.598
3.093
"3.182
4%
4%
5.051
5.196
6.1872
6.3639
Table AI-13.— Circles
Circumference of a circle - diameter X 3.1416
Diameter of a circle - circumference X .31831
Area of a circle - the square of the diameter X .7854
Surface of a ball (sphere) - the square of the
diameter X 3.1416
Side of a square inscribed in a circle - diameter X
.70711
Diameter of a circle to circumscribe a square - one
side X 1.4142
Cubic inches (volume) in a ball - cube of the
diameter X .5236
When doubled, the diameter of a pipe increases its
capacity four times
Radius of a circle X 6.283185 - circumference
Square of the circumference of a drcle X .07958 •
area
1/2 circumference of a circle X 1/2 its diameter -
area
Circumference of a circle X .159155 - radius
Square root of the area of a circle X .56419 - radius
Square root of the area of a circle X 1.12838 -
diameter
Table AI-14.— Keyway Dimensions
shaft
dia
square
keyways
Woodruff keyways*
/cey
thickness
cutter o*/a
s/ot depth
0.500
Vt X '/16
404
0.1250
0.500
0.1405
0.562
1 A v I/ c
/O ^> /lO
404
0.1250
0.500
0.1405
0.625
5/32 X 5/64
505
0.1562
0.625
0.1669
0.688
3/16 X 3/32
606
0.1875
0.750
0.2193
0.750
3/16 X 3/32
606
0.1875
0.750
0.2193
0.812
3/16 X 3/32
606
0.1875
0.750
0.2193
0.875
7/32 X 7/64
607
0.1875
0.875
0.2763
0.938
/4 X /8
807
0.2500
0.875
0.2500
1.000
IX ^ Lfi
808
0.2500
1.000
0.3130
1.125
5/16 X 5/32
1009
0.3125
1.125
0.3228
1.250
5/16 X 5/32
1010
0.3125
1.250
0.3858
1.375
3/8 X 3/16
1210
0.3750
1.250
0.3595
1.500
»/8 X 3/16
1212
0.3750
1.500
0.4535
1.625
3/8 X 3/16
1212
0.3750
1.500
0.4535
1.750
7/16 X 7/32
« . x-~—
- Cutter
1.875
'/2 X '/4
-f^T t -H(- .x^
2.000
J/2 X !4
(^ ^fry -iW^-^ ^^
2.250
5/8 X 5/16
~5~ ' \ v J
2.500
2.750
5/8 X 5/]6
3/4 X 3/8
\ ^^
Slot-depth
pN.,,' —
~ I/2W ^J U. w
3.000
3/4 X 3/g
^*S^*J 1 '
<> — x' j_j r
3.250
3/4 X 3/8
Key ^*JL.A
3.500
/ & ^s /1 6
w^^Tv
\J~JT v y
4.000
1 X !/2
T xq-/ ^-
"The depth of a Woodruff keyway is measured from the edge of the slot.
AI-14
£
1
a
9
a
5
1
•5
9
o
4)
<n
8 = ,-=; «-R!;S - = 5S5 SS = -S
r»cnco^r«— «nv>*rom
JS. Q)
.*: c
c
1
10 •— CM *v •— co«r>«— CM «» CM co 10 •— CM ^r •—
o*1?
c j:
O o
TJ
o
10
O<VOO«ICM '<rcM>vcMaa CM ao CM «o «O CM«a«r«vi«g
«VCOCM^- •«• ir> CM * .— CM "» * ^ m * co 10
^r oo co oo CM OCMOBOO
co »— CM ^ «-•«-• *m
TJ
£•
3 0»
c
locsincam o>«rcecoi» CM <o o •^ oo cM«ae^rr«
•vcMinco co^-^rcMio co »»•— ^ <Mtnco co
— 10 «o ~- 10 ao ~- **• tA <n
•-•v^-incM mco <K
C °
6.
0)
TJ
^ CM CMCMCMCM CMCMCMCMCM CM CM CM CM
8. o
: "o
X °
**? ^^ ^^5S^^ ^^^V, ^S. ^
XXXXX X XXX
5 c
o
o>
i»° trjio m ^- •» *r co CM CM •— •— inMrcocM
•» ro •— u> S •» «— S S
c:
'i
<x> m CM o cr> oo r-~ CD 10 -^r co CM »— ea <n «o to ur> co •—
.— CMCO-WT 10 •— CMCO •*• tn ~- T— IMCO^T CM
cnio^rcMcn f. 10 CM ea r~ 10
CO IO — CO »»• CM**1 »- CO
§ §
Q|
•0
$
CM •— — T to TCOCMCM"— m^cOCM»— lOCOr-^C1
•-CO CM1* ^^-CMCO^T*
If
C
1
f~-<0'»-»-cn r»-ioc«o»-en w'rcMooo to co .- r~ CM
co«» CMCO 10 — com CM** CMCO 10 •— «o ^r
•B)cocn<ro> in O in o in o
•»incN co «»in<M c*k*->
-
O»
TJ
4)
0.
v o
O
i. £
£ «>
O
W)
•«• on r~. u> -°r cMCMr—apio «o»— CMCMCH «o 10 CM CM •—
^-CMIOCMIO CM IO «— «* »— ^»- «~ •» »— CO CO CO
saaaa « = *« =
c
E
•-••— CMCMcoco^f ^r^«o>" »~ •" r-4 TM
Scoco-r-r «*
0 5
0
d»
4)
T>
0
«l
M
oo oo ••r CM «o •"r<v'^r«»c3 escst^r'W«» «eca'»-<rcM
<5trtu£tn7 ^••^cococo S«MCMCM»- •- —
"8SSS 3S««SS
tt) 0>
"° "01
"o o
C
E
--=as 5S"=s Rs*a» =a«5S
s-2«= Sa-=sa
ci»
0>
TJ
0*
0.
o
Q. £
«**» ***** *#*#* *****
***** ******
AM5
Table AI-16.— Tapers in Inches (Brown and Sharpe)
IT
ARBORS COLLETS
TAPER I V<4 P£« FOOT
taper
no.
taper
per
foot
plug
dia. at
small
end,
D
plug depth ( P)
keyway
from
end of
tpindle,
K
•hank
depth,
S
keyway
length,
L
keyway
width,
W
arbor
tongue
length,
T
arbor
tongue
dlo.,
d
arbor
tongue
thick-
nee •
t
>ongue
circle
radius,
C
tongue
radius,
a
limit for
tongue
to
project
through
test tool
eas
stand.
for
mill
mach.
misc.
1
0.50200
0.20000
%
%
13/!«
'/,
0.135
3/!6
0.170
H
Mi
0.030
0.003
2
0.50200
0.25000
IMl
1"/64
114
'/?
0.166
V,
0.220
Va
Mi
0.030
0.003
3
0.50200
0.31250
V/J
1'/4
2
1%
1%
1%
1»
21/.
23/,
H
H
K
0.197
0.197
0.197
s/l«
>/.«
Vl6
0.282
0.282
0.282
Ms
Mi
Vii
Mi
Mi
3/.«
0.040
6.040
0.040
0.003
0.003
0.003
4
0.50240
0.35000
1"/u
V/4
1%
1%
1%
2>/3?
%
"/,«
0.228
0.228
%
%
0.320
0.320
'/a
'/«
Mi
Mi
0.050
0.050
0.003
0.003
5
0.50160
0.45000
2'/«
m.
2
1%
1%
2'/,i
2Me
2'/it
2Vu
H
J/4
y<
0.260
0.260
0.260
H
H
H
0.420
0.420
0.420
Vi
'/«
'/4
Mi
Mi
Mi
0.060
0.060
0.060
0.003
0.003
0.003
6
0.50329
0.50000
2'/«
2%
2H
H
0.291
'/it
0.460
%
Mi
o.oro
0.005
7
0.50147
0.60000
2ft
3
2fc
2%
2%
2%
3'/J2
3'J/32
3"/37
1S/U
%
'Ms
0.322
0.322
0.322
%
%
%
0.5SO
0.560
0.560
M»
Mi
Mi
H
H
H
0.070
0.070
0.070
0.005
0.005
0.005
8
0.50100
0.75000
3Mi
3»/(4
4'/,
1
0.353
Vi
0.710
%
M
0.010
0.005
9
0.50085
0.90010
4'/4
4
3JI
4'/,
4H
4H
I'/l
1l/«
0.385
0.385
Vii
Vii
0.860
0.860
'/•
H
Mi
Mi
0.100
0.100
0.005
0.005
10
0.51612
1.04465
5
5»/n
6'/32
4%
5%
8Vii
5»/32
61J/3J
6%
1V.4
IVu
1S/1(
0.447
0.447
0.447
?1/3Z
%
*yfe
1.010
1.010
1.010
Mi
Mi
Mi
Mi
Mi
Mi
0.110
0.110
0.110
0.005
0.005
0.005
11
0.50100
1.24995
5%
6]/4
5%
6%
6%
7%
1M.
iy,s
0.447
0.447
?w?
?1/i?
1.210
1.210
'/!«
Mi
'/$
'/i
0.130
0.130
0.005
0.005
12
0.49973
1.50010
IV,
71/,
SK
6%
7%
m
0.510
«
1.480
14
H
0.150
0.005
13
0.50020
1.75005
1%
TMi
IMi
m
0.510
K
1.710
H
H
0.170
0.010
14
0.50000
2.00000
VA
8'/4
IJfc
Wa
1%
0.572
%
1.960
Mi
Vt
0.190
0.010
15
0.50000
2.25000
83/4
1%
¥Vn
1"/u
0.572
%
2.210
Mi
Yi
0.210
0.010
16
0.50000
2.50000
914
9
101/4
1H
0.635
%
2.450
H
1
0.230
0.010
17
0.50000
2.75000
9J/4
18
0.50000
3.00000
10'/«
AI-16
O
5
H
1
r-^
v
I
H
!i
1^1 S
csicsjf^!P» 5ptJ»P.&
1
e
& 0
•o
*» «* 1
o
M
I!"
