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LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

Class

GAGES AND GAGING SYSTEMS

Gages and Gaging Systems

DESIGN, CONSTRUCTION AND USE OF TOOLS,
METHODS AND PROCESSES INVOLVED

A Treatise and Mechanics' Reference Work upon the Funda-
mentals, Principles, and Practices of Designing, Constructing,
Using and Adapting Gages, Precision Instruments, Indicators,
Squares, Verifying Tools, Test Measurement Instruments
and Micrometers for Use in the Working of Metal Parts
and the Reducing of Surfaces to Accurate Dimen-
sions, Including Descriptions of the Value, Use
and Installation of Gaging Systems, Tools for
Manufacturing Mechanism, Testing Methods
and Measurement Systems for Insuring
the Production of Accurate Duplicate
Parts and Interchangeability in the
Modern Economic Manufacture
of Precision Machinery, Tools,
Punches, Dies and Accu-
rate Repetition Parts
of Metal

By JOSEPH V. WOODWORTH

Author of " Grinding and Lapping, Tools, Method's and Processes" " Dies, Their Construction

and Use," " Hardening, Tempering, etc., of Steel," " American Tool Making and

Interchangeable Manufacturing," "Punches, Tools and Dies for

Manufacturing in Presses"

1908

HILL PUBLISHING COMPANY

505 PEARL STREET, NEW YORK
6 BOUVERIE STREET, LONDON, E.G.

American Machinist — Power — The Engineering and Mining Journal

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ENTERED AT STATIONERS' HALL

Hill Publishing Company, New Tork, U.S.A.

PREFACE

THIS treatise is intended as a reference work and text-book
for all practical men who are engaged in the manufacture of pre-
cision tools and interchangeable parts. It is hoped that all having
to do with the manufacture of interchangeable work will find
in these pages a comprehensive treatise on the design, construc-
tion, installation and use of the most modern gages and gaging
systems that have been evolved in our best American shops.

Throughout the entire book it has been the aim to eliminate
all obsolete practices and methods; and to confine the treatment
exclusively to the design, construction, use and adaptation of the
numerous tools and systems illustrated. It has further been the
aim to make these descriptions as brief and concise as possible,
and always of the most up-to-date and approved methods of con-
struction, but never to the neglect of the fundamental principles
involved.

While a number of the tools taken and methods described are
original, the majority have been selected from the columns of
the American Machinist and Machinery. The author, therefore,
begs to extend his thanks to the publishers of these journals and
also to the writers of the articles collectively, for the valuable
data and information which have made this compilation possible.

It is hoped that the work will assist the present-day mechanic
* in the design, construction, and use of expedient and economical
gages and gaging systems, and that it will also be the means of
increasing the output and efficiency of duplicate machinery, and
at the same time be instrumental in lowering the cost of produc-
tion on interchangeable work.

JOSEPH V. WOODWORTH.

BROOKLYN, N. Y.
January, 1908

CONTENTS

SECTION I

GAGE MAKING; FUNDAMENTALS, PRACTICE, DEVELOPMENT AND EFFICIENCY
OF THE TOOLS

Gages and Gaging Systems — Their Use — Shops in which Gaging
Systems are Unknown — Interchangeability and Measurement Instru-
ments—-Gage Making — Making a Taper Plug and Ring Gage —
Grinding Out Small Ring Gages — Grinding and Lapping a Male Plug
Gage — Preparation of Emery for Lapping Gages — Lathe Attachment
for Facilitating the Cutting of Thread Gages — Measuring Gages when
Threading — Points in Gage Setting — Renewal of Thread Gages —
Indicator for Thread Gages — A Thread-Testing Gage — Making and
Using Gages for Manufacturing Mechanism — Ring Gages — Com-
bination Bench Gage — Different Forms of Pin Gages — Variation in
Size of Work Due to Type of Gage — Some Gaging and Measuring
Methods at the Works of the Westinghouse Machine Company — Limit
Gage Practice at the Works of Ludw. Loewe & Company — Use of
Gages and Indicators in Jig and Fixture Work — Indicating Gage for
Use on Milling Machine — Vernier Method of Locating Work on Milling
Machine — Boring Master Gage Plates from Models — Making Master
Plates for Watches — Use of Gages and Indicators in Accurate Index
Plate Making — Testing Gage for Index Plates — Making Another
Accurate Index Plate i~47

SECTION II

ACCURATE TEST AND INSPECTING GAGES, ELECTRIC AND OTHER MEASUR-
ING MACHINES; TOGETHER WITH SPECIAL INDICATORS FOR INSPECT-
ING DUPLICATE WORK

Inspection Gage for Wall Thickness — Test Gage for Width of Dove-
tail Channels — Decimally Graduated Gage for Dovetail Slide Inspec-
tion — Decimally Graduated Slide Gage for Dovetail Inspection —
Large Micrometer Test Caliper for Marine Engine Liners — A Test
Gage for Large Duplicate Rollers — A Set of Simple Shop Gages —
Gages for Locating Keyseats — The Testing and Comparison of End
Standards of Length — Bar Gages with Plain Parallel Ends — Cylin-
drical Gages — Sphere or Bar with Spherical Ends — Description of
Measuring Machine — Materials Used in Machines — Measuring

viii CONTENTS

Bar Gages with Flat Ends — Measuring Cylindrical Gages — Sensitive
Attachment for Measuring Instruments — A Device for Testing Gages

— A Testing Tool for Fine Work — A Roll Gage — A New English
Type of Universal Limit Gage — A Device for Testing Squares —
Micrometer Heads for Special Gages 48-87

SECTION III

LATHE, PLANER, SURFACE AND UNIVERSAL GAGES AND INDICATORS; THEIR
CONSTRUCTION AND USE

Simple and Inexpensive Lathe Indicators — A Universal Lathe
Indicator — A Decimally Graduated Universal Indicator — A Lathe
and Planer Indicator — To Adjust the Needle of a Surface Gage — A
Tool-maker's Scratch Block — A Cheap Surface Gage — A Surface
Gage and Indicator — Indicators as Applied to Milling Machines — A
Test Indicator — A Test Indicator and Holder — Inclinometer and
Indicator — A Lathe Indicator — A Test Indicator — The Use of Test
Indicators for Testing Work — The R. R. Universal Test Indicator
and Hight Gage — A Scale and Vernier for Fine Adjustment of the
Milling Machine Table — Universal Surface Gage with Micrometer
Adjustment ....'. 88-112

SECTION IV

THREAD, WORM, GEAR TOOTH, DEPTH AND MISCELLANEOUS TEST TOOLS;
THEIR CONSTRUCTION, USE AND ADAPTATION

A Worm and Spiral Gear Tooth Gage — Handy Thread, Worm and
Depth Gage — German Thread Gages — A Piston-Rod Thread Gage

— A Taper Gage — Micrometer Depth Gage — Making an Armature
Segment Templet — Making a Templet — Templets for Planing a Lathe
Bed — A Permanent Snap Gage — Set of Shop Gages — Rod Gaging
Fixture — A Planer Gage — Gages for Textile Machine Work . 113-140

SECTION V

INSIDE MICROMETER CALIPERS AND OTHER GAGES FOR INTERNAL MEASUR-
ING; THEIR CONSTRUCTION AND USE

Making Small Inside Micrometer Gages — An Inside Micrometer —
Inside Micrometer Calipers — Micrometer Gage — - Inside Gage —
Inside Micrometer for Measurements up to Four Inches — Inside
Micrometer Caliper ..V . . • • U '. . . ' : . . . . 141-151

SECTION VI

HIGHT AND VERNIER GAGES AND ATTACHMENTS; THEIR CONSTRUCTION,
VALUE AND USE

Attachments for the Vernier and Dial Test Indicator — Parallel
Vernier Gage — Hight Gage for Testing and Laying Out Fine Work
— A 6-Inch Hight Gage 152-160

; CONTENTS ix

SECTION VII

TRY-SQUARES, KNIFE-EDGE SQUARES, COMBINATION SQUARES, STRAIGHT-
EDGES, TEST AND SIZING BLOCKS, TOGETHER WITH METHODS FOR
THEIR CONSTRUCTION, TESTING, USE AND ADAPTATION

Squares and Squares — How to Produce a Correct Square — Method
of Testing and Adjusting Try-squares — Using Test Blocks in Place of
a Square — Simple Method for Testing a Flat Square — How to Make
a Knife-edge Square — Knife-edge Square with Handle — A Set of
Knife-edge Tools — A Knife-edge Straight-edge — Use of the Com-
bination Square — Parallel Motion Straight-edge — Adjustable Sizing
Block — The Making of a Real Square — A Precision Square — A
Remarkable Surface Gage — A Micrometer Hight-gage . . . 161-195

SECTION VIII

OUTSIDE MICROMETER CALIPERS, TOGETHER WITH THEIR ATTACHMENTS
FOR SPECIAL MEASURING AND GAGING

Micrometer for Screw Threads — Measuring External Screw Threads
with the Micrometer — An Equating Micrometer — 6-inch Beam Micro-
meter— 10 x 12 inch Micrometer Caliper — How to Make a Large
Micrometer — Large Micrometer Calipers at the British Westinghouse
Works — A Shop Set of Micrometer Calipers — Practical Shop Use of
Micrometers — An Outside and Inside Micrometer — Micrometer Scrib-
ing Block — Micrometer Scales — A Micrometer Gear Tooth Gage —
Micrometer Attachment for the Lathe — Micrometer Caliper for Measur-
ing the Radius of Spindle Drills and Similar Pieces Impossible to Measure
Directly — A Micrometer Stop — Testing Machine Tools with a Mi-
crometer Caliper — Testing the Accuracy of a Lathe without Special
Tools — Johansson Gages 196-233

GAGES AND GAGING SYSTEMS

SECTION I

GAGE MAKING; FUNDAMENTALS, PRACTICE, DEVEL-
OPMENT AND EFFICIENCY OF THE TOOLS.

GAGES AND GAGING SYSTEMS — THEIR USE

WONDERFUL indeed has been the progress made during the
past fifteen years in the production of interchangeable machine
parts, and repetition articles of cast, machined, punched and
stamped metals. Now it goes without saying that this progress
is due more to, and has been directly brought about through, the
introduction of gages and gaging systems for verifying measure-
ments and insuring the production of none but perfectly inter-
changeable parts; or at least for the guaranteeing of the parts
coming within an allowable limit of variation.

In the development of gages and gaging systems we may trace
a line of mechanical development, efficiency in the operation of
machinery and tools, and the elimination of hand labor that is
simply phenomenal. It may therefore be stated without fear of
contradiction that the perfection of the modern interchangeable
manufacturing system, the cheap and rapid producing of accurate
jigs, tools, dies, and fixtures for machining and producing repe-
tition parts, could never have been attained but for the develop-
ment and introduction of the numberless varieties of testing and
gaging instruments which have to-day been adopted in the most
progressive shops where accurate duplicate work is produced.

In this and the sections which follow, it is our object to illus-
trate and describe the design, construction, use and application
of gages and measuring instruments, which may be adopted to
advantage in numberless machine shops and manufacturing
establishments throughout the world, to there supersede hand
labor in the production of metal parts and to also insure the
verification of their interchangeability.

2 GAGES AND GAGING SYSTEMS

While the use of gages has progressed wonderfully in the
larger manufacturing establishments and is becoming more
generally understood and appreciated every day in the smaller
ones, there are nevertheless many others wherein their proper
design and construction, together with their value and applica-
tion, are not understood. In such shops where these error de-
tectors are not used, tools, parts of machines and small articles
of metal are being laboriously brought down to interchangeability
by hand work, and then tested for accuracy by tedious and un-
reliable methods; and the same labor could be accomplished in
one fourth the time by means of suitable gages of inexpensive
construction placed in the hands of workmen, who should be
taught how to use them properly.

Aside from the reduced cost of producing machine parts and
articles of metal, which invariably results through the introduc-
tion of a proper gaging system, the increased efficiency of the
articles produced is a factor that has to be considered.

Manufacturers, managers and superintendents of machine
building and metal working plants should realize once and for
all, that unless they install an up-to-date gaging system and place
properly constructed gages in the hands of their operators, the
production of parts that will interchange at any and all times and
places is impossible.

SHOPS IN WHICH GAGING SYSTEMS ARE UNKNOWN

We have inspected a great number of establishments all over
the United States, and we have been employed in them also; from
the small back-loft jobbing shop to the great machine works; and
we have come across a wonderfully large number wherein the
proper use of gages and gaging systems was unknown and unheard
of. Therefore, we state that if any superintendent of a shop
wherein the use of modern gages has been ignored will make a trip
of inspection through the departments of the works which he
directs, he will not have proceeded far before becoming possessed
of a painful realization that his concern is paying for a lot of unpro-
ductive labor. If he is at all progressive he will then give up some
of his time to the study of gaging systems, to a gaining of a proper
knowledge of the use of gages, and, afterwards, to the introduc-
tion of a proper system of gaging in his departments. More and

GAGES AND GAGING SYSTEMS 3

better work will be the result of this innovation, because inter-
changeability and efficiency of the articles and parts will be
guaranteed before they leave the hands of the machine operators.
There will then be no chance for inaccurate work leaving the
shop; there will then be no opportunity for the assembling of
inaccurate parts into machines or tools. Lastly, economy will
result through the cutting out of operations formerly requiring
skilled help to perform, and through the elimination of much
hand labor. The operator's skill will become an ineffective
factor, except with regard to the quantity of the output, because
the use of gaging tools will insure the production of perfect
parts.

INTERCHANGEABILITY AND MEASUREMENT INSTRUMENTS

From a mechanical point of view it may well be said that we
are living in an age of interchangeability brought about through
the use of and perfection of instruments for measurement and
detection of error. Never before have mechanics and manu-
facturers, and in general has the world of industry, made use of
gages and gaging systems as it is doing now. And there is small
wonder for this state of affairs, for these useful tools in all their
different phases have proven to the satisfaction of the greatest
mechanical economists of to-day that they are instruments that
work for the reduction of cost of production, the perfect efficiency
of products, and the education of, and increasing the skill of, the
productive workers.

Of course, to those who are unfamiliar with the gage and its
modern application, the statements contained in the foregoing
may appear extravagant; but one has only to inspect a modernly
equipped and perfectly operated manufacturing plant wherein
accurate machinery is built in large quantities, to become con-
vinced of the surprising rapidity with which the machine tools
in use therein turn out accurate work in a steady stream, — with
the operators simply occasionally testing a piece with their measur-
ing instruments, — through the use of gages and the proper
installation of gaging systems.

Of the many different kinds of gages, the ancient snap and
plug gages are the most widely known and used. The reason for
this, we might say, universal use of these two types is, that almost

4 GAGES AND GAGING SYSTEMS

all work that requires the use of various other kinds of measuring
instruments requires the use of one of these two first.

GAGE MAKING

In gage making, as in the construction of all verifying instru-
ments, the fundamental quality that works for success, and upon
which all subsequent results depend, is accuracy. This the
mechanic must always keep in mind from the very moment he
cuts off the stock until he has concluded the finish lapping. If
any error does creep in during the construction of a gage it will,
in all probability, mean a great deal of spoiled work if it is allowed
to get by unheeded, and all subsequent care in performing the
remaining operations toward completion of the tool will not avail
in eradicating the error. Of course, if the error is such that upon
investigation it is ascertained that it will not affect seriously the
interchangeability or limit of variation allowable in the parts
upon which the gage is to be used for measurement verifying,
then the case is different, as the defect will have no effect in
preventing the attainment of what the tool is required to in-
dicate.

MAKING A TAPER PLUG AND RING GAGE

In order to lay before the reader the methods of gage making,
it will be well to take up and explain in detail first the making of
a small taper plug and ring gage, as in the construction of tools
of this type, accuracy, skill, patience, and workmanship of the
highest order are absolutely necessary.

Of the steel question we will simply state that no grade of
steel, however good, is too good for gage work; therefore secure the
very best grade of steel in the market. The expenditure of a few
cents per pound over the usual price should not deter one from
procuring the very best, when it is considered that the cost of
material however great is not to be compared with the cost of
labor that will be necessary to finish the tool. Besides, a very
small defect in the raw material will often not make itself evident
until much expensive work has been done; then, as the tool is of
no use, the loss is great, A steel that can be depended upon in
annealing, hardening and tempering; a steel that will not shrink
or warp excessively; a steel that when hardened will have the
minimum of spring in .it; that is the steel to use for gage work.

GAGES AND GAGING SYSTEMS 5

The fact is well known that it is extremely difficult to pro-
duce a perfect taper plug and ring gage of special size. Of course,
in standard sizes of these gages, they may be had of manufac-
turers with their accuracy and efficiency guaranteed, because these
people make a specialty of manufacturing lines of such tools,
and their workshops are fully and splendidly equipped for turning
out such tools in quantities.

In the making of a special size of taper plug and ring gage,
it is quite impossible to secure a perfect fit by simply lapping the
tool in the ordinary manner after hardening. This is so because
the diameter is so small that it is usually quite impossible to use
a wheel to grind it; therefore it becomes necessary to use the
diamond charged lap to finish it. This lap is not used in the same
manner that the ordinary lap is worked: instead, it is used in a
manner similar to the use of a wheel for internal grinding, the
diamond-charged lap being placed in a traverse grinder or a bench
lathe, and with the female gage held in the chuck of the lathe,
it may be ground easily and accurately, care being taken not to
crowd the cutting qualities of the lap. The result of forcing the
cutting of a diamond-charged lap of this kind is a finished gage
that is "bell-mouthed."

When using the diamond-charged lap for work of the kind
above indicated, it will always be found best to keep the lap well
lubricated with kerosene oil. Lubricated in this manner the
lap will be found to cut much more freely than if used dry. The
results will also be much more satisfactory.

The diamond powder used in charging laps for grinding gages
may be had in different grades, each grade being known by a
number. On fine grinding, No. 5 will be the best to use. On
ring gage work, however, the grade known as "ungraded"
answers all purposes in a most satisfactory manner.

GRINDING OUT SMALL RING GAGES

When grinding out very small ring gages, necessitating the
use of extremely small laps, it is quite difficult to ascertain if the
lap is doing any cutting as the work revolves. In order not to
take advantage of this to crowd the lap unknowingly, a little
tool known as a "transmitter" comes in handy. This "trans-
mitter" can be quickly and easily made of a piece of, say, No. 29

6 GAGES AND GAGING SYSTEMS

drill rod, one end being split for about half an inch up, and its
two parts spread so that they will straddle the spindle of the
traverse grinder. On the other end of the rod fasten a piece of
wood shaped in a neat and comfortable manner so that it will
rest against the ear of the workman. This arrangement will act
as a telephone, and indicate to the operator when the lap is
removing material inside the gage.

After a taper ring gage has been made, it will be well to make
a perfect lap of the right taper and lap just sufficient to remove
the marks left by grinding, which are usually very slight.

GRINDING AND LAPPING A MALE PLUG GAGE

The male or plug taper gage is more easily made and finished
than the female. It can be more easily handled and can be readily
ground in a universal grinder. It can then be lapped with a
piece of babbitt that has been finished off perfectly straight, and
the finished surface charged with emery.

In the making of sets of these gages the plug gage is usually
made first. This is done so as to be able to use it as a reference
gage when grinding out the female gage. However, when the
mechanic is supplied with a model to which to make the tools,
then the female gage is made first and the plug afterwards fitted
to it.

PREPARATION OF EMERY FOR LAPPING GAGES

An essential necessary to the workman who desires to become
a first-class gage-maker is a thorough knowledge of the proper
preparation of the emery for lapping. It should be prepared in
the following manner:

Take a quantity of flour emery — say about five tablespoon-
fuls — and mix it with a cup of good lard oil. Thoroughly mix
the two materials together and allow the mixture to stand over
night. In the morning pour the mixture off into another cup,
and take extreme care not to disturb the settlings, as these set-
tlings are composed of large grains of emery and should be thrown
away. Repeat this pouring operation three or four times, and
the result will be a mixture that will produce an elegant finish
on the surfaces of both male and female gages.

GAGES AND GAGING SYSTEMS

LATHE ATTACHMENT FOR FACILITATING THE CUTTING OF THREAD

GAGES

When the last cuts are taken on the thread, it must be within
one ten-thousandth of an inch. For this reason a large disk,
shown at a, Fig. i, is of service. It should be as large as the
lathe will permit; in this case it is 4! inches in diameter and | inch
wide on the face. It is turned out -j8g inch from each side to
make it light and neat in appearance. The disk is fastened to
the cross-feed screw with a knurled screw, and is graduated in

FIG. i. — Thread Cutting Attachment.

250 divisions, and stamped on each side of the zero line from o to
125. Arm b is made the same radius as the top of the disk, and
fits the hub of the cross-feed bearing. It is split at the end and
clamped stationary with a machine screw. The graduations on
top are ten in number, and occupy the same space as nine divi-
sions on the disk, and for convenience in reading are stamped
o, 1,2, 3, 4, 5, 6, 7, 8, 9, o. Accordingly, when a line on the disk
coincides with the first line of the vernier, the next two lines to
the right differ from each other one tenth of the length of a divi-
sion on the disk, the next lines differ by two tenths, etc. This
design gives the thread chaser a positive position when feeding

8 GAGES AND GAGING SYSTEMS

in for a finishing cut, while with the ordinary micrometer dial to
feed in less than one thousandth of an inch is a case of guess work,
and the consequences very likely are that the tool feeds in too
far, the chaser begins to tear, and the thread gets rough and
loses the correct shape and lead. The chaser should be filed on
both sides the same angle as the thread, so it will start and end
with a full thread, and not more than three threads should remain
on the chaser; then it should be hardened in an open fire and
drawn to a light straw.

Another good attachment for thread gage cutting is the sta-
tionary tool-post c, Fig. i, which takes the ordinary style of
chaser. The post is fitted rather freely to the T-slot in the tool-
block and clamped with two machine screws and two nuts d.
A set-screw at the top and another at the side clamp the chaser,
and after the tool-post has been once located and set square, the
chaser will always be located properly after grinding. Where a
tool-holder is used with a removable threading tool, this tool-post
is not required, as the chaser point will drop squarely into its
seat after grinding.

MEASURING GAGES WHEN THREADING

A good method for measuring the thread when finished is to
measure in the thread angle by using an ordinary micrometer
and wires of different diameters. To measure large threads,
procure an ordinary micrometer head from any of the manu-
facturers of measuring instruments, making a C-shaped frame
like an ordinary micrometer body, except that the anvil should
be ii inches in diameter, and the frame flat on the bottom
so it will stand upright; bore a hole in the top of the frame
to fit the micrometer head, and at the same setting turn off
the face of the anvil. Great care should be taken, after harden-
ing the anvil in grinding and lapping, that it is perfectly square
with the micrometer stem.

POINTS IN GAGE SETTING

When cutting a screw plug gage it should be roughed out with
a single-thread tool, within .002 inch, and then merely finished
with a chaser so as to prolong the life of the chaser. It has been
found when chasing that the lead of the lathe is not in all cases

GAGES AND GAGING SYSTEMS 9

exactly the same with each cut. To make sure that the lead is
perfect when the last cut is taken, go over the work three times
with the chaser in exactly the same position, and by using a mag-
nifying glass see whether the tool cuts any at either side of the
thread; if not, then the lead is all right. The chaser should never
be fed in more than .0003 inch with the first cuts, and .0001 inch
with the last two cuts, to assure a smooth thread, and it is ad-
visable when cutting to keep the screw well lubricated with lard
oil, and for this purpose a square tin box and finger brush for the
oil may be kept under the chaser.

A ring thread gage is made in a similar manner, but it is never
finished with an inside chaser, except where such is required,
where taps are not at hand, After being roughed out with the
chaser it is finished with two or three taps with a difference of
two thousandths in diameter. On smaller ring gages inside
chasers cannot be used, but a set of taps, six in number, are used,
these varying in diameter, one from another, by from two to five
thousandths of an inch.

RENEWAL OF THREAD GAGES

An item which we think will be of interest is the renewal of
thread gages, with which no doubt we have all had the same
difficulty. Three plug and ring gages are made at the start, all
on the same lathe, and hence all alike. The trouble begins when
the foreman brings the manufacturing or the inspector's gage
with instructions to renew the plug, as the old one is worn below
the standard size. The old plugs were made some time ago.
Perhaps you were not around when they were made and do not
know what lathe was used, or the plugs may have been made by
an outside firm. As the pitches of lead screws on different lathes
are seldom alike, it is necessary to find a lathe to cut the thread
nearest to the master plug. Should a lathe be used that has an
error in its screw of a couple of thousandths in the length of the
thread on your master plug, trouble will follow. Making the
new plug with .002 for lapping, then hardening it and lapping it
to accurate size, it will start in the master ring gage a perfect fit,
but on screwing it in a few threads it becomes tighter, and by the
time it is half to three quarters through the ring gage, it fetches
up solid. You take it out and caliper it, thinking you may have

GAGES AND GAGING SYSTEMS

lapped it a little taper, but finding the plug perfectly parallel,
you may suspect that the master ring is a little bell-mouthed on
one side and try the plug in the opposite side of the ring gage, only
to find it acts in the same way. What is the trouble? Nothing
but a slight error between the two leads. Should an attempt
be made to lap it enough to bring the lead on the plug the same
as on the master, the result would be a very poor fit when only
a few threads are entered in the ring gage.

INDICATOR FOR THREAD GAGES

We find we cannot make a good job of a plug and ring if the
variation in the two leads is more than .0003 in the length of the

FIG. 2. — Indicator for Thread Gages.

thread on the plugs. To overcome this difficulty, we made a
little tool, or indicator, shown in Fig. 2, for comparing the lead
of any lathe screw with that of the master thread plug. Putting
a dog on the master plug, placing it in the lathe and holding the
indicator in the tool-post, with the lathe geared to the proper
pitch, we place the indicator against the side of the thread on the
master plug hard enough to bring the pointer to the zero mark,
and then start the lathe very slowly in order to watch the pointer.
If it remains throughout the whole length of the master plug at
zero, one may be sure that he will be able to make a plug on that
lathe that will not fetch up tight when half way through the
ring gage.

The proportions of this indicator are such that it multiplies
100 to i ; thus, .001 of an inch in a thread will show .100 of an

GAGES AND GAGING SYSTEMS n

inch on the graduated plate. A zero mark is placed at each end
of the plate, the graduations reading each way and marked i, 2,
3, etc., thus reading, .001, .002, etc. The levers swing on pivots
with 6o-degree points, which are adjusted by fine small, fine-
thread screws, acting as the lower bearings of the pivoted levers.
A small coil spring encircles the rear pivot, and bears against the
last lever to maintain proper pressure. When the indicator is
brought against the thread, it wants to bear hard enough to make
the last lever stand at zero.

This indicator is also a very useful tool for finding if a lathe
will cut a micrometer screw. Take the screw out of a micrometer
which is known to be right, and remove the barrel from the screw.
Chuck a piece of steel or brass in the lathe to be tested, and bore
the end to fit the measuring end of the micrometer screw with
the thread projecting. Gear the lathe to 40 pitch and apply the
indicator, and you will soon know if a micrometer screw can be
cut on that lathe.

It is often good policy when making thread plugs and rings,
to rough them out without cutting the threads, and harden them
as if they were finished, and then anneal and cut the threads.
This process no doubt does away with a lot of expansion and
contraction of the steel in the second hardening. Some like this
method, others do not. We have had very good success with it.

A THREAD-TESTING GAGE

A very efficient thread-testing gage has recently been patented
by the Dresdner Bohrmaschinen fabrik A. G., formerly Bern-
hard Fischer & Winsch, of Dresden, Germany. The handling of
this new device, as shown in Fig. 3, is simple and easily learned.
Screws can be tested by it not only to any degree of accuracy,
but the external diameter, diameter at a root of thread, pitch,
and form of thread may also be ascertained.

The testing gage, Fig. 4, comprises two hardened and ground
members parallel to one another, solidly connected by croLS-
pieces having large contact surfaces and screws. In one of the
members A, the shape and depth of the thread has been accurately
worked, while the adjoining surface B corresponds to the external
diameter. On the opposite ends of the gage, both legs are smooth,
spaced apart the minimum width admissible for the external

GAGES AND GAGING SYSTEMS

diameter of the screw. These sizes are indicated on the gage
for each size.

The gage is used as follows: One first tries to introduce the
screw between the two smooth terminal surfaces C of the legs;
if it enters the external diameter is too small, so that the screw
being unavailable need not further be tested. If, however, the
screw does not enter, the test is continued on the opposite end.
The screw should readily fit into the gage A, Fig. 4. On entering
the point of the screw, it is ascertained whether the pitch and
shape of the thread are correct. If the screw can be introduced
at B from the side and does not fit in A from the front, its external

FIG. 3. — Thread -Testing Gage.

diameter is correct, but the pitch is not. Screws having the
threads that are not stretched or otherwise deformed do not
pass through A.

MAKING AND USING GAGES FOR MANUFACTURING MECHANISMS

To-day, when a piece of mechanism or a machine is perfected
and ready for manufacturing, the first thing to be considered is
the making of the gages, which is oftentimes a very expensive item,
especially when the mechanism is of an intricate nature. To
obviate errors in the gage making is a very essential point in this
class of work, as an error in one gage may affect the accuracy of
others, or, in other words, this inaccurate gage may be used as a

GAGES AND GAGING SYSTEMS 13

master to make others too, they in their turn being used on different
parts of the mechanism. Thus the error may be multiplied a
number of times before being detected, and when at last found it
is oftentimes a difficult matter to correct it, as it may be that
that same error has by that time established a size of its own to
which many other gages have been made, and to rectify it may
mean the overthrowing of all the gages that have followed the
making of the first incorrect one. So it is obvious that the great-
est foresight and skill must be exercised when making the masters.
It happens many times that a man is given a gage to make, with
orders to get it as nearly correct as he possibly can. The tool

FIG. 4. — Thread-Testing Gage.

may be nothing more than a distance gage for locating one hole
from another, and, moreover, it may be that the second hole is
only a screw or clearance hole. The tool-maker criticises the
foreman's orders for requiring unnecessary exactness, but the
foreman knows why he gave those orders. He sees, perhaps,
that he must use that second hole as a gaging point to locate
another or third point from, as the gaging of this from the first
hole would require an unpractical gage; or there may be some
obstruction in the way so that he cannot avoid measuring from
the second hole. We do not advocate, nor is it advisable to use
more than one point on a job to gage from, but oftentimes it
cannot be avoided.

GAGES AND GAGING SYSTEMS

RING GAGES

We wish to mention right here a point which has often been
brought to our notice, and which, while having nothing to do with
the accuracy, does concern the construction of all classes of limit
gages. Take, for instance, the ring gage shown in Figs. 5 and 6,
having two hardened and lapped bushings, one in each end of the
large knurled ring which acts as a holder; there is a difference of
.001 inch in the inside diameter of these rings, or .0005 inch limit
each way from standard size. The knurled ring is marked with
the respective sizes, and on the ends are stamped "Go" and
"Not go." Now these little words tell at a glance which way the
gage is to be turned, but we think the words are not sufficient.

n R

No^Go

FIGS. 5, 6, 7, and 8. — Limit Gages.

A man working on a machine picks up that gage and uses it,
perhaps, many hundred times a day, and without taking the
trouble to look at the lettering he will try it on the work, turning
it end for end, may be, to find that neither end will go on the
work. Now if that same gage was made, as in Fig. 7, so that
the large end marked "Go" was distinguishable in form from the
small end, the man manipulating the gage would, when picking
it up, naturally turn it so that the big end could be tried first;
if that would not go on he would know it would be useless to try
the other side. We have been requested by several men to
chamfer one of the edges of such ring gages for just that reason.
There are some limit gages made as shown in Fig. 8, and on such
it is not necessary to follow the above practice as their position
need not be changed to discern the respective sizes.

GAGES AND GAGING SYSTEMS

COMBINATION BENCH GAGE

Fig. 9 shows a small combination bench gage used for testing
the diameter of a ball, also at the same setting showing if the
hole is concentric with its outer diameter; this last named opera-
tion is accomplished by a lever, the end nearest the fulcrum

FIG. 9. — Combination Bench Gage.

being hardened, ground and lapped to fit the hole in the ball,
while the other end multiplies any eccentricity of the hole, the
ball itself being held central by a snap gage fastened on the main
plate.

DIFFERENT FORMS OF PIN GAGES

Pin gages are made in many different forms and, are often
used as limit gages. They are employed mainly in gaging sur-

10. — Pin Gage.

faces that are obscure — say at or near the bottom of a hole.
Fig. 10 shows such a gage constructed for determining the depth
of a hole. It is composed of two plates, a and b, which are cut
away so that they will have a three-point bearing in the hole;
both are hardened and ground, and plate a has a tapped hole
through its center, a hole in which the handle is a press fit, this
handle holding both plates in alignment. The three pins d are
hardened and lapped at both ends, and there is a small collar on

GAGES AND GAGING SYSTEMS

each against which the spring acts, giving them a downward
pressure. The plate b has its outer diameter turned and ground
so that it fits about one third of its width into its hole, while the
remaining part rests on top of the work. The top face of b
is lapped to a level surface. When the gage is placed in the
hole to be tested, the lower ends of the pins come in contact with
the bottom of the hole, and by a little pressure on the handle
the upper plate is then forced down to its seat on the work, the
pins projecting through the holes in this plate, unless the hole
is of proper depth, when the tops of the pins must be perfectly
level with the top face of b.

Fig. 1 1 shows another style of pin page, this one being con-
structed for gaging the recess shown in the accompanying piece of
work. It is composed of the body e, which is hardened, ground
and lapped on its two flanges, and has a straight hole through

FIG. ii. — Pin Gage.

its center, also lapped out, to receive the hardened and ground
plug /, which in turn has an eccentric ground on one of its ends,
this operating the gaging pin g which is held against the eccentric
by a small spring. The small screw b engages in a slot milled
into /, and allows the latter to make a half turn. Secured on the
end of / is a knurled head, one end of which is turned to form a
flange whose diameter coincides with -the end of e; on these two
flanges are zero, or limit lines, as the case may be. The location
of these lines is governed by the length of pin g, the depth of the
cut to be gaged, and the throw of the eccentric.

Fig. 12 shows a very simple gage which has several advantages,
one of these being that the original size of the gage can never be
lost. The two collars ii are hardened, ground and lapped to the
required thickness, thus the size of the gage is established and
can be maintained with very little trouble. On these two collars
are held two plates of hardened steel, one side of each being
ground and lapped and this side resting on the collars. To com-

GAGES AND GAGING SYSTEMS 17

pensate for wear the hardened plates are removed and relapped,
so that they will be perfectly straight, and are then replaced
without in any way affecting the gage size.

Lastly we endeavor to show a gage that is extensively used
for testing the size and parallelism of a hole, and mainly adapted

FIG. 12. — Simple Test Gage.

for holes that are at least 3 inches in diameter and of unusual
length. Its construction is as follows:

Part ;', Fig. 13, is a head into which screw the three sleeves k
and the tube /. The latter is a piece of seamless steel tubing
carefully straightened, and with one end bored out to receive the
hardened and lapped bushing m, and the other end bored to

FIG. 13. — Three-Point Test Gage.

receive the micrometer nut. On this end are located also gradua-
tions similar to those on a micrometer. One end of rod n acts
as the micrometer screw, while the other end is hardened and
ground and lapped to a running fit in bushing m; this same end
is ground and lapped off to a perfect 45-degree cone, which acts
on similar ends on part o, serving as the measuring rods, these

GAGES AND GAGING SYSTEMS

being hardened, ground and lapped and the largest diameter
fitting in the hardened and lapped bushing p, while the smaller
part slides through the nut q. The spring r tends always to hold
rods o against n, and part s serves to hold the micrometer end of
the gage in alignment, it being a sliding fit on tube /.

VARIATION IN SIZE OF WORK DUE TO TYPE OF GAGE

The following is a summary of some experiments made in
connection with a limit gage system shown in Fig. 14, which we

FIG. 15. — Plug Gage,

were called upon to lay out for a large Austrian iron works. The
gages were to range from 6 millimeters (| inch) up to 250 milli-
meters (10 inches); but we decided to replace the heavy and
extensive plug gages, Fig. 15, with the cheaper flat bar gage,

FIG. 1 6. — Flat Gage.

Fig. 1 6, in sizes from 2j to 6 inches, and with the spherical end
rod gages, Fig. 17, in sizes from 6 to 10 inches.

Having grown cautious by experience in the shop, we made
trials of 2^-inchx holes with all three kinds of gages after the
following plan:

Three holes of nominally the same size — 2 J inches — were
commercially made: Hole i to a plug gage, Fig. 15; Hole 2 to a
flat gage, Fig. 16; Hole 3 to a rod gage, Fig. 17. Hole i was so
made that the go-in end of the plug gage passed with a good
sliding fit, feeling friction all over. It is generally assumed in
such cases that the hole must be at least 0.005 millimeter (about

2, 5. S. S S. 2. S 3 2. 8 § S 8 8 S § § S 8 § §

QOOOOO O O 0000 0000000000

5.s
I

! a
s

-s—

1 1 1 & 3-

5-5-

3. 2- §

20 GAGES AND GAGING SYSTEMS

0.0002 inch) larger than the gage. When the same hole i was
tested by the flat gage, the go-in end of this gage fell easily through
it, and the rod gage passed still more easily, whereas the small
end of the flat gage goes into hole 3, an absolute proof that the
difference between a plug gage and its hole must be greater than
is generally supposed. To be sure, larger new gages, Figs. 16,
17, were made, till we felt the same friction by putting them
by hand through hole 2, and found that they ought to be made
0.012 millimeter in the case of Fig. 16, and 0.02 millimeter in the
case of Fig. 17, larger than the corresponding plug gage.

The gage system shown in Fig. 14 was consequently laid out
with the flat and rod gage dimensions increased in reference to
the plug gage measurements, as illustrated by the broken line.
The starting point for the system in question was the standard
shaft; it was decided to provide hole gages only for running fits
and for push fits, or those that could be entered by hand or by a

Spherical End

FIG. 17

wooden block, that is, a good sliding fit. There was a very little
need for keying and force fits.

At the same time we found by sharp inspection by the flat
and rod gages, that almost all holes were oblong, i.e., they had
different diameters in different panels. This cannot be discov-
ered by a plug gage, but a plausible reason is the fact that
the plug gage did not enter -where the others did. The whole
thing is not at all astonishing, because everbody knows that the
finest touch (and at the same time the most difficult measurement)
is made: (I) by a rod gage with the rounded points, point touch;
(II) by spherical end rods, Fig. 17, supposed line touch; (III) by
flat gages, Fig 16, supposed small surface touch; (IV) by plug
gages, Fig. 1 5, supposed cylinder surface touch.

We say "supposed" because by consideration the touch of
each group, IV, III, II, I, must go back respectively 'to III, II,
I, o; for it is obvious that each gage must be at any rate smaller
than the hole to be tested, and consequently the two circles of
hole and gage are eccentric, and reduce the touch surface to lines,

GAGFS AND GAGING SYSTEMS

and so forth. And this must be true even for the Whitworth
plug and ring. We all know by experience how difficult it is to
insert a plug into a ring of the same size, say 2% inches. It is
necessary to grease both with the best vaseline, and if we succeed
in entering the plug without using the general tool-maker's trick
of talking to the observer while warming the ring in the mean-
time by the hand, we always see afterwards the interference
colors in the grease, an evident proof that there was no metallic,
but a grease touch between plug and ring, which means that the
ring was larger than the plug. No one risks putting them to-
gether dry; there is no doubt the surfaces would seize one another

at once.

FIG. 18. — Gage for Internal Hole Measurement.

Finally, we inspected the standard ring by the end rod, which
was exactly 2j inches in diameter, and found a much easier fit
than with the standard (greased) plug. We concluded, conse-
quently, that in general manufacturing the irregularities of holes
are so great that in reality for 2\ inches in diameter we get holes
of about 0.02 millimeter (0.007 inch) larger than we supposed.
This additional factor is smaller for small and greater for great
diameters.

Because we started with the Whitworth plug and ring, we
tried to design an instrument for internal hole measurements,
which is illustrated in Fig. 18. The tool is manufactured by the
Loewe Co., Berlin. The flattened balls a which serve to bring

22 GAGES AND GAGING SYSTEMS

the pressure of the wedge b without pinching to the small rods c
which are very carefully fitted to their rods without play, are only
intermediate pieces to secure a correct connection of the different
parts. The two thumb-screws serve to fix the end pieces for
testing snap gages, explained later on. The inclination of the
wedge is i to 100, the pitch of the screw d is i millimeter, and
the micrometer head has 100 divisions; thus we can read o.oooi
millimeter change in the distance of the two measuring ends.
The original distance is adjusted by a measuring machine, and
then the instrument is put into the hole and readjusted, until the
inspector feels the touch. At the end the increase is read on the
scale and supervised by the measuring machine. These trials
confirmed the first conclusions. For measuring holes the pieces
c have spherical ends instead of flat ones. The diameter of the
sphere to which the ends are ground corresponds to the smallest
hole to be measured. Because the holes are always larger than
this the inside walls of the hole are always touched by the center
and never by the corners of the pieces c. The spherical rounding
with great diameter has been done for convenience to superin-
spection on the measuring machine. With flat end rods inserted,
the instrument is very useful to replace in the tool-room very
expensive sets of end pieces or combination rods for testing snap
gages of limit systems having different allowances but the same
nominal size. Of course, the measuring machine is an indis-
pensable complement to this sort of gage.

SOME GAGING AND MEASURING METHODS AT THE WORKS OF
THE WESTINGHOUSE MACHINE COMPANY

The basis of all shop gaging done at these works is an 8-
foot Pratt & Whitney measuring machine, with which standard
exact inch rod gages have been made as required until the works
have a complete set of whole inch lengths up to 80 inches. These
rods are used for adjusting caliper gages, shown in Fig. 19, all of
which, except the micrometer heads, are home made. In making
these calipers a good deal of care is given to obtaining exact
alignment of the micrometer head and the anvil screw, but other-
wise they are of e very-day workmanship. The anvil screw has
considerable range of adjustment, and the calipers shown as hav-
ing an I-beam section of yoke — which form a set by themselves

GAGES AND GAGING SYSTEMS

FlG ig._Test Rods and Caliper Gages.

24 GAGES AND GAGING SYSTEMS

— giving thus a range from 10 to 40 inches by the following
intervals:

No.

Inches

10-14

14-18

18-22

22-26

26-30

30-35

35-40

The anvil screws have bastard threads, 10 per inch, though
Mr. Thomas, to whom these gages are due, thinks that were he to
make the set again he would make the pitch 20 per inch instead
of 10. As these are used only for adjusting the instruments so
that the micrometer heads will read zero for the even inches,
they are of ordinary lathe cut accuracy only. The holes in the
yoke end for these screws are not threaded, but are bored a neat
sliding fit, the nuts being half nuts only and arranged to be clamped
to the screws, or quickly disengaged by turning a knurled nut
recessed into and projecting through the web of the I-section.
This, of course, saves a lot of traversing of the screw when it has
to be moved a considerable distance. The yokes are made of
zinc-aluminum alloy, and are surprisingly light. The mixture
is of 30 parts zinc to 70 aluminum, and the castings were made
in the brass foundry of the works without difficulty.

For the delicacy of action a caliper gage must of course be stiff.
When made of steel or iron, however, there is increase of weight,
and while the stiffness is a necessity, the weight is objectionable
because it dulls the sense of touch. The lightness of these in-
struments is such that the largest size may be handled by one
man with perfect ease, and in connection with the appliances to
be described, the gaging of the largest shafts is done by one man
and of course with far greater satisfaction than would be possible
with two men on opposite sides of the shaft being gaged. Those
whose experience is limited to caliper gages of steel can hardly
appreciate the advantage which decreased weight gives. The
calipers are handled with one hand, and the contact of the measur-
ing points with the piece being gaged is felt with the same deli-
cacy and certainty that is customary with smaller work.

GAGES AND GAGING SYSTEMS 25

The method of using these instruments is unique. An end
measure rod surrounded by a wooden case is supported in a
vertical position by a stand having a heavy base. Clamped to
the upright of the stand is a support for two helical springs which
support a stirrup having a hole through its center, through which
the anvil screw of the caliper is passed. The springs hold the
anvil screw in gentle contact with the lower end of the measure
rod, which in this case is 39 inches long, and by adjusting the
anvil screw the micrometer head is made quickly to read zero
when the micrometer head screw contacts with the upper end of
the end measure rod. Should the desired size be a few thou-
sandths above the even inch dimension for a force fit, or a few
thousandths below for a running fit, or should it be desired to
add any friction of an inch to the length of the end measure rod,
the required amount is added by the graduations of the microm-
eter head when, after clamping the head, the instrument is set
for use.

The actual gaging of a 39-inch shaft in the lathe is accomplished
in the manner described in the following: Two light sling chains
surround the shaft and support a pair of springs similar to those
of the end measure rod stand, these springs again supporting a
stirrup which holds the anvil screw in contact with the shaft to
be measured as the previous one held it against the end measure
rod. Held in this way and with the extreme lightness of the
yoke, the gaging may be done with the highest degree of satis-
faction.

The reader will understand that all uncertainties regarding
deflection of the instrument by its own weight are eliminated by
its method of support. Its position is the same — vertical -
when being adjusted as when being used, and the support is at
the same point. Within the set of calipers (Fig. 19) which have
been described, two others will be seen which are made of sheet
aluminum instead of alloy, and which by reason of their extreme
lightness are found to be more sensitive than the others. The
one on the left is shown arranged for gaging bored holes, the
yoke being very convenient for this class of work, as the instru-
ments may be used with the boring bar still in place.

At the left is a cheap but very effective instrument for use in
gaging such pieces as pistons, for which the full depth of yoke is
not needed. The beam is of wood, and the sliding heads of zinc-

26 GAGES AND GAGING SYSTEMS

aluminum alloy as with the full yoke form. In this instance the
heads were first made of bronze, but their weight caused them to
be discarded without fitting them up.

On the floor below the large case will be seen a set of Starrett
inside micrometers, with a full set of extension pieces. These
are of course used for gaging holes.

In the lower right-hand corner of the large case is an appliance
for gaging T-headed shrink links for securing fly-wheel segments.
Fig. 20 shows roughly two segments of such a wheel, the faces a
being machined. The spring b on the bolt c clamps the jaws
with sufficient firmness to hold them in position, and an inside
micrometer d quickly gives the distance between the faces, from
which the deduction of the specified number of thousandths for
the shrinkage allowance gives the length of the link.

Resting on the bottom of the case and to the left of the center
is a peculiar gage for the seats of double-beat poppet valves,
which should be not only of the correct diameter and taper but
also correct with relation to one another. The sharp taper of the
gage will be understood from the fact that the bores for which
they are intended are for the insertion of additional or ''false"
seats on which the valves act. The method of using this gage
is shown in Figs. 21 and 22. The upper seat is first bored until
the upper gage bar — detached from the remainder of the gage
-fits it as shown in Fig. 21, the upper edge of the gage bar
being flush with the faced seat a of the casting. This seat bored,
the parts of the gage are assembled, the connecting pins being a
snug fit in the holes, and the lower seat is bored until the upper
gage bar again fits the upper seat, the lower one fitting its seat
also as in Fig. 22, when the relation of the two bores is obviously
the same as that of the two gage bars.

Standing vertically on the bottom of the large case and near
the center (Fig. 19) are two carefully made strips of steel, each
with an upturned end, and with a row of holes down the center
spaced one inch apart. These are for use in gaging taper pieces
for forced fits, for in the Westinghouse Machine Company's works
many forced fits are taper, the taper used being approximately
yV inch per foot measured on the diameter. Fig. 23 shows the
method of using these strips in connection with an inside mi-
crometer, the taper being greatly exaggerated. The measure-
ments are not made perpendicular to the axis, but to one side

28 GAGES AND GAGING SYSTEMS

of the bore. One point of the micrometer being held by a hole in
the strip, the other is manipulated precisely as though the bore
were straight, as indicated by the dotted arc; and the frequent
spacing of the holes in the strip enables the bores to be tested
for uniformity of taper throughout its length. The dimension
used measured in this way is the one given on the drawing as the
true diameter — the microscopic difference between the dimen-
sion as called for and as made being obviously of no importance.
Mr. Thomas has much simplified the gaging of these taper
holes by a — and otherwise unimportant — change from the
former taper of -jV incn per foot leads to decimals for the diameter
of one of the ends and for most of the intermediate inches. Thus
a hole of 10 inches diameter at the large end, and having a taper
of -IQ inch per foot, will have the following diameters at successive
inches of length when carried out to four places of decimals:

9.9948
9.9896
9.9844
9.9792
9.9740
9.9688

By changing the taper to .005 per inch (-^Q inch per foot is
equal to .005208 per inch) the values become:

9-995
9.990

9.985
9.980

9-975
9.970

The change in the taper thus gives round figures for each
inch of length, and the second set of figures is obviously much
more easily read from the micrometer than the first, and, by
subtracting from the large diameter half as many hundredths as
the piece has inches of length, the small diameter is obtained
directly, whereas with a taper of yV incn Per foot, the small di-
ameter can, in most cases, be found only by calculation. One
advantage of the taper forced fit is not recognized as often as it

GAGES AND GAGING SYSTEMS

should be. With a parallel fit the holes can be compared only
by gaging, whereas with the taper fit the plug may be in its seat
and the two compared, the distance remaining for pressing home
when the parts come to contact forming the best possible check
upon both. Thus with a taper of .005 per inch and an allowance
of .01 for pressing the plug should enter the hole within two inches
of going home. The adoption of the .005 inch taper simplifies
this relation as well as the gaging, as by using this taper, the num-
ber of inches by which the parts should not go home when as-
sembled is one inch for each five-thousandths of pressing allowance.
Fig. 24 shows a form of gage for smaller taper holes, such as
those for cross-head pins, which Mr. Thomas prefers to a full plug.
They are, of course, much lighter than full plugs, and with them

FIG. 24. — Gage for Small Taper Holes.

the holes can be gaged independently on different diameters,
while irregularities in the holes are more easily detected.

Fig. 25 shows a very simple method of testing the accuracy
of the pitch of taps. The upper view shows that the half nut
has but two threads, and by laying the tap in the half nut in
two positions, which by the supposed pitch should be an inch
apart, and then measuring the distance with the micrometer
head, the error may be found and measured.

Mr. Thomas finds, as others have found, that with the best
outfit of gages, the old-fashioned calipers still have their place,
and Fig. 26 shows such a caliper of large size and made of sheet
aluminum. This instrument has a capacity over a full circle of
65 inches and its weight is but 8| pounds. Mr. Thomas calls it
an articulated caliper from the construction of the contact ends.
These are jointed to the jaws so as to present faces squarely to

GAGES AND GAGING SYSTEMS

the work, and one of the contact points is adjustable by a fine
knurled head screw, this screw being used for the fine adjustment
of the instrument.

FIG. 25. — Testing Taps.

LIMIT GAGE PRACTICE AT THE WORKS OF LUDW. LOEWE & Co.

We insert the accompanying diagram (Fig. 27) of limit gage
practice at the Loewe shops, Berlin, Germany. The illustration

0,04

10 16 26 40

100 150 200

Diameter mm.
FIG. 27. — Diagram of Limit Gage System.

is a greatly magnified representation of the difference between a
series of shafts and holes when adapted to different classes of
fits. The abscissas give the nominal diameters. On each side

GAGES AND GAGING SYSTEMS 31

of the nominal size are descending and ascending lines, which by
their distances denote the allowances for running and push fits.
This diagram, while printed in the place we find it mainly for

FIG. 26. — Large Size Aluminum Caliper.

illustrative purposes, may reasonably be taken to agree quanti-
tatively with the practice of the Loewe firm, which has established
its standards by long experiments and experience.

32 GAGES AND GAGING SYSTEMS

USE OF GAGES AND INDICATORS IN JIG AND FIXTURE WORK

Without a doubt the "button method" of indicating holes in
drill jigs is one of the most accurate that has ever been found, as
it has come to be one of the most universal methods in use; but
there are many shops in which the use of this system is confined
to the use of buttons on work that can be swung in a lathe.
When the method has been learned thoroughly, its usefulness
will be appreciated for all available work, not only such as can
be swung in the lathe, but also on work that is too large for the
lathe and which must be done in the milling machine. For this
class of work a special indicator is necessary for setting the but-
ton in perfect alignment with the milling machine spindle. An
example of the usefulness of the button method may be found in
a large leaf drill jig for the side frame plates of a cash register,
with numerous bushing holes in the leaf, which is too large to
swing in the lathe. The location of the holes could, no doubt,
be accurately accomplished in several ways, of which the block
method is one. By this method a square block, with a hole
accurately though its center, is located on the leaf by its outer
sides, clamped in position and used as a jig bushing for the drill.
We1 cannot say that we admire this method as it invites an error
to be made too easily.

Another method would consist of placing the leaf on the mill-
ing machine and using the graduated dials of the machine, but
this method seldom gives accurate results, especially after the
screws have become worn through use. No doubt there are
many more methods that could be mentioned, but we think that
there is no method more accurate than the use of the buttons
and indicator shown in Fig. 28.

INDICATING GAGE FOR USE ON MILLING MACHINE

The leaf of the jig is first "buttoned up," this being a familiar
shop term used when applying the buttons to a piece of work.
It is needless to go into details about buttoning up work, as that
has been fully and thoroughly described in our treatise entitled
"American Tool Making." After this is accomplished, the leaf
is placed on the milling machine against an angle plate, to which
it is held by clamps, as shown in Fig. 29. The indicator is then
placed in the spindle of the. machine and applied to a button,

GAGES AND GAGING SYSTEMS

thus truing it perfectly with the center of the spindle, after which
the hole is made with drill and boring bar.

The buttons most generally used are made as shown in Fig.
30. They are hardened, ground and lapped to fit a ring gage,

FIG. 29. — Use of Indicator in Milling Machine.

i inch in diameter being a convenient size. As will be seen from
Fig. 29, the angle plate rests on two special parallels, which in
turn are bolted to the milling machine table. The object of
letting the angle plate project over the side of the table on the

GAGES AND GAGING SYSTEMS 35

parallels is to permit the insertion of the tool in place of the in-
dicator without disturbing the longitudinal position of the table,
the tools being inserted by the use of the cross-feed screw.

The indicator is shown in Fig. 28. The shank b is fitted to a
Brown & Sharpe small taper. On this shank is milled a tongue
which fits into part a, and is graduated to facilitate setting the
instrument to describe a circle of any diameter from o to 4 inches.
When the zero mark on a is in line with a similar mark on b, the
point of the indicator lever which comes in contact with the work
will revolve on the center. There are eight graduations on each

FIG. 30. — "Buttons" for Jig Work.

side of zero, each line giving J-inch movement; that is, to describe
a £-inch circle the zero line on a would have to be set in line with
the first line from the zero on b, and similarly the other figures on
b denote the circle the point will describe. The tongue and
groove joint is held firm by the knurled nut and bolt g and i.
The body of a is slotted through its center to receive the two
levers e and d, which swing on small pivot screws b having 60-
degree points. A small and delicate spring / tends to hold lever e
to zero on the graduated plate c, and also gives pressure against
lever d, which in turn acts on the work. A little stop-pin above

FIG. 31. — Shank for Indicator.

lever d holds the levers in position when at rest. A detail sketch
of lever e shows the index to be forked to read against graduations
on both sides of the arc plate c. This double graduation permits
readings to be taken from either side, as the indicator turns over
with the machine spindle. The indicator can be used to true up
a hole as well as a projection, and it can also be used to good
advantage in the drill press or lathe by placing the shank b into
a round rod shown in Fig. 31.

We have also seen another method in use for locating work on
the milling machine, which, however, is not as accurate as the

GAGES AND GAGING SYSTEMS

indicator. We refer to the arbor and bushing shown in Fig. 32.
The arbor has its end ground, and lapped to the same size as the
buttons, and a knurled ring is lapped out a nice sliding fit on the
arbor. By placing the arbor in the machine spindle and bringing
the jig button close to, and in line with it, so that the knurled
ring will slip over the button, it is certain to bring both arbor
and button in line. The trouble with this method lies in the
failure of the arbor to always run true with the spindle. Should
a bit of dirt get between the arbor and spindle, as is often the
case, or should the spindle hole not be dead true, the arbor would
not be true with the spindle, and an error would result in locating
the work.

FIG. 32. — Arbor and Bushing for Jig Work.

VERNIER METHOD OF LOCATING WORK ON MILLING MACHINE

Another good method that can be used for accurately locating
distances on the milling machine is shown in Figs. 33 and 34.
Accuracy is obtained by using a Brown & Sharpe vernier caliper
beam and vernier plate instead of the graduated disks. On the
milling machine table a, and into the T-slot, which is intended
for the feed-tripping studs, two bolts marked b are placed. They
project out beyond the nuts which hold them in position about
ij inches, this outer part having been turned to the size of the
root of the thread, and part of it flattened off to act as a resting-
place for the vernier caliper beam c, which is held in position by
two small straps and screws /. The forging g is held in position
by utilizing the forward bolt and nut To, that serve to bind the
swiveling part of the machine. On the top end of g the adjustable
block e is held by a dovetail milled in g, and a slot and small
binding bolt i. On this block e is secured the vernier plate d.
As can be readily seen by running the table to and fro, and
recording the measurements from the vernier, accurate measure-
ments can be made. Accurate up-and-down measurements are
made bv a little extra device clamped to the column of the

GAGES AND GAGING SYSTEMS

H ; '. \? ;."'/' 4

M i| ''i;!::'li: I:"!, i ' UttUM ' '• U ! J \ ' '' ^ . '' " ''^ • ' J.lt UM >

FIGS. 33 and 34. — Milling Machine Practice.

38 GAGES AND GAGING SYSTEMS

machine and end measurement rods of such lengths as the job
required, these rods being used between the knee of the machine
and the part clamped on the column. One more little kink and
this method is complete: By binding a piece of wire around g,
having a loop above to hold a magnifying glass, easy and accurate
reading is obtained. This last-named method is limited in range
and accuracy by the length and accuracy of the vernier.

BORING MASTER GAGE PLATES FROM MODELS

Accurate tool and gage work is required in most factories at
the present time, as the interchangeable system of manufacturing
calls for it, especially where they require the most accuracy. It
is always advisable to make the model first, then the gages, and
last the tools. If tools and gages are made to models instead of
drawings, as in many shops, it is absolutely necessary to make
the gages first, in order that they may be perfect to the model,
as fitting the model to jigs, fixtures and other tools may interfere
with the accuracy of the model. There are some very good
systems in some of our large shops for holding everything to
standard. By one method the first step is to make a model
machine which is as nearly perfect as mechanical skill can make
it. When complete it is assembled to see if it is perfect in all
details, and if found perfect it is taken apart and the gages are
made to fit the parts in the most accurate manner. Three sets
of duplicate gages are always made, one of which goes to the
inspecting department, the second to the manufacturing depart-
ment, and the third is held in reserve and only used as reference
or master gages. This last set acts as a tell-tale to all mistakes,
and as a standard for working gages or tools that may need re-
newal at any future time. Among these master gages are master
plates, which serve to hold standard the size and location of a
number of holes. A very neat way to make such master plates
is as follows: Plane or grind a piece of steel so that it will be per-
fectly parallel and about f-inch thick. Clamp it to the model piece
opposite the side on which the holes in the model were located,
with a thin piece of steel between model and master plate, so that
when boring the holes in the plate no damage will be done to the
model (see Fig. 35). Fit a piece of steel to the spindle of the
lathe, as though it were to be a live center, allowing it to project

GAGES AND GAGING SYSTEMS

beyond the face-plate far enough to be turned off a perfect fit to
the largest hole in the model. Care should be taken that the
face-plate runs perfectly true. After turning the stud to a per-
fect fit for the first hole, the model with the master plate is slid
on and clamped to the face-plate. The first hole in the master
plate is then bored with an allowance of .002 for grinding after
the master plate is hardened. For the second hole select the
next size smaller so that the same stud will answer for all five
holes, and proceed as before, care being taken to have the master
plate securely fastened to the model to avoid any chances of
slipping. After boring all holes in this manner the plate is ready

FIG. 35. — Boring Holes in Master Plate.

for hardening. After hardening the plate is replaced on the
model and the holes are ground out to within .0003, which is left
for the final lapping to size. Fig. 36 shows the work as swung in
the lathe. Time may be saved by making the stud in two pieces,
as in Fig. 37, thus saving the repeated fitting of the taper. The
right-hand piece is soldered into the sleeve and turned off to
form the stud, which, of course, is always turned off in position.

MAKING MASTER PLATES FOR WATCHES

In making master plates for watches, electric instruments,
clocks and similar work, in which the holes in the side plates are
to be held to a standard for the train of gears, and the holes are

GAGES AND GAGING SYSTEMS

too small to grind out after the master plate is hardened, it is
good policy to bore such holes larger than the holes in the model,
and after the master plate is hardened, grind the holes out with
a diamond-charged lap used in the same manner as an internal
emery wheel. The holes are then bushed, the bushing being
hardened and lapped to the same size as the holes in model. A
little piece of hardened drill rod is then placed in the spring chuck
of a bench lathe, and ground to fit the hole in the bushing. The
bushing is then slipped on and ground and lapped to a press fit

Master Plate

FIG. 36. — Jig Work in Lathe.

in the master plate, care being taken that the press fit is not so
tight as to interfere with accuracy of plate.

FIG. 37. — Stud for Jig Work.

USE OF GAGES AND INDICATORS IN ACCURATE INDEX PLATE

MAKING

Making index plates seems but a small item, which no doubt
it is, providing no accuracy is attached to it ; but where accuracy
is essential, it becomes quite a different task. It has fallen to a
tool-maker's lot to make several such plates in which accuracy
was required. His first plate was to have six notches for the
index finger, and he attempted to make it in the milling machine,
depending on a careful use of the dividing head; but when he
proved it up he found an error of .005 in the spacing. Thinking

GAGES AND GAGING SYSTEMS 41

the dividing head might be at fault he tried another and found
about the same error. Ultimately he tested seven heads but
could not get an accurate plate, and came to the conclusion that
he must contrive a more accurate method.

His first method gave very good results, but it necessitated
the making of two plates and a lot of hand work. This method
was as follows: Duplicate plates were placed on a hardened and
ground arbor, and cut in the milling machine between centers
with the most accurate dividing head at hand, one side of slot
being radial and the other at an angle of 20 degrees with the
radial line. After being milled they were placed on another
arbor, which was a neat sliding fit in them, and their relative
position changed, one being turned half way around. They were
then clamped together, and with the aid of a knife-edged straight-
edge, their accuracy was compared, when it was found that the
slots did not register accurately. The high surface was then
carefully scraped down, after which the plates were changed
around to a different position, and the scraping was repeated,
and so on until the two plates could be placed in any of the six
positions and have their slots in perfect alignment with one
another. This method gave one a perfect plate, but we did not
like the making of two plates to obtain one, or the hand-work
that was involved.

Our next plate was made as in Fig. 38, having hardened,
ground and lapped tool-steel pieces a inserted and held in position
by the ^-inch screws b, and by a perfect fit in the slots, which
were in turn milled about J inch deeper than the slots for the
index finger c. One side of these lapped pieces stands perfectly
radial, while the opposite side of the index slot is at an angle of
20 degrees. This style of slot assures the greatest possible ac-
curacy, because when the index finger enters the plate the radial
side of the slot stands perpendicular, thus not easily permitting
any chips to lie on it, while the other side, being at an angle, has
a tendency to force the radial side tight against the index finger.
Should a chip get between the angular side and the index finger,
it would not impair the accuracy of the divisions.

The method employed in making the plate, as well as many
others with different numbers of slots, has proven very satis-
factory. At the start the plate was milled out in the regular
way on a milling machine, using the dividing head to space the

42 GAGES AND GAGING SYSTEMS

slots as accurately as possible. At this same setting the screw
holes were drilled and counterbored so that each one would be
in perfect relation with the others. The plate was then removed
from the machine to await the finishing cut being taken, which

FIG. 38. — Index Plate.

would be but a few thousandths from each side of the slots into
which the hardened plates fit. The machine was then prepared
for the finishing cut as in Fig. 39. A dividing head was selected
of which the worm could be released from the worm wheel, thus
permitting the spindle to turn independently. Most of the latest

GAGES AND GAGING SYSTEMS

44 GAGES AND GAGING SYSTEMS

style heads are constructed in this way, but if one of that pattern
is not at hand, a regular head can be used with the aid of the
wooden wedge tapped in between the face-plate and platen of
the machine to hold it in position, the index crank being used to
turn the spindle, but not for spacing purposes. A large face-
plate was placed on the spindle of a larger diameter than the
swing of the dividing head would admit, thus necessitating the
use of the adapter which comes with every milling machine.
Into this plate six holes were drilled, the spacing being done with
the head itself. These holes were then tapped out to fit 10-32
screws, which in turn held "buttons," care being taken that all
buttons were accurately to one diameter (hardened, ground, and
lapped buttons fitting into a perfect ring gage are the only prac-
tical ones to use). These buttons will be seen in Fig. 39 marked
a. A hardened and ground arbor b was then placed in the spindle
of the head, on the end of which and projecting from the head is
lapped stud b, of the same diameter as the buttons. Another
piece d is held securely on the adapter with a bolt, and in turn
carries another hardened and lapped stud c fitted to it, also of the
same diameter as the buttons. This stud c is the stationary
point from which all divisions are made.

The form of slot shown in Fig. 38 has another advantage, in
that the wear is confined almost entirely to the beveled side where
it does not impair the accuracy of the work. Moreover, the
accuracy being determined entirely by the radial side, the pre-
cision work is confined to that side.

TESTING GAGE FOR INDEX PLATES

For testing up index plates the device shown in Fig. 40 is a
very simple contrivance. It is composed of a cast-iron plate
with a central locating stud, — for locating and swinging the
index plate, a positive stop, — adjustable, a and the indicator b.
The manner in which this gage is used is self-evident.

MAKING ANOTHER ACCURATE INDEX PLATE

Piece A, Fig. 41, we would grind parallel on both faces, then
grind and lap the hole to size, and work from the hole and face of
the index plate. This would detect the error in the blocks if out
of parallel with the hole.

GAGES AND GAGING SYSTEMS

Piece A is mounted on stud B, which is a good fit in A. The
angle iron has a hole for a loose fit for the end of stud B, which
is threaded for a nut. The hole under block d allows one to see

FIG. 40. — Gage for Testing Index Plates.

through when adjusting the blocks at right angles; piece A is
clamped to the angle iron with a strap and screw that enters stud
B; angle C is gray iron and narrow enough to allow to extend out
from the sides to the ground.

FIG. 41. — Making an Accurate Index Plate.

Fig. 42 is composed of a gray iron block D, and a piece of
finished flat steel E, which is & inch thick and worked out to the
outline of piece A, Fig. i, leaving plenty of space. The ends are
beveled, hardened and ground back on face e about a quarter

GAGES AND GAGING SYSTEMS

of an inch. In lapping this edge, make it rounding, not sharp.
Block D is finished on three sides of the sides; top, bottom, and
the face piece E is attached to. This allows you to turn it over
and prove both sides of the index blocks. The dimension x,

FIG. 42. — Index Plate Practice.

Figs. 41 and 42, should be close enough to allow the square to
be used either side up.

Fig. 43 is the old principle of the reversible parallel for testing
a square; parallel F swings on stud G, and is adjusted with the
screws shown at the top, which are pivoted to swing out of the
way to allow the parallel to be reversed end for end. To test

^7)^ -Pivot Screw

FIG. 43. — Index Plate Practice.

the square, you adjust the parallel to the square on one side; let the
parallel remain in this position, place the square at the other
side of the parallel, and it will show twice the error, if there is
any. To test the parallel, reverse it end for end, then adjust to
the square. It should fit the square on both sides of the parallel,
or it will show twice the error on one side if not parallel.

GAGES AND GAGING SYSTEMS 47

With the index plate placed in position on the angle iron,
Fig. 41, blocks a and b are leveled up, and have been found to
have the least amount to be roughed off; these are ground off;
then the index plate is revolved a quarter turn by using the
square in Fig. 43 to square to the surface just ground, and c and
d are ground to the same reading of the index wheel on the grinder
or to a hight gage. Now revolve the index plate another quarter
turn, using" the square again, and at the fourth quarter turn you
have gone around all faces of your blocks. Now take a light cut to
make up for the wear on the wheel from the roughing cuts, and
go around without disturbing the setting of the wheel, and at
the third quarter turn you can prove your square and setting
with a micrometer. Your last surface should be parallel with
the one under it. After going around the second time your
blocks are divided equally each side of the center, but are too
large. You have found approximately how much your wheel
lost in size by the roughing cuts, so you can rough them down
pretty close for the last roughing leaving just enough to finish
with. This leaves nothing to guess at; the errors can be located
and measured, all operations are tested before and after setting
and clamping. The square is used on the index plate face as
well as on the side of the blocks.

If we find that clamping in the way described distorted the
plate, we should drill a hole through stud B, and use a bolt and
nut instead of a cap screw.

SECTION II

ACCURATE TEST AND INSPECTION GAGES, ELECTRIC
AND OTHER MEASURING MACHINES: TOGETHER
WITH SPECIAL INDICATORS FOR INSPECTING
DUPLICATE WORK.

INSPECTION GAGE FOR WALL THICKNESS

IN Figs. 44 and 45 are test pieces for which the gages shown
in Figs. 46, 47, 48 and 49 were made. These tools constitute a

FIG. 44. — Work to be Tested.

set of test and inspection gages of decidedly interesting design,
possessing adaptable features which may be used to advantage
in similar gages for verifying measurements of small, accurately
machined steel parts. All four of the gages are graduated to
indicate variations down to .0005 inch.

The work, Figs. 44 and 45, for which the inspection tools were
utilized, consisted of two parts of tool steel, which were machined
to extremely accurate dimensions and were required to fit or
assemble together perfectly. The part shown in Fig. 44, as may
be seen, has a dovetailed channel milled in one side for its entire
length, and has the web punched out to form a hole at E. This
part, after all milling operations had been concluded, was hard-
ened and tempered; the temper being drawn down sufficiently low
to allow shaving the dovetailed surfaces to finish with "Novo"
steel cutting tools, after which the sides and edges of the part
were ground to limit sizes with a cup-shaped emery wheel in a

GAGES AND GAGING SYSTEMS 49

specially constructed grinder. It was after this operation that
the two gages illustrated in Figs. 46 and 47, were used to deter-
mine the degree of interchangeability attained in the parts through
the various concluding mechanical operations.

FIG. 45. — Work to be Tested.

The micrometer gage shown in Fig. 46 was used to determine
the width of the part from the dovetail to the edges, or the wall,
as is indicated in the lower view, in which is shown a cross-section
of the work in position on the dovetail locating piece L. After

FIG. 46. — Micrometer Test Gage.

gaging one side in the manner outlined, the other side is inspected
by simply reversing the work on the dovetail locator. The draw-
ing of the gage is so clear and self-explanatory that a detailed
description of construction will be unnecessary. F, G, H, I, and
J comprise the micrometer portions, L is the locater, M is the

5°

GAGES AND GAGING SYSTEMS

block upon which it is formed, N the fastening screw and dowels
which fasten and locate it in position on the body of the gage;
P is the base, and O the stem of the gage. Two flathead screws
were used for fastening the gage to the work-bench. All locating
and test parts of the gage were hardened and carefully ground
and lapped.

TEST GAGE FOR WIDTH OF DOVETAIL CHANNEL

The micrometer gage illustrated in Fig. 47 was used for
measuring the width of the dovetail channel in Fig. 44: that is,

FIG. 47. — Micrometer Test Gage.

the distance between points A and B. This gage consists of
base B, which is fastened to the work-bench when in use, stem A,
two slides T T, which have raised angular-faced projections,
which conform to the angle of the dovetail in the work, and the
micrometer portions S, R and Q. The manner in which the
gage is used to determine the width of the dovetail is clearly in-
dicated in the view at right of Fig. 47, a cross-section of the work
being shown in position. By revolving the barrel, by means of
the knurled end Q, the slide T at the right moves back to allow
removing or locating the work; while the revolving of the barrel
in the opposite direction causes the slide T to move out and ex-
pand to the full width of the dovetail channel in the work. The

GAGES AND GAGING SYSTEMS

other side, T, is fixed. A light spiral spring, which is shown in
the plan of Fig. 47, assists the slide to move back readily when
the barrel is revolved and the work is removed or located.