«^s stis
w
S^ <5
»»g§ «H«s
—
c> o o a _*-cM*n
E
•5
»f c 0.
rMe>CM«a om«aca
un«0r>.r>. cxr«.»— jp
CM c» ir» i- a T — . I-.
eaooo ^.^.CMCM
a o
0 — rsi m *rmi*r-
* ••
6 '5
S(S
M -f
Table AI- 18.— Drill Sizes for Taper Pins
Small
Diameter
Length
Large
Diameter
Drill size should be approximately
0.005 smaller than small diameter
Tapers 1/4 In. per foot
Small diameter^ large diameter- length X 0.02083
NHM0ER 7/0 8/0 5/0 4/0 3/0 2/0 0 1 2 3 4 5 8 7 1 1 10 11
DIAMETER
AT LARttE
END 0.0825 0.071 0.014 0.101 0.125 0.141 0.158 0.172 0.193 0.21! 0.250 0.211 0.341 0.401 0.412 0.511 0.707 1.157
LENQTH
DIAMETER OF SMALL END OF PIN AND DRILL SIZE
LENQTH
1.0573 0.0721
54 50
1.9547 0.0702 0.01(2
55 51 45
0.0521 0.0878 0.0138 0.0988 0.1148 0.1308 0.1458 0.1816
58 52 48 41 34 30 V4< Vit
8.0415 0.0(50 0.0110 0.0180 0.1120 0.1210 0.1430 0.1510
51 52 to Vii to K to H
(.04(1 0.0(24 0.0714 0.0134 0.1014 0.1254 0.1404 0.1 j(4 0.1774 0.2034 0.2344
58 53 41 43 38 31 29 24 'to 1 1
0,0598 0.0751 0.0901 0.10(1 0.1228 0.1371 0.1531 0.1741 0.2001 0.2311
54 41 43 37 31 21 . 25 II 9 1
0.0572 0.0732 0.0112 0.1042 0.1202 0.1352 0.1512 0.1722 0.1912 0.2292 0.2(12 0.3202
54 50 44 31 32 30 28 11 10 2 GO
0.0158 0.1018 0.1171 0.1328 0.1411 0.1818 0.1158 0.2288 0.2858 0.3178
45 31 33 30 27 II 11 2 G Mi
1H
M
1M
IVi
0.0130 0.0990 0.1150 0.1300 0.1480 0.1870 0.1130 0.2240 0.2830 0.3UO 0.3130
48 41 33 Vt to 20 tf, M* F N W
0.0114 0.1124 0.1274 0.1434 0.1844 0.1104 0.2214 0.2804 0.3124 0.3104
'At to W -to 20 Mi 3 F N W
0.0131 0.1091 0.1241 0.1401 O.Htl 0.1171 0.2111 0.2571 0.3011 0.3771 0.4(01
43 38 31 28 '/it 14 3 K N U 'to
0.1045 0.1195 0.1355 0.1585 0.1125 0.2135 0.2525 0.3045' 0.3725 0.4555
31 32 30 24 11 4 0 'to « Mi
0.1111 0.1401 0.1888 0.1979 0.23(1 0.21(1 0.35(1" 0.4391 0.5310 0.8540
32
21
20
10 'to
«to
4to
0.1357 0.1117 0.1127 0.2317 0.2137 0.3517 0.4347 0.5331 1.I4K
30 '/fa Mi 1 J "/ii 'to 'to 4to
1H
1*
2 0.0993
41
0.1143
34
0.1303
0.1513
21
0.1773
'to
0.2203
'to
0.2473
C
0.2113
M
0.3173
'to
0.4503
Mi
0.5414
"At
2
0.1251
31
0.1481
27
0.1721
11
0.2031
1
0.2421
1
0.2141
L
0.3821
T
0.4451
Mi
0.5442
2V4
2K
Table AI-18.— Drill Sizes for Taper Pins— Continued
NUMBER 7/0 6/0 5/0 4/03/02/00 1 2 3 4 5 $ 7 1 9 10 tl
DIAMETER ~~~~~"
AT LARGE
END O.OS25 0.071 O.OJ4 0.109 0.12S 0.141 0.15S 0.172 0.193 0.219 0.250 0.219 0.341 0.409 0.492 0.591 0.707 9.157 X
LENGTH DIAMETER OF SMALL END OF PIN AND DRILL SIZE LENGTH
3 ................................................ 0.1305 0.1515 0.117$ 0.22*5 0.2795 0.34S5 0.4295 0.5295 9.9435 17975 3
30 24 14 2 1 R in, «H4 H »/fe
3U ............................................................ 0.1923 0.2213 0.2733 0.3413 0.4243 0.5233 0.9393 0.7923 3K
« '/a "A* 0 Z "At H M/fa
3tt ............................. ................................ 0.1771 0.2191 0.2911 0.3391 0.4191 0.5111 0.9331 9.79T1 3Vi
n/t4 J 6 Q "/it Vi K n/a
3K ........................................................................ 0.2629 0.3309 9.413S O.S129 9.9279 0.79U IK
_ F »/t4 "At M "yfe "A* _
4 ........................................................................ 9.2577 0.3257 9.4097 9.5077 9.9227 9.7797 4
W P Y H M/4* «M4
45* .............................................................................. 0.3205 0.4035 0.5025 9.9175 0.771J 4W
0 X »V4« »%4 »%4
4^ .............................................................................. 9.3153 9.3993 0.4973 9.9123 9.7993 4V4
Mi »/i4 »/44 »»/4» K
4K .................................................................................... 0.3931 9.4921 9.9971 9.7911 4W
_ W »A* 'Vb H _
5 .................................................................................... 0.3979 9.4999 9.9019 0.7559 5
H »%t »/4f M
5y4 .......................................................................................... 9.4917 0.5997 0.7507 5K
u/4i »/44 *'^
5Ji .......................................................................................... 0.47C5 0.5915 9.7455 SH
1V4» »A4 "^
SV, ......................................................................................... 0.4713 0.5993 9.7493 SK
_ M^4 »/t« 4T>44 _
9 .......................................................................................... 9.4990 0.591* 9.73SI 9
»/i4 Mi "/fa
6% ................................................................................................ 9.5759 9.7299 «H
9.5709 0.7249 SW
%• "/4»
9.5954 9.7194 9H
7 .............................................................................. 0.5992 9.7142 7
»A4 «%4
7y, ................................... 1.7999 7V4
««>44
VA .......... ... ............................................ 9.7834 m
Table AI-19.— Grinding of Twist Drills
Fig. 1-19-1 Fig.I-19-2
Fig.I-19-3 Fig.I-19-4
Fig.I-19-5 Fig.I-19-6
Fig. I -19 -7
Fig.I-19-9
(Do Not Dip High-Speed Drills In Water)
Drilling different grades of materials sometimes requires modification of
the commercial 118° drill point for maximum results. Hard materials require
a blunter point with the more acute angle for softer materials.
Fig. 1-19-1
and M9-2
Fig. M9-3
Fig. 1-19-4
Fig. M9-5
Fig. M9-6
Fig. M9-7
Fig. 1-19-8
Fig. 1-19-9
Fig. M9-10
ANGLE OF POINTS
Average Class of Work
Alloy Steels, Monel Metal,
Stainless Steel, Heat
Treated Steels, Drop
Forgings (Automobile
Connecting Rods) Brinell
Hardness No. 240
Soft and Medium Cast
Iron, Aluminum, Marble,
Slate, Plastics, Wood, Hard
Rubber, Bakelite, Fibre
Copper, Soft and Medium
Hard Brass
Magnesium Alloys
Wood, Rubber, Bakelite,
Fibre, Aluminum, Die
Castings, Plastics
Steel 7% to 13%
Manganese, Tough Alloy
Steels, Armor Plate and
hard materials
Brass, Soft Bronze
Crankshafts, Deep Holes in
Soft Steel, Hard Steel,
Cast Iron, Nickel and
Manganese Alloys
Thin Sheet Metal; Copper,
Fibre, Plastics, Wood
Point
Flg.I-19-10
118 included angle
12° to 15° Up clearance
125° included angle
10° 'to 12° lip clearance
90° to 130° included angle
12° lip clearance
Flat cutting Up for marble
100° to 118° included angle
12° to 15° lip clearance
60° to 118° included angle
15° lip clearance
Slightly flat face of cutting
lips reducing rake angle to
56
60 included angle
12° to 15° Up clearance
150 included angle
7° to 10° lip clearance
Slightly flat face of cutting
lips
118° included angle
12° to 15° lip clearance
Slightly flat face of cutting
lips
118° included angle
Chisel Point
9° Up clearance
-5° to +12° lip angles
For drills over 1/4"
diameter make angle of bit
point to suit work
Table AI-20.— Allowances for Fit
( Grinding Limits for Cylindrical Parts )
Diameter
(inches)
Limits
(inches)
Diameter
(inches)
Limits
(inches)
Running Fits — Ordinary Speed
Driving Fits — Ordinary
Up to 1/2
1/2 to 1
1 to 2
2 to 3-1/2
3-1/2 to 6
- 0.00025 to -0.00075
- 0.00075 to -0.0015
- 0.0015 to -0.0025
- 0.0025 to -0.0035
- 0.0035 to -0.005
Up to 1/2
1/2 to 1
1 to 2
2 to 3-1/2
3-l/2to 6
+ 0.00025 to + 0.0005
+ 0.001 to + 0.002
+ 0.002 to +0.003
+ 0.003 to + 0.004
+ 0.004 to +0.005
Running Pita — High-Speed, Heavy
Pressure and Rocker Shafts
Forced Fits
Up to 1/2
1/2 to 1
1 to 2
2 to 3-1/2
3-1/2 to 6
- 0.0005 to -0.001
- 0.001 to -0.002
- 0.002 to -0.003
- 0.003 to -0.0045
- 0.0045 to -0.0065
Up to 1/2
1/2 to 1
1 to 2
2 to 3-1/2
3-1/2 to 6
+ 0.00075 to + 0.0015
+ 0.0015 to + 0.0025
+ 0.0025 to + 0.004
+ 0.004 to + 0.006
+ 0.006 to + 0.009
Sliding Fits
Driving Fits — For such Pieces
as are Required to be
Readily Taken Apart
Up to 1/2
1/2 to 1
1 to 2
2 to 3-1/2
3-1/2 to 6
- 0.00025 to -0.0005
- 0.0005 to -0.001
- 0.001 to -0.002
- 0.002 to -0.0035
- 0.003 to -0.005
Up to 1/2
1/2 to 1
l-l/2to 2
2 to 3-1/2
3-1/2 to 6
+ 0 to + 0.00025
+ 0.00025 to + 0.0005
+ 0.0005 to + 0.00075
+ 0.00075 to + 0.001
+ 0.001 to + 0.0015
AI-21
I
H
MOIlVrtOVdO
Nouvnovuo
moMi 40
«M*ru 40 -ON
•MoitiAta
[ 40UMMOH
•s-
JIS
2K
rw
SR
SIS
•815
*
sts
•C1
NOuvnavMO
B1OWIO
XMNI
BMOttlMQ
JO UIBMOH
XBONI ^
•Muni do -o«
Nouvnavvo
XMNIM
•Nunx M -ON
110UIO
XMNI
•NMSIAKI
JO UMMON
NouvnavMO
X10MI ilO
•NMnx to -«m
gtouio
XBOMI
MOMIAM
IlO UNNOM
our
sp
sia
T-
*
SJS
a?
RIS
SI9
rsa
aa
SR
•8,
2ta
Vftfft.
set
X
3ft
tfi'Sf,
aia
•si*
aw
SB?
aa
rrs
-t)
a-s
a
SB
SB
tra
IS
as
STS
aa
#
•a
a
6V
U
f
O
S «
O
Table AI-22.— Machinability Ratings/Other Properties of Various Metals
SAE
AISI
Tensile
Strength
Yield
Point
Elongation
in 2 in.
Reduction
In Area
Hardness
Machinability
Rating
Number
Number
psi
psi
(%)
(%)
Brinell
(%)
Carbon Steels
1015
C1015
65,000
40,000
32
65
137
50
1020
C1020
67,000
45.000
32
65
137
52
x!020
C1022
69,000
47.000
30
58
143
62
1025
C1025
70,000
41,000
31
58
130
58
1030
C1030
75,000
46,000
30
56
138
60
1035
C1035
88,000
55,000
30
56
175
60
1040
C1040
93,000
58,000
27
52
190
60
1045
C1045
99,000
60,000
24
47
200
55
1095
C1095
100,000
60,000
23
47
201
45
Free-Cutting Steels
xlll3
1112
B1113
B1112
C1120
83,000
67,000
69.000
73,000
40,000
36,000
15
27
32
45
47
55
193
140
117
120-140
100
80
Manganese Steels
x!314
x!335
A1335
71,000
95,000
45,000
60,000
28
20
52
35
135
185
94
70
Nickel Steels
2315
A2317
85,000
56,000
29
60
163
50
2330
A2330
98,000
65,000
25
50
207
45
2340
A2340
110,000
80,000
22
47
225
40
2345
A2345
108,000
75,000
23
46
235
50
Nickel-Chromium Steels
3120
A3 120
75,000
60,000
30
65
151
50
3130
A3130
100,000
72,000
24
55
212
45
3140
A3140
96,000
64,000
26
56
195
57
3150
A3 150
104,000
73,000
19
51
229
50
3250
107,000
75,000
24
55
217
44
Molybdenum Steels
4119
91,000
52,000
28
62
179
60
x4130
A4130
89,000
60,000
32
65
179
58
4140
A4140
90,000
63,000
27
58
187
56
4150
A4150
105,000
71,000
21
54
220
54
x4340
A4340
115,000
95.000
18
45
235
58
4615
A4615
82,000
55,000
30
61
167
58
4640
A4640
100,000
87,000
21
50
201
60
4815
A4815
105,000
73,000
24
58
212
55
Table AI-22.— Machinability Ratings/Other Properties of Various Metals— Continued
Tensile
Yield
Elongation
Reduction
Machinability
SAE
AISI
Strength
Point
in 2 in.
in Area
Hardness
Rating
Number
Number
psi
psi
(%)
(%)
Brinell
(%)
Chromium Steels
5120
A5120
5140
A5140
52100
E52101
Chromium-Vanadium S
6120
A6120
6150
A6150
Other Alloys and Metals
Aluminum (1 IS)
Brass, Leaded
Brass, Red or Yellow
Bronze, Lead-Bearing
Cast Iron, Hard
Cast Iron, Medium
Cast Iron, Soft
Cast Steel (0.35 C)
Copper (P.M.)