It will be noticed that both gages described in the foregoing
are simple in design and of comparatively inexpensive construc-
tion, when the rapidity with which the work may be handled and
inspected in them, and the required accuracy of the tests, are
considered. In case of wear in any of the precision parts of
either gage, the error may be rectified by simply making suitable
adjustments, provision for which may be seen in the drawings;
thus no difficulty is experienced in maintaining the accuracy of
the tools.

FIG. 48. — Test Indicator.

DECIMALLY GRADUATED GAGE FOR DOVETAIL SLIDE INSPECTION

In Fig. 45 is shown the dovetail slide which is required to
assemble on the part shown in Fig. 44. This piece is also made
of tool steel, is accurately machined all over, is shaved on the
dovetail surfaces, A and B, and then ground on the back. It
was for verifying the interchangeability of this part that the
decimally graduated inspection gages shown in Figs. 48 and 49
were used for determining the exact amount of variation in the
parts from the inner edge of the dovetail A and B, to the ground
edges of the body portion at C and D.

The gage consists of a flat cast-iron base, F, cored at G and
equipped with four steel legs, K K K K. W W is the test and

52 GAGES AND GAGING SYSTEMS

gage portion, and consists of a dovetail piece of tool steel which
is fitted and gibbed into a channel in F, as shown by gib P and
screws O O. This piece is milled away in the center so as to
provide a clearance for the pointer /, which is pivoted on a small
pin at N. The projecting end Q of W is hardened, ground and
lapped to conform to the angle of the shaved dovetail surfaces
of piece, Fig. 45; it is also drilled longitudinally in the center to
accommodate the plunger R, which is fitted to "float" in the
reamed hole. The rounded end of R at 5 rests against the edge
of the pointer. Pin T in the end of the plunger prevents it from
getting away, and the light spring M serves to keep the plunger
out when the work is not against it. Knurled head screw U,
spanned by yoke V and screwed into F, is utilized to correct any
inaccuracies in the precision parts which occur through use and
wear. The graduations for reading the tests are at /, at the
extreme end of F, with the end / of the point matching them.
When the pointer registers at o, the work is up to the require-
ments; if it points at T at the left, the work is considerably too
large; if it points at 5 on the right, the work is .0025 too small.

In using the gage it is placed on the bench before the inspector
and the dovetail slide, Fig. 45, is located on it, with one dovetail
edge resting against the angular face of Q, and the edge D resting
against plunger R; thus, upon the inspector pressing down and
in upon the work the edge forces the plunger R inward, and
therefore causes the pointer to register the reading at /. A
spanner of small diameter drill rod at H H acts as a guard for the
pointer.

DECIMALLY GRADUATED SLIDE GAGE FOR DOVETAIL INSPECTION

In Fig. 49 we have another decimally graduated test gage,
used in the inspection of part Fig. 45. It is used to determine
the exact width of the dovetail portion, from A to B. A base
of cast-iron is machined to accommodate the hardened and ground
angular-faced pieces / and F. Piece / is fastened and located by
screws K K and / /, while piece F is left free to slide in the holder.
It will be noticed in the plan view of this gage that the dovetail
edges G and H of I and E, respectively, are at an angle of a few
degrees with the dovetailed channel in the base; thus as the
slide F is pushed forward the space between G and H decreases ;

GAGES AND GAGING SYSTEMS

and as it is pulled back in the opposite direction the space in-
creases; therefore by simply entering the work so that the dove-
tail part rests between G and H, and then pushing the slide
forward until the work is clamped or held tightly, a reading may
be instantly made by noting the relation of the graduated lines
with zero point 0 at P.

Although gages of the type described in the foregoing may
appear quite simple and easy to construct, considerable skill and
care are necessary in the grinding, lapping and graduating, in
order to produce reliable precision instruments for the inspection
of accurate work.

?0 ir

.•)_

i _

H G

4N i

// \\\

-3 f

F \

E j

i ~J~»

FIG. 49. — Graduated Slide Test Gage.

LARGE MICROMETER TEST CALIPER FOR MARINE ENGINE LINERS

The gage illustrated in Fig. 50 was used for gaging sixteen
liners for four marine engines. The outside diameters of the
liners — 40, 56, 77 and 108 inches — were turned for a press fit
in the cylinders. There were, of course, four gages made, all like

GAGES AND GAGING SYSTEMS

the drawing. The size was taken from the cylinders with the
ordinary gage made of a stick of wood with wood-screws in each
end for adjustment. The gage in the drawing was then set for
the outside diameter from the gage, enough larger to make a
good press fit. As one can see from the drawing, the gages were
made of ordinary iron pipe and fitting, and they cost but little.
The top clamp of each gage was extended out and a hole was
drilled through for a hook. From a column near the front of the
lathe a rope was run up to a wooden bracket, the end of the
bracket running out to the center of the lathe. The rope was

Section on A-B

FIG. 50. — Gage for Marine Engine Liners.

run out to the end of the bracket and then down to the lathe
with a hook on the end, which went through the eye in the top
of the gage. The gage was then hoisted up until the adjustable
screws were in line with the center of the lathe, and then fastened,
so that to try the gage over the liner for size, a helper held one
point on the line on one side, while the machinist raised and low-
ered the gage on the other side.

A TEST GAGE FOR LARGE DUPLICATE ROLLERS

The gage shown in Figs. 51 and 52 was used on a lot of cast-
steel rollers for battleship turrets of the " Kearsarge" type. The
rollers were to go between two tracks on which the turrets re-
volve, and had to be as near alike as they could be made, so the

GAGES AND GAGING SYSTEMS

weight of the turret and guns would be evenly distributed. Tap-
bolts, shown in the end view Fig. 52, hold the V-blocks in place.
They were put in before the V-blocks were planed, and then the
surface plate, with V-blocks in place, was put on the planer and

FIG. 51. — Test Gage for Duplicate Rollers.

set so that one V-block would be planed deeper than the other,
and thus bring the bottom side of the taper roller parallel with
the surface plate. The roller was set in the V-blocks, so the

FIG. 52. — Test Gage for Duplicate Rollers.

distance between the inside of the flange of the roller and V-
blocks at the bottom was equal at each end. The V-shaped
piece E on the top of the roller was planed on the V-side to fit
the taper of the roller. It was then placed on the sample roller,
which was set in the V-blocks already planed, and the top edge
of the V-piece was laid off with a surface gage and planed and

GAGES AND GAGING SYSTEMS

then scraped, the distance between the flanges of the roller and
the ends of V-piece being kept equal. After the rollers were
turned to size they were placed on the V-blocks, the block under
the small end of the roller being one half the taper higher, so
that the bottom of the roller would be parallel with the surface
plate. Plate E was then placed on the roller and the gage F

FIG. 53. — Simple Shop Gages.

moved along the edge of E. If there was any variation in hight
or in taper it would soon show it.

A SET OF SIMPLE SHOP GAGES

The illustration, Fig. 53, shows a plan adopted to provide an
equipment of gages for end measurement. Outside gages A
were made in exact inches between the shoulders a a, and the

FIG. 54. — Keyseat Gage.

blocks B, of which there were two sets made, included sizes from
J to i |f inch by thousandths, and one iTV~inch block. The
latter was used in place of a tV-inch block, which would have been
too thin to hold with the clamp as made. Male gages to cor-
respond were made of square steel and ground to length after
hardening. By this method a large range of accurate gages was
available at a comparatively small cost.

GAGES AND GAGING SYSTEMS

GAGES FOR LOCATING KEYSEATS

Figs. 54 and 55 and 56 show side and end views of scratch
gages for scratching lines on chalked surfaces of the spindles
before they are placed in the fixture, for locating the positions of
keyseats in relation to the shoulders, it being found that when
operators worked from drawings it was almost impossible to
obtain uniform results.

The gages consist simply of light bars with hardened scratch-
pins or points inserted at the proper distances from the ends,

FIG. 55. — Key seat Gage.

and each gage is lettered to indicate the particular size of spindle
for which it is to be used.

Correct depth of keyways is obtained by making use of the
graduated dial of the elevating screw of the milling machine.

FIG. 56. — Keyseat Gage.

A NEW SYSTEM OF GAGES FOR THE PLANER

We present in Figs. 57, 58 and 59 a gaging appliance as
used by the Bullard Machine Tool Co., Bridgeport, Conn. It is
certainly unusual as well as highly meritorious.

The gage is intended for the three slots of boring machine
tables, in which chuck jaws are inserted. For reasons of inter-
changeability as well as economy of production, it is obviously
desirable that these slots be uniform, and this the device secures
with a minimum of labor.

The boring mill tables to be slotted come to the planer with
the lathe work completed, and with a concentric hole through the
center which enables them to be mounted upon a post having a
tongue fitted to the planer table slot in such a manner that the

GAGES AND GAGING SYSTEMS

FIG. 57. — Planer Gage.

work shall be in line with the slot. On the front end of the planer
table is bolted the bracket casting shown in the figures. This
casting has a tongue at a, Fig. 57, fitting into the planer slot. The
initial or plug gage for the chuck jaw groove is seen at b, Figs.
57 and 59, where its shape will be seen to be that of the groove
to be made. It has a tongue c fitting into a corresponding groove
in the bracket casting and is held in position by the knurled
headed bolt d. The bracket is composed of two pieces arranged

GAGES AND GAGING SYSTEMS

;;©

FIG. 58. — Planer Gage.

to slide vertically upon one another at e, Fig. 58, whereby the
vertical adjustment of the gage as a whole is accomplished. The
gage is surrounded by a series of beveled plungers /, one of these
plungers being provided for each face of the plug gage which is
reproduced in the boring machine table. The construction of
these plungers is shown in Fig. 58, where they will be seen to have
a tail g, sliding through a threaded bush b, while a coiled spring
i forces the plug toward the gage a. It will be seen that with

GAGES AND GAGING SYSTEMS

the gage a inserted in the fixture the spring will force the various
plugs to contact with the gage, and in this condition the bushes
h are carefully adjusted until the tails g are exactly flush with
them. The ends of the tails and bushes are carefully hardened
and ground, and of course by applying the end of the finger to
them the adjustment can be determined with a good deal of
accuracy. A thousandth of an inch can easily be split into
several pieces by this method.

With this adjustment made, the plug gage a is removed and
the tool is inserted in the planer. When brought opposite the
different plungers, the tools are adjusted until they press the

LLU

FIG. 59. — Planer Gage.

plungers back to such a point that the tails g and bushes h are
again truly flush, when the tool obviously occupies the same
position as the corresponding face of the original plug gage, and
is correctly set for the finishing cut of the corresponding face of
the slot to be made.

Connected with each plunger will be seen a ball-handled pin j
projecting through a cam-shaped slot in the main casting. These
pins enable the operator to draw the plungers back, and also to
facilitate the placing of the plug gage in the fixture.

It will be observed that the fixture described not only sizes
the slot, but positively positions it as well, and it would seem to
be applicable to a considerable variety of duplicate work done on
the planer.

GAGES AND GAGING SYSTEMS 61

THE TESTING AND COMPARISON OF END STANDARDS OF LENGTH

End standards of length, called gages, are tested and com-
pared with one another by means of measuring machines, made
by many engineering firms both in the United States and Europe.
These machines are identical in principle, and differ little in
form from the original one invented by Sir Joseph Whitworth.
Their principle is that the gage rests against one jaw, fixed, of the
machine, while the other jaw is moved forward by a micrometer
screw until it touches the gage. Compression, more or less, of
machine and gage, is required before any indication can be
obtained that both jaws are firmly in contact with the gage.
These machines will in the future be spoken of as mechanical
touch machines, as distinguished from the new machines called
electric-touch machines. In practice it has been found desirable
to introduce some index of the touching, e.g., a gravity-feeler,
spirit-level, or the raising of liquid in a fine tube.

The weight of the gage, often large, should never — as is
sometimes done — be supported by the grip of the two jaws; for
then there is considerable end-thrust of the jaws, with consequent
longitudinal strain in the machine, in addition to the vertical
strain due to the weight of the gage. If the whole or part of the
weight of the gage be supported by the jaws, though the latter
be parallel to one another initially, they will not be so after being
weighed. The errors which enter into the measurements made
by these machines differ in kind and degree according to the
nature of the gage. There are three kinds of gage.

BAR GAGES WITH PLAIN PARALLEL ENDS

Each jaw has a flat face, and each end of the gage has a flat
face. Each of the four faces has defects in planeness and in
being not strictly parallel to the other three. If in addition a
gravity-feeler be used, it introduces extra errors. To admit so
many errors of unknown amount in the measurement of gages
may be permissible in present-day engineering practice, but it
does not satisfy the demands of exact measurement. Thus to
obtain accuracy, surface contact should be abandoned and point
contact used, and these gages should be measured between two
rounded points or spheres, in which case no assumptions are

62 GAGES AND GAGING SYSTEMS

made as to the perfectness or parallelism of the surfaces involved.
For each point contact we require a more delicate means of per-
ceiving contact than the mechanical one; hence the electric-
touch method is employed. It has been developed by P. E.
Shaw, of England, in a series of researches since 1900.

CYLINDRICAL GAGES

The flat faces of the jaws touch the cylinder with two line
contacts at opposite ends of the diameter of the cylinder. Non-
planeness and non-parallelism of the jaw-faces, as also imper-
fections in the cylinder, introduce errors, though these are less
serious than for Bar gages. Thus for accuracy line contact should
be superseded by point contact, the measurement to be made
between lines or edges on the jaws, the lines being not parallel
with the axis of the cylinder.

SPHERE OR BAR WITH SPHERICAL ENDS

The face of each jaw touches the sphere at a point. Since
the jaw faces are imperfect, error can only be avoided by providing
that the contact of the two faces with the sphere always occurs at
the same places. Thus, for accuracy, contact may be made as
usual between the flat faces of the jaws, if the surface be made
true and contact be always at the same points on the flat faces.

From these remarks it appears that for each kind of gage,
measurement should be made by point contact, the jaws to sup-
port no part of the weight of the gage, and the end thrust on them
to be reduced as much as possible. The method described below
fulfils these conditions, and has in addition the advantage of
being more sensitive than the old method.

DESCRIPTION OF MEASURING MACHINE

The latest form of the machine is shown in Figs. 60, 61, and
62. In general appearance it is somewhat like the usual me-
chanical touch machines mentioned in the foregoing.

There are two headstocks and a table in the center, all resting
on a massive cast-iron bed. The headstocks each carry microm-
eter screws and nuts with graduated heads, and these measure
the gage, which rests on and is clamped to the table. The gage

GAGES AND GAGING SYSTEMS 63

being clamped to the table is set true with respect to the axes of
the micrometer screws, by adjustments of the table. The left
screw point is brought into electric contact with the gage; then
the right screw point is brought into electric contact with the

PJLUJLUOJLOJUULULUL^^

FIG. 60. — Measuring Machine.

gage, and when the current passes through the gage from one
measuring point to the other, the two dividing heads are read.
To turn the graduated heads the screw system is not actually

FIG. 61. — Measuring Machine.

touched by hand, but is worked by a hand-pulley and string, the
former being attached to the base of the headstock, there being
a large pulley on and concentric with the head. The left head-
stock is a replica of the right headstock; to save space, only the
measuring point of the left headstock is shown. Gage d rests

64 GAGES AND GAGING SYSTEMS

on the table / and is clamped to it. The table top can be brought
into any desired plane by two rotations, as follows:

The table is fitted with five adjustments, being movable
through a small angle about a horizontal axis, and also through a
small angle about a vertical axis, as well as adjustable in hight.
It can further be traversed either along or across the bed.

In Figs. 60 and 61 is shown a nut N working in bearings Elf
E2, and having the screw Sl in it. A steel cone n is screwed into
the right end of the nut N, and bears against the stop m. There
is a helical spring F which presses forward against the bearing
Elt and back against the nut, forcing the cone n against stop m.

FIG. 62. — Measuring Machine.

The point of n lies truly in the axis of nut N, and the front face of
m is ground truly plane, and by a special device is made accurately
normal to the axis of the nut N. By this means, when the nut
is turned it should be a true rotational motion, without any
periodic to-and-fro translations along its axis, such as occur
with the usual coned or flat bearings. Subsequent calibration
of the screw shows how nearly this ideal has been approached.
Fixed to the nut N is a graduated wheel Q, and a double vernier
g is shown attached to the casting R. The wheel is centered true
with the nut axis by means of the double vernier in the usual
way. The casting R has a -front part T, to which an upright
plate U is screwed. This plate carried the bearing E, the bracket
V on which runs the yoke a and pulleys rlf r2, Fig. 62.

GAGES AND GAGING SYSTEMS 65

The screw Sl would rotate with the nut if free, but as the
yoke q which runs on the bracket V is clamped to the screw, the
latter acquires a simple translatory movement along its axis, in
or out of the nut, according as the latter rotates right-or left-
handedly. The screw spindle carries an index mark by which
the position of the screw in the nut can be seen on the fixed scale
S, Fig. 62.

In this micrometer system of rotating nut and translating
screw, it is essential for accuracy that the nut have no transla-
tion and that the screw have no rotation. The former condition
should be achieved by the cone end method of working; the
latter, by making the yoke and bracket rigid and insuring by a
weight that the former presses the latter with constant force.
Backlash and looseness between micrometer screw and nut are
minimized by the pull of weights ^ and ^, Fig. 62, from which
pulley strings pass over pulleys r± and r2 to the yoke ends. By
this means the screw is pulled back into the nut by a steady force.

The casting R is electrically insulated from the plate W by
a mica sheet, and by having the screws which bind R and W
bushed with ebonite. The base of plate W is grooved to fit the
part X of the bed, and presses that part by four studs; one other
stud presses on the flat part Y, Fig. 62. Thus the headstock
rests firmly on the bed at five points of support, and has only
one degree of freedom — along the length of the bed. Fixed on
the side of W is shown a bar V, on which the hand-pulley Z can
be pulled forward and clamped, so as to take up slack in the
pulley cord.

The two micrometer screws and nuts were cut and ground
with great care on the most advanced plan, and when examined
under the microscope the screws appeared highly polished and
regular. The calibration described below shows that there is a
small periodic movement at each rotation of the nut, probably
due to its bearings being eccentric with respect to its axis. But
this movement is perpendicular to the line of measurement, and
the resultant errors in the micrometry are of a lower order and
probably negligible.

The screw heads are about 2 inches, and the nuts about 4
inches long, so that the screws do not leave the massive nuts at
any point in the run. Steadiness in temperature of the screw
is thus obtained. The screw diameter is i centimeter, the pitch

66 GAGES AND GAGING SYSTEMS

J millimeter, the graduated head has 500 divisions, and the
vernier reads tenths; so one vernier division corresponds to
Ttf,£tfiF millimeter (or approximately .0000039) in the micrometry.
The bed is 5 feet long and weight 200 pounds; it rests on three
studs, two i foot apart under one neutral line, and one under
the other neutral line. A voltaic circuit, consisting of a cell Clt
a resistance box Rlt switch X, and a telephone 7\, are joined to a
binding-screw /x on the bed, and to another binding-screw 12, on
each headstock. The switch is put to right or left, according
as one wishes to make contact between the gage and the left
screw, or between the gage and the right screw.

The micrometer microscope Ml rigidly mounted on the right
headstock, Fig.'6i, is used for reading the standard invar scale
S3. By this means, as in the Pratt & Whitney measuring machine,
the end standards may be compared with line standards of length.

MATERIALS USED IN MACHINE

The bed is of cast-iron. Most of each headstock is of cast-
iron, in one piece, but the front plates and brackets and the
base-plates of the headstocks and table are of wrought iron.
Brass is used for the nut bearings and for most of the table. The
micrometer screws are of silver steel, and the micrometer nuts
of bell metal, which is very hard. The part of the screw spindle
projecting from the front of the nut is of first-grade invar. All
caps and fittings on the screw end are also of invar. Since invar
cannot be ground very true, the faces of the cups are of thin steel.
The idea is that these projecting parts, being of small dimensions
and necessarily uncovered, are more liable to temperature changes.
The consequent errors in micrometry are small since the expan-
sibility of invar is so minute. The terminal points of the screw
spindle are beads of iridio-platinum, which, being hand-made
and non-oxidizable, is the best substance for electric-contact
work. The beads are continuous, with a short piece of iridio-
platinum wire which was hammered into the hole drilled in the
end of the invar.

MEASURING BAR GAGES WITH FLAT ENDS

These are measured in the electric-contact measuring machine
between two points. The gage is put on the table and clamped.

GAGES AND GAGING SYSTEMS

It must first be set so as to have one face normal to a screw axis
by adjusting the table.

As will be seen from the contour curves, Figs. 63, 64, 65, 66,
the flat ends are never true planes, but for the above purpose the
gage is taken to be set when the contact readings on all points on
a circle near the edge of the face are identical.

Set

Sot

FIGS. 63 and 64. — Contour Curves of Gages.

The flat faces are roughly 6 millimeters across; the left screw
point is brought into electric touch with the gage at the center
of the left face, marked / in column A, Tables i and 2. The
right screw point is then brought up to touch the right face, the
circuit being now arranged to pass from the left screw through the

Set

FIGS. 65 and 66. — Contour Curves of Gages.

gage to the right screw. The two micrometers are read as in
columns B and C. Then the table, and the gage with it, are
moved i millimeter to the left; the contact is now made at the
place 2 in column A. The micrometer head readings are taken
and entered in columns B and C, as before. The whole face,
except near the edge, is thus tested in thirteen symmetrical
places.

68 GAGES AND GAGING SYSTEMS

Results follow for two new gages, made by the best firms, in
Tables i and 2. The numbers in columns B and C, and in other
tables below, are those read on the micrometer heads, so that
they give only comparative values from place to place, and would
have to be changed alike to represent absolute values of the
length of the gages. Column D is the sum of columns B and C;
the larger the sum the less the thickness of the gage on the line
in question. The small disagreement between the results for the
two sets is shown in column A. The gage is well covered through-
out the readings. For the 25-millimeter gage, Table i, the errors
arising for any one position lie between o and 0.4^1. l These
errors can be attributed mostly to bad polish of the surfaces.
Grooves are visible, and small changes in setting the surfaces
would bring the measuring point now over a ridge, now over a
hollow.

The errors in reading the micrometer can be ignored, for if
any observation be repeated before the gage is moved, the differ-
ence in the reading never amounts to more than o. I/A, generally
less. Thermal expansion may produce a small deformation,
since about three quarters of an hour elapses between a reading
in Set I and the corresponding one in Set II. (See Tables, pp.

69 and 70.)

The difference in the gage thickness in different places amounts
to 3-6/x. To show the nature of the gage, contour figures are
drawn, one for each set. These curves are not contours for one
surface in the usual way, but represent the joint effect of the two
end faces of the gage.

In the 1 5o-millimeter gage differences are slightly more, -
o.i/u, to 0.5/u. (thermal expansion exercises more influence for long
gages) than for the 25-millimeter gage. But the difference in
the gage thickness from place to place amounts to 5.8^1. The
contour figures are given. The faces are not normal to the length
of the gage, and no reading can be taken at places 5 and 9; when
in these positions one screw end touches the gage, the other screw
end does not make contact on the other face, but, if continued,
would meet the gage on its side. The actual length of this gage
was found to be, at 18.5 deg. C, 1 50.0332 millimeters, and 1 50.0325
millimeters in two distinct evaluations, taken at place i, Table 2.

1 Micron, the millionth part of a meter, or j-g^ of an English inch, repre-
sented by the Greek letter /*.

GAGES AND GAGING SYSTEMS
TABLE i. — 25-MILLIMETER GAGE

SET I

SET II

D =

,
—

D'-o

B + C

B'-C'

116.5

147-9

264.4

117.6

146.9

264.5

+ O.I

"7-5

146.3

263.8

117.4

146.7

264.1

+ 0.3

U7-3

146.9

264.2

118.2

146.3

264.5

+ 0.3

117.9

I477

265.6

118.7

146.9

265.6

0.0

117.

149-9

266.9

118.

148.9

266.9

0.0

117.

147.4

264.4

"7-5

147.1

264.6

+ 0.2

117.8

147.6

265.4

118.4

J47-3

265.7

+ 0.2

116.6

147-5

264.1

117.9

146.6

264.5

+ 0.4

118.

147-5

265-5

118.1

147-7

265.8

+ 0.3

118.

147-5

265.5

117.7

147.9

265.6

+ O.I

117.7

146.

263.7

117.3

146.6

263.9

4- 0.2

118.9

148.5

267.4

II9-5

147.9

267.4

0.0

119.

147-5

266.5

119.6

147.1

266.7

+ 0.2

TABLE 2.— iso-MILLIMETER GAGE
THE UNITS ARE MICRONS

395-

96.2

491.2

395-

96.

491.

— O.2

397-

93-8

490.8

396.

94-5

49°- 5

- °-3

396.

94.9

490.9

395-

95-5

490-5

- 0.4

398.7

93-5

492.2

398.

93-9

491.9

- °-3

394-

98.7

492.7

396.

96.6

492.6

— O.I

396.

95-5

49 1 -5

396-

95 -°

491.

~ 0.5

398.3

96.7

495-

399-

95-5

494-5

- o-5

396.

93-7

489-7

396.

93-4

489-4

- o-3

397-

93-4

490.4

397-5

92.8

49°>3

— o.i

398.

91.7

489.7

399-

90.5

489.5

— O .2

396-

92.9

488.9

396.

92.7

488.7

— 0.2

GAGES AND GAGING SYSTEMS

TABLE 3. — THREE -QUARTER INCH CYLINDRICAL GAGE
THE UNITS ARE MICRONS

DEGREES

CENTI-
METERS

FROM
END

SET 1 SET II

A — D'

D =

A + B

D' = A'
+ B'

- D

o-5

236.9

197.8

434-7

233-5

201.2

434-7

o.o

I.O

242.0

192.6

434-6

238.0

196.7

434-7

+ O.I

i-5

241.1

193-5

434-6

238.0

196.7

434-7

+ O.I

2.0

2344

199.8

434-2

231.0

2O3.I

434-1

— O.I

2-5

226j6

207.6

434.2

233-0

2 1 1. 2

434-2

0.0

3-°

235-3

199.0

434-3

231.0

2O4.2

434-2

— O.I

°-5

237.6

197.0

434-6

231.0

203.6

434.6

0.0

I.O

233 -o

191.7

434-7

238.0

196.5

434-5

— O.2

i-5

241.0

193-4

434-4

236.5

197.8

434.3

— O.I

2.O

234.0

20O.2

434-2

230.0

2O4.0

434-0

— 0.2

2-5

220.0

208.3

434-3

223.0

211. 2

434-2

— O.I

3-°

233-0

201.3

434-3

230.0

2O4.I

434-1

— 0.2

°-5

234.0

200.6

434-6

230.0

204.6

434-6

O.O

I.O

240.O

2944

434-4

236.0

I98.5

434.5

+ O.I

i-5

240.O

J94-3

434-3

237.0

197.5

434-5

+ 0.2

2.0

233-5

200.8

434-3

230.0

2O4.2

434.2

— 0.1

2-5

225.O

209.1

434-1

223.0

2II.2

434.2

+ O.I

3-o

233-0

201. 1

434-1

229.0

205.2

434-2

+ O.I

135

°-5

234.0

200-5

434-5

231.0

203.4

434-4

— O.I

I.O

24O.O

194.6

434-6

238.0

196.5

434-5

— O.I

i-5

240.O

194.3

434-3

236.0

198.3

434-3

0.0

2.0

233-0

2OI.O

434-0

229.0

205.2

434-2

+ O.I

2-5

225.O

209.2

434.2

22I.O

213.3

434-3

+ C.I

3-°

234.0

200.3

434-3

229.0

205.2

434-2

— O.I

180

°-5

235-0

199.7

434-7

225.0

202.6

434-6

— O.I

I.O

237.8

196.8

434-6

238.0

196.5

434-5

— O.I

i-5

239.0

J95-4

434-4

238.0

196.4

4344

0.0

2.O

232.0

202.1

434.1

230.0

2O4.2

434-2

-f O.I

2-5

224.O

201.2

434.2

222.O

2O2.2

434-2

0.0

3-o

232.0

202.2

434-2

230.0

204.2

434-2

0.0

GAGES AND GAGING SYSTEMS 71

MEASURING CYLINDRICAL GAGES

These are measured between lines or edges. The screw ends
have cylinders or edges mounted perpendicular to the screw
axes. A preferable method is to work between the screw points,
and to move the table carrying the gage up and down past the
screw points so as to just establish electric touch in passing.
In this way the straight lines mentioned above are virtual lines
due to the passage of the measuring points past the gage.

Before commencing measurement the axis of the gage is set
perpendicular to the screw axis. Put the gage on the table, its
axis being horizontal and across the length of the gage. Move
the gage by the table till its other end makes contact with the
left screw end. If the two contacts have identical micrometer
readings, the gage is set.

The results for a f-inch gage are shown in Table 3.

Readings are made along the gage at six places from 0.5 to
3 centimeters from one end. After one set of six readings the
gage is rotated on its axis to position 45 degrees, 90 degrees, 135
degrees and 180 degrees from the original one, and for each posi-
tion six readings are taken, as before.

Set I takes about three quarters of an hour, and is completed
before Set II is commenced; corresponding measurements are in
one line. In no case do the results of the two sets differ by more
than ± O.2/X.

The gage is a very good one; the differences in various places
are not more than o.y/u, though there is a distinct tapering in
every position, the handle end being thickest. There is a slightly
different angle of taper in the different positions. The 180-
degree position results are almost identical with those for
o-degree position, as they ought to be.

SENSITIVE ATTACHMENT FOR MEASURING INSTRUMENTS

We have often wondered why the system of sensitive measure-
ment, such as is found on a Bath indicator, is not more exten-
sively used. No matter how finely and accurately micrometers
and verniers may be made, dependence must in all cases be placed
on the sensitiveness of a man's hand to obtain the exact dimen-
sions of the piece to be measured. In order to overcome this

72 GAGES AND GAGING SYSTEMS

difficulty and eliminate the personal equation in the manufacture
of duplicate and interchangeable parts, we have tried the sensi-
tive attachment to the micrometer shown in Fig. 67, and found it
of much value.

The auxiliary barrel A is held to the anvil of the micrometer
by means of a thumb-screw B. In the inside end of the barrel
is a secondary anvil C, the base of which bears against the short
arm of the indicating lever D. The action will clearly be seen
by reference to the cut. The micrometer is so set that when a
g-age, G, of exact size is placed between the measuring points,
the long arm of the indicator stands at the o mark. If the pieces
being calipered vary in the least from the standard size, it will
be readily noted by the movement of the pointer. Hard rubber
spheres turned from rough were found to vary from 3 to 5 thou-
sandths after having passed the inspector's test with an ordinary

FIG. 67. — Special Micrometer.

micrometer. With this attachment the inspector's helper could
detect very minute variations from the limit size. The same
device was used to gage the size of all brass disks about half the
diameter of the rubber spheres, and in fact anything within the
limit of the micrometer can be made to show to the naked eye
variations as small as a ten thousandth. Considerable trouble
was experienced with a pair of small brass miter gears, because
of the difficulty of getting the outside diameter just right.
Inasmuch as they were finished on a screw machine, some of the
holes were not concentric with the face, causing the gears to bind.
Fig. 68 shows a gage which was quite inexpensive and at the same
time showed up the slightest inaccuracy.

A DEVICE FOR TESTING GAGES

In some shops certain thin bow-back gages are used, which
will get out of true if accidentally dropped, or if a light rap is

GAGES AND GAGING SYSTEMS

given to the machine. When it happens the inspector will take
a two-foot rule, try the gage, and finally send it to the tool-room
for repair. Here the tool-man tries it on a steel rule, gets the
mate to it, and adjusts them by peening. We have here in
Figs. 69 and 70 a micrometer caliper which was designed several
years ago for the purpose of testing gages such as these.

The caliper will test both inside and outside gages. Piece A,
Fig. 70, can be adjusted to any inch on the bar by loosening thumb-
nut B, and the desired inch can be located through the opening
C. The adjustments for thousandths can be taken from the
micrometer adjustment at the other end. D, Fig. 69, is a support
for the bar and can be removed along the bar when necessary.
This caliper can be used to set inside and outside calipers.

FIG. 68. — Bevel Gear Gage.

A TESTING TOOL FOR FINE WORK

The sketch Fig. 71 shows a very fine tool for testing work
to .0001 inch and less; you can measure much closer with this
than with micrometers. The jaws are i inch long, are .001 inch
farther apart at the point than at the back, and the fixed jaw is
graduated in tenths on one side; thus variations of .001 inch or
less may be detected in work placed between the jaws. Say we
have a piece to test, like the one shown in the sketch, to see if
its faces are perfectly parallel; move the jaws down on the work,
say, 4, 5 or 6, and try all four corners and see if they come to the
same point. If they do, the piece is exact. If not, whatever is
out is plainly shown by the graduations. Any one with fine
work to do will appreciate this tool. We thought we could grind
them close enough with our micrometers, but we could not, so
we made one of these tools and it worked admirably. You will
be surprised to see how closely you can measure with it. This
tool must be hardened and ground all over.

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GAGES AND GAGING SYSTEMS

A ROLL GAGE

The engraving, Fig. 72, shows a gaging implement which has
been devised especially for gaging rolls, such as are used in the
cold rolling of sheet metal, where, as our readers know, very
great accuracy is often required. The gage consists essentially
of a curved plate, which rests on top of the roll to be gaged.
Rising from the center of this plate is a cylindrical standard
having graduations upon it, and attached to a piece sliding upon
this standard there is a swinging bar which is graduated and
carries two measuring jaws. The one at the left is plain and
solid, while the one at the right is made of an open framework,
and with a contact piece attached to the short arm of a multi-
plying lever which is connected to the shorter arm of a second

FIG. 71. — Tool for Accurate Testing.

multiplying lever, which indicates variations of diameter on the
curved scale shown above, the graduations of this scale being to
half-thousandths. In using the gage the horizontal beam is set
on the standard to the nominal diameter of the roll, as indicated
by the graduations on the standard. The left-hand jaw is set
also to the graduation corresponding to the nominal diameter
of the roll and the right-hand jaw, so that at the beginning of
measurement the point will indicate zero. Then when the gage
is moved endwise upon the roll, any variation of diameter is shown
upon the graduated scale. The horizontal arm is free to swing
in a vertical plane during this process. Usually the lower roll
is not truly cylindrical, but is largest in the middle, there being
a straight or cylindrical section in the middle with slightly taper-
ing sections at each end, the result being that when pressure is
put on the rolls, the upper line of the lower roll is practically

GAGES AND GAGING SYSTEMS

straight and the metal is rolled to practically uniform thickness.
This gage is especially adapted for indicating when the designed
taper has been secured; the grinder's experience telling him what
the proper taper is. The object of making the flat-hand jaw
solid is that it may be the heavier, so that placing the finger

FIG. 72. — Instrument for Gaging Rolls.

upon the horizontal bar at the right and swinging this bar slightly,
the contact points are made to pass over the largest diameter
of the roll. All the contact pieces are made cylindrical, but do
not turn freely. They can, however, be turned by loosening the
screws so as to bring fresh contact surfaces in use when the
instrument has become worn.

GAGES AND GAGING SYSTEMS 77

A NEW ENGLISH TYPE OF UNIVERSAL LIMIT GAGE

Fig. 73 shows the Newall working gage with its adjusting dial
and zero in position. The pair of contact points at the left is
fixed in position, but the pair at the right is adjustable by a screw-
driver. One of the opposing pairs of points is intended for the

FIG. 73. — English Universal Limit Gage.

lower and the other for the upper limit of the piece for which
the gage is to be adjusted. When adjusting the gage both pairs
of points, with dial and zero removed, are first adjusted to true
size by a standard plug gage — a set of such plugs being all that
is required in the way of fixed gages. The setting dial and zero
-shown to larger scale in Fig. 74 — are then slipped over the
contact points as shown in Fig. 73, and by a screw-driver the
point which carries the dial is adjusted the required amount above

78 GAGES AND GAGING SYSTEMS

or below the standard to give the lower limit of size, and is then
locked. The dial and zero are then reversed and the outer point
is adjusted to the upper limit of size. The fit of dial and zero
on the screw points is by a taper, such that pressure with the
thumb will fasten them in position securely enough for the purpose.
The dial reads both ways from zero, in order to provide for set-
ting the gage above the plug size for a forced fit, or below it for
a running fit.