Ingot Iron
Low-Alloy, High-
Strength Steel
Magnesium Alloys
Malleable Iron
Standard
Pearlitic
Pearlitic
Stainless Steel
(12%CrF.M.)
18-8 Stainless Steel
(Type 303 P.M.)
18-8 Stainless Steel
(Type 304)
73,000
109,000
S
103,000
49,000
55,000
25-35,000
22-32,000
45,000
40,000
30,000
86,000
35,000
41-45,000
98,000
53-60,000
80,000
97,000
1 20,000
80,000
80,000
55,000
80,000
70,000
42,000
45,000
15-30,000
8-20,000
55,000
33,000
18-25,000
65,000
35-40,000
55,000
75,000
86,000
30,000
40,000
32
25
27
14
32
3-16
25
34
45
18
18-25
14
4
23
60
65
67
57
51
5-18
34
70
34
64
75
70
143
50
174-229
60
235
45
179-217
50
217
50
95
300-2,000
RF 100
150-600
40-55
200
30-65
200-500
220-240
50
193-220
65
160-193
80
170-212
70
RF 85
65
101-131
50
187
80
500-2,000
110-145
120
1 80-200
90
227
80
207
70
150
45
150
25
Properties for wrought materials are for hot-rolled
condition.
Properties in this table are only a rough guide to
the machining of various common steels and alloys.
Table AI-23.— Selection Chart for Cutting Fluids
Ferrous Metals
Nonfcrrous Metals
Group
1
II
Ill
IV
V
VI
Machinability
Ov«r70%
50-70%
40-50%
Under 40 %
Over 100 %
Undtr 100%
Materials
Low-carbon Steels
Stainless Steels
Aluminum and Alloys
High-carbon Steels
Ingot Iron
Tool Steels
Brasses and Bronzes
Malleable Iron
Cast Iron
Wrought Iron
High-speed
Magnesium
Copper
Cast Steel
Steels
and Alloys
Nickel
Stainless Iron
Zinc
Inconel
Severity
Type of Machining Operation
Monel
(Greatest) 1.
Broaching; internal
Em. Sul,
Sul. Em.
Sul. Em.
Sul. Em.
MO. Em.
Sul. ML.
2.
Broaching; surface
Em. Sul.
Em. Sul.
Sul. Em.
Sul. Em.
MO. Em.
Sul. ML.
2.
Threading; pipe
Sul.
Sul. ML
Sul.
Sul.
Sul.
3.
Tapping; plain
Sul.
Sul.
Sul.
Sul.
Em. Dry
Sul. ML.
3.
Threading; plain
Sul.
Sul,
Sul.
Sul.
Em. Sul.
Sul.
4.
Gear shaving
Sul. L
Sul. L.
Sul. L.
Sul. L.
4.
Reaming; plain
ML. Sul.
ML. Sul.
ML. Sul.
ML. Sul.
ML. MO. Em.
ML. MO. Sul.
4.
Gear cutting
Sul. ML. Em.
Sul.
Sul.
Sul. ML.
Sul. ML
5.
Drilling; deep
Em. ML
Em. Sul.
Sul.
Sul.
MO. ML Em.
Sul. ML
6.
Milling; plain
Em. ML Sul.
Em.
Em.
Sul.
Em. MO. Dry
Sul. Em.
6.
Milling; multiple cutter
ML.
Sul.
Sul.
Sul. ML.
Em. MO. Dry
Sul. Em.
7.
Boring; multiple head
Sul. Em.
Sul. HDS
Sul. HDS
Sul. Em.
K. Dry Em.
Sul. Em.
7.
Multiple-spindle automatic screw ma-
Sul. Em. ML
Sul. Em. ML
Sul. Em. ML.
Sul. ML. Em
Em. Dry ML.
Sul.
chines and turret lathes: drilling
HDS
HDS
forming, turning, reaming, cutting
off, tapping, threading
8.
High speed, light feed automatic screw
Sul. Em. ML
Sul. Em. ML
Sul. Em. ML
Sul. ML. Em
Em. Dry ML.
Sul.
machines: drilling, forming, tapping
threading, turning, reaming, box mill
ing, cutting off
9.
Drilling
Em.
Em,
Em.
Em. Sul.
Em. Dry
Em.
9.
Planing, shaping
Em. Sul. ML
Em. Sul. ML
Sul. Em.
Em, Sul.
Em. Dry
Em.
9.
Turning; single point tool, form tools
Em. Sul. ML
Em. Sul. ML
Em. Sul. ML
Em. Sul. ML
Em. Dry ML.
Em. Sul.
(Least) 10.
Sawing; circular, hack
Sul. ML. Em
Sul. Em. ML
Sul. Em. ML
Sul. Em. ML
Dry MO. Em
Sul. Em. ML
Grinding; 1. plain
Em.
Em.
Em.
Em.
Em.
Em.
2. form
Sul.
Sul.
Sul.
Sul.
MO. Sul.
Sul.
(thread, etc.)
Key
K.= Kerosene
L.= Lard Oil
MO.="Mineral oils
ML. = Mineral-lard oils
Sul.= Sulphurized oils, with or without chlorine
Em. = Soluble or emulsifiable oils and compounds
Dry=No cutting fluid needed
HDS = Heavy duty soluble oil
APPENDIX II
FORMULAS FOR SPUR GEARING
Having
To Get
Rule
Formula
Diametral pitch
Pitch diameter and
number of teeth.
Outside diameter and
number of teeth.
Number of teeth and
circular pitch.
Number of teeth and
outside diameter.
Outside diameter and
circular pitch.
Addendum and num-
ber of teeth.
Number of teeth and
circular pitch.
Pitch diameter and
circular pitch.
Number of teeth and
addendum.
Pitch diameter and
circular pitch.
Circular pitch
Circular pitch
Circular pitch
Pitch diameter
Pitch diameter
Pitch diameter
Pitch diameter
Outside diameter
Outside diameter
Outside diameter
Number of teeth
Divide 3.1416 by the diam-
etral pitch.
Divide the pitch diameter by
the product of 0.3183 and the
number of teeth.
Divide the outside diameter
by the product of 0.3183 and
the number of teeth plus 2.
The product of the number
of teeth, the circular pitch,
and 0.3183.
Divide the product of the
number of teeth and the out-
side diameter by the number
of teeth plus 2.
Subtract from the outside
diameter the product of the
circular pitch and 0.6366.
Multiply the number of teeth
by the addendum.
The product of the number
of teeth plus 2, the circular
pitch, and 0.3183.
Add to the pitch diameter
the product of the circular
pitch and 0.6366.
Multiply the addendum by
the number of teeth plus 2.
Divide the product of the
pitch diameter and 3.1416 by
the circular pitch.
CP =
PD =
3.1416
DP
OP
0.3183 NT
CP =
OD
0.3183 NT + 2
PD = 0.3183 CPNT
NT OD
NT +2
PD = OD - 0.6366 CP
PD = NT ADD
OD = (NT + 2) 0.3183 CP
OD = PD + 0.6366 CP
OD = (NT + 2) ADD
3.1416PD
NT =
CP
AIM
Circular pitch
Circular pitch
Circular pitch
Circular pitch
Circular pitch
Circular pitch
Pitch diameter and
number of teeth.
Pitch diameter of gear
and pinion.
Outside diameter and
number of teeth.
Number of teeth and
diametral pitch.
Outside diameter and
diametral pitch.
Number of teeth and
diametral pitch.
Pitch diameter and di-
ametral pitch.
Pitch diameter and
number of teeth.
Pitch diameter and di-
ametral pitch.
Chordal thickness
Addendum
Working depth
Whole depth
Clearance
Diametral pitch
Diametral pitch
Center distance
Diametral pitch
Pitch diameter
Pitch diameter
Outside diameter
Outside diameter
Outside diameter
Number of teeth
One half the circular pitch.
Multiply the circular pitch by
0.3183.
Multiply the circular pitch by
0.6366.
Multiply the circular pitch by
0.6866.
Multiply the circular pitch by
0.05.
Divide 3.1416 by the circular
pitch.
Divide the number of teeth by
the pitch diameter.
Add pitch diameter of gear
(PDg) to pitch diameter of
pinion (PDP) and divide by 2.
Divide the number of teeth
plus 2 by the outside diameter.
Divide the number of teeth by
the diametral pitch.
Subtract from the outside
diameter the quotient of 2
divided by the diametral pitch.
Divide the number of teeth
plus 2 by the diametral pitch.
Add to the pitch diameter the
quotient of 2 divided by the
diametral pitch.
Divide the number of teeth
plus 2 by the quotient of the
number of teeth divided by
pitch diameter.
Multiply the pitch diameter by
the diametral pitch.
ADD = 0.3 183 CP
WKD = 0.6366 CP
WD = 0.6866 CP
CL = 0.05 CP
3.1416
CP
Dp -NT
DP~PD
PP* + PPp
2
NT + 2
DP =
OD
DP
PD = OD -
Dp
OD =
NT + 2
DP
OD = PD +
OD = NT + 2
NT = PD DP
AII-2
Having
To Get
Rule
Formula
Outside diameter and
the diametral pitch.
Number of teeth
Multiply the outside diameter
by the diametral pitch and
subtract 2.
NT - OD DP
-2
Diametral pitch
Chordal thickness
Divide 1.5708 by the diam-
etral pitch.
, 1.5708
lc DP
Diametral pitch
Addendum
Divide 1 by the diametral
pitch.
1
Diametral pitch
Diametral pitch
Working depth
Whole depth
Divide 2 by the diametral
pitch.
Divide 2. 1 57 by the diametral
pitch.
\X/ \£ T^ ™~ **
T"%T^
WD 2'157
DP
Diametral pitch
Clearance
Divide 0.157 by the diametral
pitch.
CL - °'157
CL~ DP
APPENDIX III
DERIVATION OF FORMULAS FOR
DIAMETRAL PITCH SYSTEM
1. TOOTH ELEMENTS based on a #1
diametral pitch gear (fig. AIII-1)
a. Addendum (ADD)— 1.000
(1) The distance from the top of the
tooth to the pitch line.
b. Circular Pitch (CP)— 3.1416
(1) The length of an arc equal to the
circumference of a 1-inch circle,
covers one tooth and one space on
the pitch circle.