FIG. 74. — Dial of Limit Gage.

GAGE FOR MEASURING HAIR LINES ON TYPE FACES

The drawing, Fig. 75, shows a device for measuring hair lines
on the faces of type, which we made a few months ago for a type-
making firm. We take it for granted that it is all right and fills
the bill, as we have never heard from it since it was finished.
The sketch is drawn from memory, and is only intended to show
the principle of it.

A is a block of tool steel made in the shape shown and worked
up true with the hole, which receives the adjusting screw E and
micrometer screw G, also the rod F. The block B is then made
and ground true with the hole, which is tapped any fine pitch,
from 24 to 40, as it is only for adjusting. The block has about
J inch of thread for the screw, while the remainder is bored out
to receive the spring H. The bottom of the block must have a
nice even bearing where it is in contact with the main block, also
in the holes, and must work very nicely and without the least

GAGES AND GAGING SYSTEMS

shake. The plate / is a piece of tool steel, hardened and ground,
and lapped to a nice straight edge on line /. The corresponding
line or face against which the type rests is also lapped. The plate
/ is beveled off to a knife-edge and must fit nicely along the main
block, the type when in place just high enough to allow it to
pass over. The block D is fitted and pinned to the rod F, which
is also a nice fit in the holes, and on the bearing face represented
by line K, and is pushed forward by spring L against the type to
hold it in place while the measures are being taken. The mi-
crometer barrel was sawed from a half-inch micrometer, turned

FIG. 75. — Gage for Type Faces.

to fit the block and pinned with a small taper pin. The screw E
should be a tight fit in the block B, so that when it is once set
there will be no liability of its turning. The screw should be
threaded about f inch to allow for adjusting the block B, which,
when the micrometer screw is at o or zero, is brought so that it
is exactly on the line /, and should not be moved unless in case
of wear on the ends of the screws, as they are always in contact.
Now let W represent a type in place ready to be measured. The
micrometer screw is turned to the right^followed by the block B,
until the knife-edge on / is at a point where the operator wishes
to take his reading, which is done with the aid of a very strong
glass.

GAGES AND GAGING SYSTEMS

A DEVICE FOR TESTING SQUARES

Another testing device which we noticed in a machine shop
attracted our attention, and this is shown at Figs. 76 and 77.

FIG. 76. — Square Testing Device.

The system of inspection in these shops is very rigid. Every
piece is inspected as the different operations on it are completed
upon it, and, of course, in doing this squares are used where
necessary. There were constant complaints of the work not

GAGES AND GAGING SYSTEMS

coming square from the milling machines and the planers, and in
very many cases where the inspectors declared a piece to be "out
of square," and it was returned to the workman, he was able to
show that by the square he had used — and which had been
supplied to him from the tool-room — the piece was square.
An investigation disclosed the fact that a piece might really
be right by one square and a little off by another, and the trouble
was thus traced to the squares themselves, although these had
come from the same establishment and were believed, and for
the same matter are still believed, to be the best and most
accurate squares that are to be purchased anywhere. So the
device Figs. 76 and 77 was made to test squares and to enable

po-

FIG. 77. — Square Testing Device.

them to be corrected when found slightly out. The surface
plate which forms the plate of the device was carefully fitted by
scraping to an original plate, and at the back of this it attached
a standard which supports a straight-edge that has its sides as
nearly straight and parallel with each other as it was possible to
make them. This is adjustable vertically through a small dis-
tance, so that the lower end of it can be brought close to the
stock of a square placed upon the surface plate when testing the
inside edge, or close to the surface plate when testing the outside
side of a square blade. At each edge of the straight-edge, but
just back of it, a long narrow mirror is placed. These mirrors
swivel on pivots at top and bottom, so that the light which strikes
them can be reflected to pass through the opening between a

82 GAGES AND GAGING SYSTEMS

square blade and the edge of the straight-edge, if there is any
such opening; and when the straight-edge has been adjusted by
means of knurled head screws, provided for that purpose, so
that one edge of it exactly shuts out the light between itself and
the square blade, the square is swung around to bring the same
edge of the blade against the opposite edge of the straight-edge.
This of course shows double the error that actually exists, and
the square is then lapped until it will stand this test. It is now
found that when an inspector declares a piece to be out of square,
it will be found to be out also by the square the workmen used;
in other words, the squares now agree with each other. It is,
of course, a very refined test, and the device is beautifully made
and finished. A drawing of the device is shown at Fig. 77, which,
however, does not show the mirrors, one of which is seen in the
engraving, Fig. 76. Perhaps they were added to strengthen
the light after the device was made. In adjusting the straight-
edge to agree with a square being tested, it swivels upon the
pivot seen near the top of the standard in the drawing, and the
adjusting screws are graduated to read to .001 millimeter per
foot of length, and this, of course, enables errors to be known in
definite terms of magnitude.

MICROMETER HEADS FOR SPECIAL GAGES

Considerable use is now being made of micrometer heads on
special gages of various kinds, and as the advantages of these
applications become more widely known, the use of these heads
will undoubtedly increase. Their convenience of application to
gages of various sorts, and the fact that they enable the varia-
tion from the exact size to be read in thousandths, render them
superior in many cases to limit gages of the usual kind, and they
are moreover applicable to a great variety of uses to which the
usual fixed type gages would hardly be applied at all. Such
gages are comparatively cheap, as the heads supply much of the
really accurate work ready made, and they cost but little.

At the beginning, and in many cases still, these heads were
obtained by cutting off the yoke of a complete micrometer caliper,
but they are now being supplied by various makers without the
yoke. Fig. 78 shows one of these heads as made by J. T. Slo-
comb & Co., of Providence, R. I., which does not differ from

GAGES AND GAGING SYSTEMS 83

the head of a complete caliper, except that it has turned and
flanged seat for insertion in an eye of the special gage to which
it is to be applied — the attachment of the head to the body of
the gage being by soft solder.

Fig. 79 shows a cross-section of the head and illustrates a
feature of the Slocomb head which renders it especially applicable
to this use, namely, the provision for adjusting for wear in order
to preserve the zero, which, it will be seen, is in the head itself.

FIG. 78. — Micrometer Head.

The main nut a is threaded into the- barrel by a screw having
thirty-two threads per inch, and as the measuring screw has
forty. threads per inch it will be seen that by turning the nut in
the barrel the screw is adjusted along the barrel by the differen-
tial action of the two threads — this action being such as to give
a movement of .0062 per revolution. Another feature of this
head is the supplementary nut b, which is fitted with a row of
V-shaped teeth on the end which faces the main nut a, these
teeth engaging corresponding teeth in the main nut. By first

FIG. 79. — Micrometer Head.

withdrawing the screw and then turning nut b one or more teeth,
any looseness imthe threads due to wear may be taken up. Still
another feature is the insertion of a light spring between nuts a
and b, the object of which is to put a slight friction on the screw
and thus prevent its accidental displacement.

Fig. 80 shows an instrument which is used in rebabbitting or
otherwise re-establishing the journals of a lathe headstock.
The micrometer head is carried by a ring which is so jointed to
the stock of the tool as to turn upon it, and thus permit readings
to be taken vertically or horizontally. One end of the babbitting

GAGES AND GAGING SYSTEMS

or testing mandrel is shown in position, the live spindle of the
lathe being supposed to be removed. It is obvious that with a

FIG. 80. — Testing Parallelism of Lathe Centers.

suitable support at the headstock end of the mandrel, it may
by these means be adjusted to exact parallelism with the V's of
the lathe.

FIG. 81. — Gaging Bevel Gear Faces.

Fig. 8 1 shows a gage for determining the proper location of
the bevel faces of bevel gears in relation to the hub face. This
test is in reality applied to the blanks before the teeth are cut,

GAGES AND GAGING SYSTEMS 85

but by an oversight the photograph was taken with a completed
gear in the gage.

Fig. 82 shows a tool of obvious utility in determining the
degree of truth in a planer table. Other obvious uses for it are
in boring mill and drill press tables and to lathe face-plates.

Fig. 83 shows a fixture for determining the correct diameter
of the ball race in the crank shaft gear, back of the teeth, and
under-cut so that the direct application of fixed gages is im-
possible. The gear is mounted on the spindle carried in the

FIG. 82. — Testing Truth of Planer Table.

left-hand head of the fixture, and is carried longitudinally in the
spindle bearing against an adjustable stop, which when once
established is permanent. The abutment gage for the ball race
is in front of the gear, and the spindle bearing has a transverse
sliding movement, permitting the ball race to be brought into
contact with the stop gage, when the micrometer may be read
-the adjustment being preferably such that the reading when
the work is exactly right is zero. It will be noticed that in this
case, as in the others, the micrometer not only tells if the work
is right, but if wrong it tells by how much, and furthermore, the
limits between which the work is done may be determined after

GAGES AND GAGING SYSTEMS 87

the gage is made and increased or diminished, if found advisable,
instead of being — as with fixed gages — determined, and per-
haps unwisely, before the gage is made.

Fig. 84 shows a gage for measuring the taper seats of a crank
bracket in which the taper ends of the frame tubes are inserted.
Certain diameters of these seats are required to be at proper
distances from the axis of the bracket, and the accuracy of this
is determined by the insertion of a taper plug — seen separate
at the left — and then taking a reading with the micrometer.

SECTION III

LATHE, PLANER, SURFACE, AND UNIVERSAL GAGES
AND INDICATORS; THEIR CONSTRUCTION AND USE.

SIMPLE AND INEXPENSIVE LATHE INDICATORS

AFTER being neglected for a number of years, it is well that
at last the value and economy in the use of indicators in the tool,
jobbing and manufacturing shops are becoming recognized and
appreciated. A knowledge on the part of the mechanic of the
uses and adaptability of the various designs of these handy and
accurate tools will enable him to turn out more and better work
with less effort and worry on his part than he possibly imagines.
Their use guarantees the accurate location and running of the
work in hand, and insures against error through neglect in having
the fundamental placing correct. There is no guesswork where
indicators are used.

A very simple and comparatively inexpensive lathe indicator
can be constructed on lines similar to the one shown in Fig. 85.
It is simply a rod centered to fit the lathe centers, or one lathe
center and the work, as the case may be, and a needle or a surface
gage. It can be used in a variety of ways. For instance, to
chuck a piece of work to be bored on the carriage place one end
against the center punch mark which locates the hole, and the
other on the live centers; if the needle does not travel parallel to
the face-plate the work is not chucked true. It may be necessary
to turn the face-plate and needle together if the face-plate is not
true. Of course this will locate only one point of the work, and
care must be taken to chuck the piece so that the other end of
the hole will come where it is wanted.

By having suitable centers in the ends of the rod, it can be
used to set the tailstock center in line. The method is the same.
Sometimes it can also be used to advantage in chucking work
on the face-plate, as it is easier to rotate the light indicator than

GAGES AND GAGING SYSTEMS

to pull a heavy face-plate round. This is especially true when
the work is liable to upset your calculations by sliding off on the
ways. For everything except the last case the rod should be
short in order to magnify the error as much as possible. The
live center should also be true.

FIG. 85. — Simple Lathe Indicator.

A UNIVERSAL LATHE INDICATOR

Figs. 86 and 87 illustrate a universal indicator of novel and
ingenious construction. It consists of a machine steel holder A,
\ x i inch, carrying on its head a graduated arc B and pointer C,
both held in position by a knurled thumb-screw (not shown),

DH.12J

FIG. 86. — Universal Indicator.

which binds the arc to the holder, but allows the pointer to play
over the face of the arc.

To the side of A is firmly bound a stiff spring D, which in
turn carries near its upper edge a boss or hollow sleeve E, holding
a sliding pin, which works against the short arm of the pointer
at a. This is for testing the face of the work held in the chuck
or on a mandrel, or to find whether a piece on the center is out of
round.

90 GAGES AND GAGING SYSTEMS

To the outer end of D is secured, by means of a knurled thumb-
screw, the slotted pin F, carrying the yoke G, both together
making a universal joint which carries the long, light pointer or
needle for testing by center punch mark in the usual way.

By binding the needle in the yoke through means of the
thumb-screws to prevent side motion, and adjusting the spring
and joint by means of thumb-screws b and c, the needle is brought
into position to test the truth of the hole.

All parts are detachable when not needed by simply removing
their respective thumb-screws.

FIG. 87. — Universal Indicator.

A DECIMALLY GRADUATED UNIVERSAL INDICATOR

Figs. 88, 89 and 90 show a front elevation and a vertical
transverse section of an extremely complete and accurate universal
indicator as attached to an angular steel base, and in use as a
depth gage. The construction is as follows: A tubular body or
shell a, through the center of which a rod b passes and is held in
any desired position by the friction collar c, which is slotted at d.
The friction collar c is fitted free in the enlarged bore of a with a

GAGES AND GAGING SYSTEMS

limited amount of longitudinal movement, and is held in the
shell by the plug e, which is fitted tight. The shell is cut away
to give a flat surface on one side for the placing of the indicator
needle and spring. Indicator needle / is pivoted to the shell by
a small screw at g, the heel of the needle bearing on the friction
collar c by the pressure of the feather spring h. The spring is
"sweat" into a small slot in the needle, and rests against the
pin /. The needle point is shown about in its normal position,

FIGS. 88 and 89. — Decimally Graduated Indicator.

with the friction collar resting on the plug e. An upward move-
ment of the rod b and friction collar c would move the needle
point to the right. Scale ; is graduated to read approximately
to thousandths of an inch, within a range of twenty-five thou-
sandths.

The tools are applied to the ordinary surface gage as illustrated
in Fig. 90. A taper hole in the body or shell at k provides means
of attaching it to the wire rod of the surface gage. The engrav-
ings show the operation of taking the deflections from end to
end of the cross rail of a planer from the platen.

92 GAGES AND GAGING SYSTEMS

The slot at w, Fig. 89, may be used in connection with a steel
rule or the blade of a square. The tool-maker will find many
other uses for the instrument than those herein shown, such as
testing a lathe center, showing the amount of wear of tool slides,
leveling work in the milling machine or planer, inspection of
finished work, etc. The indicator may be carried in the vest

FIG. 90. — Decimally Graduated Indicator.

pocket, its weight, without the rod, being three quarters of an
ounce. The inventor of this handy tool is Charles E. Hauer, a
tool-maker, and foreman in the factory of the Westinghouse
Electric & Manufacturing Company.

A LATHE AND PLANER INDICATOR

The following description of a lathe and planer indicator
refers to the one illustrated in Figs. 91 and 92. It is unexcelled

GAGES AND GAGING SYSTEMS

for the work for which it was designed. It is graduated to in-
dicate thousandths, and by multiplication of the needle move-
ment by compound levers, the slightest error is easily detected.
The projecting barrel A allows the feeler B to be used in a very
contracted space and in deep holes. The end of the barrel is
tapered and the holder for the feeler B fits over it. The position
of the feeler relative to the barrel may be changed by simply
twisting it round. The movement of the feeler is transmitted
through F to the lever D, which is restrained by the spring G,

FIG. 93. — Adjusting Surface Gage.

and which engages the pointer C. The body of the holder fits
in an ordinary tool-post. The cut is nearly a full size reproduc-
tion of the indicator.

To ADJUST THE NEEDLE OF A SURFACE GAGE

To set the gage, Fig. 93, from the table, get somewhere within
one quarter inch of the mark on the square. With the thumb
and forefinger on the crook A, turn the needle until it reaches the
point desired. By turning the needle it will travel in the path
indicated by the dotted lines shown, on account of the bend
near the point.

GAGES AND GAGING SYSTEMS

A TOOL-MAKER'S SCRATCH BLOCK

A, Fig. 94, is the body or block which is bored to receive the
shaft B, to which is keyed the worm gear C, this being held against
the shoulder by the sleeve J, which screws in to the block far
enough to make a bearing on the outer shoulder and still let the
worm gear and shaft work easily without end thrust. The shaft
B also shoulders in the block at M, and when the nut / is tight-
ened on the sleeve J, the gear and shaft must be free to turn with-

JIG. 94. — Tool-Maker's Scratch Block.

out end play. H is a washer, or rather two half washers, drilled
when together to receive the pointer K, the thumb-nut G binding
the pointer, at the same time bringing the back of the washer
against the shoulder on B, which is just flush with the face of the
block, but not allowing the washer to bind on the block.

The shaft, gear, washer, pointer, and all now being free to
turn, after being set very near and before the pointer is tightened,
may be worked as desired by the worm D, the end of which fits
into the conical bearing O, and is held in position by the sleeve E
which screws into the block and against the shoulder on D, so
that it will turn easily without any end play. The knurled head

96 GAGES AND GAGING SYSTEMS

F is pinned by the taper cross-pin L to the worm. The worm
wheel was made with a £-inch 24-thread master tap in the lathe.
Any one wishing to make a scratch block will find this to be a
very good one.

A CHEAP SURFACE GAGE

The principal part of the gage Fig. 95 is made from an old
pair of calipers. A is a small base, with a slot milled down the
center for one leg of the caliper, which is then held in by pins.
B is a reinforcement on the other leg so as to make it strong enough
to hold the scriber C. The base is cut away at D to admit the
stud on the caliper. With the split nut a fine adjustment is
obtained as well as a quick one.

FIG. 95. — Cheap Surface Gage.

A SURFACE GAGE AND INDICATOR

Fig. 96 show a surface gage and indicator with a number of
features not usually found and embodied in such instruments.
It will be noticed in the first place that the post or spindle has a
taper fit in the base, the latter therefore being removable, and
as there is a good center in each end of the spindle, the instrument
may be used upon the lathe centers, as well as upon planers,
shapers, milling machines and elsewhere. The scriber used, it
will be noticed, is shown in the sketch with a minute prick punch
in the lower end of it. This punch is normally held up against
a shoulder by a little helical spring, a tap with a light hammer
bringing it down to make its mark when required. The scriber

FIG. 96. — Surface Gage and Indicator.

98 GAGES AND GAGING SYSTEMS

may be usually set in such a direction as to bring the prick punch
perpendicular to the surface with which it is at the time con-
cerned. The scriber is of course reversed end for end when lining
is to be done.

Upon the spindle are fitted the two split sleeves which may
be clamped at any point by their respective screws. The upper
of these may be called the fixed sleeve, and the lower the adjustable
sleeve. The sleeves are normally held apart by the compression
spring and drawn toward each other in opposition to the spring
by a long stud so fixed, screw attached to the lower sleeve and a
milled-head nut fitted to it, which bears upon a shoulder on the
upper side of the upper sleeve. The thread of the screw is 40 to
the inch, and the periphery of the nut having 25 divisions, the
reading is in thousandths of an inch. The nut is extended up-
ward into a closed thimble which entirely covers the end of the
screw. The upper sleeve being clamped securely, the screw of
the lower sleeve may be loosened just enough to permit the lower
sleeve and its appurtenances to be moved, and the movement is
indicated by the reading of the nut. The adjustable sleeve
carries the scriber in front, which may be clamped in any position,
as shown. At the back it carries a mounting for the surface
indicator, which is used for inspecting and indicating the minute
variations of plane surfaces. The rod of the indicator may be
slid edgewise in its mounting as required, and it may be reversed
as shown in the upper figure. The indicator consists of a little
vertically moving hardened steel-plunger, the inner end of which
bears against the short end of the spring-actuated lever, the long
end of which is a finger which traverses the graduated quadrant,
giving readings to the thousandths of an inch. The mounting
which carries this indicator is bent upon itself so as to form a
long slit or opening and to permit the piece to be sprung apart
by the pressure of the horizontal milled head-screw seen in the
upper figure. This screw is used for giving minute movement
of the indicator when required to bring the reading of the figure
accurately to one of the graduation marks, or when the indicator
is used in connection with the scriber, to bring them both to co-
incident graduation marks. The applications of this instrument
will suggest themselves to those who are familiar with the cruder
instruments of the same class, and which are used so extensively.

GAGES AND GAGING SYSTEMS

INDICATORS AS APPLIED TO MILLING MACHINES

While the usefulness of the graduated multiplying indicator
as applied to the lathe, planer and testing work is pretty gener-
ally understood, there are many other operations in all depart-
ments of metal manufacture, where by its use work can be both
facilitated and improved. Having lately experimented with
very satisfactory results for the purpose of determining its actual
value in a regular line of machine-tool milling, we will try and
describe a few operations where it was used to advantage.

In Fig. 97 a freshly ground cutter is shown mounted on a
lathe mandrel (previously tested) in a pair of Pratt & Whitney
centers having an indicator attached, to determine if (when re-

FIG. 97. — Testing Cutter with Indicator.

volving) all the teeth are "even" or concentric. This is espe-
cially useful when applied to machine-relieved cutters. Fig. 98
shows a rig for holding the indicator while truing a cutter when
both cutter and arbor are in place on the machine.

Arbors are ground from .003 to .005 inch smaller than the
sizes of standard holes in cutters, to permit the shifting of the
cutters when truing. Indicators having flat shanks or stems are
most convenient when they are used occasionally, or on different
machines, as they then can be readily clamped to fixtures, work
or table, and in many positions. When they can be suspended
from the overhanging arm, as in Fig. 99, or column, those with
round shanks or stems are best.

Fig. 100 shows how single or double-ended facing and boring
cutters in boring-bar are tested, both for diameter of hole to be

IOO

GAGES AND GAGING SYSTEMS

bored and for truth, displacing the old cut-and-dried method by
one absolutely certain.

Anticipating objections which may be made to having arbors
smaller than holes in cutters on account of shifting, we will say
that with a 4-pitch gear cutter having a hole .01 inch larger than
arbor, we milled 50 inches of steel \ inch deep at a speed of 37
feet per minute and .098 inch table feed per revolution; and

FIG. 98. — Truing Cutter.

again, 15 inches, \ inch deep, at a speed of 41 feet and .150 inch
feed per revolution without shifting the cutter; also the arbor
was not splined. This forces the conclusion that when arbor
collars are properly porportioned and in good condition, they
will not slip unless abused or overloaded; also that keyways, for
the most part, are unnecessary. Cutters properly ground, run-
ning true, with every tooth doing its proper share of work, last
longer, do better work, and can be crowded harder than when
any of these essentials are missing. We neglected to state that
in truing we established a limit of error of .002 inch, though .001
inch is easily attainable.

IOI

GAGES AND GAGING SYSTEMS

A TEST INDICATOR

The drawings, Figs. 101 to 104, illustrate an indicator which
we designed and made. The important feature of this tool is
the dial, which though only ij inches diameter, gives room to
show errors highly magnified, the ratio being 350 to i.

The graduations read in half thousandths, but quarter-thou-
sandths or even smaller amounts can easily be estimated. The

FIGS. 99 and 100. — Uses of Test Indicator.

limit is ten one-thousandths, or one turn of the pointer. When
in use the plunger A touches the work and any imperfection will
cause it to move the lever B, which through link C actuates the
gear segment D and rotates the pinion E with the spindle carrying
the pointer. The latter is returned to zero by a volute spring F.
The attachment G is used for inside work, or for testing any
surface at right angles to the indicator. The tool H is used in
testing centers in lathe work held on the face-plate or in the
chuck.

102

GAGES AND GAGING SYSTEMS

All working parts are encased, and the dial is with a heavy
watch crystal, which makes it dust proof. A watch crystal may
seem out of place in a machinist's kit, but it is a good thing to
have if for no other reason than that it silently demands the
careful treatment such a tool deserves.

This indicator is not only adapted to lathe work, but is often
found very useful when setting in the shaper or the planer, and
especially in setting shaper vises perfectly true.

FIGS. 101, 102, 103 and 104. — Test Indicator.

A TEST INDICATOR AND HOLDER

Figs. 105 and 106 illustrate a test indicator which we found
to be very useful. Fig. 105 shows the body of the instrument
with the cover removed. The tool carries, as shown, a pointer A
which is of tool steel, hardened, ground and lapped to fit sleeve B
and bushing C, rod A being shouldered near D to prevent it falling
out of the sleeve. Member A is of course the "feeler"; C is a
hardened bushing which supports the inner end of A; it is beveled
internally to leave only about -^-inch bearing and is forced in
the tap hole in E by screwing sleeve B down on top of it. The
pin A after passing through B and C passes through a clearance
hole in E, where it engages with the forked lever F which works
on a pivot carried between an adjusting screw in the body and a

GAGES AND GAGING SYSTEMS

103

conical seat at G in the cover (Fig. 106). A silk thread fastened
to one of the arms at the forked end of the lever (the other arm
being merely a stop for the lever) passes several times around
drum H, thence through a hole in the lower end of the latter,
which is countersunk at one side so that a knot to fasten the
thread may be drawn into it.

At / is shown a hair spring which is driven on the drum shaft
and held at / in a drilled hole in the body of the tool by a small

FIGS. 105 and 106. — Test Indicator and Holder.

knurled plug forced into the hole. The hair spring keeps an
even tension on the thread by pulling on the drum from the
opposite direction. On the upper end of the drum shaft is a
watch hand K which is revolved by any movement of pin A and
lever F.

Fig. 1 06 shows the cover and the dial with the watch hand at
zero on the dial. The cover is a piece of sheet steel fastened to
the indicator body with small machine screws and having a hole
through it to act as the upper bearing for the drum shaft. The
dial has a beveled edge as represented, and is fastened in place

IO4

GAGES AND GAGING SYSTEMS

by means of a ring and two small screws. A piece of photographic
film with the emulsion washed off is cut out and laid on the
shoulder just above the pointer and held in place by a round
spring of piano wire in the beveled seat L, thus effectually keeping
the dial free from dust.

In graduating the dial we fastened the disk in place on the
cover of the indicator, then placed the indicator in a tool-holder,
held it in the lathe tool-post and brought the end of A in contact
with the face-plate of the lathe, first, however, scribing a zero
line on the dial. Then we forced the pointer against the face-

FiG. 107. — Inclinometer and Indicator.

plate till the indicating hand was at zero. Next, we slipped a
piece of sheet metal .015 inch thick under A and scribed a Iftie
where indicated, and so on.

INCLINOMETER AND INDICATOR

The photograph, Fig. 107, shows a simple and useful tool
which we have just made and which can be used as a level, as an
indicator, and for getting the angle of an inclined surface. The
tool is graduated at each side, one pointer serving for both sides,
as the top part of the pointer, or hand, is double and the quadrant
passes between the two points; thus it can be easily read from

GAGES AND GAGING SYSTEMS

105

either side. The pointer is fastened to a shaft, the ends of which
are pointed; on the bottom is fastened a weight which always
keeps the hand vertical, and when the tool is placed upon a sur-
face to see if it is level or at an angle, the hand shows it at once,
or rather after a second or so, for it vibrates a little. The test
indicator which we have added to the base has at the end a
hardening wheel; a coiled spring keeps the plunger away from
the weight at the bottom of the pointer. When this indicator is
used it is pushed against the work, and the rod, pushing against
the weight, moves the hand in the direction of O on the quad-
rant, the weight of the tool holding it. A movement of .001

FIG. 1 08. — Lathe Indicator.

causes the hand to move from one line to the next. It will be
observed in the photograph, that there are pins or stops which
keep the hand from striking against the quadrant; also a screw
to lock the hand so that the tool can be carried about.

A LATHE INDICATOR

The instrument shown in Figs. 1 08 and 109, recently patented
by John C. Miller, Bloomfield, N. J., is to be used in connection
with a lathe or a milling machine for setting the center of the
work, or any center punch mark on the work, in line with
the center of the spindle. The operation of the device is
evident. The disk C has a split hub and a nut by which it is
clamped anywhere on the sleeve F. The center in the closed

io6

GAGES AND GAGING SYSTEMS

end of this sleeve is placed on the center of the machine spindle,
and the center on the end of G is placed in the center of the piece
of work to be located, the spring acting to press both centers
with sufficient force to hold the instrument securely. Near the
periphery of the disk is a micrometrically adjusted pointer, and
by turning the instrument around the contact of this pointer
with the face-plate will indicate in which direction the work
requires to be moved to correct setting. Any desirable limit of
precision may be observed in the micrometer, and the work may
be set without the present difficulty.

FIG. 109. — Lathe Indicator.

A TEST INDICATOR

As tool-makers are always interested in seeing something new,
especially if it is a good tool to add to their collection in the
tool chest, the following will be of interest:

The photograph, Fig. no, shows a test indicator which is all
right. As is plainly shown, it will go where any lathe, shaper or
planer tool will go, or it can be used in the milling machine, as
the whole mechanism is arranged within the stock.

We find it sensitive to 1-20000 part of an inch on smooth
work revolving in the lathe. This seems rather fine, but this
error can be easily detected by closely observing the pointer.

As will be noticed, the lever system is arranged sidewise, so
as not to weaken the section where the tool-post screw clamps.
The body is made of a piece of cold rolled steel with one end
turned down as shown. The push-pin is of tool-steel, and presses
against the main lever.

GAGES AND GAGING SYSTEMS

107

Spring

Pivot

Counter Sunk Screw Bearing
for Pivot

FIG. no. — Test Indicator.

THE USE OF TEST INDICATORS FOR TESTING WORK

In Fig. 1 1 1 is shown a method for determining by the use of
an indicator the variations in the diameter of numbers of round
pieces, or at various points, longitudinally or circumferentially,

B V

FIG. in. — Testing Round Pieces.

of a single piece or between a number of pieces of unknown di-
ameter and one of known diameter. An indicator is fixed upon
a plane surface B, and the piece to be tested, A, is rolled back and
forth between it, and by contact with the shoe of the indicator

io8 GAGES AND GAGING SYSTEMS

spindle it causes the pointer to travel the graduated circle, pieces
of larger or smaller diameter causing it to be traveled a greater
or less distance, respectively. This rig is also useful for com-
paring two or more portions of a flat or square surface of a num-
ber of pieces. When testing a number of pieces — round -
the small collar at the upper end of the spindle is adjusted
vertically so as to allow the lowest part of the shoe to hang
slightly lower than when A is in contact; otherwise it would be
necessary to raise the spindle each time work was to be inserted.
The chief advantages of this arrangement are its rapidity and
also its reliability; so that different persons are more likely to
get similar results than by using micrometers, the results from

FIG. 112. — Setting a Grinding Machine.

which are governed by variations in instruments, body heat and
personal temperament.

In Fig. 1 12 is shown a method of setting a grinding machine
to grind straight or to a desired taper in thousandths of an inch
for any portion of — or the entire length — work without stop-
ping the machine. By depressing the indicator spindle until
the shoe comes into contact with work A, variations in diameter,
if any, are instantly shown. This can also be used to determine
the diameter when a number of pieces are to be ground, and the
operator can always instantly inform himself as to the amount
of stock that is still to be removed; also, before beginning to
grind, how much stock must necessarily be removed to make a
piece round, if it should not run true, or, in shop language, to
"see if it will true up/' B is the wheel, H the hood over the
wheel to which the indicator is affixed, and P the swiveling plate
carrying head and tail stocks.

GAGES AND GAGING SYSTEMS

109

In Fig. 113 we show a straightening press with centers, at-
tached to which is an indicator / secured by an L-clamp D. Where
this device was employed, as a great deal of work to be ground
was turned on screw machines and centered afterwards, with an
allowance of only .003 to .005 inch for grinding, and as the grinder
operators often found it impossible to judge before beginning
to grind whether pieces ran true enough to grind all around, it
was necessary to have some means by which this point could be
determined quickly. The center stocks supporting the blocks
and bar can be moved independently, and the center stocks can,
if desired, be moved to the right or the left end of the bar, so that

FIG. 113. — Straightening Press.

any portion of any piece can be tested. The addition of the
indicator to the press does not decrease its efficiency as a straight-
ening press but rather increases it.

THE R. R. UNIVERSAL TEST INDICATOR AND MIGHT GAGE

The illustration, Fig. 1 14, shows the Roach & Ridlon tools,
which consist of the indicator attached to the rod by a swiveling
clamp; a plunger for aligning jig and die work; a small button to
take the place of the ball on the indicator when the tool is used
in the drill press aligning jig and die work, and the case-hardened
tool-holder which can be used as a boring tool-holder when not
in use in connection with the indicator. The tool is compact
and neat in appearance. It is graduated to read to thousandths
of an inch.

I IO

GAGES AND GAGING SYSTEMS

FIG. 114. — Universal Indicator.

GAGES AND GAGING SYSTEMS

SCALE AND VERNIER FOR FINE ADJUSTMENT OF THE MILLING

MACHINE TABLE

Referring to the use of the scale and vernier of a vernier
caliper for making accurate adjustments of the milling machine
table, the Brown & Sharpe Manufacturing Company make a
special scale and vernier which they supply for this purpose,
and which we illustrate herewith in Fig. 115. The scale is 24
inches long, and the vernier reads to thousandths. The scale
is mounted by screws having T-shaped nuts to enter the trip-
dog slot of the table, and the vernier is attached to the front of
the saddle of the machine. In the illustration a shows the

FIG. 115. — Vernier Adjustment.

clamp screw for the vernier and b an adjusting screw by which
the zero is adjusted.

In the engraving the finer divisions of the scale are omitted.

UNIVERSAL SURFACE GAGE WITH MICROMETER ADJUSTMENT

The general principle of this gage can be seen at a glance in
Fig. 116: There is a micrometer adjustment for the needle, and
in tilting the spindle, as shown in the upper sketch, the level
comes in play as before, and the reading in thousandths in a
vertical line can be taken with precision ; or, if desired, the needle
can be reversed by swinging half round, bringing the thumb-
screw at the bottom, when the level comes in play again the
same as before.

112

GAGES AND GAGING SYSTEMS

FIG. 116. — Surface Gage with Micrometer Attachment.

SECTION IV

THREAD, WORM, GEAR TOOTH, DEPTH AND MISCEL-
LANEOUS TEST TOOLS, THEIR CONSTRUCTION, USE
AND ADAPTATION.

A WORM AND SPIRAL GEAR TOOTH GAGE

IT is apparent from the great interest manifested in all articles
published relating to screw-cutting and forms of teeth in spiral
and worm gearing, that there is a large amount of this class of
work being done throughout the country. Those interested in
spiral and worm gearing may make use of the thread tool gage
shown here, with which spiral and worm gears can be figured out
near enough for all practical purposes.

From the accompanying illustrations, Figs. 117 and 118, it
will be seen that there are two scales used in this gage ; the upper
one is the circular pitch scale A, graduated on the top edge only,
the reading being taken from point d directly above the center
pin. The lower graduation is read by setting the point / on the
thread gage to correspond with the width of the thread tool at
its end, this being taken from a table of tooth parts, such as one
published by the Brown & Sharpe Company.

Note that C is adjustable independent of the main slide, but
is set in correct relation to it, and, as shown in Fig. 117, is set
for the width of a tool for a rack of 2 inches circular pitch. The
protractor is for reading the angle of the spiral.

All graduations of the straight scales read one thousandth
of an inch.

In figuring gears, if any two quantities are given it will
determine the third of the following: Circular thickness at pitch
line, normal thickness at the pitch line, angle with a perpendicu-
lar to the axis. As a worm thread gage it will give the correct
size at right angles to the thread for a thread tool for any pitch.

In operation the readings at d and e are made correct for half

n4 GAGES AND GAGING SYSTEMS

the desired pitch, and at / for the width of a rack tooth of that
pitch — this reading being taken from a table, as already
explained. The protractor and scale are then adjusted to the
angle of the thread or helix with a perpendicular to the axis, and
the parts are then locked in position. The whole slide is then
moved until the corner of the scale reaches the vertical right-
angle stop. The tooth scale below now reads correctly for a

FIG. 117. — Gear Tooth Gage.

thread of that angle and pitch, and the tool can be ground to fit
the jaws of the gage.

In Fig. 1 17, both the upper scales are set to i inch for i inch
thickness of tooth, or 2 inches circular pitch. The lower scale is
set at / for a tooth thickness of .62 for a rack tooth. The thumb-
nut near the zero of the protractor is next loosened, the protractor
is set to read 30 and the slide is moved until the upper scale
strikes the stop, as in Fig. 1 18, and we read at e, .87 inch normal
thickness of thread, and at / .40 inch for the width of the thread
tool at that point.