(2) Measure the circular pitch on
the pitch line. If you could draw a
circle inside the tooth using the
1-inch ADD as the diameter, the
circumference of the circle would be
3.1416. Using your imagination,
break the circle at one point on the
circumference, imagining the cir-
cumference is a string. Lay the
imaginary string on the pitch line at
one side of the tooth. Stretch the
other end as far as possible on the
pitch line; it will stretch to a
corresponding point on the next
adjacent tooth on the pitch line.
c. Circular Thickness (CT)— 1.5708
(1) One-half of the circular pitch,
measured at the pitch line.
d. Clearance (CL)— 0.15708
(1) One-tenth of the chorda! thickness;
move decimal one place to the left.
Figure AIII-1.— Tooth elements on a #1 diametral pitch gear.
e. Dedendum (DED)— 1.15708
(1) The sum of an addendum plus a
clearance.
(2) 1.000 -ADD
+ 0.1570- CL
1.1570 -DED
f. Working Depth (WKD)— 2.000
(1) The sum of two addendums.
(2) 1.000 -ADD
+ 1.000 - ADD
2.000 - WKD
g. Whole Depth (WD)— 2.15708
(1) The sum of an addendum and a
dedendum.
(2) 1.0000 -ADD
+ 1.1570 - DED
2.1570- WD
h. Diametral Pitch (DP)
(1) The ratio of the number of teeth per
inch of pitch diameter.
(2)
NT
PD
DP
i. Chordal Addendum — ac
(1) The distance from the top of a
gear tooth to a chord subtending
(extending under) the intersections
of the tooth thickness arc and the
sides of the tooth.
(2) ac = ADD +
(CT)a
4(PD)
j. Chordal Thickness — tc
(1) The thickness of the tooth,
measured at the pitch circle.
t- = PD sin
90?
N
2. GEAR ELEMENTS
a. Number of Teeth (NT)
(1) Connecting link between the tooth
elements and gear elements.
(2) Number of teeth in gear.
PD
(3)
ADD
= NT
b. Pitch Diameter (PD)
(1) Diameter of the pitch circle.
(2) For every tooth in the gear there
is an addendum on the pitch
diameter.
(3) ADD x NT = (PD)
c. Outside Diameter (OD).
(1) The diameter of the gear
(2) Since there is an addendum (ADD)
on the pitch diameter (PD) for each
tooth, the two elements are directly
related. Therefore, the outside
diameter is simply the pitch
diameter (PD) plus two addendums
(ADD), or simulated teeth. The
formulas read:
(a) ADD x NT = PD
(b) ADD x (NT + 2) = OD
(c) PD + 2 ADD = OD
d. Linear Pitch (LP)
(1) The linear pitch is the same as the
circular pitch except that it is the
lineal measurement of pitch on a
gear rack.
(2) CP = LP
(3) Figure AIII-2 illustrates linear
pitch.
3. GEAR AND TOOTH ELEMENT RE-
LATIONSHIP
TOOTH
GEAR
a.
ADD
h. PD
b.
DED
i. OD
c.
CP
j. ac
d.
CT
k. tc
e.
WD
f.
CL
g.
DP
LINEAR
PITCH
ADDENDUM
TOOTH
THICKNESS
Figure AIII-2.— Linear pitch.
(1) NT is the connecting link between
tooth elements and gear elements.
(2) To complete calculate a gear, one tooth
and one gear element must be known.
(3) For every tooth in the gear there is a
CP on the PC.
(4) For every tooth in the gear there is an
ADD on the PD.
1. ADD =
2. CP =
3. CT =
FORMULAS
1.000
DP
3.1416
DP
1.5708
DP
4. CL =
0.15708
5. DED =
6. WKD =
DP
1.15708
DP
2.000
7. WD =
DP
2.15708
DP
MT
8. DP = £•=: or transpose any other formula
with DP involved.
9. NT =
PD
ADD
10 PD = ADD x NT
11. OD = ADD x (NT + 2)
ATTT
APPENDIX IV
GLOSSARY
When you enter a new occupation, you must
learn the vocabulary of the trade so that you
understand your fellow workers and can make
yourself understood by them. Shipboard life
requires that Navy personnel learn a relatively new
vocabulary — even new terms for many common-
place items. The reasons for this need are many,
but most of them boil down to convenience and
safety. Under certain circumstances, a word or
a few words may mean an exact thing or may
mean a certain sequence of actions which makes
it unnecessary to give a lot of explanatory details.
This glossary is not all-inclusive, but it does
contain many terms that every Machinery Repair-
man should know. The terms given in this glossary
may have more than one definition; only those
definitions as related to the Machinery Repairman
are given.
ABRASIVE.— A hard, tough substance which
has many sharp edges.
AISL— American Iron and Steel Institute.
ALLOWANCE. — Difference between max-
imum size limits of mating parts.
ALLOYING. — Procedure of adding elements
other than those usually comprising a metal or
alloy to change its characteristics and properties.
ALLOYING ELEMENTS.— Elements added
to nonferrous and ferrous metals and alloys to
change their characteristics and properties.
ANNEALING.— The softening of metal by
heating and slow cooling.
ARBOR.— The principal axis member, or
spindle, of a machine by which a motion of
revolution is transmitted.
ASTM. — American Society for Testing Metals.
BABBITT.— A lead base alloy used for
bearings.
BENCH MOLDING.-The process of
making small molds on a bench.
BEND ALLOWANCE. -An additional
amount of metal used in a bend in metal
fabrication.
BEVEL. — A term for a plane having any
angle other than 90° to a given reference plane.
BINARY ALLOY.— An alloy of two metals.
BISECT.— To divide into two equal parts.
BLOWHOLE.— A hole in a casting caused by
trapped air or gasses.
BOND. — Appropriate substance used to hold
grains together in grinding wheels.
BORING BAR.— A tool used for boring,
counterboring, reboring, facing, grooving, and so
forth, where true alignment is of primary
importance.
BRINELL.— A type of hardness test.
BRITTLENESS.— The property of a material
which causes it to break or snap suddenly with
little or no prior sign of deformation.
BRONZE.— A nonferrous alloy composed of
copper and tin and sometimes other elements.
CALIBRATION.— The procedure required to
adjust an instrument or device to produce a
standardized output with a given input.
CARBON.— An alloying element.
AIV-1
CASTING.— A metal object made by pouring
melted metal into a mold.
CHAMFER.— A bevel surface formed by
cutting away the angle of one or two intersecting
faces of a piece of material.
CONTOUR.— The outline of a figure or body.
DRIFT PIN.— A conical-shaped pin gradually
tapered from a blunt point to a diameter larger
than the hole diameter.
DUCTILITY.— The ability to be molded or
shaped without breaking.
EXTRACTOR.— Tool used in removal of
broken taps.
FABRICATE.— To shape, assemble, and
secure in place component parts in order to form
a complete device.
FALSE CHUCK.— Sometimes applied to the
facing material used in rechucking a piece of work
in the lathe.
FATIGUE.— The tendency of a material to
break under repeated strain.
FILE FINISH.— Finishing a metal surface
with a file.
FILLET. — A concave internal corner in a
metal component.
FINISH ALLOWANCE.— An amount of
stock left the surface of a casting to allow for
machine finishing.
FINISH MARKS.— Marks used to indicate
the degree of smoothness of finish to be achieved
on surfaces to be machined.
GRAIN. — The cutting particles of a grinding
wheel.
HARDNESS.— The ability of a material to
resist penetration.
HONING.— Finishing machine operation
using stones vice a tool bit or cutting tool.
INVOLUTE.— Usually referred to as a cutter
used in gearing.
JIGS.— A fixed fixture used in production
machining, or to hold a specific job for
machining.
KNOOP.— Trade name used in hardness
testing.
MANDREL.— Tool used to mount work
usually done in a lathe, or milling machine.
NORMALIZING.— Heating iron-base alloys
to approximately 100°F above the critical
temperature range followed by cooling to below
that range in still air at room temperature.
OCCUPATIONAL STANDARDS.— Re-
quirements that are directly related to the work
of each rating.
PERISCOPE.— An instrument used for
observing objects from a point below the object
lens. It consists of a tube fitted with an object lens
at the top, an eyepiece at the bottom and a pair
of prisms or mirrors which change the direction
of the line of sight. Mounted in such a manner
that it may be rotated to cover all or part of the
horizon or sky and fitted with a scale graduated
to permit taking of bearings, it is used by
submarines to take observations when submerged.
PERPENDICULAR.— A straight line that
meets another straight line at a 90° angle. Also
a vertical line extending through the outline of the
hull ends and the designer's waterline.
PIG IRON.— Cast iron as it comes from the
blast furnace in which it was produced from iron
ore.
PINHOLE.— Small hole under the surface of
the casting.
PLAN. — A drawing prepared for use in
building a ship.
PLASTICITY.— The property which enables
a material to be excessively and permanently
deformed without breaking.
PREHEATING.— The application of heat to
the base metal before it is welded or cut.
PUNCH, PRICK.— A small punch used to
transfer the holes from the template to the plate.
Also called a CENTER PUNCH.
QUENCHING.— Rapid cooling of steels at
different rates.
STRENGTH.— The ability of a material to
resist strain.
REAMING. — Enlarging a hole by revolving
in it a cylindrical, slightly tapered tool with
cutting edges running along its sides.
RECHUCKING.— Reversing of a piece of
work on a faceplate so that the surface that was
against the faceplate may be turned to shape.
REFERENCE PLANE.— On a drawing, the
normal plane from which all information is
referenced.
RPM. — Revolutions per minute.
SCALE. — The ratio between the measurement
used on a drawing and the measurement of the
object it represents. A measuring device such as
a ruler, having special graduations.
SECTOR.— A figure bounded by two radii
and the included arc of a circle, ellipse, or other
central curve.
SPOT FACING.— Turning a circular bearing
surface about a hole. It does not affect a pattern.
STANDARD CASING.— The half of a split
casing that is bolted to the foundation, as opposed
to the half, or cover, which can be removed with
minimum disturbance to other elements of the
equipment.
STRAIGHTEDGE.— Relatively long piece of
material whose working edge is a true plane.
STRESS RELIEVING.— Heat treatment to
remove stresses or casting strains.
STUD.— (1) A light vertical structure member,
usually of wood or light structural steel, used as
part of a wall and for supporting moderate loads.
(2) A bolt threaded on both ends, one end of
which is screwed into a hole drilled and tapped
in the work, and used where a through bolt can-
not be fitted.
SYNTHETIC MATERIAL.-A complex
chemical compound which is artificially formed
by the combining of two or more simpler com-
pounds or elements.
TEMPER.— To relieve internal stress by heat
treating.
TEMPLATE.— A pattern used to reproduce
parts.
TOLERANCE.— An allowable variation in
the dimensions of a machined part.
VICKERS. — A scale or test used in metal
hardness testing.
VITRIFIED BOND.— A man-made bond
used in grinding wheels.
WAVINESS.— Used as a term in the testing
finish machining of parts.
ZINC.— An alloy used widely in die casting.
INDEX
AC, WC, and RF series anodes-general
purpose, 14-34 to 14-35
Acid test, metals, 4-16 to 4-17
Addendum, 1-7
Adjustable gauges, 2-5 to 2-13
Advanced engine lathe operations, 9-1 to
9-23
classes of threads, 9-12 to 9-14
cutting screw threads on a lathe, 9-16 to
9-20
cutting the thread, 9-18 to 9-19
engaging the thread feed mechanism,
9-18
finishing the end of a threaded piece,
9-20
lubricants for cutting threads,
9-19
mounting work in the lathe, 9-16 to
9-17
positioning of compound rest for
cutting screw threads, 9-17
resetting the tool or picking up the
existing thread, 9-19 to 9-20
using the thread-cutting, 9-17 to
9-18
left-hand screw threads, 9-20 to 9-21
measuring screw threads, 9-14 to 9-16
ring and plug gauges, 9-14
thread micrometer, 9-14
three wire method, 9-15 to 9-16
multiple screw threads, 9-21 to 9-23
pipe threads, 9-12
straight pipe threads, 9-12
tapered pipe threads, 9-12
screw threads, 9-7 to 9-12
other forms of threads, 9-11 to
9-12
the Acme screw thread, 9-11
the buttress thread, 9-11 to 9-12
the square thread, 9-11
V-threads, 9-9 to 9-10
Advanced engine lathe operations— Continued
tapers, 9-1 to 9-7
methods of turning tapers, 9-3 to 9-6
setting over the tailstock, 9-4 to
9-5
using the compound rest, 9-5 to
9-6
taper boring, 9-6 to 9-7
threads on tapered work, 9-23
Angular cutters, 13-16
Angular holes, drilling, 5-27 to 5-29
equipment, 5-27 to 5-29
operation, 5-29
Angular indexing, 11-14 to 11-15
Angular milling, 11-36 to 11-42
Anodes for the electroplating process,
preparation of, 14-34 to 14-61
Apron, engine lathe, 7-7 to 7-8
Arbors, 11-28 to 11-32
Assemblies, shaper, 12-1 to 12-5
crossrail assembly, 12-3
drive assembly, 12-1 to 12-2
main frame assembly, 12-1
table feed mechanism, 12-4
toolhead assembly, 12-4 to 12-5
Assistant repair officer, 15-4
Attachments, milling machine, 11-52 to 11-54
Attachments, special, milling machines, 11-11
to 11-12
B
Ball valve, 15-17 to 15-18
Bandsaw terminology, 5-6 to 5-9
Basic engine lathe operations, 8-1 to 8-24
knurling, 8-21 to 8-24
setting up the toolpost grinder, 8-22
to 8-24
machining operations, 8-14 to 8-19
cutting speeds and feeds, 8-14 to 8-17
chatter, 8-16 to 8-17
cutting lubricant, 8-16
direction of feed, 8-17
INDEX-1
Basic engine lathe operations — Continued
machining operations — Continued
facing, 8-17
planning the job, 8-14
turning, 8-18 to 8-19
finish turning, 8-18 to 8-19
rough turning, 8-18
turning to a shoulder, 8-19
methods of holding the work, 8-5
care of chucks, 8-12
holding work between centers, 8-6 to
8-8
centering the work, 8-6 to 8-7
mounting the work, 8-7 to 8-8
holding work in chucks, 8-10 to 8-12
draw-in collet chuck, 8-11
four-jaw independent chuck,
8-10 to 8-11
rubber flex collet chuck, 8-12
three-jaw universal chuck, 8-11
holding work on a faceplate, 8-12 to
8-13
holding work on a mandrel, 8-8 to
8-10
holding work on the carriage, 8-13
using the center rest and follower
rest, 8-13 to 8-14
parting and grooving, 8-19 to 8-21
boring, 8-20 to 8-21
drilling and reaming, 8-20
preoperational procedures, 8-1 to 8-2
lathe safety precautions, 8-1
machine checkout, 8-1 to 8-2
setting up the lathe, 8-2 to 8-5
preparing the centers, 8-2 to 8-5
aligning and testing, 8-3 to 8-4
truing and grinding, 8-4 to 8-5
setting the toolholder and cutting
tool, 8-5
Bed and ways, engine lathe, 7-1 to 7-3
Bench and pedestal grinders, 6-2
Bench work and layout, 3-1 to 3-44
benchwork, 3-20 to 3-44
layout, 3-10 to 3-20
mechanical drawings and blueprints, 3-1
to 3-10
Blueprints and mechanical drawings, 3-1 to
3-10
common blueprint symbols, 3-3 to 3-8
limits of accuracy, 3-9 to 3-10
units of measurements, 3-8 to 3-9
working from drawings, 3-1 to 3-3
Boring mill operations, 11-60 to 11-64
drilling, reaming, and boring, 11-60 to
11-61
in line boring, 11-61 to 11-62
reconditioning split-sleeve bearings, 11-62
to 11-63
threading, 11-63 to 11-64
Boring turret lathe, 10-17 to 10-21
forming, 10-18
grinding boring cutters, 10-17 to 10-18
taper turning, 10-20 to 10-21
threading, 10-18 to 10-20
Brinell hardness test, 4-21 to 4-22
Brittleness, metals, 4-2
Broken bolts and studs, removing, 15-28 to
15-31
removing a broken bolt and retapping the
hole, 15-30 to 15-31
removing a broken tap from a hole,
15-31
Buttress thread, 9-11 to 9-12
Calibration servicing labels and tags, 15-36 to
15-39
Carbide tool grinder, 6-10
Carriage, engine lathe, 7-6 to 7-7
Chip breaker grinder, 6-11 to 6-13
Chip breakers, ground-in, 6-13 to 6-14
Circular milling attachment, 11-52
Components, horizontal turret lathes, 10-1 to
10-8
feed train, 10-4 to 10-5
feed trips and stops, 10-5 to 10-7
headstock, 10-4
threading mechanisms, 10-7 to 10-8
Compound rest, engine lathe, 7-15
Compound indexing, 11-15 to 11-16
Contact electroplating, 14-11 to 14-33
introductory information, 14-13 to 14-22
operating the power pack, 14-24
power pack components, 14-22 to 14-24
selecting and preparing plating tools,
14-24 to 14-33
selecting the power pack, 14-24
Continuous identification marking, 4-12 to
4-13
Coolants, 13-2 to 13-3
Corrosion resistance, 4-3
Cross traverse table, 13-4
Cutoff saw continuous feed, 5-4 to 5-5
band selection and installation, 5-4 to 5-5
cutoff saw operation, 5-5
Cutter sharpening, 13-10 to 13-12
dressing and truing, 13-11
tooth rest blades and holders, 13-11 to
13-12
Cutter sharpening setups, 13-13 to 13-19
angular cutters, 13-16
end mills, 13-16 to 13-18
formed cutters, 13-18 to 13-19
plain milling cutters (helical teeth), 13-13
to 13-14
side milling cutters, 13-14 to 13-15
staggered tooth cutters, 13-15 to 13-16
Cutters and arbors, 11-18 to 11-32
arbors, 11-28 to 11-32
cutters, 11-18 to 11-28
Cutting screw threads on a lathe, 9-16 to 9-20
cutting the thread, 9-18 to 9-19
engaging the thread feed mechanism, 9-18
finishing the end of a threaded piece,
9-20
lubricants for cutting the threads, 9-19
mounting work in the lathe, 9-16 to 9-17
positioning of compound rest for cutting
screw threads, 9-17
resetting the tool or picking up the
existing thread, 9-19 to 9-20
using the thread-cutting, 9-17 to 9-18
Cutting speeds and feeds, engine lathe, 8-14
to 8-17
chatter, 8-16 to 8-17
cutting lubricant, 8-16
direction of feed, 8-17
Cutting tool materials, 6-14 to 6-16
carbon tool steel, 6-14
cast alloys, 6-14 to 6-15
cemented carbide, 6-15 to 6-16
ceramic, 6-16
high-speed steel, 6-14
Cutting tool terminology, 6-12 to 6-13
Cylindrical grinder, 13-7 to 13-9
sliding table, 13-8
using the cylindrical grinder, 13-8 to 13-9
wheelhead, 13-8
D
Derivation of formulas for Diametral pitch
system, AIII-1 to AIII-3
Designations and markings of metals, 4-8
to 4-11
ferrous metal designations, 4-8 to 4-10
nonferrous metal designations, 4-10 to
4-11
Diamond wheels, 6-5
Differential indexing, 11-16 to 11-18
adjusting the sector arms, 11-18
wide range divider, 11-16 to 11-18
Direct indexing, 11-12
Division officers, 14-4
Double seated valves, 15-23
Drilling and reaming, engine lathe, 8-20
Drilling machines and drills, 5-18 to 5-27
drilling machine safety precautions, 5-18
drilling operations, 5-22 to 5-27
twist drill, 5-20 to 5-22
types of machines, 5-18 to 5-20
Drilling, reaming, and boring, 11-51 to 11-52
Ductility, metals, 4-2
Duplex strainer valves, 15-23
E
Elasticity, metals, 4-2
Electroplating, summary of, 14-55 to 14-58
Engine lathe, 7-1 to 7-15
apron, 7-7 to 7-8
bed and ways, 7-1 to 7-3
carriage, 7-6 to 7-7
compound rest, 7-15
feed rod, 7-8
gearing, 7-8 to 7-15
headstock, 7-3 to 7-5
lead screw, 7-8
tailstock, 7-5 to 7-6
Engine lathe tools, 6-16 to 6-18
boring tool, 6-17
internal threading tool, 6-18
left-hand facing tool, 6-16
left-hand turning tool, 6-16
right-hand facing tool, 6-16
right-hand turning tool, 6-16
round-nose turning tool, 6-16
square-nosed parting (cut-off) tool, 6-16
and 6-17
threading tool, 6-16
Engineering handbooks, 1-7
Enlisted personnel, 15-4 to 15-5
Equipment and materials, layout, 3-11
Face milling, 11-33 to 11-36
Fastening devices, benchwork, 3-36 to 3-44
gaskets, 3-42 to 3-43
gaskets, packing and seals, 3-42
keyseats and keys, 3-41 to 3-42
packing, 3-43
Fastening devices, bench work — Continued
pins, 3-42
screw thread inserts, 3-39 to 3-41
seals, 3-43 to 3-44
threaded fastening devices, 3-36 to 3-39
Fatigue, metals, 4-2
Feed rod, engine lathe, 7-8
Feeds, speeds, and coolants, 11-54 to 11-58
coolants, 11-57 to 11-58
feeds, 11-56 to 11-57
speeds, 11-55 to 11-56
Ferrous metals, 4-3 to 4-6
alloy steels, 4-5 to 4-6
cast iron, 4-5
pig iron, 4-3 to 4-5
plain carbon steels, 4-5
wrought iron, 4-5
FG and FF series anodes-general purpose,
14-35 to 14-36
FG, FF and some special anodes-special
purpose, 14-37
Fixed gauges, 2-13 to 2-18
graduated gauges, 2-14 to 2-17
nongraduated gauges, 2-17 to 2-18
Formulas, 14-59 to 14-61
Formulas for spur gearing, AII-1 to AII-3
Gate valve, 15-18 to 15-20
Gearing, lathe, 7-8 to 7-15
idler gears, 7-9 to 7-11
quick-change gear mechanism, 7-11 to
7-15
Gears, 15-8 to 15-12
diametral pitch system, 15-10 to 15-11
machining the gear, 15-11 to 15-12
spur gear terminology, 15-8 to 15-9
Globe valve, 15-14 to 15-17
Glossary, AIV-1 to AIV-3
Grinders, bench and pedestal, 6-2
Grinding attachment, 7-23
Grinding cutters, 12-24 to 12-27
Grinding machines, precision, 13-1 to 13-21
Grinding wheels, 6-2 to 6-10
diamond wheels, 6-5
grain depth of cut, 6-6 to 6-7
grinding wheel selection and use, 6-7 to