GAGES AND GAGING SYSTEMS 115

The change in the thickness of the teeth due to angularity,
and also tne distinction between pitch and lead, are seemingly
not well understood by a great many draftsmen. We have no-
ticed the use of the word "pitch" to refer to size of tooth only,
and "lead" to express distance traveled in one revolution only.
While this has been thrashed out a great many times, it is cer-
tainly not followed in all drafting rooms.

Any draftsman who has to do with the reception of orders for
"hobs" knows what a mixed-up muddle they are often in, and
sometimes four or five letters have to be written to get the correct
sizes.

FIG. 1 1 8. — Gear Tooth Gage.

HANDY THREAD, WORM AND DEPTH GAGE

The following illustrates and describes a gage devised for
finding the proportions of screw and worm threads, and the
tools for cutting them.

The United States standard involute worm thread and the
Acme standard thread have a flat top and bottom, which neces-
sitates grinding the thread-cutting tool with a flat end varying
in width with the pitch. Solid gages are on the market for shap-
ing such thread tools, but these are limited to a few common
pitches, whereas odd or fractional pitches are very often required.
The gage in Figs. 1 19 and 120 has an opening on one side between
the jaws B B of an angle of 60 degrees for the United States

GAGES AND GAGING SYSTEMS

standard form of thread. On the other is an opening of 29 de-
grees for the involute worm thread or rack cutter, and also for
the Acme thread, which is at the same angle as the worm thread
or rack tooth. When closed the angular sides of the openings

NO. OF THD.PERIN.
DEPTH=.5-rTHOS.PER IN + .01

U.S. STANDARD.
WIDTH = PITCH -r 8
DEPTH = PITCH X.65

INVOLUTE WORM THREADS.
WIDTH = CIRCULAR PITCH X .31
DEPTH = CIRCULAR PITCH X . 6866
WIDTH = . 974 ^ DIAMETRAL PITCH
DEPTH = 2. 157 4- DIAMETRAL PITCH

OPEN

FIG. 119. — Thread Gage.

meet, forming a sharp V, and the measuring points A A measure
exactly .500 inch, or \ inch, when closed. When measuring point
caliper i inch apart, the tail end E of the slide C is just flush
with end of gage. The formulas stamped on the sides of the
gage are always handy.

CLOSED
FIG. 120. — Thread Gage.

In using the gage the proper width of point of tool is figured
out by the formula and added to .500 inch. The gage is then
set to the actual width of tool plus .500 inch by a common
micrometer caliper, as shown in Fig. 119. Proceed in the same
way for depth, except to subtract the actual depth of the
thread from one inch, and set the gage by the caliper as before.

GAGES AND GAGING SYSTEMS 117

The following are some of the actual jobs done:

A hob and worm were to be made 3^ threads per inch:

3J thread per inch = = y\ pitch; .3" x .31 = .093'" = width

point of tool.

.093 4- .500 = .593", setting of gage.
3" x .6866 = .206", depth of thread, i.ooo - .206 = .794" =

'• setting of gage for depth.

A rack cutter was used to be shaped up of .4o8-inch linear
pitch, to work with a spiral gear (Seller's motion):
.408" x. 3 1 = width of point of milling cutter + .500 inch =

setting of gage.
.408" x .6866 = depth of rack tooth, i" - (.408 x .6866) = set-

ting of depth.

A single-thread screw was to be made of -j^-inch lead,
Acme standard form of thread:

Ty lead = 2f thread per inch = --~ == .0052 = width of tool.

Depth of thread = '— + .01.

The gage shown in Figs. 119 and 120 is made in the same
manner as a common caliper gage; Fig. 121 shows a simpler form
of this gage. A piece of sheet steel A is offset the thickness of
the stock as at D. A cut is made in the offset portion of A for
B to slide in. A piece C is riveted to A to keep the slide from
coming away from A. A slot is cut in A for the tightening screw
to slide in. We think it is preferable to have the tail end of the
slide square, as shown in Fig. 121, and not pointed as in Figs.
119 and 120. Then when the gage is set for depth, an ordinary
depth gage may be set for the thread gage and used for measuring
the depth of thread.

GERMAN THREAD GAGES

It is the custom in a German shop to make the form of the
thread on worms and spindles according to gage like that shown
in Fig. 122, and this is the practice all over Germany; but as no
one is able to insert the gage parallel to the axis of the screw, it

ii8 GAGES AND GAGING SYSTEMS

is evident that the form of the thread becomes wrong, because
the shape of the thread ought to be parallel with that of the axis
of the screw. The resulting error grows with the angle of the
thread.

FIG. 121. — Thread Gage.

In Figs. 123 and 124 we show how to measure the thread
correctly on one line and in correct position with the radial line

Gage for Shape of Tool.

Gage for Shape of
Thread Recess

FIG. 122. — German Thread Gage.

parallel and vertical to the axis of the spindle. The sketch is
self-explanatory, the main part being the two-lipped cone of 29
degrees which is moved in the direction of its own axis, guided
by its cylindrical shank. The whole piece is finished by grinding

GAGES AND GAGING SYSTEMS

119

and by preventing from turning by a dog. The two-lipped cone
may be reground when worn.

The best results in manufacturing will be obtained when
both gage and tool are of the same character, and we therefore

FIG. 123. — German Thread Gage.

purpose making the finishing tool similar to the cone gage. This
tool is to be clamped in a tool-holder, which will fix it in correct
position, one of the lips being used as a scraping tool for turning

FIG. 124. — German Thread Gage.

the right-hand side of the thread in one direction, and the other
lip being used for shaping the other side of the lathe running in
the other direction.

Some hints for correctly making the "V" of the gage may
be given: First, bore the hole for the shank of the gage and then

120

GAGES AND GAGING SYSTEMS

turn the outer surface; then after roughing out the "V" clamp
the piece by the outer surface of the boss, as shown in Fig. 125;
using an index plate as shown, one face of the "V" is ground.
Then turn the piece 180 degrees by means of the index plate,
and then with the same position of the grinding wheel grind the
other face of the "V."

A PISTON-ROD THREAD GAGE

The gage shown in Fig. 126 consists of a piece A made of
i x | inch flat iron, with its two ends bent up about half an inch

FIG. 125. — Grinding Gage.

and filed to form two V edges, which should be 60 degrees, or the
same angle as the threads, in order to fit fairly to the old thread.
The distance between the two should be about equal to the length
of the thread in the cross-head, in order that these V's may
approximately represent in the gage the first and the last thread
in the cross-head.

Another piece of the same flat iron is bent up, as shown at B,
and riveted to the middle of A, its free end being bent over and
brought into line with the two V edges, and at such a distance
from them that when a V point is filed on the free end of B the
old thread will slip in between the three points. The piece B
is finished by bending and filing the point until a good caliper fit

GAGES AND GAGING SYSTEMS

121

is secured, and we now have a gage which not only gives us
diameter of the thread at one point, but gives us the effective
diameter at the points where it is important for us to know it,
and also provides us with means of gaging the new thread, which
may or may not be of the exact pitch of the old one, but which
if made to this gage will screw in every time and make a fair fit,

FIG. 126. — Piston-Rod Thread Gage.

which is all that the repair man on piston-rod threading expects
or desires, and in fact is all that the building did in the first
place.

FIG. 127. — A Taper Gage.

A TAPER GAGE

The sketch, Fig. 127, shows a taper gage made some time ago,
and it is one of the handiest tools imaginable. The edges of this
tool must be narrow, say ^ inch. The lower jaw slides up or
down to adjust to the work; the upper one swings on a stiff joint
C to adjust to the taper; both jaws are locked with thumb-screws.

As it is half a foot from A to B, the graduation is made one
half size, J inch reads i inch to the foot taper, making it read
the same as the lathe taper attachment.

122 GAGES AND GAGING SYSTEMS

We will suppose that the lathe centers need replacing; set the
gage on the old center, then set the taper attachment the same as
the gage to turn up the new one.

The tool can be easily made by any machinist and will prove
a great time and trouble saver in the shop.

MICROMETER DEPTH GAGE

We show a micrometer depth gage which was constructed
some time ago, and which has since been in frequent use. It
is inexpensive to make, and seems to have points of advantage
over some other tools used for the same purpose. The frame
may be a malleable iron casting, or may be milled from soft steel
case-hardened, and the base ground true.

. Fig. 128 is a side elevation, and Fig. 129 a plan and partial
section on the line M M, Fig. 1 28.

F C

FIG. 129. — Micrometer Depth Gage.

In Fig. 128 it may be observed, first, that the sliding rod A
is graduated with fine lines running entirely around and \ inch
apart. Second, the sliding piece B can, by means of the mi-
crometer nut C and screw D, together with the spring E, be given
a movement on A of J inch; third, an indicator point on B
traverses graduations on the side of the frame. These are .025
inch apart, corresponding to one revolution of C. Fourth, there
is a line on B where A is exposed, that may be adjusted opposite
any line on A. Fifth, one end of A has a large and the other a
small contact face; either end may be used down. Sixth, inserted
in the lower end of D is a small broad-headed screw, forming a
shoulder against which B is held by the pressure of the spring E.
This shows better in Fig. 130.

Fig. 131, which is a plan of sliding piece B, shows the manner
in which D is held adjusting in B. This is similar to the clamping
device for the anvil adjustment on the Brown & Sharpe microm-
eter. The tapped hole for the screw is counterbored, as shown

GAGES AND GAGING SYSTEMS

123

-M

FIG. 128. — Micrometer Depth Gage.

124 GAGES AND GAGING SYSTEMS

by the dotted lines, and is so situated that a portion of the screw
head binds against D, making a very rigid connection.

G, in Figs. 128, 129 and 132, is a U-shaped piece embracing
By each leg encircling rod A, and is provided with a set-screw to
tighten against B. This is used to clamp B to A when desired.

Fig. 129 shows the device for clamping rod A in the frame.
The knurled screw F acts against a small shoe, the face of which
conforms to the round surface of A. On this shoe is turned a
stem which is encircled by a coil spring, one end of which presses
against the screw F. This spring keeps a constant pressure of
the shoe against A, which is quite important. In the side of the
shoe can be noticed a small pin inserted, which slightly protrudes

MS)

FIGS. 130, 131, and 132. — Details of Depth Gage.

through a slot in the frame. This is to enable the shoe to be
held back by the thumb-nail while A is being reversed.

Two methods of measuring depths with tool are apparent:
One is to clamp B to A at a suitable line, then operate by means
of nut C. The contact is felt very distinctly, and the nut may
be turned a little too far and then turned back lightly until it
stops. When used in this way the tool is very sensitive. The
spring causes an ideal contact between A and the work. Or the
rod A may be used independently and slid down to contact and
tightened with knurled screw F. The nut C may be adjusted
till the lines match and the reading is taken.

When B is clamped to A at a suitable line, the gage is very
handy to apply to the work as it progresses, when the exact

GAGES AND GAGING SYSTEMS 125

amount still to be planed or milled off can be seen at a glance.
Or the micrometer can be set at the proper reading, and the rod
used independently. Then the amount still to be removed can
be judged by noting the proximity of the line on A to that on B.

This tool can be adjusted for wear at any time, by setting a
flush end nut C at zero, then loosening the binding-screw in the
back piece B, and turning with a screw-driver until the lines on
A and B coincide, then resetting the binding-screw.

In making the graduations on the frame they should be so
placed that the operator will bring the indicator point practically
opposite o or .050 inch.

MAKING AN ARMATURE TEMPLET

In making armature segment templets, a little money spent
at the start will prove a source of great saving when it comes to
handling the thousands of punchings when assembling the ma-
chines; therefore we will describe in detail the best practice and
the way to go about it.

The placing of the dovetails is one of the essential points,
but the location of the slots is equally important, as when assem-
bling the punchings in the machine in any way the slots must
line up. The method we are about to describe of making these
templets is based on a system of reversing on six accurately
located pin-holes, and not filing to any. lines but working entirely
to a gage and plain external measurements. The pins for the
six holes are T%- inch diameter, but i inch long, hardened, ground
and lapped, and all exactly the same size. The end driven into
the templet is perfectly flat, with only the extreme corner taken
off with an oilstone; the other end is beveled off to about T\ inch
diameter, so that, when driving, a slightly slanting blow will not
drive the pin in crooked.

We are now ready to describe the method, and will use the
templet shown in Fig. 133 for reference; it is to have 36 slots
and 12 segments complete the circle.

For the templets, of which we will make two — an original
and a duplicate — we will take J-inch sheet brass, which we will
hammer flat on a plate with a mallet. Then we will lay the two
pieces one on top of the other, and in some out-of-the-way place
near each end, as a and b in the sketch, we drill two fVinch h°les

i26 GAGES AND GAGING SYSTEMS

for two rivets. We now rivet the two plates together, and with
a bandsaw saw out approximately the radius and dovetails so
as to relieve some of the strains before we put any accuracy into
the templets.

Now they are put on the radial planer, and the outside edge
planed, and the inside marked to correct radius, by taking a
sharp-pointed side tool and running in about -£$ inch, with the
square side towards the templet; this groove is used as a gage to
which it is easy to file the inside. As the templet is now planed
we must next determine the center distances of the dovetails
A B, which is the most essential step and the basis of the whole
templet.

About the place we want to locate the dovetail at A, we drill
and ream a T\-inch hole as shown. The location of this hole is

FIG. 133. — Making an Armature Templet

not particular, only it must be a straight, smooth hole through
both templets. Into the hole drive one of the six pins spoken
of before.

Now measure the distance from the outside planed edge to
the center of the pin, which can be done accurately, and subtract
this from the outside radius ; figure the chord from an arc of that
radius having 12 segments to the circle.

360°

radius x sine of — = \ chord.

2 x number of segments

Having figured the length of the chord, add .375 = diameter
of bushing of jig shown in Fig. 134, to the chord, and set the jig
accurately by measuring to your figures.

Next slip one end of the jig over that one pin in the templet,
and place the locating arm on the bushing; and adjust it so that
it will just touch the outer curve edge; transfer the arm to the
other bushing, and locate the jig and clamp. Now drill and

GAGES AND GAGING SYSTEMS 127

ream the pin-hoie at B. Since the templet depends on these two
pins as centers, there is no chance for any errors in the center
distance of the resulting dovetails. Drill another pin-hole some-
where near the point C, and through both templets by driving
out the two rivets. We have now drilled three holes without
laying out; for locating the fourth hole, D, we reverse the du-
plicate templet on the line x y, and drive in the pin on the dove-
tail, then line up the planed edge with a square to shut out light,
clamp the templet and drill through the original, using the drilled
hole in the duplicate as a jig, and vice versa.

Now we have the three pins A, C, D, so reverse the duplicate,
bringing dovetail A under dovetail B of the original, and using

1-r.r

Arm for locating jig

FIG. 134. — Making an Armature Templet.

the drilled holes in each templet for a jig drilled through the
other templet.

We now have all six holes drilled, the last four in correct
relation in the two accurately located dovetail pin-holes, which
we distanced by measuring machine measurements; therefore
we have the foundation for an accurate templet, as the rest of
the templet is derived by reversing on the six pins.

Now upon the original we will lay out the dovetails and slots
approximately, which is not difficult. Place a center square on
the outer edge, put a half pin in the dovetail pin-hole, place the
blade of the center square against this, draw the radial line x y,
and from this line proceed with the laying out. The next step
is to drill and counterbore out the stock in the slots, after having
again pinned the two templets together. There is not much

128

GAGES AND GAGING SYSTEMS

danger of springing the templet by removing this stock, as a
rib, not shown in the sketch, is left intact at the upper end.

A counterbore ^ inch small is plenty small enough, as with
a little care in laying out, the slots will not be out that much.

For filing the slots and dovetails, so as to insure their being
perfectly straight and square, we use the filing jig, Fig. 135. This
needs no explanation, except that the two screws, E and F,
against which the outer edge of the work rests, are adjusted so
that the hardened steel plates on the jig will always take a posi-
tion that will make the sides of the slots parallel.

Before the filing place the original templet on top of the

Hardened Steel Plates,

1 1

Flat Spring

FIG. 135. — Making an Armature Templet.

duplicate and drive in the two dovetail pins; and in order to
make it firmer drive in two more pins in any of the other two
holes. Next place the jig with the hardened plates on one side
of the slot, which is on the radial line with the dovetail (slot No.
i, Fig. 133). Use the laying out again only as an approximation,
and, to allow for errors, place the jig about .010 inch from the
line representing the edge of the slot; then clamp the jig by tight-
ening the screw G passing through the jaws, file the slot down to
the hardened plates on the jig, and then remove the latter.

Now drive out the pins and reverse the duplicate on the line
xy, which will bring our filed side of the duplicate under the
unfiled side of the original, and vice versa. Now by means of a
straight-edge set the filing jig even with the filed surface, and file

GAGES AND GAGING SYSTEMS 129

through the other templet; then with a micrometer and inside
caliper obtain the width of the slot now filed. If it measures
.010 inch too small, place the filing jig on again, and with a .005-
inch thickness gage and a straight-edge set the jig to take off
.005 inch, and then bring the templets back to their original
position and file out the other side, using the surface just filed
on one templet as a gage for setting the jig. Now this slot is
right up to plug size and reversible. In just exactly the same
way we locate this we file the dovetail, only we have a dovetail
gage instead of working to measurements. Now we have one
slot and one dovetail complete on both templets; by simply
reversing the duplicate we can bring and finish slot and dovetail
under the unfinished slots and dovetail of the original, and, using
the former as a guide to set the filing jig to, we finish that dove-
tail and slot. Now we have two slots and both dovetails finished
and exactly reversible and all center distances correct.

Next comes the spacing of the slots: Since the templet has
eighteen slots between the dovetails, then there is one slot just
half way between the two dovetail slots. This slot is numbered
10 on the sketch, and it is a simple matter to get it exactly in the
center by simply using the reversing method just described.
Now we have two dovetail slots, and this central slot in both
templets complete. There is no slot central between No. 10 and
No. i, but we find there is a rib; the trick is to get this rib just
the right thickness so the rest of the slots divide up evenly. To
do this proceed as follows:

With a scratch gage and the planed surface as a guide, draw
an arc i inch from the planed surface clear across the templet,
as shown at m n. Subtract this i inch from the outside radius
and figure the width of the rib at its intersection with this line.

It is plenty close enough to figure the chord between the
centers of two slots and subtract the width of the slot; the re-
mainder equals the thickness of the rib at the intersection of
the line m n.

Make a little snap gage of a piece of metal exactly this figure
size, and file the rib by the reversing method described before,
only instead of reversing on pins, use two flat plugs in slots i
and 10, and a pair of parallel clamps. The ribs can be filed very
accurately to size, as it has a slight taper, generally about .008
to the inch; so if the gage slides to within J inch of the arc, there
is .001 inch yet to come off the rib.

130 GAGES AND GAGING SYSTEMS

When the rib has the right thickness and is reversible, we
finish the other side of the slot by placing our filing jig just the
right distance away to make the slot the right size.

We have now slots 5 and 6 finished; upon investigation we
find that in between the slots i and 5 is a central slot, 3; we get
this slot central by reversing, using our flat plugs in holes i and
5. Slot No. 8 we get in the same way. Slots No. 2, 4, 7, and 9
we use our little sheet metal snap gage again.

The slots from i to 10 are now finished and correct, and by
reversing these ten slots into different positions and using them
as gages to set the gage to, we file the incompleted slots.

A templet made in this manner is accurate in every detail,
can be reversed, and slots can be shifted in any way, and there

.1875

.375

.125 -'V,

FIG. 136. — A Locating Templet.

will be no greater error than .001 inch anywhere. A templet,
as described above, is generally completed in from forty to fifty
hours.

Another advantage of duplicate templets is, the duplicate
can be used in making the die, thus saving the original as a
master.

MAKING A TEMPLET FOR LOCATING PARTS

Piece A, Fig. 136, is a templet that was used on a certain
operation in experimenting to locate certain parts accurately
from a bushed .090 hole in wing a, to a .1875 hole at right angles
to it. The four holes in A are body size for 10-32 screws, and
need not be very close; the piece that goes on is located by the
.1875 hole. Wing a was hardened up as far as we could without
hardening the thin part. There were nine of these wanted.
There was nothing out of the ordinary in machining them in the
soft stage; they were left about .025 inch large, and this was
found more than enough to finish >to size.

GAGES AND GAGING SYSTEMS 131

The first thing we did was to lay out the four 10-32 screw
holes fairly close, as we were going to use them to work piece A
from. The hole for the bushing was laid out approximately
between surplus stock; this hole was drilled and reamed on a
drill press, and the screw holes were drilled; then wing a was
hardened and the hole lapped for the bushing. There were
fifteen bushings made to get what we wanted. In testing roughly,
we used an indicator test, and threw three of them away right
off; and with the flat surface test with a finish hole cast out two
more, which left us one extra one. This sounds extravagant, but
we don't think it was so, considering what would have happened
if we had not detected the poor ones in time. The bushings were
first rough lapped, then rough ground on the outside, so they
would fit a holder with a round hole to clamp them while we
were lapping the hole. This is good practice on bushings, for if

A '

o-f-

B !

,0!)0 Plug
Paper
FIG. 137. — Grinding Surface Parallel.

there are any surface strains you take them out, and you hold
the work as true as you can get it.

After finishing and tapping the bushings home we ground
surface b parallel with .090 plug in Fig. 137, and the proper dis-
tance from it, using a piece of gray iron milled out for the wing
to enter, with a sixteenth play on the side. Piece B was ground
in place on the magnetic chuck, so as to make contact with the
other pole through a loose piece of iron C, with paper between
B and C. Piece d is a block to rest A on while grinding b, surface
C being ground parallel with b by resting d on the chuck. About
.002 was left to finish and correct errors liable to show in the
squaring-up test.

The work was then taken to a lathe with draw-in chucks.
Fig. 138 is a plan of the face-plate, with a floating or false plate
attached with screws or straps. The floating plate was faced off
true, and a f-inch hole drilled through to let a pin held in the

132

GAGES AND GAGING SYSTEMS

chuck and turned down to .1875 inch stick through far enough to
set piece D properly; the required distance being obtained between
the .090 plug placed in D and the .1875 pin just turned, by using
a templet (shown by dotted lines) of the right thickness to go
between them. The wing a (Fig. 136) was set approximately
central with the .1875 hole with an adjusting screw, tapped
through one side of piece D, as in Fig. 139. In setting wing a,
we used a line drawn across surface C (Fig. 137) central with the
wing; then with a fine point set central, and turning the spindle
half way around, we set the setting piece. Piece D once set was

0 ,^XN \

FIG. 138. — Work Located in Lathe.

not disturbed. We had to move the adjusting screw to keep
within our surplus stock. Using a light strap to hold A up
against the adjusting screw point, with the .090 plug in A and
D, we drilled and bored the holes to size.

Piece D was finished the right distance from the bottom up
to the plug .090, and used as a gage to test A when grinding
surface b, Fig. 137; it was made of gray iron, and the .090 holes
were not bushed.

Block E, Fig. 140, is gray iron, with face e square with the
bottom. The channel is the right hight to allow the .090 hole
to be squared up by using a plug about i| inches long, and
tapping A up or down until it shuts out light in any of the three

GAGES AND GAGING SYSTEMS

133

positions possible when on grinding block F. We used 6-32
machine screws to attach piece A to block F, and after it was
tapped square with E ground surface /; and then turned the
piece over on the other face, squared the plug and ground surface

)

._ "

^0^

•

X
F

Poin« of Screw

FIGS. 139 and 140. — Details of Templet Making.

g. Surfaces / and g at this stage are parallel, but unequal dis-
tances from the center of the .1875 hole. Angle G, Fig. 141, is
what we use for measuring from a plug up to a narrow edge.
Piece A is shown in position to be measured over points marked
a with a micrometer. The angle G is hardened steel, ground

FIG. 141. — Details of Templet Making.

and lapped and assembled as shown. After measuring these
pieces, we tested them by putting them on a plug, and seeing
then if they would reverse without the edges falling or rising.
Wing a, Fig. 136, was ground roughly, leaving .0005 on a side;
then a finishing cut of .0003 was taken, which left .0002 to lap
— which is all we want on a piece like this. Surfaces / and g,

134 GAGES AND GAGING SYSTEMS

Fig. 140, rested on a chuck, and surfaces b and c between two
square parallels when grinding wing a.

The work was tested at every stage in making these templets
in this way.

FIG. 142. — Lathe Bed.

TEMPLETS FOR PLANING A LATHE BED

A templet or gage is first made to prove and secondly to bring
work to a standard. The manner in which these gages are made
often causes a great difference in the time consumed in fitting.

The superintendent was a good mechanic and a nice man to
work for, but the shop was new, and he had much to contend
with. When the better templets were shown to him, he at once
allowed them to be made. In Fig. 142 is shown the end view of
the lathe bed, and in Fig. 143 the templet first made. Tnis was
required to fit the V's and the flats at the same time.

O Q

FIG. 143. — Lathe Bed Templet.

The body of this templet was made of i x 2 inch machine
steel, with V's cut in J-inch tool steel plates. One inch round
stock was turned down on the ends and set in to give the hight
of the flat bearings, as shown.

In using this templet it was necessary on account of its nar-
row bearings to use a square to line it up across the bed, and
also vertically. It was a very slow job of cut and try, until the

GAGES AND GAGING SYSTEMS 135

templets, Figs. 144 and 145, were made. After the bed was
roughed out, the proper distance from the first side of one V to the
first side of the other was obtained by the use of the half templet,
Fig. 144, then the other two sides of the V's were finished until
the whole templet, Fig. 145, rubbed chalk marks off the four
sides of the Vs.

The flat bearings were finished last. The hardened steel
plugs A A in templet, Fig. 145, were fitted so as to hold paper
between their faces and the. job. The templet for planing the
tool carriage was of course just the reverse to Fig. 145. The
saving of time in using the last templet was over 3 to i.

FIGS. 144 and 145. — Lathe Bed Templet.

A PERMANENT SNAP GAGE

The snap gage shown in Figs. 146 and 147 consists of jaws
B B and center piece A, the latter being exact width of dimension
desired. After pieces B B have been ground and lapped, they
are put together by means of screws, as shown. Plug D, Fig.
148, is a good gage to test the snap gage with.

In constant use a gage of this kind will wear, especially if
used to test round pieces such as would naturally be turned and
twisted in the gage, and give rise to hills and valleys. This may
be detected by a plug gage, as shown, one of which is the same
size as the snap gage, and the other end .001 or .0005, or any limit
that may be established, larger. When the big end of the plug
will enter the snap gage, it should be . taken apart, ground if
necessary, lapped and put together, when we have again a new
gage with a little or no gage expense. One end of the plug is
marked size by S, the other end limit by L.

This is no doubt a very superior form of gage. Its great
merit lies in the fact that the more expensive piece A, which
determines the size, is not subject to wear, while the correction
of the gage .when worn does not involve any expensive work, by
merely the resurfacing of pieces B. The screws should be a loose
fit in A, to avoid any tendency to swell that piece. Most of

i36

GAGES AND GAGING SYSTEMS

these gages that we have seen (and they are the accepted form
of gage in some leading and first-class works) have but a single
end, two screws only being used and one end of A being extended
beyond the jaws to form a handle, thus making a gage which is
more like the usual form. The construction shown has the ad-
vantage that at a trifling additional expense two gages are made.
It would, however, be obviously impracticable to make these of
different dimensions to act as limit gages.

FIGS. 146, 147, and 148. — Permanent Snap Gage.

ROD GAGING FIXTURE

Having to gage for length a number of steel rods of various
diameters and lengths, and it being necessary that there should
not be more than one-thousandth variation either way, the gage
in Figs. 149 and 150 was devised to detect the slightest inac-
curacy of length.

In a gray-iron base block A were cut a series of V-grooves
of depths according to the diameter of the style of shaft for which
each was intended. At one end of A a groove was cut a slight

GAGES AND GAGING SYSTEMS

137

angle; running freely in this groove was a steel strip B, screwed
to which was a steel block C, having a hardened and ground face,
which was square with the grooves in the base. At one end of
C were placed graduations, and also on the slide plate D. At
the other end of the block A was fitted a hardened and ground
steel block E, which received one end of the shafts and was cut
away according to the lengths of these. A shaft to be gaged
was placed in the groove which bore its number, and the block
B advanced until the face of C contacted with the end of the
shaft, the vernier marking on the end of the block then showing
whether the shaft length was to the required degree of accuracy.

--10.625 -•

FIGS. 149 and 150. — Rod Gaging Fixture.

A PLANER GAGE

The sketch, Fig. 151, shows a gage which is perhaps a little
out of the ordinary; it is used to gage the width of planer beds,
the top rails being planed to a similar gage, and the object being
to jig the side screw holes in the top rail.

The main casting A floats in the blocks B which rests in the
V's of the planer bed. These supports are about 6 inches long,
and serve to keep the gage screw with the tracks.

C and D are hardened and ground steel disks, held in posi-
tions by flat-head screws. Opposite these disks are two holes
through the casting A, fitted with hardened bushings and plungers

j38 GAGES AND GAGING SYSTEMS

E and F. The outer end of the plungers and bushings are ground
flush when the gage is set to the standard size, or 22| inches.

The method of getting this size may be of interest, the avail-
able tool being a 1 2-inch vernier. Two pieces, G and H, were
turned and fitted to a bushing, the ends square to nj inches,
and two pointed screws used to draw the ends together, as shown.
This measuring rod was used between the points C and D and
E and F, first getting C and D square with the inside of the gage.

The general dimensions of the casting A were as follows:
Main web and cross ribs, \ inch thick; outer rim, \ x i^ inches;
inner rim, f x i \ inches, except at supports, where it is \ x 2j.

FlG. 151. — Planer Gage.

GAGES FOR TEXTILE MACHINE WORK

Fig. 1 52 shows the gages used in the manufacture of spindles
for textile machinery.

When a drawing is received for a new spindle, the first thing
done is to make a sample, which is used as standard for all others
of that kind made. Hardened and ground plugs are made for
the different diameters and tapers, and are used to make the
gages from and for testing the gages.

For grinding straight work over 4 inches in length ordinary
yes-and-no ring gages are used. The operator also has a try-
gage, like A, made from |-inch stock, thickened to f inch at the
contact points. The operator uses this gage without removing
.the work from the machine. When this gage will go over the

GAGES AND GAGING SYSTEMS

139

work easily, the operator removes the work from the machines
and tries his yes-and-no gages, which have a limit of .0015 inch,
and he rarely has to put the work back in the machine. As the
gage wears it is peened at a to bring it back to size.

At B is a spindle on which the taper has to be ground very
accurately, and the gage has to be a certain distance from the

FIG. 152. — Gages for Textile Machine Work.

extreme point within the limit of .01 inch. Three gages are
used, C, D, and E. C is the ring gage to get the taper by, and
has a step on top .01 inch high. D is the spanner gage to get the
length by, made from J-inch square stock. E is the try gage.
The slot is cut in the top so that it will slip over the center, so as
not to back the center off when trying the gage. When the
operator rings up the machine for grinding this taper, he first

140 GAGES AND GAGING SYSTEMS

grinds one spindle to size, and then adjusts the little piece of
steel b, so that it will just rub against the side of the rest. This
gage will then show every time when the work is down to size.
In grinding each piece, he uses this gage, and when he feels it
touch the rest he removes the work and tries his ring gage, and
then his spanner, which has to touch on the lower step, but not
on the top one; anything between the two is all right.

The gage F is the one used for gaging, our taper grinding up
to f inch diameter and 6 inches long. When taper and size are
correct the end of the spindle will come flush with the top of
wire c, the top ring will be flush with the wire d, and the two
middle rings will be flush with the marks on this wire. For
small, accurate work this gage can be recommended. As the
gage wears, the wire c can be driven out and a longer one inserted,
and if the holes do not wear equally, the ones that wear least can
be polished out. All of our gages for lathe work up to J inch
are made like G, but with only one hole, the roughing gages being
made with point contact and the finishing with line contact, as
shown.

For gaging taper work, like H, on the turret lathe, we use a
gage like /, and the taper is determined by placing the gage on
the work and holding up to the light; the size is determined by
the gage touching both the taper and the shoulder on work.
On lathe work above J inch we use the gage K, made from -fg-
inch flat stock. For pointing to length we use an adjustable
spanner gage like L, made from round stock.

These gages are all easily and cheaply made, and fulfil all the
requirements of spindle making, and will perhaps be of use to
others.

SECTION V

INSIDE MICROMETER CALIPERS AND OTHER GAGES
FOR INTERNAL MEASURING; THEIR CONSTRUCTION
AND USE.

MAKING SMALL INSIDE MICROMETER GAGES

THERE are now on the market numerous different makes of
inside micrometers and inside micrometer gages, the smallest
measuring as small a hole as 2 inches. Now all machinists know
that there are more holes bored below 2 inches in diameter
than over 2 inches. But so far none of our tool manufacturers
has undertaken to fill the demand for measuring tools for these
small diameters, although we all agree that closer measurements
can be taken with an inside micrometer gage than with an inside
caliper.

Tools of this kind for small sizes can be made cheaply and
would soon find a market. For making a micrometer gage to
measure from £ inch up, let us take a piece A, Fig. 153, of -^-
inch machinery steel, put it in the lathe with a spring chuck, center
it and drill a hole \ inch deep for tapping, with a J-inch tap,
40 thread. Then take a wabble drill, or rather make it of a piece
of Stubbs' steel; flatten and grind it out of center. Drill with
this -fo inch deeper, and then tap it and turn a short taper a and
thread it with a fine thread, cut it off ^f inch long, turn it around
in the chuck, and round and polish the end with a radius less than
J inch. With a thin milling cutter split the piece at a into four
jaws. Make a small knurled nut D to fit at a for closing the
jaws. Case-harden this sleeve on the large end. Next cut the
same thread that we have in the sleeve on a J-mch Stubbs wire;
round one end and cut it off ^f inch long. On the round end of
this screw B file a head, as at C, and harden this end.

For a wrench to turn the screw make a round disk E \\ inches

141

142

GAGES AND GAGING SYSTEMS

diameter, ^ inch thick, with a hole in the center to fit the end of
screw B, and graduate the disk into, twenty-five equal parts to
correspond with our 40 threads on the screw, and thus read to
thousandths of an inch. Harden the disk around the hole. Next
make a handle H, 4 to 6 inches long, to hold the sleeve A when
measurements are taken. At F is riveted an indicator or hand
that swings on the handle, and has an edge that points to the
thousandths on the disk.

With an outside micrometer and disk E for a wrench, we
turn screw B in the sleeve A, and set it to any size from J to

FIG. 153. — Small Inside Micrometer.

1£ inch, and lock the screw by the knurled nut D. Or we place
the pointer on the handle to match at zero on the disk when
screw is turned into the sleeve, and the tool measures % inch,
and lock the handle with screw /.

We now have a micrometer for inside measurement within
the limits of T3g- inch. If we make another sleeve A ^f inch long,
drill and tap as before \% inch deep, and in this fit a screw ^f
inch long, and use the same disk, handle and nut, we can then
measure a hole from |£-inch diameter to i inch, and still with
T%- inch of screw left in the sleeve, giving it a good, steady hold
when locked with the knurled nut. The next largest sleeve
should be §| inch deep, and a screw §| inch long, drilled and
tapped ff inch long. This would enable us to measure from I

GAGES

AND GAGING SYSTEMS

'43

to IT\ inches. And still another sleeve i^f inches long, with its
screw the same length, would measure from iT9^ to 2f inches.

This makes four sleeves, but all being small and made of soft
material and case-hardened, they could be made at little expense
in a screw machine even; the same disk and handle and nut being
used for them all, if we wish. One advantage with them is that
we can reach into very deep holes and still have a sensitive and
reliable measuring tool. One disadvantage is that the screw is

FIG. 154. — Inside Micrometer Assembled.

exposed to dust and scratches, the same as older styles of outside
micrometers; but this can be prevented by having four or five
split brass sleeves, which are easily made to slip over the screw
and cover most of it.

AN INSIDE MICROMETER

The half-tone, Fig. 1 54, shows an inside micrometer assembled.
Its capacity is from £ inch to 3^ inches. Fig. 155 shows details.

The two members D are made of flat tool steel, .070 inch thick.
The three holes, E F G, are drilled in line, the distance from E

144

GAGES AND GAGING SYSTEMS

to F being twice the distance from F to G. The locating and
finishing of these holes must be done with the greatest care, as
upon them the accuracy of the tool is to a great extent dependent.