6-9
sizes and shapes, 6-2 to 6-3
truing and dressing the wheel, 6-9 to 6-10
wheel installation, 6-9
wheel markings and composition, 6-3 to
6-5
H
Hacksaws, power, 5-1 to 5-3
blade selection, 5-2 to 5-3
coolant, 5-3
feeds and speeds, 5-3
power hacksaw operation, 5-3
Handtools and drills, grinding, 6-23
Hardness, metals, 4-2
Hardness test, 4-19 to 4-24
Brinell hardness test, 4-21 to 4-22
Rockwell hardness test, 4-19 to 4-21
Scleroscope hardness test, 4-22
Vickers hardness test, 4-22 to 4-24
Headstock, engine lathe, 7-3 to 7-5
Heat resistance, metals, 4-3
Heat treatment, 4-17 to 4-19
annealing, 4-17 to 4-18
case hardening, 4-19
hardening, 4-18
normalizing, 4-18
tempering, 4-18 to 4-19
High-pressure steam valves, assembling, 15-24
to 15-25
High-speed universal attachment, 11-52
Hones and honing, 13-19
Horizontal boring mill, 11-58 to 11-64
boring mill operations, 11-60 to 11-64
Combination boring and facing head, 11-59
to 11-60
right angle milling attachment, 11-60
Horizontal turret lathes, 10-1 to 10-8
classification of horizontal turret lathes,
10-2 to 10-4
components, 10-4 to 10-8
Identification of metals, 4-13 to 4-17
acid test, 4-16 to 4-17
spark test, 4-14 to 4-16
Indexing equipment, 11-7 to 11-11
dividing head, 11-8 to 11-9
gearing arrangement, 11-9 to 11-11
Issue room, tool, 2-1 to 2-5
control of tools, 2-4
organization of the toolroom, 2-1 to
2-4
safety in the toolroom and the shop, 2-4
to 2-5
INDEX-4
Knee and column milling machines, 11-1 to
11-7
major components, 11-3 to 11-7
Knurling, engine lathe, 8-21 to 8-24
setting up the toolpost grinder, 8-22 to
8-24
Lathe safety precautions, 8-1
Lathes and attachments, 7-1 to 7-25
attachments and accessories, 7-15
carriage stop, 7-23
center rest, 7-21
follower rest, 7-21
grinding attachment, 7-23
lathe centers, 7-19 to 7-20
lathe chucks, 7-17 to 7-19
lathe dogs, 7-20 to 7-21
milling attachment, 7-23 to 7-24
other types of lathes, 7-25
taper attachment, 7-21 to 7-23
thread dial indicator, 7-23
toolholders, 7-16 to 7-17
toolposts, 7-15
tracing attachments, 7-24 to 7-25
engine lathe, 7-1 to 7-15
apron, 7-7 to 7-8
bed and ways, 7-1 to 7-3
carriage, 7-6 to 7-7
compound rest, 7-15
feed rod, 7-8
gearing, 7-8 to 7-15
idler gears, 7-9 to 7-11
quick-change gear mechanism,
7-11 to 7-15
headstock, 7-3 to 7-5
lead screw, 7-8
tailstock, 7-5 to 7-6
Laying out valve flange bolt holes, 2-17
Layout and bench work, 3-1 to 3-44
benchwork, 3-20 to 3-44
assembly and disassembly, 3-21
fastening devices, 3-36 to 3-44
gaskets, 3-42 to 3-43
gaskets, packing and seals, 3-42
keyseats and keys, 3-41 to 3-42
packing, 3-43
pins, 3-42
screw thread inserts, 3-39 to 3-41
seals, 3-43 to 3-44
threaded fastening devices, 3-36
to 3-39
Layout and benchwork — Continued
benchwork—Continued
precision work, 3-21 to 3-35
broaching, 3-24
classes of fit, 3-30 to 3-32
hand reaming, 3-22 to 3-24
hand taps and dies, 3-24 to 3-29
hydraulic and arbor presses, 3-32
oxyacetylene equipment, 3-32 to
3-35
removal of burrs and sharp
edges, 3-22
removing broken taps, 3-29 to
3-30
scraping, 3-21 to 3-22
safety: oxyacetylene equipment, 3-35
to 3-36
flashback and backfire, 3-36
layout, 3-10 to 3-20
layout methods, 3-11 to 3-20
making layout lines, 3-12 to 3-20
materials and equipment, 3-11
mechanical drawings and blueprints, 3-1
to 3-10
common blueprint symbols, 3-3 to
3-8
surface texture, 3-3 to 3-8
limits of accuracy, 3-9 to 3-10
allowance, 3-9 to 3-10
tolerance, 3-9
units of measurements, 3-8 to 3-9
English system, 3-8
metric system, 3-9
working from drawings, 3-1 to 3-3
Left-hand screw threads, 9-20 to 9-21
M
Machine shop maintenance, 15-27 to 15-28
Machine shop, repair, 15-5 to 15-6
Machinery Repairman rating, scope of, 1-1 to
1-7
Machining operations, 8-14 to 8-19
cutting speeds and feeds, 8-14 to 8-17
facing, 8-17
planning the job, 8-14
turning, 8-18 to 8-19
Materials and equipment, layout, 3-11
Measuring gauges, shop, 2-5 to 2-23
adjustable gauges, 2-5 to 2-13
care and maintenance of gauges, 2-21 to
2-23
fixed gauges, 2-13 to 2-18
micrometers, 2-18 to 2-21
Measuring screw threads, 9-14 to 9-16
ring and plug gauges, 9-14
thread micrometer, 9-14
three wire method, 9-15 to 9-16
Mechanical drawings and blueprints, 3-1 to
3-10
common blueprint symbols, 3-3 to 3-8
limits of accuracy, 3-9 to 3-10
units of measurements, 3-8 to 3-9
working from drawings, 3-1 to 3-3
Metal buildup, 14-1 to 14-61
contact electroplating, 14-11 to 14-33
introductory information, 14-13 to
14-22
applications, 14-18 to 14-19
health and safety precautions,
14-15
list of successful, typical repair
applications, 14-19 to 14-20
operator qualification, 14-14 to
14-15
plating tool coverings, 14-14
plating tools, 14-14
power pack, 14-13 to 14-14
processing instructions, 14-20 to
14-21
quality control, 14-21 to 14-22
solutions, 14-14
terminology, 14-15 to 14-18
operating the power pack, 14-24
during the plating operation,
14-24
prior to plating, 14-24
power pack components, 14-22 to
14-24
ammeter, 14-22
ampere-hour meter, 14-22 to
14-23
d.c. circuit breakers, 14-22
forward-reverse switch, 14-24
output leads, 14-24
output terminals, 14-23
start button, 14-23
stop button, 14-23
voltmeter, 14-22
selecting and preparing plating tools,
14-24 to 14-33
covering the full length, 14-26
optimum contact area for the
plating tool, 14-26
plating tool anode materials,
14-31
plating tool covers, 14-31 to
14-33
Metal buildup — Continued
contact electroplating — Continued
selecting and preparing plating
tools — Continued
proper plating tools, 14-24 to
14-26
solution feed tool, 14-26
special tools, 14-29 to 14-30
standard tools, 14-26 to 14-29
selecting the power pack, 14-24
preparation of anodes for the electro-
plating process, 14-34 to 14-61
AC, WC, and RF series anodes-
general purpose, 14-34 to 14-35
FG and FF series anodes-general
purpose, 14-35 to 14-36
FG, FF, and some special anodes-
special purpose, 14-37
final preparation, 14-49 to 14-52
draft a flow chart, 14-49
familiarization with the equip-
ment and procedures, 14-49
general setup, 14-52
prepare the part for plating,
14-49 to 14-51
setting up the equipment, 14-52
formulas, 14-59 to 14-61
general preparation instructions,
14-52 to 14-54
activating, 14-54
cleaning and deoxidizing, 14-52
to 14-54
desmutting, 14-54
etching, 14-54
plating, 14-54
machining and grinding, 14-59
grinding nickel and cobalt
deposits, 14-59
machining, 14-59
masking, 14-37 to 14-49
preplating instructions, 14-55
SCC and SCG anodes-special
purpose, 14-36
SCC and SCG series anodes, 14-34
storage and shelf life of solutions,
14-37
summary of electroplating, 14-55 to
14-58
evaluating adhesion, 14-58
evaluating deposits, 14-58
guidelines for the operator,
14-57
INDEX-6
Metal buildup — Continued
preparation of anodes for the electro-
plating process—Continued
troubleshooting, 14-58 to 14-59
low thickness deposit, 14-59
nonuniform thickness of the
deposit, 14-59
poor adhesion, 14-58
poor deposit quality, 14-59
took too long to finish the job,
14-59
verifying the identity of the base
material, 14-54 to 14-55
thermal spray systems, 14-1 to 14-11
applying the coating, 14-6 to 14-7
applying the sealant, 14-7
masking for spraying, 14-6
spraying the coating, 14-6 to
14-7
approved applications, 14-1
finishing the surface, 14-7 to 14-11
grinding, 14-10 to 14-11
machining, 14-8 to 14-10
requirements, 14-8
preparing the surfaces, 14-3 to 14-6
cleaning, 14-4
surface roughening, 14-5 to 14-6
undercutting, 14-4 to 14-5
qualification of personnel, 14-2
safety precautions, 14-2
types of thermal spray, 14-2 to 14-3
powder-oxygen-fuel spray, 14-3
wire-oxygen-fuel spray, 14-2 to
14-3
Metal cutting bandsaws, 5-5 to 5-18
bandsaw terminology, 5-6 to 5-9
sawing operations, 5-15 to 5-18
selection of saw bands, speeds and feeds,
5-9 to 5-12
sizing, splicing, and installing bands, 5-12
to 5-15
Metal disintegrators, 5-29 to 5-31
Metals and plastics, 4-1 to 4-28
designations and markings of metals,
4-8 to 4-11
ferrous metal designations, 4-8 to
4-10
nonferrous metal designations, 4-10
to 4-11
hardness test, 4-19 to 4-24
Brinell hardness test, 4-21 to 4-22
Rockwell hardness test, 4-19 to 4-21
Scleroscope hardness test, 4-22
Metals and plastics — Continued
heat treatment, 4-17 to 4-19
annealing, 4-17 to 4-18
case hardening, 4-19
hardening, 4-18
normalizing, 4-18
tempering, 4-18 to 4-19
identification of metals, 4-13 to 4-17
acid test, 4-16 to 4-17
spark test, 4-14 to 4-16
metals, 4-3 to 4-8
ferrous metals, 4-3 to 4-6
alloy steels, 4-5 to 4-6
cast iron, 4-5
pig iron, 4-3 to 4-5
plain carbon steels, 4-5
wrought iron, 4-5
nonferrous metals, 4-6 to 4-8
aluminum alloys, 4-7
copper alloys, 4-6 to 4-7
lead alloys, 4-8
nickel alloys, 4-7
tin alloys, 4-8
zinc alloys, 4-7 to 4-8
plastics, 4-24
characteristics, 4-24 to 4-25
machining operations, 4-25 to 4-28
drilling, 4-25
finishing operations, 4-28
lathe operations, 4-25 to 4-28
sawing, 4-25
major groups, 4-25
properties of metals, 4-1 to 4-3
brittleness, 4-2
corrosion resistance, 4-3
ductility, 4-2
elasticity, 4-2
fatigue, 4-2
hardenability, 4-2
hardness, 4-2
heat resistance, 4-3
machinability, 4-3
malleability, 4-2
plasticity, 4-2
strain, 4-1
strength, 4-1 to 4-2
stress, 4-1
toughness, 4-2
weldability, 4-3
standard marking of metals, 4-11 to 4-13
continuous identification marking,
4-12 to 4-13
Micrometers, 2-18 to 2-21