The upper parts of the members D are filed away, so as to
leave G a little more than half a hole. The trunnions H of the
swivels A and B fit in the hole G, and the swivels A and B cannot
fall out of G unless they are swung around in line with the mem-
bers D.

The swivel A goes in the left member D, as shown in the half-
tone. Its barrel is .250 inch outside diameter, and is bored .172
inches — a sliding fit for the end of the micrometer screw L.

FIG. 155. — Details of Inside Micrometer.

The swivel A is also provided with an adjusting screw I to take
up wear.

The swivel B is bored .250 inch — a sliding for A; the rear end
of B is threaded at / to form a nut for the micrometer screw.
The outside is .310 inch diameter, and is graduated as shown in
the half-tone, the inch spacing being of course only ^ inch apart
because of the two-to-one ratio of the legs D.

The thimble C is bored .310 inch to fit over B. It is .40 inch
outside diameter, and is secured to the micrometer screw in the
usual way. The micrometer screw, .250 inch diameter, is
threaded forty threads per inch. The thimble is divided into
fifty spaces instead of twenty-five, for the same reason that the
inch graduations on B are half an inch apart.

GAGES AND GAGING SYSTEMS

145

The contact points of the instrument are disks .250 inch
diameter, with rounded faces. The ends of the members D are
counterbored at E to receive a small projection on the side of the
disk, which is fastened in place by a small machine screw. When
a disk becomes worn, it may be turned around so as to present
a new face to the work. The U-shaped spring K keeps the end
of the micrometer screw L in with the adjusting screw /.

With this rule measurements within .001 of an inch may,
with practice, be made.

INSIDE MICROMETER CALIPER

In Figs. 156 and 157 are contained sketches of an inside
micrometer caliper which is quite easy to make, and is very useful

FIGS. 156 and 157. — Inside Micrometer for Shrink Fits.

in making shrink fits, etc. The frame A is a brass casting made
in the form shown to allow a considerable adjustment of rods B
and also to make a place for the lock-nut C. One end of the
frame D is drilled out with a J-inch drill, and tapped with a -f?
tap (special). The other end E is drilled J inch to receive the
rods. The frame is placed on centers; the end D is turned to
| inch, and the end E to J inch, and is threaded and tapered as
per sketch.

The barrel and screw are made separately, the barrel being
shrunk on the screw at F. The screw has 40 threads per inch,
and is -fa inch at top and J inch at the bottom of the thread.
The tap is made to correspond with this, and is also used to tap
the lock-nut. The barrel was graduated on a mandrel in the lathe.

146

GAGES AND GAGING SYSTEMS

using a 5o-tooth gear, and marking at every second tooth, making
25 divisions. A straight line is drawn on the end of the frame
at D. The screw is screwed into the frame until the barrel is
within J inch from the angle of the frame, bringing the division
marked 0.25 exactly on the line. The frame can then be gradu-
ated accurately by revolving the barrel and scribing at each
revolution until T5o is marked off. The clamping device holds
the rods firmly in place. We have made four of these calipers,

FIG. 158. — Micrometer Gage for Large Work.

which are in daily use and giving satisfaction. The one we have
is nickel-plated, which adds considerably to the appearance of
the tool. There are six rods allowing measurements from 10
inches to 36 inches.

MICROMETER GAGE

The gage shown in Fig. 158 is designed for large wprk, and
having a graduated head is conveniently used in connection
with calipers when making allowance for shrink or press fits.

GAGES AND GAGING SYSTEMS 147

The screw A is 40 threads per inch, and its head is slotted to
suit finger B, which is made of thin spring steel and sweated in
the slot. The barrel C is graduated to 25 divisions and slotted,
as shown, so as to form a spring fit on screw A. The other end
of this barrel has four slots, and in connection with knurled nut
D holds the ^-mch rod E in place. F is an extension barrel
which is screwed on the lower end of barrel C. If a rod, as E,
is used and it does not pass through both barrels, C and F, a
short T\-inch rod is placed in C to allow F to clamp thereon.
The nut D of course fits the lower end of F.

INSIDE GAGE

Having several gun-metal castings to force over gray-iron
bodies, we made a gage similar to the one shown in Fig. 159.
The casings, Fig: 160, were bored \ inch taper in 8 or 9 feet, and
were large enough in diameter to crawl through. We divided
the casing and gray-iron body into a number of equal spaces, as
indicated, set our lathe to the required taper, and then calipered
the small end of the casing and turned the small end of the body
to suit that size. We next calipered the casing at point 2, to
find the size that the body should be at the corresponding point,
and if the taper body was on the large side, we tapped the handle
of the cross-feed till it was right; in this manner we calipered
at the different points to keep the work to the required taper, as
in the long casing the accuracy of the taper hole bored could not
be depended upon. The reason the casing was bored taper was
that it could be slipped nearly half way over the body without
coming to a bearing.

The body of the gage is made of a piece of J-inch brass gas
pipe (although it could be made of iron pipe) about 6 inches
long. The end A is tapped ij inches deep with a ^ tap to re-
ceive a screw B, which has a J-inch hole drilled about -ft inch
from the tapered end to admit a piece of wire for adjustment.
A TVinch hole C is drilled 3 inches from end D, and a stop E
about J inch long is forced down tight in the pipe until it is past
hole C, then the side of the hole is filed flat and flush with the
stop, as shown.

Both ends of the pipe are threaded for a length of J inch with
J-inch pipe thread, and then split on quarters with a hack-saw

148

GAGES AND GAGING SYSTEMS

to permit them to be tightened up on the extension rod F, and
the adjustment screw by the brass hexagon nuts, which are
drilled out for J-inch pipe thread.

Extension rods F are made of J-inch steel wire, and should
vary in length by about \ inch. In calipering a hole, you insert
a rod in the end of the pipe till it reaches stop E, and clamp it
by its nut, then adjust screw B to get the required size, and
clamp it also.

GAGES AND GAGING SYSTEMS

149

INSIDE MICROMETER

The Towndrow micrometer, Fig. 161, measures from .995 to
4 inches, in thousandths, and consists of a head cross-wise to
receive a split and internally thread bushing, which is clamped

Gray Iron Body

1 •

t /

J ,

• ;

' i

i :

' '

;

Gun Metal Casing

FIG. 160

by a small eyebolt threaded to fit the end of the knurled handle.
The bushing thread is 40 per inch, and one end is provided with
twenty-five graduations, so that with one measuring point
screwed in tight, the other may be turned by a small knurled
spanner to give the desired setting. The measuring points are

FIG. 161. — Inside Micrometer and Attachments.

of such length that with the removable one screwed up against
the one that is fixed, an even inch setting results; the adjustable
point is then unscrewed to give intermediate setting by thou-
sandths. Provision is made in the instrument for adjusting for
wear on the points.

I5o GAGES AND GAGING SYSTEMS

AN INSIDE MICROMETER CALIPER

We have had occasion to bore holes in the lathe, which was
necessary in order to make as straight and as near a certain size
as possible; and, as is often the case, in some of the shops the
supply of reamers was jimited, and it required some very careful
feeling with ordinary spring calipers to reach the desired result.
Now there was not then on the market an inside micrometer
caliper which would caliper less than 2 inches, and at the time
we made the one about to be described, the one which we could
get our hands on would not caliper less than 2| inches. Some one
probably suggests, "Why not use solid gages?" Well, solid
gages are all right for some work, but the supply of them, like
those of the reamers, was limited, and they were not limit-gages
either. This caliper is not intended at a measuring instrument,

FIG. 162. — Special Inside Micrometer.

but is to be used, in connection with outside micrometer caliper,
for setting for the required size, either above or below, and may
be readily adjusted or detected in thousandths of an inch.

It consists of frame a, Fig. 162, the spindle b, micrometer
sleeve c, movable contact piece /, set-screw g, friction i, and
friction-spring /. All parts are steel except friction piece i,
which is brass; and all wearing surfaces are hardened. The frame
a is in one piece, drilled, reamed, and tapped to receive the spindle
b. The straight portion of the spindle is made of nice working
fit in the frame by grinding (after it is hardened) for about ij
inches from the point. In fact, it is necessary, to the proper
working of the caliper and the fits, for all the moving parts to
be made in this manner.

The sleeve c is made a tight fit on the end of b, and has twenty-
five divisions. The spindle- is threaded twenty-four per inch,
and the angle of its point is such that one revolution causes the

GAGES AND GAGING SYSTEMS 151

contact piece b to move twenty-five thousandths of an inch, and
has a range of one-tenth inch.

The contact piece d is first turned to fit in its proper place,
but the body of it is made considerably longer than necessary.
A point reamer, the same shape and size as the point and un-
threaded portion of the spindle, is then inserted, and a conical
hole made in the piece of such a depth that the point of the reamer
just comes through. It is then cut in two, leaving a half conical
face on d to form a seat for the point of the spindle b. This method
avoids the necessity of making a perpendicular key-seat in d, and
a pin or key in the frame to keep the piece from turning, which
would be required if the angular face of d were made flat. The
movement of d will be uniform if the point of the spindle is not
forced upon it to a greater depth than that to which the conical
hole was reamed.

SECTION VI

HIGHT AND VERNIER GAGES AND ATTACHMENTS;
THEIR CONSTRUCTION, VALUE, AND USE.

ATTACHMENTS FOR THE VERNIER AND DIAL TEST INDICATOR

AMONG the valuable small tools in general use in machine
shops and manufacturing machinery plants, none is higher up

• .3-rM

^ s • n

FIG. 163. — Vernier Attachments.

than the vernier gage. Very often such tools are made still more
valuable by the aid of some little attachment. Fig. 163 shows
the vernier transformed into a hight gage. The base is made of
gray iron, having a slot cut near one side so the tool can be brought
nearer to the work when locating a jig button. Having set the
sliding jaw of the vernier to zero, place it in the block or stand
and clamp it securely by the jig A; place the scribing and hight
gage attachment B on the sliding jaw and fasten with screw C.
Setting the attachment down even with the block or surface
plate enables one to work from the bottom of the surface plate
when locating jig buttons, laying out work, scribing lines, etc.

GAGES AND GAGING SYSTEMS

'53

Having the buttons located on the plate or jig, the indicator
is now wanted for truing up for boring the holes. In many

FIG. 164. — Dial Test Indicator Attachment.

instances the lathe is not available or suitable to do the work;
therefore we must use the milling machine or the drill press.
In Figs. 164 and 165 a dial test indicator (Brown & Sharpe) is

154 GAGES AND GAGING SYSTEMS

shown fastened to a shank fitting to a drill-press spindle. A
T-slot is cut for the bolt A for clamping; this slot also permits
adjustment of the indicator. The attachment B is now clamped
to the hub C by screws D, and the arms G are adjusted, one to
the button E and the other to the rod F. The joint H is shown
in cross-section in the bottom view and requires no further de-
scription or explanation. When using this device in the drill-
press or milling machine, the spindle of course must be turned
by hand, and the reading of the dial noted while turning slowly
and adjusting the work until true.

This device can also be used in the lathe by using a shank
fitting the tail stock, the arms G being adjusted to suit the button

FIG. 165. — Dial Test Indicator.

or the bored hole, as the case may be. As the work in this case
revolves, its truth is readily ascertained.

PARALLEL VERNIER GAGE

The cut, Fig. 166, shows a parallel vernier gage that has proven
to be very handy in measuring when lapping and milling snap
gages; it can also be used as a small hight gage to measure the
distance from a shoulder to the base on a planer or milling ma-
chine job. After a snap gage has been ground or lapped in a
machine to within, say, .0005 inch, it must be hand-lapped, for
a slight tipping to one side or the other is bound to occur in the
machine, and as a consequence the surface becomes belly-shaped.
The tool illustrated is used in connection with the lapping in order
to get perfectly straight and parallel surfaces. It has a rise of

GAGES AND GAGING SYSTEMS

'55

| inch in its length from .600 to i.ioo inch, and it. may be used
for any greater hight by fastening half-inch blocks^ on top of the
slide with screws. If such blocks are used they must be hardened,
ground and lapped true. The slide B is made of tool steel and
is composed of two pieces. The top plate is hardened and ground
and soldered on. Four small screws hold gibs in position and
provide adjustment; the tapered knurled screw C serves to lock
the top slide at any point on the base A by lifting the binder D,
which is slotted on the under side to fit the dovetail on A. The
flat spring E is placed in the top of the hole in B in order to push
the bushing down clear of the dovetail, A, so that the slide B
may move freely when released. A ^-'mch hardened sheet

FIG. 1 66. — Parallel Vernier Gage.

steel plate is also soldered on to the bottom of the base A, thus
forming hardened working surfaces on top and bottom. The
tool is ground square and parallel all over, and the top and bot-
tom are lapped, care being taken to have the sliding parts scraped
straight in order that the measurements will register correctly
for all settings.

When it is finished and assembled, the graduations should be
marked. This can only be done by hand. Mark the slide B in
the center with a zero line and locate it at .600, .700, .800, etc.,
positions on the base by using a micrometer, and mark each
position with a line and the proper figures, as shown in the cut.
Then divide each space into ten equal parts. To make the
vernier the top scale must be laid off so that ten spaces cover the

156 GAGES AND GAGING SYSTEMS

distance of eleven on the lower scale, 5$ of the divisions on the
lower scale being on each side of the zero line when set, as shown
in the cut. The divisions on the vernier should be numbered
from i to 5 on the right-hand side, and from 5 to 9 on the left-
hand side of the zero mark. It will thus read in tenths, hun-
dredths, and thousandths. The graduation of the instrument
is similar to that of vernier calipers, and is read in the same way;
but it is much plainer on account of the pieces being wider. In
the position shown the gage reads .850 inch. If one or more
thousandths is wanted, move the slide along until i, 2, 3, etc.,
meet the corresponding lines on the bottom scale.

Under no circumstances should this tool be hardened, as it
will warp so that it is impossible to lap it straight. This is the
reason that the hardened steel plates are soldered on top and
bottom, so as to give it a hard surface on the principal wearing
parts.

HIGHT GAGE FOR TESTING AND LAYING OUT FINE WORK

In Fig. 167 is shown a tool constructed for laying out and
testing fine work. It has a range by thousandths, from zero up
to 5 inches, the adjustments being accomplished by the plug
fitting the five bushed holes in the beam slide, and the micrometer
screw at o. The holes serve to divide accurately the 5 inches
into equal steps, while the screw and micrometer nut p give the
fractions of an inch in thousandths. The beam q fits into base-
block e, and is secured there by tapered dowels. An easy way
to obtain a rectangular hole in such a block is to mill a slot of the
desired width, starting at the rear end of the block, and then fit
a piece of steel, as shown at s in the rear part of the slot, this
piece being secured in place with dowels. Also through the
forward part of a block there is a slot which allows the measuring
or scribing jaw t to come flush with the bottom of the base; this
jaw, as well as the base block, is hardened and accurately lapped.
The knurled head-screw u bears against a flat spring which always
holds the slide in position when the hardened and lapped plug v
is withdrawn. The micrometer screw, which has 40 threads per
inch, is splined and slides on a key which is inserted in the slide.
Against this key the tapered and knurled screw w bears, thus
locking the micrometer screw at any point. One of the essential
points, when building a tool of this description, is not to have

GAGES AND GAGING SYSTEMS

the bushing holes in perpendicular alignment; in other words,
they do not want to be located so that the plug v can be entered
into No. 3 holes in the slide, and yet go in a No. i or No. 2 hole
in the beam.

FIG. 167. — Tool for Laying Out Work.

The rectangular hole through the slide is formed in the same
way as the hole through the base block — that is, by milling a
slot and inserting a piece of steel at the open end. The microm-
eter nut p is made in two parts; the knurled and graduated ring
being a press fit on a hardened and lapped nut. The advantage
of this construction is that it allows the tool to be correctly
adjusted without much trouble.

158 GAGES AND GAGING SYSTEMS

A SIX-INCH HIGHT GAGE

The following description pertains to the hight gage constructed
as shown complete in Fig. 168, and in detail in Fig. 169. It
has a range by thousandths, from zero to 6 inches, is rigid and
accurate, and can be quickly set to exact position by inserting
a plug, as shown. The set of six independent holes through
both slide and beam are fitted with hardened steel bushings,
ground and lapped to fit the plug, which locates the various
inch settings.

The beam a, — which forms the main body of the instrument,
is made of tool steel, and one end is fitted to base b, which is held
in position by two straight pins. In a gage of this design we must
not have the bushing holes in perpendicular alignment so that
the plug c will enter any other hole than the corresponding hole
in slide d. The holes in the beam are not drilled till after the
gage is assembled. The base block is made of mild steel and
case-hardened, and in the edge of the block there is a slot which
allows the scribing jaw to come flush with the - bottom of the
base. A hole is bored and tapped to fit the rod e, and this hole
must be parallel with the hole for the beam. An easy way to
make the rectangular hole is to mill a slot of the desired width
for a driving fit for the beam, starting at the rear of the block,
and then fit a piece of soft steel in the rear of the slot. This
piece is riveted securely in place with a soft steel wire, and finished
on the outside to coniform to the base, which is now as good as
solid. The bottom of the block is turned out in the center to
within | inch of the edge.

The screw / is J U. S. standard and cut twenty threads per
inch; a TVinch hole is bored through the center to receive rod e
and is recessed in the middle to give it a free sliding fit. The upper
end of the screw is turned to a driving fit in the slide d, and
secured in position with a pin. The top of the thread is turned
off .01 inch to allow the scriber to slide freely on the screw. The
nut h is used for lowering and raising the slide, but instead of
having the graduations placed directly upon it, the micrometer
nut is made in two parts; the knurled and lapped nut fits the
graduated ring i, being a press fit. The advantage of this con-
struction is that it allows the tool to be correctly adjusted without
much trouble. The ring i is graduated with fifty divisions, each

ift 3

160 GAGES AND GAGING SYSTEMS

equaling a movement of the scriber of .001 inch. This ring may
be turned by means of a small spanner wrench so as to bring the
zero line into correct position to compensate for wear. A knurled
locking nut is also provided for holding the scriber in any fixed
position.

The scriber is of tool steel, hardened and lapped to a finished
surface; it should be ground at an angle on top when the edges
are worn. The rear end is slotted to fit the rib of the slide, and
provided with two screws to compensate for wear. On the scriber
there are two zero marks, which show at a glance the measure-
ments being taken. The slide is also of tool steel, and at the top
a hole is bored to fit the end of the screw, but not till the rectangu-
lar opening is milled to assure its being parallel. The rectangular
opening through the slide is made in the same way as that through
the base by milling a slot and riveting in a piece of steel at the
open end. At the front is a rib for the scriber to slide on, and
one side is milled at an angle and has graduations of .025 inch
for a distance of i inch.

The knurled head screw k bears against a flat spring, which
always holds the slide in position when the plug c is withdrawn.
When the tool is assembled, the scriber is set to zero with the
standard length gages i, 2, 3 inch, etc., and fastened with the
knurled head-screw. The holes are now drilled and reamed
through slide and beam at the same setting; the same operation
is performed with lapping after the bushings are driven in.

SECTION VII

TRY-SQUARES, KNIFE-EDGE SQUARES, COMBINATION
SQUARES, STRAIGHT-EDGE TEST AND SIZING
BLOCKS, TOGETHER WITH METHODS FOR THEIR
CONSTRUCTION, TESTING, USE AND ADAPTATION.

SQUARES AND SQUARES

THERE is no doubt whatever that the commercial hardened
squares are used in many shops wherein their blades are nearer
straight than anything else ever seen there. In such shops these
squares are for all practical purposes straight and true and square.
To refine them still more, and to charge the higher price that
would thereby be made necessary, would obviously be a mistake
for such shops. It is clear enough, however, that there is a class
of work requiring greater refinement; but it by no means follows
that it would pay any manufacturer to put the finest and most
accurate squares upon the market. In those shops where the
finest and most accurate squares are needed, there are always
to be found men who, given the proper facilities, can make them.
In other words, where the work requiring the use of such squares
is done, men must be employed who are capable of making the
squares, whether they actually do make them or not; and as
most of the work of producing such squares is necessarily done
by hand anyway, there is probably little chance of there being
ever any great commercial demand for such tools. Therefore
every good mechanic should be interested in learning of the
proper methods to use, and the mode of procedure to be followed
when a square that will be "perfect" is required to be made.

How TO PRODUCE A CORRECT SQUARE

It has been claimed that to produce a correct try-square is
an extremely difficult jub. Oftentimes that opinion has its
foundation in the comparison of many commercial squares with

161

162

GAGES AND GAGING SYSTEMS

one. another. Most likely none of the lot so examined are proper
tools as test-squares. In the case of some workmen it is little
wonder that their squares are not true and square, from the fact
that their association is with files and other tools, to say nothing
of the many tumbles they get in their lifetime.

In order to construct a correct square, we must have a stand-
ard, by which we may know for a certainty when our square
is truly square. Fig. 170 is a standard of this kind, which, with
its mate or opposite, determines correctness. A is a base with a
parallel across its center. At right angles to this parallel piece
is a second parallel pivoted to A in the center, and held at each
end by binding-screws to A when in exact position.

• FiG. 170. — Standard for Square Testing.

Special care must be taken that these parallel pieces are made
true in every way. Now it is self-evident that when B is at.
right angles with A, we have a compound square made up of four
right angles. To construct a duplicate to fit we can follow out
the removal of discrepancies by eight changes of position if we
use the template shown, Fig. 171 ; or if we make a template with
four sides, we can obtain thirty-two trial positions in the con-
struction of an external and internal standard square. Having
thus produced an exact square gage, both external and internal,
we are provided with a standard of our own, and we are not
dependent on that "other fellow's" make for a test-square.

Fig. 172 illustrates a convenient method of constructing a
correct square. The base is D, and is a plane plate. On this is

GAGES AND GAGING SYSTEMS

163

mounted the piece C, which has been trued by the square, Fig.
170. This fixture is for the purpose of locating the parts in
correct position while being fastened together with taper pins.
Now if we want a good job we must have a true taper reamer to
ream holes to be fitted with good tool steel taper pins that fit

FIG. 171. — Template.

the holes exactly. Press them in — don't drive with a hammer
if you want a fine job — while the parts are held rigidly in place
on the exact square block, and the result will be that the larger
part of all squares thus put together will need no subsequent
correction.

o o

o
o o

FIG. 172. — Constructing a Square.

First produce good true beams and blades, square and parallel,
and then the matter of holding them together rigidly is an easy
one if we do the job right, as shown. If we hold the beam and
blade together by sweating or solder, we must have a fixture for
holding the parts square all the same. If the blade and beam
are held in place by taper pins, as illustrated, do not rivet over

i64

GAGES AND GAGING SYSTEMS

the ends to hold the pins in. That will be wholly unnecessary
if the pins fit well. When the square is together, grind off the
ends of pins neatly with the sides of the beam.

Fig. 1 73 shows one form of a master square by which all forms
of squares may be tested, and in the test the constant correctness
of it is manifest. The beam is made of two pieces, N N, with
blocks O O in each end. The whole is carefully finished parallel
and square. The blade is also a carefully finished piece, and is
mortised into the center of the beam. The openings V V serve
to test any square, the inside with inside, or its outside, and by

FIG. 173. — Form of Master Square.

the numerous changes which can be made in trial an absolutely
perfect square can be produced.

METHOD OF TESTING AND ADJUSTING TRY-SQUARES

There are a number of geometrical methods for laying out the
right angles which give theoretically perfect results, but a geo-
metrical method and a practical shop method for producing
right angles are two vastly different affairs. Thus, for example,
the geometrical conception of line is length without breadth,
which is a condition in working mechanics impossible to realize
except as the boundary of a solid.

GAGES AND GAGING SYSTEMS

165

A solid or its equivalent, which will have two boundaries at
right angles for testing or adjusting try-squares, is ordinarily
produced by a series of tests for inaccuracies with other gages or
squares of more or less truth. This may or may not be satis-
factory, the results depending entirely on the skill and patience
of the workman.

Fig. 174 shows a method for testing and adjusting try-squares
which requires nothing besides ordinary tools more than four
disks of exactly the same size, but what size is immaterial, except

FIG. 174. — Testing a Try-Square.

that the disks should, of course, be in proportion to the size of
the square to be tested. To obtain four disks of the same size
is not difficult, that is within the limits of, say, one ten-thousandth
of an inch.

USING TEST-BLOCKS IN PLACE OF A SQUARE

Figs. 175 and 176 illustrate two test-blocks that are used for
squares in connection with a surface plate. A small hardened
surface plate, finished on both sides, is very useful in making
various tests and measurements.

i66

GAGES AND GAGING SYSTEMS

Fig. 175 is simply a hardened cylinder, counterbored at the
ends to allow the wheel to run by in grinding the end faces. The
cylinder is ground perfectly straight and lapped to any exact
size. The ends are then lapped on a surface block. In using
this test-block, place both the block and the article to be tested
on the surface plate, and test for light, or use the rubbing test.

Fig. 176 is the same as Fig. 175, with the addition of knife
straight-edges on opposite sides, which makes of it a double knife-
edge square to be used with the surface plate. The advantage
of these test-blocks is the comparative ease with which they are

FIGS. 175 and 176. — Test Blocks.

made, and the fact that they can be made accurate in any shop
that has a good grinder. If the opposite sides are ground and
lapped parallel, and the ends squared at the same time, the sides
must be square with the ends, which makes the test-blocks accu-
rate squares.

SIMPLE METHOD FOR TESTING A FLAT SQUARE

Fig. 177 shows a simple and easy way of testing a flat square,
such as a carpenter's square, 24 x 16 inches. A good straight-edge
is clamped upon a planer platen or a horizontal face-plate, and one
edge of the square is backed against it. Instead of drawing a

GAGES AND GAGING SYSTEMS

167

line along the edge a, use two iron plugs of equal diameter. They
happened in this case to be two inches thick and three inches
long. These plugs were placed on the face-plate as shown.
Guiding one edge of the square against the straight-edge, the
other edge a was brought to bear against the two plugs, and to
make sure of their bearing or contact, the square and plugs are
moved along together for a short distance, the square pushing
the plug. Then the square is backed and turned over and brought
to approach the plugs from the other side — see dotted lines -
close enough to try the touch at both plugs with tissue paper.
If there is a slight difference in the diameters of the plugs, one
may put one in place of the other and divide the difference.

Plug

Straight-edge clamped to plate

FIG. 177. — Testing a Flat Square.

How TO MAKE A KNIFE-EDGE SQUARE

While the purpose of the following is to describe how to make
a fine square, and how it should be used, it may not be amiss to
say that probably in no other line of manufacture has the inter-
changeable system been applied for so long a time, or brought to
as high a state of perfection, as in the casting of type for printing.
This does not mean only that the type of any one foundry will
interchange with those of any other. The difficulty of main-
taining an absolute interchangeability and its practical necessity
will be readily understood if we take a page of this book as an
illustration. If the body of each type in a line was just .0001
inch out of square on its lower side, we would have a curved line;
if some were out of square at the top, others at the bottom, and
still others square, we would have a zigzag line. As each body

1 68

GAGES AND GAGING SYSTEMS

type must be firmly bearing against its neighbors when locked in
the form, we would have a column of dancing letters that would
drive the reader distracted.

Fig. 178 represents a square largely used in making the parts
of the molds — which are themselves interchangeable, and are

FIG. 178. — Square for Mold Work.

used on automatic machines — its precision block and a lap-
ping plate.

In Fig. 178 the beam a and the blade b are held together by
screws C as shown.

FIG. 179. — Rectangular Prism.

Fig. 179 is a rectangular prism, in which the sides a and b are
lapped parallel and end c perpendicular to them. Necessarily,
if c is square with either side it must be so with the other. All
parts should be made from machine steel, deeply case-hardened,
and allowed to thoroughly "work" before finishing, but will

GAGES AND GAGING SYSTEMS 169

require frequent correction as long as used. On account of its
extreme sensitiveness the square is worthless without the block
with which to test and correct it. The block is corrected by
micrometer and its square.

In Fig. 178 the space d is left to catch dust and ravelings of
cloth that would interfere if the corner were left sharp.

Figs. 1 80 and 181 show a lapping plate which consists of a
cast-iron plate having a rectangular recess filled with lead or

FIG. 180. — Lapping Plate.

babbitt metal, carefully planed and charged with flour of emery,
by means of cast-iron stick and water. There should be a pair
of these — for roughing and finishing — and care must be taken
to so use them that the wear is about uniform. When the lead
is poured the casting should first be made very hot to contract
with the lead in cooling.

u u

FIG. 181. — Lapping Plate.

In making the square the beam and blade are hardened,
ground and lapped; the beam on one side, the blade on two
adjoining sides, and the screw end.

As it is quite impossible to lap the end of the blade perfectly
square, the corner e is honed after assembling until it is square,
and afterwards corrected in the same manner as needed. The
square should never be taken apart for that purpose.

The length of the beam is usually about 2| inches, and the
blade 1} inches. The block is slightly larger than the square.
The lapping plate is about 10 x 14 inches.

GAGES AND GAGING SYSTEMS

With practice an error of .0001 inch can be easily detected,
and in the work for which they are used the limit of error is slightly
less.

KNIFE-EDGE SQUARE WITH HANDLE

It must be admitted that a square of such fineness as the
knife-edge, if used much, will naturally spring out of truth from
the heat of the hand and fingers while holding it. We have
used the square shown in Fig. 182, with a wooden handle fastened
to the beam of it. The handle is also convenient for picking up

FIG. 182. — Knife-Edge Square.

the square. The space left for dust at the vertex of Fig. 178 is
a .drawback sometimes, but for certain work this is the most val-
uable part of the square. The square shown in Fig. 182 was
made of tool steel, hardened and drawn to a light straw.

A SET OF KNIFE-EDGE TOOLS

Fig. 183 shows a knife-edge bevel; at the top is shown the
stock. It is one of the handiest tools for use on the surface
grinder. It is made of tool steel, hardened and ground all over.

Figs. 184 and 185 show two knife-edge straight-edges A and
B; Fig. 1 86 is a test-bar, Fig. 187 a knife-edge square, and Fig.
1 88 a test-block. Considerable trouble will be experienced in

GAGES AND GAGING SYSTEMS

171

'" /

FIG. 187

FIG. 183

FIG. 184

FIG. 185

FIG. i 86

^j
.*.

183

Ji Round

Knife-Edge Tools.

FIG. 188

172 GAGES AND GAGING SYSTEMS

keeping tools like these true, especially in winter. The warmth
of the hand will throw them out of truth. This can be overcome
by putting in the fiber or hard rubber, as shown by the dotted
lines. These tools should be kept in a box with a little oily
waste to prevent rust.

A KNIFE-EDGE STRAIGHT-EDGE

Fig. 189 shows not a lethal weapon, but a knife-edge straight-
edge. It was made by grinding and lapping an old flat-ground
English razor. It remains true longer than many bought straight-
edges, and this quality may be attributed to the long years of

FIG. 189. — Knife-Edge Straight Edge.

seasoning it underwent while in use as a razor, previous to its
regeneration as an instrument of precision.

The handle protects the edge very thoroughly. One of the
washers has been left off the little pivot for the blade, so that
the handle may be easily removed should it be necessary.

USES OF THE COMBINATION SQUARE

No doubt we all have seen at times our ideas and inventions
improved upon, or used to better advantage than we have used
them. So the sketches, Figs. 190, 191, and 192 may convey some
new ideas in conjunction with the combination square. We
do think it might be of advantage to the makers to offer an extra

GAGES AND GAGING SYSTEMS

'73

base for a slight advance in cost. Fig. 190 shows the square used
as a hight gage which will go into places that surface gage cannot.
Fig. 191 shows it used as an outside caliper. Fig. 192 shows how

FIG. 190. — Use of Combination Square.

odd shapes may be calipered on the outside. Edward Etler, a
planer hand at the R. K. Le Blond shops, Cincinnati, Ohio, is
responsible for these ingenious ideas.

FIG. 191. — Use of Combination Square.

ADJUSTABLE SIZING BLOCK

Fig. 193 shows a sizing block which was made for use on the
planer. The body of the tool A is made of machine steel. After
the slot is cut in it the machine steel piece B with the foot C is
fitted to it, a nice snug sliding fit. The hole D is then drilled
and tapped J inch, twenty threads, and is so located that only

174

GAGES AND GAGING SYSTEMS

about one fourth the circumference of the tap cuts into B. B is
then removed and a ^-inch rose bit is run down into the hole in

FIG. 192. — : Use of Combination Square.

A, cutting the threads away. The steel screw, Fig. 194, \ inch
in diameter, twenty threads, is then made. At its lower end is
the V-groove F, into which the screw E engages when the tool

FIGS. 193 and 194. — Sizing Block.

is assembled. A groove G is milled in the piece B, so that the
screw H may hold B and A, and allow it to slide up and down
freely without binding on the screw, Fig. 194. An indexing

GAGES AND GAGING SYSTEMS 175

point is fastened to the top of A, and reaches up to the divided
collar on Fig. 194. The collar is divided into fifty parts, and as
the screw is twenty threads, each division equals .001 inch. The
face / of body A is graduated to twentieths and tenths, which
may be easily done if left till the last by using the tool itself
for spacing. The foot C and the top of the sliding block B are
used for sizing. The capacity of the tool as shown is from \ to
3! inches by thousandths.

THE MAKING OF A REAL SQUARE

There are classes of work for which the commercial square
that can be purchased in the tool store or of the makers is not
nearly good enough; though of course this is not saying that the
commercial article is not good enough for the vast majority of
work, and also a very good value for the price asked for it, as
good indeed as could reasonably be expected. We all know that
all our tools and machinery lack more or less of being absolute
perfection, and it is a part of the business to know when a thing
is good enough for the purpose it is designed for; or as good as
people can be induced to pay us for making it.

Other things being equal, it is perhaps generally true that
the harder the materials we work with, the more readily errors
in our work manifest themselves. The carpenter's square does
not need to be nearly so accurate as that of the machinist, partly
because if the end is not cut off precisely square the relatively
soft material will yield sufficiently when it is forced to place, to
make the joint good enough, and something like the relative
difference between the harder and the softer materials is seen
when we compare un hardened metals with hardened and ground
or lapped steel. For such work the store square even of the very
best make is sometimes not nearly fine enough, and it may be
useful if we describe the methods that have been followed in
making squares that are much more refined and which in fact
enable us to produce work which is so nearly square as to make
it possible to detect error in it by the most refined tests that can
be applied.

The best manufactured square, as shown in Fig. 195, consists
of a stock a, which is made of three hardened pieces, the central
portion b (corresponding in thickness to the blade) and the two

176

GAGES AND GAGING SYSTEMS

outside pieces d d; these three pieces are hardened and finished
true all over, sweat or soft-soldered together, and finally riveted
with two or more rivets clear through.

To better resist hard usage and prevent breakage, the blade
is hardened only on the edges, as shown by the dotted lines.
The blade is fastened into the stock by sweating or soft-soldering,
and by moderately heating it may easily be removed and reset
in case of wear or accident.

In use, and where the work is not too large, such a square is
put upon the work and held up to a strong light for inspection.

Another method used, especially with large work, is to apply
narrow strips of paper at each of the blade ends for contact, these

FIG. 195. — Making a Real Square.

strips being manipulated by the finger, and when they are pinched
or held alike, one can be pretty sure the work is very nearly like
the square. The paper strips in connection with the micrometer
calipers have one advantage over the eye inspection, in that they
not only tell us when the work is out, but very nearly how much,
which is really. what we want to know. In the "American Ma-
chinist," some years ago, was illustrated a square invented by
G. A. Bates, in which the blade is pivoted on a projection of the
stock, and by a system of levers and a scale is made to indicate
the truth or untruth of whatever it is applied to, and which way
and how much it may be out. Just why this square has not
come into use would be hard to say; though it is probable that,
like a great many other things mechanical, it was born too soon.
For very fine work, such as gages, instruments and some

GAGES AND GAGING SYSTEMS

177

kinds of tools, no square with a flat-edge blade will answer the
purpose, for the simple reason that the contact between the
work and edge of the blade is too broad and will shut out light
when they are not really together at all; and the paper strip
method would not answer, because the paper is too uneven in
thickness and too rough to give the required accuracy. And
besides, most work of that character would be too small to handle
in that way; so what are called knife-edge squares are used.
For some reason, probably because of their necessarily high cost,
this class of square is not listed in any maker's catalogue. The
few that are in use have mostly been made by the workmen
using them.