Micrometers — Continued
miscellaneous micrometers, 2-21
outside micrometer, 2-19 to 2-20
thread micrometer, 2-21
Milling attachment, 7-23 to 7-24
Milling machines and milling operations,
11-1 to 11-64
cutters and arbors, 11-18 to 11-32
arbors, 11-28 to 11-32
mounting and dismounting
arbors, 11-31 to 11-32
cutters, 11-18 to 11-28
selection, 11-28
types and uses, 11-19 to 11-27
feeds, speeds, and coolants, 11-54 to
11-58
coolants, 11-57 to 11-58
feeds, 11-56 to 11-57
speeds, 11-55 to 11-56
horizontal boring mill, 11-58 to 11-64
boring mill operations, 11-60 to
11-64
drilling, reaming, and boring,
11-60 to 11-61
in line boring, 11-61 to 11-62
reconditioning split-sleeve bear-
ings, 11-62 to 11-63
threading, 11-63 to 11-64
combination boring and facing head,
11-59 to 11-60
right angle milling attachment, 11-60
indexing the work, 11-12 to 11-18
angular indexing, 11-14 to 11-15
compound indexing, 11-15 to 11-16
differential indexing, 11-16 to 11-18
adjusting the sector arms, 11-18
wide range divider, 11-16 to
11-18
direct indexing, 11-12
plain indexing, 11-13 to 11-14
knee and column milling machines, 11-1
to 11-7
major components, 11-3 to 11-7
milling machine attachments, 11-52 to
11-54
circular milling attachment, 11-52
high speed universal attachment,
11-52
rack milling attachment, 11-52 to
11-53
raising block, 11-54
right-angle plate, 11-54
tookmaker's knee, 11-54
vertical milling attachment, 11-52
Milling machines and milling operations-
Continued
milling machine operations, 11-32
angular milling, 11-36 to 11-42
calculations, 11-38 to 11-40
cutter setup, 11-36 to 11-37
machining two flats in one
plane, 11-41 to 11-42
square or hexagon work mounted
between centers, 11-40 to
11-41
work setup, 11-37 to 11-38
drilling, reaming, and boring 11-51
to 11-52
boring, 11-51 and 11-52
drilling and reaming, 11-51
face milling, 11-33 to 11-36
cutter setup, 11-34
operation, 11-34 to 11-36
work setup, 11-34
plain milling, 11-32 to 11-33
slotting, parting, and milling, key-
seats and flutes, 11-42 to 11-51
external key seat, 11-43
fly cutting, 11-51
parting, 11-42 to 11-43
reamer flutes, 11-49 to 11-51
slotting, 11-42
straight external keyseats, 11-43
to 11-45
straight flutes, 11-47
tap flutes, 11-47 to 11-49
Woodruff keyseat, 11-45 to
11-47
milling machine safety precautions, 11-64
special attachments, 11-11 to 11-12
slotting attachment, 11-11 to 11-12
workholding devices, 11 -7 to 11-11
indexing equipment, 11-7 to 11-11
dividing head, 11-8 to 11-9
gearing arrangement, 11-9 to
11-11
vises, 11-7
Multiple screw threads, 9-21 to 9-23
N
NAVSEA publications, 1-6 to 1-7
Naval Ships' Technical Manual, 1-6
NAVSEA Deckplate, 1-6 to 1-7
Nonferrous metals, 4-6 to 4-8
aluminum alloys, 4-7
copper alloys, 4-6 to 4-7
lead alloys, 4-8
Nonferrous metals — Continued
nickel alloys, 4-7
tin alloys, 4-8
zinc alloys, 4-7 to 4-8
Nonresident training courses and training
manuals, 1-3
O
Offhand grinding of tools, 6-1 to 6-23
bench and pedestal grinders, 6-2
carbide tool grinder, 6-10
chip breaker grinder, 6-11 to 6-13
single-point cutting tools, 6-12 to
6-13
cutting tool terminology, 6-12 to
6-13
cutting tool materials, 6-14 to 6-16
carbon tool steel, 6-14
cast alloys, 6-14 to 6-15
cemented carbide, 6-15 to 6-16
brazed on tip, 6-15
mechanically held tip (insert
type), 6-15 to 6-16
ceramic, 6-16
high-speed steel, 6-14
engine lathe tools, 6-16 to 6-18
boring tool, 6-17
internal-threading tool, 6-18
left-hand facing tool, 6-16
left-hand turning tool, 6-16
right-hand facing tool, 6-16
right-hand turning tool, 6-16
round-nose turning tool, 6-16
square-nosed parting (cut-off) tool,
6-16 to 6-17
threading tool, 6-16
grinding engine lathe cutting tools, 6-18
to 6-20
grinding tools for roughing cuts,
6-19 to 6-20
steps in grinding a tool bit, 6-18 to
6-19
grinding handtools and drills, 6-23
grinding safety, 6-1 to 6-2
grinding wheels, 6-2 to 6-10
diamond wheels, 6-5
grain depth of cut, 6-6 to 6-7
grinding wheel selection and use,
6-7 to 6-9
sizes and shapes, 6-2 to 6-3
truing and dressing the wheel, 6-9 to
6-10
Offhand grinding of tools— Continued
grinding wheels — Continued
wheel installation, 6-9
wheel markings and composition, 6-3
to 6-5
bond grade (hardness), 6-4
bond type, 6-4 to 6-5
grain size, 6-4
manufacturer's record symbol,
6-5
structure, 6-4
type of abrasive, 6-3 to 6-4
ground-in chip breakers, 6-13 to 6-14
operation of the carbide tool grinder,
6-11
shaper and planer tools, 6-21 to 6-23
turret lathe tools, 6-20 to 6-21
wheel care and storage, 6-23
wheel selection, 6-11
On-the-job training, 1-3
Operator qualification, 14-14 to 14-15
Pantographs, 12-16 to 12-30
cutter speeds, 12-24
engraving a dial face, 12-29 to 12-30
engraving a graduated collar, 12-29
grinding cutters, 12-24 to 12-27
pantograph attachments, 12-27 to 12-29
pantograph engraver units, 12-18 to 12-19
setting copy, 12-19 to 12-20
setting the pantograph, 12-20 to 12-23
using a circular copy plate, 12-29
Pipe threads, 9-12
straight pipe threads, 9-12
tapered pipe threads, 9-12
Piston rings, making, 15-31 to 15-32
Plain indexing, 11-13 to 11-14
Plain milling, 11-32 to 11-33
Planers, 12-12 to 12-16
construction and maintenance, 12-14
operating the planer, 12-14 to 12-16
surface grinding on the planer, 12-16
types of planers, 12-13 to 12-14
Plasticity, metals, 4-2
Plating tools, 14-14
Plating tools, selecting and preparing, 14-24
to 14-33
covering the full length, 14-26
optimum contact area for the plating
tool, 14-26
plating tool anode materials, 14-31
plating tool covers, 14-31 to 14-33
Plating tools, selecting and preparing —
Continued
proper plating tools, 14-24 to 14-26
solution-feed tool, 14-26
special tools, 14-29 to 14-30
standard tools, 14-26 to 14-29
Power pack, 14-13 to 14-14
Power pack components, 14-22 to 14-24
ammeter, 14-22
ampere-hour meter, 14-22 to 14-23
d.c. circuit breakers, 14-22
forward-reverse switch, 14-24
output leads, 14-24
output terminals, 14-23
start button, 14-23
stop button, 14-23
voltmeter, 14-22
Power saws and drilling machines, 5-1 to 5-31
continuous feed cutoff saw, 5-4 to 5-5
band selection and installation, 5-4
to 5-5
cutoff saw operation, 5-5
drilling angular holes, 5-27 to 5-29
equipment, 5-27 to 5-29
angular drill, 5-28 to 5-29
chuck, 5-27 to 5-28
guide holder, 5-28
guide plates, 5-28
slip bushings, 5-28
operation, 5-29
drilling machines and drills, 5-18 to 5-27
drilling machine safety precautions,
5-18
drilling operations, 5-22 to 5-27
correcting offcenter starts, 5-25
counterboring, countersinking,
and spotfacing, 5-25 to 5-26
drilling hints, 5-24 to 5-25
holding the work, 5-23 to 5-24
reaming, 5-26
speeds, feeds and coolants, 5-22
to 5-23
tapping, 5-26 to 5-27
twist drill, 5-20 to 5-22
types of machines, 5-18 to 5-20
metal cutting bandsaws, 5-5 to 5-18
bandsaw terminology, 5-6 to 5-9
band tool guides, 5-8 to 5-9
file bands, 5-7 to 5-8
polishing bands, 5-8
saw bands, 5-7
sawing operations, 5-15 to 5-18
angular cutting, 5-16
contour cutting, 5-16 to 5-17
disk cutting, 5-17
Power saws and drilling machines — Continued
metal cutting bandsaws — Continued
sawing operations — Continued
filing and polishing, 5-17 to 5-18
general rules, 5-15
inside cutting, 5-17
straight cuts with power feed,
5-15 to 5-16
selection of saw bands, speeds and
feeds, 5-9 to 5-12
band speeds, 5-12
band width and gauge, 5-10 to
5-12
tooth pitch, 5-10
sizing, splicing, and installing bands,
5-12 to 5-15
band length, 5-13
band splicing, 5-13 to 5-14
installing bands, 5-14 to 5-15
metal disintegrators, 5-29 to 5-31
power hacksaws, 5-1 to 5-3
blade selection, 5-2 to 5-3
coolant, 5-3
feeds and speeds, 5-3
power hacksaw operation, 5-3
power saw safety precautions, 5-1
Precision grinding machines, 13-1 to 13-21
cylindrical grinder, 13-7 to 13-9
sliding table, 13-8
using the cylindrical grinder, 13-8 to
13-9
wheelhead, 13-8
cutter sharpening setups, 13-13 to
13-19
angular cutters, 13-16
end mills, 13-16 to 13-18
formed cutters, 13-18 to 13-19
grinding a tap, 13-19
plain milling cutters (helical teeth),
13-13 to 13-14
sidemilling cutters, 13-14 to 13-15
staggered tooth cutters, 13-15 to
13-16
hones and honing, 13-19
portable honing equipment, 13-20
setting the clearance angle, 13-12 to 13-13
speeds, feeds, and coolants, 13-1 to 13-3
coolants, 13-2 to 13-3
depth of cut, 13-2
traverse (work speed), 13-2
wheel speeds, 13-1 to 13-2
stationary honing equipment, 13-20 to
13-21
stone removal, 13-21
stone selection, 13-21
Precision grinding machines— Continued
surface grinder, 13-3 to 13-7
cross traverse table, 13-4
sliding table, 13-4
using the surface grinder, 13-6 to
13-7
wheelhead, 13-4
workholding devices, 13-4 to 13-6
magnetic chucks, 13-5 to 13-6
universal vise, 13-6
tool and cutter grinder, 13-9 to 13-12
cutter sharpening, 13-10 to 13-12
dressing and truing, 13-11
tooth rest blades and holders,
13-11 to 13-12
wheelhead, 13-9
workhead, 13-9
Precision work, 3-21 to 3-35
broaching, 3-24
classes of fit, 3-30 to 3-32
hand reaming, 3-22 to 3-24
hand taps and dies, 3-24 to 3-29
hydraulic and arbor presses, 3-32
oxyacetylene equipment, 3-32 to 3-35
removal of burrs and sharp edges, 3-22
removing broken taps, 3-29 to 3-30
scraping, 3-21 to 3-22
Preplating instructions, 14-55
Pressure seal bonnet globe valves, 15-23 to
15-24
Processing instructions, 14-20 to 14-21
Properties of metals, 4-1 to 4-3