FIG. 196. — Making a Real Square.

A hardened steel square of a size usually below the 3-inch,
such as was described above, is sometimes used as a starter.
The blade is heated and taken out of the stock, and this latter
is then refmished on its two edges by grinding and lapping until
they are flat and as near perfectly parallel to each other as it is
possible to get them, by the use of the micrometer caliper or other
gaging device. The blade is now taken in hand and its inside,
and sometimes its outside, edge beveled off, as shown at a in
Fig. 196 (enlarged).

The sharp edge is slightly rounded, like a knife-edge straight-
edge so it will stand wear a little better. It is now put in place
in the stock, care being taken to have the contact surface nicely
tinned and all the surplus solder removed. They are set by trying

i78

GAGES AND GAGING SYSTEMS

on a block, preferably hardened, and which is as near square as
it is possible to make it, and temporarily held and clamped on
the sides of the stock and over the blade. It is then heated to
melt the solder and to secure the blade. On account of the
heating necessary to melt the solder and the disturbing influence
of contraction and expansion, it will be found very difficult to
get the blade set even approximately right, and sometimes as

1 1

i 1

.2 gx

r
f-
t

i-4

j
j

3."

-J

FIG. 197. — -Making a Real Square.

many as four and five trials are necessary. After this the hand
is resorted to in order to get it to the required degree of accuracy.

This difficulty in setting the blade has led to several designs
in which the blade is held by pin, screw, or keys, doing away
entirely with the necessity for heating. One of this variety,
which has given entire satisfaction, is shown in Fig. 197.

Every piece in this tool is hardened, even the screws and
pins, and it is found that by so doing they "stay put" for a longer
time.

GAGES AND GAGING SYSTEMS

179

The stock a, in Fig. 197, is made of a single piece. The slot
which holds the blade ends in a round hole d, which serves the
double purpose of preventing fire-cracks during hardening, and
makes a clearance that is useful while lapping out the slot; which
must be done so that it closely and without shake fits the blade
which has previously been finished. The stock and blade are
pivoted together and free to turn on pin e, which need not be
fitted with any great accuracy.

In the stock are the two screws /, and above them the two
loose drill-rod pins g, all shown by dotted lines.

FIG. 198. — Square Setting Block.

It will be seen that with this construction the blade may be
quickly and accurately set, and firmly, and that when the fine
edge of the blade becomes worn, it is a very small job to remove
and reset it, that is, if we have a block which is square to set to.
Such a block is prepared in the following manner:

It should be of steel, either tool steel hardened through, or
machinery steel, case-hardened, and of a form shown in Fig.
198, the sides or edges being slightly longer than the square blade.

From one side the center is milled out, merely to make it
lighter and more convenient to handle. After hardening it should

i8o GAGES AND GAGING SYSTEMS

be immediately drawn slightly to take out the strains, preferably
in hot sand or oil, and as slowly as possible.

It is then ground on a grinding machine on its flat side and
four edges, and all these are made as near square to each other as
it is possible to get them by grinding. Then, unless the job is
urgent, the block should be laid away, the longer the better, but
at least a week, to allow it to settle before beginning to finish by
lapping.

It will of course be understood that for work of this character
the lap must be very true and flat to be of any use whatever.
A good lap for this purpose, and for general tool and gage work,
is prepared as follows: It should be about 15 x 24 inches, of cast-
iron, with the cast face downwards. In form it is a flat plate
2 inches thick, ribbed on the under side with ribs f inches thick
and 4 inches deep, arranged like the ribs on the Brown & Sharpe
surface plates, and bearing its weight on three points to avoid
springing.

In order to get a flat plate and do anything like fine work,
it is necessary to have three of these plates, all alike. They
should be planed smooth all around the four edges and on top,
which should also have grooves planed in it running lengthwise
only, about J to W inch apart, and of a shape that would be made
by a 6o-degree thread tool with the point slightly rounded.

These grooves should be about ^\ inch wide at the top, and
planed in at one cut, so that they may be slightly rough on the
edges, and so hold the emery better.

After planing, put one of them face up on a bench or box,
where it can be got at from two opposite sides; turn another
plate on this one, faces together, and with benzine and No. 100
emery between, and with two good strong laborers to operate,
proceed to grind or lap them together, keeping the surface wet
with benzine. When they begin to bear all over, lay one aside
and take a new fresh plate; next lay aside the first plate and lap
together the second and third, and proceed in this manner until
all are finished. This of course is on the old principle that no
three surfaces can all fit each other unless all are true planes.

It is not at all necessary to use red ink or blue as a marking
to indicate when they surface each other, as by wiping them clean
with benzine and waste, and standing at some ten or fifteen feet
— with the plate in a horizontal position between the eye and

GAGES AND GAGING SYSTEMS 181

the window, it will be very easy to see where the bearing is, as
of course there will be no small spots such as there are when two
plates are scraped together. The high places will appear to be
highly polished, while parts which do not bear will appear dead
and like ground glass. The finishing is done with the finest
flour emery, and very little of that.

When new they will warp and spring out of shape, and use
will wear holes in them, when they are once more put through
the lapping process with each other.

For spreading the emery and benzine and charging the plates
when in use, it is well to have a cast-iron charging block which
is about 5x7 inches and four inches thick. On the top and
one end are U-shaped handles. The face, which is planed, has
semicircular grooves about \ inch wide and about I inch apart,
planed both ways to form squares. These grooves form air
passages, and prevent sting and hard work. To charge, apply
emery to the lap by shaking it in from a box with small holes
punched in the cover like a pepper-pot, wet down with benzine
from a common oil can; then rub the charging block over the
surface from side to side, and gradually working from end to end
to cover the whole surface. This block is frequently used also
to clean and sharpen the surface of the lap, when it is rubbed
over simply with benzine. For finishing such work as we now
have in hand, the charging block is rubbed over the lap with
benzine only, and the lap is then wiped dry with the waste, wiping
from end to end only, and with the grooves, as in this way much
less lint will be caught than if we try to wipe across them, or if
the grooves are planed both ways.

It is often convenient in doing small work on a lap of this
size to have a little emery on one end and the other clean, so
that both roughing and finishing may be done without waste of
time.

Care should of course be exercised to distribute the wear as
evenly as possible. On the start, in lapping the parts of the
square, benzine and flour of emery or carborundum are used until
the wheel marks are out of the surfaces, while the finishing is done
with the lap wiped perfectly dry and clean, the emery bedded
into the cast-iron lap being sufficient to cut and polish.

We will now assume that the square, Fig. 197, has been fin-
ished, and the blade and stock set as nearly square as by other

182

GAGES AND GAGING SYSTEMS

means. Referring to Fig. 199, which we will assume is the block,
we lap the side a perfectly flat and use it as a starter. By lapping
we now fit the angle b to the square. The testing is done by
carefully wiping the square and block surface with the bare hand,
or a piece of chamois, applying the square and holding up to the
eye before a strong light. When they fit together so closely as
to shut out the light the whole length of the blade, we proceed
in like manner to angle c to d.

Now when we get clear around and come to apply the square
with angle e, we may find, as in the sketch (which is greatly
exaggerated for illustration), that there is a considerable space /
between the outer end of the blade and the block, and this shows
that the square is just one fourth of this opening over 90 degrees,

FIG. 199. — Lapped Block.

or, in other words, that the "square's" error is multiplied by
four, as shown by this opening on the last or final trial. Should
the opening appear at the other end of the blade, it would merely
mean that the angle is less than 90 degrees. In either case we
reset the blade by one fourth of the opening shown as near as
we can estimate, and proceed to fit the angle to the square as
before, and repeat this process as many times as it may be neces-
sary to shut out the light on all four corners or angles.

By having the surface clean and dry, and carefully applying
the edge of the stock with the blade a little way off, and working
it gently to get the air out, we get a good, firm contact, and
thus by very gently working it down till the blade barely touches,
we can do a very accurate job ; for it seems to be very well known
that under conditions light may be seen through an opening,

GAGES AND GAGING SYSTEMS 183

which is only one forty-thousandth part of an inch wide. This
will probably be as close to square as we care to go. But there
is another method of testing that seems to admit of still greater
refinement, and it is as follows: After wiping the block as clean
as possible with the bare hand, there will still remain on the sur-
face a thin film of moisture. By gently moving to exclude the
air, as before, get the block and stock in close contact, and now
bring the blade to bear, and when it does, move it sideways, back
and forth by the stock about ^ inch, when upon removal and in
a good light it will be seen to have left a slight but distinct mark
in the moisture upon the surface of the block. Unless the mark
extends the full length of the blade, it shows that while it may
have been close enough to close out the light, it did not actually
touch all over, and by careful work it may be made to do so.
The color of this mark should also be noted as it varies with the
pressure between the edge and the flat surface, and is another
guide to refinement. It should be uniform in appearance from
end to end.

The outside or back of the square is left until the block is
completed, when it is tested by standing both block and square
on a true flat surface, and proceeding as before, except that
the edge is now lapped with a small hand lap to bring it true
instead of by moving the screws as before; and of course the
block is not lapped, because it has been previously made square.

It is necessary while finishing both edges of the blade, to
tilt or roll it on an angle both ways over its slightly rounded
edge, making it bear as shown by the dotted lines c, Fig. 196.
Were this not done, the square might be anything but true, if
it were turned ever so slightly at an angle to the work. It is
this rolling over and making the edge touch its full length in
any position that takes the most time and patience.

A tool of this kind is best made at times and worked in be-
tween other jobs, as it will not do to hurry it in the least, and
neither the block nor the square can be held in the hand any
length of time without being warped or expanded out of shape
by the heat of the hand. If these operations be extended over
several months or years, at the end of that time the steel will
become so settled as to stay in shape fairly well. For some time
after the block is started it will be noticed that the corners fall
away and the flat surfaces persistently get high in the center.

1 84

GAGES AND GAGING SYSTEMS

A quicker but somewhat less accurate way of testing a square
is shown at Fig. 200. The piece a being made parallel on its
two sides, the angle b is fitted by scraping or lapping to the square.
If the square be now applied to angle c, the error, if any, will be
multiplied by 2 instead cf by 4, as in the other method. This
last method has the further disadvantage of depending entirely
on the parallelism of the two sides of the test-block.

One rule in squaring work should be: Hold the stock against
the shortest side of the work, if there be one, whether that side
is to be changed or corrected or not. In this way the angle or
error, if there be one, between the work and the blade is extended

FIG. 200. — Testing a Square.

and much more readily seen than if applied to a short surface,
such as the end of the bar.

It will perhaps seem to some good workmen that the square
and block above described are carried to an unnecessary degree
of refinement for the result that is to be attained.

To illustrate its use, we will consider the making of a snap
gage of the style, Fig. 201, composed of a core a, having its jaws
b secured by screws to its two edges. It will of course be under-
stood that the two edges of the core a must be parallel to each
other, and with the aid of such a square as described, it may
be very quickly tested by squaring from one flat side which is
previously finished for convenience in grinding. Again, for

GAGES AND GAGING SYSTEMS

"85

making the test piece or end measure, Fig. 202, which is some-
times used in connection with Fig. 201, the two end surfaces
must be parallel to each other, and that is most quickly tested
by having two sides, as a b, finished, though not necessarily square
to each other, and squaring from these sides both ways over
each end. These illustrations will serve to indicate many uses

FIG. 201. — Snap Gage.

to which such a tool may be put, and where the time required
for testing would be only a small fraction of what would be
required for a test by measurement.

A PRECISION SQUARE

The ordinary try-square indicates plainly enough when a
piece of work to which it is applied is out of square, provided
a good light is obtainable; but when the variation is very slight

FIG. 202. — End Test Piece.

the light must be a strong one, and the amount of variation
must always be estimated; it is not directly indicated.

We present herewith drawings of a square which is much
less dependent upon strong light — i.e., a square which does
not require that light shall shine directly through between the
blade and the work; and one which, while it still leaves the varia-
tion from the true right angle to be estimated, very materially
assists in estimating correctly.

1 86

GAGES AND GAGING SYSTEMS

:The square is the invention of G. A. Bates. The blade is
pivoted at A, Fig. 203, and can move through a small arc. In
doing so it moves an indicating lever B, which is pivoted at C,
and connected to the blade at D; the result being that when the
blade is moved in one direction the lever moves in the opposite
direction through a much greater arc, and the variation between
the two lines shown — one drawn upon the upper end of the
lever, and the other on an adjustable plate attached to the blade
— is many times the variation of the work from a true right

FIG. 203. — Precision Square.

angle, and the slightest variation is very readily seen even when
it is difficult, or even impossible, to see between the blade and
the work, as is required to be done with the ordinary square.
At the same time, when it is desirable to clamp the blade either
square with the stock or at a slight angle to it, as is sometimes
required, it is readily done by simply turning the knurled screw
E at the end of the stock, the action upon this screw of the clamp-
ing lever F being clearly indicated. It is needless perhaps to
remark that the clamp has not the slightest tendency to disturb
the adjustment of the blade.

GAGES AND GAGING SYSTEMS

187

To insure that there shall be no lost motion in the connectidh
between blade and indicating lever, the pin which connects them
is fixed in the blade, and the hole in the lever is opened, as is
shown, and the spring piece a is slightly depressed so that it
always bears snugly against the pin. NThe corner between the
blade and stock is opened slightly, as shown, so that trouble
from dirt collection there is avoided. Fig. 204 shows the stock
separately.

In using a sample square, from which our engravings were
prepared, Mr. Bates found it to be capable of standing tests of
very great refinement, and at Fig. 205 we show a device gotten
up for testing and adjusting the square. It is called an adjusting
testing block, and is composed of an approximately square block
having a groove planed around its four sides, as shown in the

FIG. 204. — Stock of Precision Square.

partial section at the right. Into this groove are fitted four
pieces which are pivoted at one end, and at the other end can
be adjusted by the screws shown; the larger screw raising the
pieces, and the other smaller screws having the opposite tendency,
so that by their combined action the piece is readily adjusted
and firmly held.

Starting as accurately as possible, two of these pieces, ad-
jacent to each other, were adjusted to fit the square, and the
block was then adjusted around to the place of beginning where
the error of the square was shown magnified in a way familiar
to all mechanics who have ever tried to make a block really
square on four sides. This error was then divided and adjusted
as nearly as possible, and the process repeated until the square
would go all around, showing the least variation. It was then
assumed that both testing blocks and square were really square,
as in fact they were.

1 88

GAGES AND GAGING SYSTEMS

This has been patented by its inventor, who, as a result of
his experience with it, calls it his "precision" square. A speci-
men we have had the privilege of examining is certainly an ad-
mirable tool, whether considered as a piece of fine tool making,
or in respect to its action when in use.

A REMARKABLE SURFACE GAGE

This surface gage is the original of its kind. It was designed
by George Win cock, a man celebrated in the old gun, and early
sewing-machine days. It was made in the Mott Street factory
of the Singer Company, about the year 1867, perhaps before.

FIG. 205. — Device for Adjusting Square.

In 1868 rumors of a remarkable tool of this kind became the
subject of shop talk among tool-makers in New York City, in
Hartford, in Boston, and elsewhere, in consequence of the migra-
tions and professional tours of members of that aristocratic guild
of mechanics who had seen and described it.

Tool-makers in those days were favored creatures, and Win-
cock was a king among them. He went into the shop in the
morning dressed in faultless fashion, with gloves and silk hat.
Imagine a man standing at the vise in lavender trousers and a
duck vest, with his shirt sleeves rolled back, and a silk handker-
chief for an "apron." The handkerchief corners would be tucked
into his vest pockets for a fastening. Then believe the still

GAGES AND GAGING SYSTEMS 189

more marvelous fact that neither of the garments would be soiled,
and the "apron" would last a week quite clean, and a man thus
clothed would do as much first-class work as any other man then
or since. Wincock was a whole man in the shop and out of it,
and many of the old-timers remember his kindness of heart as
well as his other peculiarities.

Later on the gage did good service in the United States Watch
Factory, Marion, N. J., where Wincock arrived in 1874, and
began a mercantile career. Having no further use for this tool,
he gave it to a friend — first to show to some of his friends -
and when he carried it back to him he said, "Keep it; you are
the only man out here that I knew at the bench, and you have
use for it, I haven't." He said that it cost him about one hun-
dred and fifty dollars to make it. The friend still possesses it,
and it has continually reflected credit on its designer. Every
mechanic accepts its decisions when it is carefully applied to
use. Its service to the owner personally is and has been incal-
culable. He has been able to prove perfections and detect errors
with his instrument, which, without it, would in certain cases
either have cost its value to provide as accurate special appliances
for, or the results obtained would have been in doubt.

While the readings on the scale have no positive value, a
person experienced in using this gage can detect differences of
less than .0003 inch between one hight and the other when they
are compared. Fig. 206 is the front elevation of this gage. Fig.
207 is a horizontal section cut through the base, showing the
construction of the peculiar ornamentation of that part, and
the shape of the seat below it. Fig. 208 is a horizontal section
through the head, and Fig. 209 is the view of the bracket H,
showing its construction and the arrangement of the worm K
upon it, as well as the hub / by which the whole head is attached
to the support G.

We have never seen one of these gages made, and do not know
how all the operations on it are performed, but we do know that
they can be made. The base C seems to be bored, as indicated
by the dotted lines, and the column G, with the sub-base D in
one piece, is let through the base C, and fits it tightly. If this
column, after it has been roughly turned, is carefully trued in
a chuck on a dividing head, with the lower head outward, and
placed before a drilling head at the proper angle and one hole

190

GAGES AND GAGING SYSTEMS

FIGS. 206 to 209. — Remarkable Surface Gage.

GAGES AND GAGING SYSTEMS 191

carefully drilled to the size of the small end of the taper plugs E,
which make the convex fluting in the sub-base, then if the dividing
head should be turned one-sixth the circle and another hole drilled,
and thus for the remaining four holes each to the proper depth,
all would be located in their proper position. It is understood
of course that there is solid stock all about these holes when they
are drilled, and that the holes extend by a short distance above
the tops of the flute visible in Fig. 206. The plugs E seem to
have the taper of the ordinary pentagon pin broach, so we pre-
sume they were reamed by hand. After reaming, they should
be fitted with temporary plugs, which should be well greased
and driven in snugly. The plugs should be of brass, so that the
color may guide the operation, because it is probable that
the joints will not otherwise be seen in turning and polishing
the sub-base. After the column is completely finished in every
other particular, these temporary plugs are removed and others
of polished steel are driven into their places, giving the effect
shown.

The cap F is an independent piece, and at its knurled flange
is larger than the column G, to prevent the accidental removal
of the head. The top of the column is drilled and tapped, and
the cap F is provided with a screw stem which fits it, the joint
being directly under the knurled flange.

The base C on this column is soft steel, and as such inferior
because it catches grit and scratches on a surface plate; hence
this base and column have not been used by the writer. In its
place a hardened steel base of circular outline was made, to which
was fitted a column double the hight of this one. This overcame
the trouble.

The bracket H, shown in Figs. 208 and 209, has within the
hub /, which fits the column G, a spring gib or shoe I1, which
covers the point of the screw H1, and prevents it from marring
this column. The probable construction of the gib is indicated
by these sections. We can find no joint, but believe the sleeve
/ to be inserted within the bracket H after the gib has been
made, as shown. The worm extension H2 seems to be a solid
part of the bracket H, which it may very well be. It is presumed
that the worm is keyed on, as shown in Fig. 209.

The worm gear / loosely fits the bracket H2, and engages the
worm K. It is recessed to receive the circular plate M of the

192 GAGES AND GAGING SYSTEMS

adjustable stock M R R. This plate is penetrated by the hub
of the bracket H; it is covered by the washer N, and clamped
by the screw O. The dowels P enter the slot Pl of the washer N,
and prevents it turning. The worm K is used only in fine adjust-
ment. When the screw 0 is loose, the adjustable stock M R R
may freely be turned in any position, because the plate M has a
circular seat. When the screw O is partly tightened, the worm
can adjust, but when wholly tight it holds the stock rigidly in
its position.

The stock M R R supports the gage arm T, and secures it
to the required position by means of the screws 5 S. The beak
of the arm T is bored vertically, of a parallel small size, to which
is fitted very carefully the plunger W, so as not to shake but to
be quite free, so as to slide end-wise with perfect ease. This
plunger is kept in place by a shoulder which rests on the arm
T, and it has a small hemispherical tip which receives the short
arm of the index X. This index X is pivoted in the fulcrum
post Y one-tenth of an inch from the center of the plunger W.
It must have perfect freedom on its fulcrum, and be well guided
in its position. The spring / is attached to the post I1, and has
stiffness just sufficient to surely overbalance the weight of the
index arm and keep a pressure upon the plunger W. The value
of this gage as a delicate instrument depends on the adjustment
of these parts, but when they are correctly set they will remain
so for years. Since we have had this gage it has required two
new plungers and one new spring.

The scale V has been lost many years. It is of but little
value because it is found better to gage from a touch, or when
the plunger W just touches the work so that the index at its
outer end is perceptibly disturbed.

The scratch point U is hardened and screws into the arm T,
precisely as cap F does into G. It has never been used.

The uses of these special features should be clear to every
mechanic, where they apply to the detection or the confirming
of hights and parallels, and it is only necessary to say that it
is better practice to set the gage to the lower piece, or end, and
at the higher place to place paper of uniform thickness under
the base of the gage until the difference is equaled. Then measure
the paper with micrometer gage. Handle the gage with a cloth
tied to it whenever the hand comes in contact, because a warm

GAGES AND GAGING SYSTEMS 193

hand will expand a length of four inches about three thousandths
of an inch at times. This has explained many contradictions
in our experience.

In turning or grinding cylinders this gage will give the truth
of the result, and frequently surprise the opera-tor who imagines
he is getting a perfectly concentric job. To do this, stand the
gage on a flat, rigid surface, and set the front of the plunger W
on the top of the revolving surface. The index will show whether
it is true, eccentric, or not round. If true the index will stand
dead still; if eccentric it will rise and fall regularly; if not round
it will rise and fall irregularly.

Work in the lathe being trued up can be proved in the same
manner by this gage. Lathe centers, milling arbors, and in
fact all arbors, can be inspected by the same method. Face-
plates and shoulders can be tried for truth as well as cylinders,
by turning the gage arm one-quarter way over to meet them
squarely. In fact, every rotation piece may be inspected per-
fectly for truth by this tool.

In the sketch here given, it is believed that the device
is fairly well shown. Considering the fact that it was designed
and made so many years ago, it is wonderful that it exhibits so
much that has been proved to be correct practice, and if it were
a production of to-day it would be considered as being ahead of
progress rather than behind it.

A MICROMETER HIGHT-GAGE

The sketch, Fig. 210, is of a hight gage made on a plan of a
surface gage. It consists of a central standard fixed in a base.
The standard is threaded throughout its length 1 6 threads (or
any number, for that matter), and then the threads are milled
away, leaving a section on two opposite sides threaded, and on
two opposite sides blank. The inside of the nut enclosing the
standard is relieved on two sides to correspond. This enables
the rapid moving up or down of the arm by simply loosening the
clamp screw that binds it, turning it one fourth of the way around
and then sliding it to the desired hight, swinging it round to a
square position, and fastening the screw again. To locate the
arm just right, a needle point is fixed on the top of the arm, that,
with the marks on the standard, determines its location and sets

194

GAGES AND GAGING SYSTEMS

it central. The arm is extended and holds a round button of
steel with hardened face. This button is bored and threaded to
fit on a screw fastened in the end of the arm, as shown. Said
screw is in a recess which is filled by the button. This button
has 50 graduation marks on its circumference, and the screw

/Hardened Face

50 Graduations

Thread 20 to the Inch

FIG. 210. — Micrometer Hight Gage.

is threaded 20 to the inch, allowing adjustments of one thousandth
of an inch.

The standard, graduated to sixteenths, makes a familiar
reading, and the finer measurements can be obtained from the

GAGES AND GAGING SYSTEMS 195

micrometer button. The top face of the button when set at
zero is equal to the hight of nut on the standard at the reading
point. The button is limited to two revolutions, as the arm
can be shifted to make the difference, and a reading of less than
zero on the button is possible, thus compensating for the difference,
between the sixteenth threads on the standard and the twenty
threads on the button.

The clamp screw is to have a soft metal seat to bear against
the thread when fastening the arm in place; the whole to be
finished, making a handy, quick and reliable tool.

SECTION VIII

OUTSIDE MICROMETER CALIPERS, TOGETHER WITH
THEIR ATTACHMENTS FOR SPECIAL MEASURING
AND GAGING.

MICROMETER FOR SCREW THREADS

THE first micrometer of the thread-measuring type with which
we are all familiar was apparently made so nearly right that it
has not seemed worth while to change it after mechanics have
become so accustomed to its use. We suppose that if the screws
had been cut originally 25 to 50 to the inch instead of to 40, the
other divisions being made to correspond, the tool would have
been just as satisfactory. And so when we propose improvements,
it behooves us to make haste slowly in order that the improve-
ment may become, like the micrometer itself, a permanent one.

The device we have in mind is for accurately measuring screws,
and without reflecting on the efficiency of the other devices,
we will say that this is a practical, satisfactory device, and so
decided in a large screw-manufacturing concern after experi-
menting with everything known in this line. It is nothing but
a pair of spherical points attached to a standard micrometer,
as shown in Fig. 211. These points find a bearing just where
the nut should fit the screw. If we have a nut and bolt perfectly
fitting each other, and proceed to take a cut off the outside of
the bolt, we cannot observe any difference in the fit; so that
we very often find that the diameter of the nut inside cuts very
little figure in the fit. What we propose is to have sets of spheres
of standard sizes, with the standard projections from the face
of the anvil. The spheres should be so large as not to strike the
bottom on the standard screw, and small enough to go below
the top of the "V." We estimate that one pair of spheres will
answer for five or more pitches, and by having all fitted alike
we take in fine threads of large diameter, and all odd sizes within

196

GAGES AND GAGING SYSTEMS

197

the limits of our tools. Then if there was not too much of an
opening in the anvils, the micrometers could be used for ordinary
work as well. The size when the spheres are in place should
be stamped on each.

The usual custom in screw factories is to have a set of hard-
ened and ground gages, and when making taps to take the size
from the gages with the spherical point micrometers. Now if
it was known what these sizes were, it would not be necessary
to have the gages. These gages are so expensive as to debar all
except the largest companies from enjoying the luxury. A
maker of micrometers could get up an index giving all these

FIG. 211. — Micrometer for Screw Threads.

sizes for standard screws, and all screws could be ordered by

these micrometers, thus:

Nominal size, "V" thr. per inch,

i inch 13

Bearing size measured with No. 5 point, .627.
It would not be necessary to mention No. 5 points, as each

would have an index stating what pitches each pair of points

was adapted to; and, they being alike, the man in San Francisco

would measure exactly like the man in Boston.

MEASURING EXTERNAL SCREW THREADS WITH THE MICROMETER

Figs. 212 and 213 illustrate an improved method of measuring
screw-thread diameters in the thread angle by using ordinary

198

GAGES AND GAGING SYSTEMS

micrometer calipers and wires of a suitable diameter. Without
doubt this is one of the most accurate, as it has come to be
one of the most universal, methods in use. Since we became
acquainted with it and learned its usefulness, we have used it
successfully on all available work, but find it very inconvenient
to hold the wires, a screw plug and the micrometer calipers all
at once. Therefore we have made a slight improvement in the
tool, placing it upon a stand with three legs. A hardened and

S e

FIGS. 212 and 213. — Screw Measuring Micrometers.

lapped disk is screwed on the top of the stand, as shown, as it
gives a better measuring surface and is easier to handle.

In shops where the work is of great accuracy and only the
practical minimum limit of error or variation is allowable, two
sets of test micrometers should be provided, one for general use
and the other for occasional reference only. The new microm-
eters should be given to the most skilled workmen for use on the
finest work only, while those micrometers which have become
worn, or are to a certain extent inaccurate, should be used on
work in which a greater limit of error is allowed.

GAGES AND GAGING SYSTEMS

AN EQUATING MICROMETER

199

A very ingenious micrometer and recording gage of English
design is illustrated in Fig. 214. The micrometer portion of this
instrument follows the usual lines of construction, except that
the barrel, which is usually knurled, is in this case formed into a
multiple-threaded worm which operates a disk mounted below
and carrying a series of figures representing various equivalents
of the measurement made by the jaws of the micrometer. A
bracket is fastened to the bow of the micrometer for carrying
this worm disk, and there is also a fixed disk which stands in
front of the revolving one and has a series of holes through which

FIG. 214. — Equating Micrometer.

the numbers on the revolving disk become visible as the work
is rotated.

As shown in the cut, the jaws of the micrometer are set at .3
inch, and on the dial may be read its metric equivalent 7.62
millimeter; also 300, denoting the number of thousandths; and
i, over S. W. G. indicating that .3 is the equivalent of No. i
Stubbs wire gage. At the bottom of the disk is another dial for
Stubbs steel wire, in which the size N is indicated. This, how-
ever, is slightly misleading as the letter will not occupy the exact
center of the opening until the jaws of the micrometer have
been moved .002 inch more, giving an opening of .302. A line
on the worm disk corresponding with a similar line on the beveled
edge of the hole in the outer disk indicates when the exact open-
ing is reached. It is, of course, perfectly practical to apply this

2OO

GAGES AND GAGING SYSTEMS

arrangement to any kind of measurements for which the microm-
eter may be used, and in place of the equivalents here indicated
we may have fractions of an inch, sheet metal gages, screw sizes,
or any other equivalents that may be desired by the user. This
instrument is manufactured by Grinshaw & Baxter, London,
England.

6-lNCH BEAM MICROMETER

The sketch, Fig. 215, shows a 6-inch beam micrometer that
any mechanic can make with little trouble. After the forgings
are shaped out, holes are drilled and reamed approximately .1
inch apart, and taper eccentric pieces to fit held in position by

Open \i "and Set at let Eccentric Stutf

Open

FIG. 215. — Beam Micrometer.

screws as shown. The pins can be easily adjusted
by turning the eccentric studs.

lox 12 INCH MICROMETER CALIPER

inch apart

Fig. 216 is a sketch of a pair of lox 12 inch micrometers
that are very easily made. With the standard gages 3, 5, 7, 9
and 1 1 inches, one can set at any place. This one was made
from one end to the other complete, as at the time the tool was
made it was not possible to get micrometer heads. The beam
is of tool steel — not annealed — and all screws are hardened.

How TO MAKE A LARGE MICROMETER

We have often thought how handy it would be to have a
large micrometer. We could measure our work and tell just

GAGES AND GAGING SYSTEMS

201

how much was to come off, and as most feed screws are graduated
it would be an easy matter to feed in so many thousandths, and
the work would caliper just what we wanted it to. We hap-
pened to see a micrometer head at $3.50. It struck us imme-

FIG. 216. — Twelve-Inch Micrometer.

diately that it was just the thing we could use. After seeing
this micrometer head, we began to think there was no reason
why we should not frame and attach that head to it, then all it
would cost us would be the price of the head. We started in

, , — _—

•

I 0 0

0 0

p ..£

1 ^ f

o!:bj

; o i

O y

FIG. 217. — Large Micrometer.

and in due time finished the micrometer, which we have since
found very valuable.

We think the drawings, Figs. 217 to 220, will clearly show
the shape and relative sizes of the different parts required. The
beam and two carrier arms, Figs. 218 and 219, were made from
drawn stock; the side piece 5 was cut from sheet steel about TV

202

GAGES AND GAGING SYSTEMS

inch thick. Holes were drilled and the parts riveted together
with the beam between to keep them the proper distance apart.
The riveting ought to be invisible after it is polished. The clamp-
ing device which holds the micrometer consists of a holder H,
which by means of the nut N draws the micrometer down on the

o o
S

o o

FiGS. 218 and 219. — Details of Large Micrometer.

"V" cut on top of Fig. 219. The holder was made from a piece
J x f x j, drilled and cut in shape, as shown by the dotted lines
in Fig. 220. The screw was afterwards inserted and pinned.
The advantage of having the micrometer detachable is plain,
as it can be used elsewhere for distance as a depth gage. For
accurate measurements distance rods are necessary. They can

FIG. 220. — Details of Large Micrometer.

be made in the following manner: First, run the micrometer out,
reading 1000 against the anvil; then run it back to zero to fit
in the i-inch rod. Next move the micrometer back and run it
out, reading 1000 against the i-inch rod, and repeat the first
operation, and so by continuing as many distance pieces may
be made as would be desired. We recommend copying shop
standards, if any such are obtainable.

GAGES AND GAGING SYSTEMS 203

As both carrier arms are movable, they may be put on any
length of beam; but the size for measuring 6 inches, we think,
will be found most convenient.

LARGE MICROMETER CALIPERS AT THE BRITISH WESTINGHOUSE

WORKS

We are pleased to place before our readers a partial descrip-
tion of another set of large aluminum zinc calipers, of which
one size is shown in Fig. 221, that may in a sense be said to be
the descendant of those illustrated in Section I, having been
made and being in use in the Manchester Works of the BritisH
Westinghouse Electric & Manufacturing Company, Limited.

No special novelty of design is claimed. The sizes range from
12 to 48 inches, each size up to 36 covering 4, and above that
size 6 inches, each. The part of the design that consumed the
most time was the adjustable tail spindle (anvil), as the short-
comings of the m-thread-per-inch and half-nut clamp method
had been noted. The method employed is much more expensive,
but still not wholly satisfactory, the principal trouble with it
being to keep it in a state for its proper use, which is part of the
trouble with any tool that is used by many.

The tail spindles are of tool steel ground to ^g-inch diameter,
each clamped in a reamed ^-inch hole in tail end of micrometer
frame, by two ££ screws provided with knurled nuts, as shown
in Fig. 222. This provision is ample with proper use. The
tail spindle shown in Fig. 223 is hollow and provided with a Cl-
inch rod through the center. The anvil is hardened, ground and
lapped. It was made £| inch because that is the diameter of
the commercial micrometer screws used at the head of the mi-
crometer frame. The accompanying sketches will plainly show
the construction of tail pieces and method of clamping. With
this tail spindle ready adjustment to zero is secured.

While these micrometers were being planned and made, no
method of taking measurements with the larger ones had been
decided upon. The chain and spring-supported stirrup leave
much to be desired. Before the first measurement was taken
with a large one, the method shown in Fig. 221, with the anvil
at the top, had been decided upon, and it instantly proved its
adaptability to the most delicate measurements; .0005 inch

204

GAGES AND GAGING SYSTEMS

variation in size being readily detected, as it would be with a
i -inch or 2-inch micrometer.

FIG. 221. — Large Micrometer.

The advantage of this method is obvious. The hand is at
the point of contact; it is not also on the frame, distorting it with
warmth; but the greatest advantage lies in the fact that the
micrometer hangs in stable equilibrium. The workman says:

GAGES AND GAGING SYSTEMS

205

" It comes up to the work itself," not wanting to leave the highest
point of the work. The only care necessary to secure this ad-
vantage is to place the anvil at the proper hight, which hight
after the first few trials is generally guessed correctly to within
an inch, the necessary adjustment taking but a few seconds.

By the half-tone the I-beam section and general outline of
the frame will be seen. While there is a heavier section near
the tail than the head, the fact that the instrument is to be used
in all positions kept out any tendency to follow the well-known
Thomas form.

Of course strict adherence to the principle of setting the
micrometer while it is in the same position and supported in the

FIG. 222. — Knurled Nuts for Micrometer.

same way that it is to be while taking measurements is neces-
sary. Checking back on the measuring rod after taking an
important measure is to be insisted upon. Our own use of the
suspended method, shown in the photograph, has been satis-
factory, so much so that we feel it cannot be recommended too
highly. It not only gives better results than any other method
known to us, but it requires no "tackle" except a helper's finger
or thumb placed against the work at the right spot. While
this method does not secure the possibility of one man taking a
measure by himself when using the larger sizes, the helper's part
is an inert part; any other support that could be readily attached
to the work, and movable, would do as well as the helper's finger
or thumb.