Q
Quality assurance, 15-36 to 15-39
R
Rack milling attachment, 11-52 to 11-53
Raising block, 11 -54
Repair Department and repair work, 15-1 to
15-39
machine shop maintenance, 15-27 to
15-28
making piston rings, 15-31 to 15-32
quality assurance, 15-36 to 15-39
calibration servicing labels and tags,
15-36 to 15-39
calibrated, 15-38
calibrated-in-place, 15-39
Repair Department and repair work-
Continued
quality assurance— Continued
calibration servicing labels and
tags— Continued
calibration not required — not
used for quantitative measure-
ment, 15-38 to 15-39
calibration void if seal broken,
15-39
inactive, 15-39
rejected, 15-39
special calibration, 15-38
removing broken bolts and studs,
15-28 to 15-31
removing a broken bolt and re-
tapping the hole, 15-30 to 15-31
removing a broken tap from a hole,
15-31
repair department organization and
personnel, 15-1 to 15-5
assistant repair officer, 15-4
division officers, 14-4
enlisted personnel, 15-4 to 15-5
repair officer, 15-1 to 15-4
repair department shops, 15-5 to 15-7
machine shop, 15-5 to 15-6
other repair shops, 15-6 to 15-7
repair work, 15-7 to 15-27
gears, 15-8 to 15-12
diametral pitch system, 15-10 to
15-11
machining the gear, 15-11 to
15-12
spur gear terminology, 15-8 to
15-9
repairing pumps, 15-25 to 15-27
shafts, 15-12 to 15-14
manufacturing a new shaft,
15-12 to 15-13
repairing shafts, 15-13 to 15-14
valves, 15-14 to 15-25
assembling high-pressure steam
valves, 15-24 to 15-25
ball valve, 15-17 to 15-18
constant-pressure governor,
15-20 to 15-23
double seated valves, 15-23
duplex strainer valves, 15-23
gate valve, 15-18 to 15-20
globe valve, 15-14 to 15-17
INDEX-11
Repair Department and repair work —
Continued
repair work — Continued
valves—Continued
pressure seal bonnet globe
valves, 15-23 to 15-24
testing valves, 15-25
spring winding, 15-32 to 15-36
tables for spring winding, 15-32
to 15-36
Right-angle plate, 1 1-54
Ring and plug gauges, 9-14
Rockwell hardness test, 4-19 to 4-21
Safety, 1-4 to 1-5
Safety, grinding, 6-1 to 6-2
Safety: oxyacetylene equipment, 3-35 to 3-36
flashback and backfire, 3-36
SCC and SCO anodes-special purpose, 14-36
SCC and SCO series anodes, 14-34
Scope of the Machinery Repairman rating,
1-1 to 1-7
addendum, 1-7
on-the-job training, 1-3
other training manuals, 1-3 to 1-4
purposes, benefits, and limitations of the
planned maintenance system, 1-5 to 1-6
benefits, 1-6
limitations, 1-6
purposes, 1-6
safety, 1-4 to 1-5
sources of information, 1-6 to 1-7
drawings, 1-7
engineering handbooks, 1-7
manufacturer's technical manuals,
1-7
NAVSEA publications, 1-6 to 1-7
Naval Ships' Technical Manual,
1-6
NAVSEA Deckplate, 1-6 to 1-7
training, 1-2 to 1-3
formal schools, 1-2 to 1-3
training manuals and nonresident training
courses, 1-3
typical assignment and duties, 1-2
Screw threads, 9-7 to 9-12
other forms of threads, 9-11 to 9-12
V-threads, 9-9 to 9-10
Shafts, repair, 15-12 to 15-14
manufacturing a new shaft, 15-12 to
15-13
repairing shafts, 15-13 to 15-14
Shaper and planer tools, 6-21 to 6-23
Shapers, planers, and engravers, 12-1 to 12-30
pantographs, 12-16 to 12-30
cutter speeds, 12-24
engraving a dial face, 12-29 to 12-30
engraving a graduated collar, 12-29
grinding cutters, 12-24 to 12-27
grinding single-flute cutters,
12-24 to 12-27
grinding square-nose single-flute
cutters, 12-27
grinding three- and four-sided
cutters, 12-27
pantograph attachments, 12-27 to
12-29
pantograph engraver units, 12-18 to
12-19
copyholder, 12-19
cutterhead assembly, 12-19
pantograph assembly, 12-19
supporting base, 12-18 to 12-19
worktable, 12-19
setting copy, 12-19 to 12-20
setting the pantograph, 12-20 to
12-23
using a circular copy plate, 12-29
planers, 12-12 to 12-16
construction and maintenance, 12-14
operating the planer, 12-14 to 12-16
feeds, 12-14 to 12-15
holding the work, 12-15 to 12-16
rail elevation, 12-15
table speeds, 12-14
surface grinding on the planer, 12-16
types of planers, 12-13 to 12-14
shapers, 12-1 to 12-12
shaper assemblies, 12-1 to 12-5
crossrail assembly, 12-3
drive assembly, 12-1 to 12-2
main frame assembly, 12-1
table feed mechanism, 12-4
toolhead assembly, 12-4 to 12-5
shaper operations, 12-6 to 12-12
shaping a rectangular block,
12-8 to 12-9
shaping an internal key way,
12-10 to 12-11
shaping angular surfaces, 12-9
shaping irregular surfaces, 12-11
to 12-12
shaping keyways in shafts, 12-9
to 12-10
speeds and feeds, 12-7 to 12-8
Shapers, planers, and engravers — Continued
shapers — Continued
shaper safety precautions, 12-6
toolholders, 12-5 to 12-6
types of shapers, 12-1
vertical shapers, 12-12
Single-point cutting tools, 6-12 to 6-13
Slotting attachment, milling machines, 11-11
to 11-12
Slotting, parting, and milling keyseats and
flutes, 11-42 to 11-51
Spark test, metals, 4-14 to 4-16
Speeds, feeds, and coolants, 13-1 to 13-3
coolants, 13-2 to 13-3
depth of cut, 13-2
traverse (work speed), 13-2
wheel speeds, 13-1 to 13-2
Spring winding, 15-32 to 15-36
tables for spring winding, 15-32 to 15-36
Spur gear terminology, 15-8 to 15-9
Square thread, 9-11
Standard marking of metals, 4-11 to 4-13
continuous identification marking, 4-12 to
4-13
Stationary honing equipment, 13-20 to 13 ""
Stone removal, 13-21
Stone selection, 13-21
Strain, metals, 4-1
Strength, metals, 4-1 to 4-2
Stress, metals, 4-1
Surface grinder, 13-2 to 13-7
cross traverse table, 13-4
sliding table, 13-4
using the surface grinder, 13-6 to 13-7
wheelhead, 13-4
workholding devices, 13-4 to 13-6
Symbols, common blueprint, 3-3 to 3-8
surface texture, 3-3 to 3-8
Tabular information of benefit to Machinery
Repairman, AI-1 to AI-25
Tailstock, engine lathe, 7-5 to 7-6
Taper attachment, 7-21 to 7-23
Tapers, 9-1 to 9-7
methods of turning tapers, 9-3 to 9-6
taper boring, 9-6 to 9-7
Terminology, 14-15 to 14-18
Testing valves, 15-25
Thermal spray systems, 14-1 to 14-11
applying the coating, 14-6 to 14-7
approved applications, 14-1
Thermal spray systems— Continued
preparing the surfaces, 14-3 to 14-6
qualification of personnel, 14-2
safety precautions, 14-2
types of thermal spray, 14-2 to 14-3
Threads, other forms of, 9-11 to 9-12
Three wire method, 9-15 to 9-16
Tool bit, steps in grinding a, 6-18 to 6-19
Toolholders, 7-16 to 7-17, 12-5 to 12-6
Toolmaker's knee, 11-54
Toolposts, 7-15
Toolrooms and tools, 2-1 to 2-23
shop measuring gauges, 2-5 to 2-23
adjustable gauges, 2-5 to 2-13
adjustable parallel, 2-12 to 2-13
cutter clearance guage, 2-12
dial bore gauge, 2-10
dial indicators, 2-5 to 2-7
dial vernier caliper, 2-8 to 2-9
gear tooth vernier, 2-12
internal groove gauge, 2-10
surface gauge, 2-13
universal bevel, 2-10 to 2-12
universal vernier bevel protractor,
2-10
vernier caliper, 2-7
vernier height gauge, 2-8
care and maintenance of gauges, 2-21
to 2-23
dials, 2-23
micrometers, 2-21 to 2-23
vernier gauges, 2-23
fixed gauges, 2-13 to 2-18
graduated gauges, 2-14 to 2-17
nongraduated gauges, 2-17 to
2-18
micrometers, 2-18 to 2-21
depth micrometer, 2-20 to 2-21
inside micrometer, 2-20
miscellaneous micrometers, 2-21
outside micrometer, 2-19 to 2-20
thread micrometer, 2-21
tool issue room, 2-1 to 2-5
control of tools, 2-4
organization of the toolroom, 2-1 to
2-4
safety in the toolroom and the shop,
2-4 to 2-5
Tracing attachments, 7-24 to 7-25
Training, 1-2 to 1-3
formal schools, 1-2 to 1-3
Training manuals and nonresident training
courses, 1-3
Traverse (work speed), 13-2
Turret lathe tools, 6-20 to 6-21
Turret lathes and turret lathe operations,
10-1 to 10-28
horizontal turret lathes, 10-1 to 10-8
classification of horizontal turret
lathes, 10-2 to 10-4
components, 10-4 to 10-8
feed train, 10-4 to 10-5
feed trips and stops, 10-5 to
10-7
headstock, 10-4
threading mechanisms, 10-7 to
10-8
turret lathe operations, 10-8 to 10-24
boring, 10-17 to 10-21
forming, 10-18
grinding boring cutters, 10-17 to
10-18
taper turning, 10-20 to 10-21
threading, 10-18 to 10-20
horizontal turret lathe type work,
10-21 to 10-24
a shoulder stud job, 10-22
a tapered stud job, 10-22 to
10-24
tooling horizontal turret lathes, 10-9
to 10-17
grinding and setting turret lathe
tools, 10-12 to 10-16
holding the work, 10-11 to
10-12
selecting speeds and feeds,
10-16
using coolants, 10-16 to 10-17
turret lathe safety, 10-1
vertical turret lathes, 10-24 to 10-28
taper turning on a vertical turret
lathe, 10-27 to 10-28
tooling vertical turret lathes, 10-26
to 10-27
U
Units of measurements, 3-8 to 3-9
English system, 3-8
metric system, 3-9
V-threads, 9-9 to 9-10
Valves, 15-14 to 15-25
assembling high-pressure steam valves,
15-24 to 15-25
ball valve, 15-17 to 15-18
constant-pressure governor, 15-20 to
15-23
double seated valves, 15-23
duples strainer valves, 15-23
gate valve, 15-18 to 15-20
globe valve, 15-14 to 15-17
pressure seal bonnet globe vlaves, 15-23
to 15-24
testing valves, 15-25
Vickers hardness test, 4-22 to 4-24
file hardness test, 4-22 to 4-24
Vertical milling attachment, 11-52
Vertical turret lathes, 10-24 to 10-28
taper turning on a vertical turret lathe,
10-27 to 10-28
tooling vertical turret lathes, 10-26 to
10-27
Vertical shapers, 12-12
Vises, 11-7
W
Weldability, metals, 4-3
Wheelhead, 13-4
Wheel speeds, 13-1 to 13-2
Wire-oxygen-fuel spray, 14-2 to 14-3
Workholding devices, 11-7 to 11-11, 13-4
to 13-6
U.S. GOVERNMENT PfWfflNG OFFICE: 1990-731-068/20043
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11