GAGES AND GAGING SYSTEMS

207

A SHOP SET OF MICROMETER CALIPERS

The half-tone, Fig. 224, shows a set of twelve Slocomb microm-
eter calipers covering the range of sizes which it is usually desir-

FIG. 224. — Set of Shop Micrometers.

able to determine with accuracy in the modern machine shop.
The range of each caliper is i inch. The frames up to 6 inches are
drop forged from bar steel, and the larger sizes are steel casting
with openings in the web-like lattice work girders. • All are
finished in black enamel, and those above 3 inches are plainly

2o8 GAGES AND GAGING SYSTEMS

marked with figures indicating their range. Where the calipers
are made for metric measurements the figures run consecutively
all through the series, the first starting at o and going to 25
millimeters, the second 25 to 50, and so on, the last being 275
to 300 millimeters. The set as shown is of course intended for
the tool-room. There are hooks above for the workmen's checks,
and a grooved board below for a set of end measures for correct-
ing the adjustment.

This plan of having a series of calipers, each complete in
itself, and each with a range of an inch, is one to commend to
shop managers, both because a number of micrometers are some-
times needed by the different men at the same time, and because
no caliper should be very much larger than the size it is to be
used for.

PRACTICAL SHOP USE OF MICROMETERS

A lathe hand of indifferent ability will work to within a thou-
sandth of an inch of size if provided with a rigid caliper accurately
set. The average machinist, with the same gage and in the
same time, can work to within a ten -thousandth of a size, though
requiring more time. These men could have nowhere near
approached these limits with any degree of certainty using the
ordinary caliper. Now the question naturally arises in the mind
of the foreman alive to the economic possibilities of his position,
whether or not a caliper of the necessary rigidity and accuracy
could be furnished for general use in a shop at a reasonable cost?
Limit gages are of course out of the question, for it would be
beyond reason to expect a gage or several gages for every size
used in a shop. The micrometers, however, fill the bill admirably,
except for the expense of providing them for general use in a
large shop, and the fact that the treatment they received — in
a majority of cases — would not be such that they could be called
instruments of precision very long.

The accompanying sketch, Fig. 225, is of an adjustable snap
gage that has been used several years as part of a shop system
of measurements, and has been found very satisfactory. These
gages can be made at very small cost, especially if a number of
them be made at the same time. The one shown here will take
in anything up to 3 J inches, the size of a gage most used in gen-
eral lathe work. The frame is of cast steel, very light and rigid;

GAGES AND GAGING SYSTEMS 209

the rod and screw are T5g- inch in diameter, the latter having 20
threads per inch and locked when adjusted by the thumb-screw
shown. We experienced no difficulty in making the rod and
screw come exactly in line. It was done in the following manner:
The holes were drilled in the lathe centers and then split with a
hack-saw, whose soft back had been cut down until it would
pass through the holes. The holes for the thumb-screws were
drilled next, the top half to the whole diameter of the screw,
and the bottom half tapped. A cast-iron sleeve, i^ inches long
and | inch diameter, was then made to fit snugly over the shank
of the tap, which had been shortened by cutting off the square
end. The shank was entered one half the length of the sleeve
and tap and fitted with a pin. The hole for the adjustment

FIG. 225. — Adjustable Snap Gage.

screw was then tapped from the inside of the gage outward, the
shank end of the tap being supported in line by a rod passed
through the other hole into the sleeve and rigidly clamped by
the thumb-screw. The tap was turned by a small bar fitting
into holes drilled around the sleeve. The ends of the rod and
screw are hardened and ground.

Under the system that has been employed and found so
satisfactory we used o.i inch square steel wire for " points," as
the men called them. If a man had certain sizes to turn that
had to be quite accurate, he would cut off pieces of this wire
about the length required, stamp the size on it and round and
taper the ends so that they were about ^V incn in diameter.
These points he made approximately to size, and then gave them
to the foreman, who tested them with a vernier caliper in his
office, fitting each with a rub or two of the file, or perhaps a blow

210

GAGES AND GAGING SYSTEMS

of the hammer on a small anvil beside the instrument, to bring
it up to size. It is then a simple matter when the work is roughed
down nearly to size to quickly and accurately set the snap gage
to, the point, making practically a solid gage. These "points"
are very quickly made, and can of course be kept for future use.
A man seldom requires more than the suggestion that he could
get his points ready while his machine was running before he
made a practice of doing so. For sizes over 10 inches we used
a piece of broom handle or other wood, with a pointed wood in
either end, flattened for wrench.

When extreme accuracy was necessary in the smaller sizes,
a small piece of wood was drilled out and pressed over the wire
to keep the heat of the fingers from expanding the gages while
setting. These "points" cannot be beaten for inside gages,

FIG. 226. — Outside and Inside Micrometer.

especially in getting the size of a hole already bored, when it is
necessary to turn a piece to fit it exactly.

Besides this snap gage, we have a number of the regulation
micrometer calipers of all sizes in the tool-room, and accessible
to any one competent to use them; but it has been noticed that
it was not long before there was hardly any call for them even
by our best workmen, after they had become accustomed to the
new system. We have never known a machinist who had tried
the system but who was in love with it, and besides producing
the work within the desired limits we found the total time con-
sumed much shortened.

AN OUTSIDE AND INSIDE MICROMETER

The half-tone 226 shows a micrometer designed and pat-
ented by Frank 6. Marbach, Medina, Ohio, for both outside
and inside measurements, its range being from o to I inch,

GAGES AND GAGING SYSTEMS

211

and for the latter from f to if inches. The thimble of this
instrument has the usual graduations upon its periphery, but
the graduations for the inch movement are placed upon the beam
instead of on the hub of the head, rotating with the thimble
while the usual spindle is replaced by a threaded shank affixed
to the movable jaw. To compensate for the least motion between
the nut (which is adjustable) and the spindle, two zero lines
about 1 inch apart are placed upon the hub, and the reading
for the outside and inside measurements are taken from different
lines, one being stamped "Out," and the other " In." The upper

FIGS. 227, 228, and 229. — Micrometer Scribing Block.

part of the beam is graduated from zero to zero, and the lower
row of graduations giving inside readings starts at 625. While
the tool shown corners but an inch travel, it is obvious that by
increasing the length of the beam and making the jaw — which
is now fixed — adjustable by inches, the caliper could be made
to cover a range of, say, 6 inches or more.

MICROMETER SCRIBING BLOCK

Sketches in Figs. 227, 228, 229 show a very useful tool, a
micrometer scribing block. It has an easy and fine adjustment
for accurate lining out, but its chief advantage over the ordinary

212 GAGES AND GAGING SYSTEMS

scribing block lies in its use as a hight gage, as differences are
read direct, dispensing with paper or sheet gages, or in fact any
gage. Its main parts are base A, screw B, nut C, sleeve D, and
scriber E. The nut has a long bearing on the screw, and has
a slit sawed up about a half inch in length. Screw B has a key-
way in it in which fits pin F, which stops the sleeve from rotating.
Sleeve D also is slit. Nut C is graduated with forty divisions,
and rests against a line on the sleeve. The spring keeps spring
D up against the nut. To lock the sleeve to the screw, knurled
screw G is turned, which tightens the sleeve on the nut, which
in turn is tightened on the screw.

MICROMETER SCALES

Having seen a set of scales like those shown in Figs. 230 to
234, in use for a long time by a workman in the shop, we con-
cluded they would be of interest to others, and describe them as
follows: The positiveness and accuracy found in their use cer-
tainly justify the employment of the term micrometer in naming
them.

They are tapering steel scales graduated on both sides, one
side having divisions of hundreds, and the other of sixty-fourths.
Measurements can be taken very quickly, for the instant contact
is made between the two points the reading is obtained; there
is no yielding, as with a common, a vernier, or even a micrometer
caliper. The different scales in the set make a series of over-
lapping measuring bars about TV inch thick, one scale supple-
menting the other after the manner of a set of taper broaches
or reamers; and a surplus at the ends in excess of the graduated
part of the scale is left for convenient handling.

Take, for example, the scale shown in Fig. 230, and we have
two divisions on the left hand, from 26 to 28, representing the
distance required to increase the width of the scale from 26 to
28, and then subdivisions (common to the whole scale in the
practice, but omitted in the drawings) give an easy advance in
thousandths, making the latter more easily visible than sixty-
fourths on the usual scale. Entering the scale, as shown in Fig.
234, a much more certain measurement of .29 is obtained than
would be possible with the ordinary scale held with lines opposite
the edges of the opening. The lines on the scale are made at

GAGES AND GAGING SYSTEMS

213

right angles to the lower sides, as shown in the cuts. It will
be seen that the taper is \ inch to the foot.

In Figs. 235 and 236, let A be a part of the saddle on a planer
or shaper, B the cross-head, and C a bar clamped by D to the
latter. The bar C is clamped to the top of the cross-head in
Fig. 236, instead of on the front, as in Fig. 235, and the scale is

,71

— -

^] ! ' '

T
*

~T
g

^•;

~|
53

'
g

;

g1 Is1 Is1 Is1

J L

8. I-, hi I L

•| 1

•

~T~1

^T~

«!

M 1

51 Is '

1 1 1

= ! H

Micrometer Scales

FIGS. 230 to 236. — Micrometer Scales.

used horizontally. If a dividing tool TV inch thick has made a
cut into a piece of metal, and it is intended to make the groove
in the work T% inch wide, then instead of measuring on the work
or the tool, a piece C is brought up and clamped to the cross-
head, and the ^-inch measurement taken with the scale as shown
in Figs. 235 and 236.

Fig. 237 illustrates an accurate and convenient way of setting
a surface gage point to hight. A piece of work shown in Fig.

214

GAGES AND GAGING SYSTEMS

238 laid out in this way and tested up by the points, and bored
out on lathe face-plate, came perfect.

Fig. 239 shows a positive method of intersecting lines, one
at K getting a distance from the edge of the work by means of

FIG. 237. — Setting a Surface Gage.

a block clamped as shown ; and one at L giving a point on a line
any required distance from the stud M.

A piece of metal is to be planed, say, from i^ to i inch thick-
ness: Slide the scale between the tool and the planer bed to i^

FIG. 238. — Work Laid Out.

and rough-cut one side, turn the work over, set the tool to 1.02
and do the same to that side. Then if .01 is right for a finishing
cut, set the tool to i.oi for one side and to i inch for the other;
the work being fastened to the planer bed. Fig. 240 gives an

GAGES AND GAGING SYSTEMS

215

idea of the use of two scales together, giving here 2.756 inches.
Decimal and common fractions are easily convertible by reversing
the scale; and once determine the number of thousandths required

FIG. 239. — Method of Intersecting Lines.

for an easy, tight, driving or scraping fit, a cut can be taken
with extreme accuracy for either by the use of these scales.

A MICROMETER GEAR TOOTH GAGE

Fig. 241 clearly shows all that is essential of a recently de-
vised gage, and also the application of it. This gage is pat-

I I I I I Ml M MM I I I I I I

H ii :

FIG. 240. — Two Micrometer Scales Together.

ented by J. Boulet, Beverly, Mass. As will be seen, its sole
function is the measuring of the thickness of spur gear teeth
at the pitch line, for the purpose of ascertaining their accuracy,
and discovering any errors in the cutting. The jaw at the right

2l6

GAGES AND GAGING SYSTEMS

is fixed to the bar of the instrument, while the other jaw is moved
in either direction by the micrometer screw, the nut of which is
fixed to the other end of the bar. By this means the thickness
of the tooth may evidently be measured as accurately as in any
other application of the micrometer, provided the points of the
measuring jaws are brought to the proper location on each side
of the tooth. The positions of the jaws relatively to the tooth
are determined by the central vertical micrometer screw. The
point of this screw is always central relatively to the jaws, and

FlG. 241. — Micrometer Gear Tooth Gage.

the micrometer adjustment brings the jaws to the correct hight
for the pitch line, according to the pitch of the gear tooth to be
measured. To keep the vertical screw always central between
the jaws, it must evidently move in the same direction as the
movable jaw, but at half the speed. The small horizontal screw
which moves the block which carries the central or depth mi-
crometer is a continuation of the screw which moves the thick-
ness measuring jaw, but the pitch of the screw is only one half
that of the larger screw, and the pitch is also reversed. Thus,
if the principal screw is forty to the inch and right-handed, the
small screw for moving the depth gage must be eighty to the
inch and left-handed. This instrument will, of course, do its

GAGES AND GAGING SYSTEMS

217

work as accurately as any other micrometer, employing this
familiar means of minutely indicating the movements of the
measuring jaws, provided it is accurately made, which, of course,
it must be.

MICROMETER ATTACHMENT FOR THE LATHE
The sketch, Fig. 242, shows a device for clamping a microm-
eter head to the lathe bed. The inner side of the 45-degree
angle is left short so that the fixture is not unnecessarily high,
and also to allow it to be removed from the ways of the lathes
with the fewest possible turns of the knurled head screw. The
micrometer head is held in place by means of a brass screw, so

FIG. 242. — Micrometer Attachment for .Lathe.

that it may be readily removed if wanted for any other purpose.
When turning where the distance from one shoulder to another
must be very accurate, or where a given amount is to be faced
from a piece of work, the fixture should be clamped so as to allow
the carriage, the barrel being turned, to keep the micrometer
spindle in contact with the side of the carriage until the required
distance has been traveled.

MICROMETER CALIPER FOR MEASURING THE RADIUS OF SPINDLE
DRILLS AND SIMILAR PIECES IMPOSSIBLE TO MEASURE DI-
RECTLY

The principle of this gage is shown in the sketch, Fig. 243.

As we have a constant angle of —

65 degrees, the line will

218 GAGES AND GAGING SYSTEMS

always be a fixed ratio with the correct radius of the piece to
be measured. So we have only to multiply the radius of the
piece to be measured by the constant 1.103 an<^ set tne gage to
this amount. The constant is found by the reckoning:

= 1.103.

cos. 25° 0.90631
To set the caliper at zero, it is necessary to have a measuring
disk, say lo-millimeter diameter, then we reckon the distance,
Fig. 243, for this disk as follows: 5 x 1.103 = 5-5!5' an<^ a^d to
this r = 5, giving 10.515; to this amount we set our screws, then
put the disk between the point of the screw and the anvil, and
tighten the anvil when the gage is ready for measuring any
diameter up to 20-millimeter radius. For larger diameter, we

FIG. 243

make the same arrangements with a measuring disk 3o-millimeter
diameter, and are then able to measure the radius of the pieces
up to 6o-millirneter diameter.

This gage is especially valuable in milling to the center of
things where the periphery is interrupted, as in spindle drills,
etc., a section of which is shown, Fig. 244.

Example: — To stake a center of a piece 19.5 diameter, we
set the gage according to the first case and reckon: 9.75 x 1.103
— amount we ought to read on the micrometer scale when the
center has been reached. Fig. 245 shows the instrument with
the measuring disks.

A MICROMETER STOP

Every mechanic knows when he is facing a piece of work,
how difficult it is to move the lathe carriage just the right amount
when there is a thousand or two for the finishing cut.

GAGES AND GAGING SYSTEMS

219

The stop, Fig. 246, is clamped to the lathe bed at any con-
venient point, and adjusted to abut against the carriage, when
reading can be taken and the carriage moved accurately any
distance within range of the stop, in this case i inch. It can
be used for a variety of work, such as recessing an exact depth
below a finished surface, stepping from one surface to another
by means of a distance piece between stop and carnage, etc.

Having a piece of work on the face-plate, and after measuring
the location of a hole just bored, it was found to be just one thou-

FIGS. 244 and 245. — Micrometer Radius Gage.

sandth out of center. It was but little work to clamp the stop
to the face-plate, take a reading from the side of the work, loosen
bolts and tap over the right amount by measurement.

TESTING MACHINE TOOLS WITH A MICROMETER CALIPER

It is of course obvious that the micrometer caliper can be
applied in many ways, and for the purpose of making many other
tests of the accuracy of machine tools besides those given else-
where in this book. We present herewith a few of these, and

220

GAGES AND GAGING SYSTEMS

many others will readily suggest themselves as the occasion for
them arises. It is often desirable to test a drill press, to see
whether the spindle is at right angles with the table or platen.

FIG. 246. — Micrometer Stop.

A test for these is shown in Fig. 247. A parallel strip or piece
of bar stock A is clamped to the end of the spindle, or if more
convenient to a piece held in a chuck. On the end of this piece,

FIG. 247. — Testing Drill Press Table.

and near the end of the table, is clamped the caliper, as shown.
A measurement is then taken at B and noted, and the spindle
and caliper turned around to the position shown by the dotted
lines, and another measurement at C, when the alignment side-

GAGES AND GAGING SYSTEMS 221

ways may be noted. Two other measurements, one in front, the
other at the back, will complete this test.

Sometimes it is desired to know the deflection of the platen
under the pressure of drilling, as of course that affects the align-
ment of the machine and the quality of the work turned out.
For this purpose the caliper should be clamped by any other
convenient means, which will readily suggest itself, to the slid-
ing head of the drill spindle, and in such a way as not to interfere
with the work. The caliper may be extended down to measure
the table or platen direct or two blocks on the table, or to work
itself, as may be most convenient.

Before any pressure is put on the drill spindle, a measurement
should be taken and noted; then the drilling commenced, and
after the drill has started properly, the spindle stopped with the
feed still on and another measurement taken, when the deflection
under working conditions may be noted.

When a drill press is used on one line of work, it is by this
means an easy matter to throw the spindle out of line just enough
to compensate for deflection and be right under working con-
ditions.

In using the ordinary machine vise, such as we find on the
planer, shaper, and milling machine, we often want to know
whether or not the fixed jaw is square, or, in other words, whether
work held against it by the movable jaw will be planed or milled
square and true with that side. We usually find it out by putting
the work in place and taking a cut over it and then trying it
with a square. In Fig. 248 is shown what will usually be found
a quicker and more satisfactory method.

The square A is clamped against the solid jaw B by a small
bar of brass or other soft metal or stick of wood, as shown at C.
The caliper is clamped on a tool shank held in the shaper or on
the milling machine arbor, as the case may be, and a measure-
ment taken to the edge of a square blade, as shown at D; then by
moving the slide another measurement is taken, as shown by
the dotted lines at E. This of course will show at once whether
the jaw is at right angles with the machine slide, which is neces-
sary to produce square work.

When the work is supported on parallel strips or directly on
bottom F of the vise, to find whether that face is- parallel with
the slide of the machine, it is of course only necessary to dispense

222

GAGES AND GAGING SYSTEMS

with the square, and opening the vise to its full extent, apply
the caliper direct to that surface at not less than four points,
or at the extreme corners, which will show at once how the work
is expected to come out.

It is often desired to set the vertical tool slide of a shaper
or planer nearer vertical, or at right angles to the platen, than
may be done by the graduations. If a machine vise with a
square jaw be at hand, it may be done, as shown at Fig. 249, in
which the parallel strip A is held against the jaw B, as in the
square in Fig. 248; then by clamping the caliper to a tool shank

FIG. 248. — Testing Machine Vise.

held on the slide, measurements taken at both ends of the parallel
strip by running the slide up and down will show whether the
slide is in its proper position or not.

This also affords a ready means of setting the head exactly
at any desired slight inclination, so as to produce slightly tapering
work of definite proportions. Say, for instance, it is desired to
plane down a surface nearly vertical, but with an inclination of,
say, .005 inch in 4 inches. In such a case it would be necessary
to make two marks upon the piece A, Fig. 249, four inches apart,
then set the head so that the micrometer would show the required
difference of .005 inch when applied at the two different points
thus marked.

GAGES AND GAGING SYSTEMS

223

Another way of testing which would usually be much more
handy for the planer, especially where the vise is not so much
used, is to clamp to the platen a square with its blade standing
vertical and crossways to the platen, and make the measurements
to the edge of this blade, as shown on the parallel strip held in
the vise in Fig. 249.

The truth of the two screws that operate the cross-rail of a
planer, which is all that it is usually desired to know, may be very
easily and quickly tested by clamping the caliper to the end of a
long bar of steel, such as is used for tools and clamped in the tool-

FIG. 249. — Testing Machine Vise.

block. Starting with the cross-rail down near the platen, make
a measurement near one edge, then run the saddle and tool-block
to the other side and measure again. By now raising the cross-
rail, say 6 inches, and letting down the bar carrying the caliper,
measure again on both edges of the platen. Continue this opera-
tion until the full hight of the housing is reached, and if a record
of the readings has been made, it is easy to see at a glance how
near alike the screws are, and if there be an error just how it is,
and how much.

Most milling machines, and especially universal ones, have
graduated dials reading to thousandths of an inch on most all

224 GAGES AND GAGING SYSTEMS

the slides. On such machines the caliper, as shown, used in these
various tests, is not of so much advantage, as the reading may
be taken direct from the machine itself when testing the platen
for truth in both ways with the cutter arbor and spindle. But
on such machines as do not have these graduated dials, the
clipper method of testing and for setting the work in the proper
way upon them will be found both quick and handy, and after
the habit of using it is acquired, quick and accurate setting of
work will be greatly facilitated.

There are test indicators on the market which read to thou-
sandths of an inch over quite a range, and some of them would
answer the purpose of these tests much better than the micrometer
caliper, as they would be much quicker and would in themselves
take care that the contact pressure is the same at all readings.
Special indicators have not found a place in this article for the
reason that they are special tools, while the object of this is to
show how the tests may be made cheaply and quickly without
special tools.

TESTING THE ACCURACY OF A LATHE WITHOUT SPECIAL TOOLS

When the new lathe comes into the shop, and sometimes in
the case of an older one, it is desirable to know about how true
it is, or more accurately speaking, how its various parts line up
one with the other. Sometimes it is not merely desirable to
test the lathe, but may be necessary, and perhaps if it were not
considered to be, and usually made, such an expensive job, more
lathes would be tested and made right when found not to be
true, and very likely a great deal of time would be saved by the
ability to turn out better work.

There are many ways to test lathes by the use of specially
devised indicators and micrometers, and good straight-edges
and round true arbors; and a good many articles have been
published describing these tools and methods which are well
enough for manufacturers of lathes, but not at all adapted to
the needs of the lathe users. What we want to consider now
is how to do the job without special tools or fixtures, and with
just the ordinary stuff that is found kicking around the floor of
almost any jobbing shop, and can be easily had in any other
kind of a shop. At this date there are not many machine shops

GAGES AND GAGING SYSTEMS 225

in this country which do not possess at least one ordinary i-inch
micrometer caliper, and this we will use in the testing of lathes.
Shops which do not possess such a caliper do not usually want
to test lathes. The caliper is not absolutely necessary, however,
and the job can be done without it, but can be done more quickly
by using the caliper, which will not only show when a thing is out,
but also just how much, which is exactly what we want to know.

Perhaps it will be well to begin with the foot-stock and see
if its spindle is parallel with the ways or shears of the bed, a
necessary thing if good work is to be done.

For this test we will consider a lathe of about 16 inches swing
and 6-foot bed. The first thing we will need is a piece of centered
shaft, or an arbor, about 2 inches diameter, 4 feet long. It need
not be either straight or round, but should be well centered and
square up true on the ends. Put this arbor on the centers with

FIG. 250. — Testing Lathe.

the foot-stock spindle clear back. Make some kind of a mark,
as with chalk, near the tail center end of the arbor, as at A,
Fig. 250.

In the tool-post of the lathe mount the i-inch micrometer
caliper, as shown in Fig. 251, with the thimble end to the work.
This may be done by bending a tool shank or piece of iron, as
at A, Fig. 251, and the caliper can be held in place upon it by
almost any kind of a clamp that comes handy, such as B. By
moving the carriage and tool-block, bring the thimble end of the
caliper near the mark A on the arbor in Fig. 250, open the caliper
to bring the thimble in contact with the arbor — though it would
be a good plan perhaps to interpose a piece of paper between the
caliper and arbor, which may be pulled between them in order
to always get about the same contact. When the proper contact
is made note the reading and back off the caliper by turning
the thimble, but do not move the tool-block. Now loosen the
foot-block, and run the spindle out to near the end of the screw,

226

GAGES AND GAGING SYSTEMS

and clamp again; then measure again just as before, and if the
two readings agree, the tail spindle is in line sidewise. The
caliper should now be changed to the position shown in Fig. 252,
and the two measurements taken on top of the arbor the same
as taken at the side. The mark A is now turned upward, since
we are assuming that the arbor is not true, and this enables us
to measure from the same spot for each measurement of a given
test.

Perhaps the thing to do next is to test the truth of the live
center. Measure to the spot on the arbor near the live center,
either from the side or top, then turn the spindle, say quarter
way around, holding the arbor in the original position, and measure
again ; repeat this about four times, and if all the readings agree
the center is about right.

FIG. 251. — Micrometer Test.

A way to test the center hole is to put the center in place,
being careful to have it clean, and turn or grind it true; then
remove and put it back again turned half way around from the
first position, when the error of the hole, if there be any, will
be double and may be more rapidly measured. Sometimes the
front and back end of this hole are not true with each other,
and in this case about the only way to test or find out how much
it is out is -to fit a piece to the hole, having a straight end, which,
in this case, should be both true with the taper shank and straight.
By putting this in place and measuring with the caliper held as
in Fig. 251 at both ends and turning the spindle, it may be seen
at once whether the hole is in its proper place.

Next we will line up the head and tail centers. Put the caliper
in position, Fig. 251, and measure to the marked spot on the

GAGES AND GAGING SYSTEMS

227

arbor, then turn the arbor end for end and run the carriage
along without changing the cross-slide, and measure again. If
the two readings agree, all right; if not, adjust the foot-stock
until they do agree, when the center will be in line with the shears.

To find if the centers are the same hight, place the caliper
in position, Fig. 252, and measure near each center by reversing
the arbor as before.

To find whether the live spindle is in line with the centers
and shears, clamp a parallel strip or rough piece of bar iron,
such as B, Fig. 250, on the arbor near its end, and on that clamp
the caliper as shown. Then with the largest face-plate in the
spindle, and a mark on the plate (as it is not assumed to run true

FIG. 252. — Micrometer Test.

at all), measure to the plate with the mark at the top and again
at the bottom by turning both the spindle and the arbor. Any
difference in the readings will show at once which way the spindle
inclines vertically. Repeat this operation by measuring both at
the front and at the back, by which the alignment laterally with
the shears may be noted.

To find whether the cross-slide is at right angles with the
spindle and shears: If a good straight-edge be at hand, one way
is to take a cut over the large face-plate, and apply the straight-
edge, when, if the spindle is in line with the shears and the plate
is flat, the cross-slide will be shown to be at right angles. But
perhaps it is not convenient to take a cut right over the plate,
and so we will consider a way of doing it without any cutting at

228

GAGES AND GAGING SYSTEMS

all. Mount the caliper on a tool shank, as shown in plan in Fig.
253, with the thimble pointing to the face-plate. Most tool-
blocks will not go far with the thimble pointing to the face-plate.
Most tool-blocks will not go far back of the center, so the caliper
should be mounted somewhat in front of the tool -post, as shown,
so that it may travel an equal distance each side of the center,
and should go as far as possible from it in each direction. Measure
to a mark on the face-plate, as shown in full lines at A, then
back of the thimble, and move the tool-block and caliper to the
position shown by the dotted lines at B. Turn the spindle to
bring the mark on the plate to that side and measure again,

FIG. 253. — Micrometer Test.

and if the two readings agree the cross-slide is at right angles
with the spindle and also with the shears, if the spindle is properly
in line; if not, its position may easily be found by noting the
alignment of the spindle, as shown by the preceding test.

It may be preferable to make this last-named test with the
micrometer arranged as in Fig. 250, except that the piece B
should then be nearer the middle of the length of the arbor. A
piece of any convenient form can be held in the tool-post and
brought into contact position with the micrometer, first in front
and then at the back of the arbor, rotating the latter upon the
center to bring the micrometer into position, and moving the
cross-slide by the screw. This method has the advantage of

GAGES AND GAGING SYSTEMS 229

eliminating any error that might arise from end motion of the
spindle when rotating it; but it is to be observed that it shows
only whether the cross-slide is square with the lines of the centers,
and nothing more than that. If, however, the centers have
previously been lined up with the shears by the method described,
then this last-named test also shows whether the cross-slide is
square with the shears or not. And if the spindle has been
previously lined up with the line of centers, as previously described,
then this last-named test shows also whether or not the cross-
slide is square with the spindle.

It will be seen that the micrometer caliper is not absolutely
necessary for any of these tests, as by the use of a common cap
screw, fitted rather snugly in the piece held in the tool-post and
on the arbor, all the tests may be made, and perhaps just as
accurately as with the caliper, but with the disadvantage of not
indicating how much the various points are out of position.

The method of testing the lathe is not given with the belief
that it is the very best that can be used, but it is a very cheap
and simple method covering most of the points desirable to be
tested, and at a cost that will not prohibit its frequent use.

The use of the end of the thimble of the micrometer caliper
is not a new idea at all, though perhaps it is as applied in this
way and for this purpose. One of the very early calipers, made
in France, and illustrated in the American^ Machinist some years
ago, had a hardened contact point on the end of the thimble,
and another extended from the ordinary anvil; the caliper was
intended for internal measurements as well as for the ordinary
outside work.

A NEW SWEDISH COMBINATION GAGING SYSTEM

An interesting and rather unusual set of gages of Swedish
origin has been brought out by the Grbnkvist Drill Chuck Company
of Jersey City under the name of the Johansson Gages. The re-
markable features of this system are the exquisite finish of the
surfaces which enables the use of them either singly or in multiple
by the simple process of wringing them together. In Fig. 254 the
complete set of gages is shown in its box, which is 10 x 15! inches
and weighs yj pounds. In the various series in this case are gages
ranging from o.iooi to 0.1009 inches in thickness rising by
o.oooi up to gages of 2 to 4 inches rising by i inch.

GAGES AND GAGING SYSTEMS

231

It will readily be seen that by taking proper selections of these
gages and wringing them together a complete gage can be made
of any size desired. It is estimated that at least 80,000 different
sizes may be made and in all probability this is a low estimate.
No thickness has yet been discovered which cannot be accom-
plished by the various combinations, and the majority of the points
can be reached by several different combinations enabling an accu-
rate checking up in case of doubt.

Fig. 255 shows 22 gages supporting each other horizontally.
It gives the best idea of the manner in which they are to be used,

FIG. 255. — Twenty-two Gages Support Each Other.

and yet when built up in this manner the feel of the gage is the
same as of a solid piece and this holds for any combination.

Fig. 256 shows one large piece and two small pieces aggregat-
ing the same measurement. On the outside faces two more pieces
are wrung on, lapping half on the single piece and half on the built-
up piece. The whole may be supported by any one of the pieces
without falling apart. An indefinite number of combinations
may be successively subjected to this test, which, as regards the
accuracy of the pieces, is of course almost absolute.

Fig. 257 shows the way these gages are used in multiple for
plug gages. The two outside pieces are lapped to a circle; the
two wrung together will measure a half-inch hole. Any of the
flat gages can be used between the outside pieces to make a gage
for any size of hole desired. Fig. 258 again shows a one-inch
snap gage with a built-up piece in it -0.5 plus 0.2 plus 0.050
plus 0.150 plus o.ioo.

Though the adhesion of these gages is the same as if they

o W

cxO

o o

GAGES AND GAGING SYSTEMS 233

were strongly magnetized, yet as a matter of fact they are not
magnetized at all. They can only be held together when wrung
so that the air is excluded. Yet the tension of pieces which have
been wrung together is greater than that of air pressure, so that
it is evident that some molecular attraction is combined with the
force of the air pressure in holding them.

In brief, then, we are furnished with a complete set of gages
enabling the mechanic to secure any size that he wants, including
binary fractions; to check up his gages with other gages from the
same set and to do much that has hitherto been possible only by
use of measuring machines or micrometers.

The smallest increment is small enough for determination of
not only limits but tolerances, and the gages would seem to furnish
all needed means for determining working gages of any required
degree of accuracy.

INDEX

PAGE

Accuracy of the lathe without special tools, testing the 224

Adjust the needle of surface, how to 04

Adjustable sizing block ^3

Adjusting caliper gages 22

snap gage 208

try-squares, method of testing 164

Age of interchangeability, living in 3

Aluminum caliper 29

American Machinist 176, 229

tool-making, treaties 32

Ancient snap and plug gage 3

Anvil screws of micrometer with bastard threads 24

Arbor and bushing for indicating jig buttons 36

Armature templet, making an 125

Attachment for cutting of thread gages 7

for the lathe, micrometer 217

for measuring instruments 71

Attachments for the vernier and dial test indicator 152

hight and vernier gages and 152

Austria'n work, gage practice in 18

Ball, testing diameter of 15

Bar gages with flat ends, measuring .- 66

gages with plain parallel ends 61

with spherical ends, sphere 62

Bates, Mr. G. A 186

G. A., invention of 186

Bath indicator 71

Beam micrometer, 6-inch 200

Bench gage, combination 15

Bernhard Fisher & Winsch, Dresden, Germany n

Best manufactured square 175

Bevel, knife-edge 170

Bored work, gaging the recess in 16

Boring cutters, gage for testing 99

master gage plates from model 38

235

236 INDEX

PAGE

Boulet, Beverly, Mass 215

Bow-back gages 72

British Westinghouse works, large micrometer at 203

Brown & Sharpe Mfg. Co 111,113

micrometer 122

Bullard Machine Tool Co., Bridgeport, Conn 57

Button method of hole placing in jigs 32

for jig work 35

Caliper gages, adjusting 22

for marine engine liners, large micrometer part 53

Cheap surface gage 96

Combination bench gage 15

square used as hight gage 173

squares ' 161

squares, use of 172

Swedish gages (Johansson) 230

Commercial hardened squares 161 '

Comparison of end standards of length testing and 61

Correct square, how to produce one 161

Correcting squares when slightly out 81

Cutting of thread gages, lathe attachment for 7

Cylindrical gages 15 , 62

gages, measuring 71

gages, three-quarter inch 70

Decimally graduated gage for dovetail slide inspection 51, 52

graduated universal indicator 90

Depth gages 113

gages, handy worm and thread 115

gage, a micrometer 122

Description of measuring machine 62

Detecting error in index plates 44

Development of gages i

Device for testing gages 72

for testing squares 80

for testing up index plates 44

Dial test indicator, attachments for the vernier and 152

Diamond-charged lap, use of 5

powder, use for charging laps 5

Different forms of pin gages 15

Disk for thread cutting 7

Dovetail channel, gage for width of 50

slide, gage for testing 51

INDEX 237

PAGE

Dresden Bohrmaschined fabrik A. G n

Drills and similar pieces, impossible to measure directly 217

Duplicate rollers, test gage for large 54

work, inspecting 48

Electric measurement instruments 48

Emery for lapping gages, preparation of 6

End standard of length, testing and comparison of 61

Engine liners, large micrometer test caliper for 53

English razor as straight-edge 170

type of universal limit gage 77

Equating micrometer 199

Essential necessary to the workman 6

External screw threads with the micrometer, measuring 197

Fine adjustment of milling machine table in

Fixture-work, use of gage in jig and 32

a rod gaging 136

Flat ends, measuring bar gages with 66

square, simple method of testing 166

Fly-wheel segments, gaging 26

Form of pin gages, different 15

Gages, adjusting caliper 22

bow-back 72

cheap surface 96

combination bench 15

cylindrical 62

depth 113

determining proper relation of bevel gear faces 83

development and efficiency of the tools i

device for testing 72

diameter of ball race one crank shaft gear ^ 85

different forms of pin 15

dovetail slide inspection 51

end measurement 56

fundamentals i

gaging systems i

gear tooth 113

grinding and lapping a male plug , 6

grinding out small 5

238 INDEX

PAGE

Gages, hight, six-inch ^8

index plates, testing 44

indicator for accurate index work, use of 40

indicator for thread I0

indicator in jig and fixture work, use of 32

inside 147

internal measuring ^ 141

Johansson 229

large duplicate rollers, test 54

large work, micrometer 146

lathe 88

lathe attachments for thread 7

locating keyseats 57

making 1,4

making a small micrometer, inside 141

manufacturing mechanisms, making and using for 12

measuring bar with flat ends 66

measuring cylindrical 71

measuring hair lines on type faces 78

measuring methods of Westinghouse Machine Co 22

micrometer 146

micrometer adjustment, universal surface in

micrometer caliper for testing 73

micrometer depth 122

micrometer heads for special 82

micrometer hight 193

millimeter (25) 69

millimeter (150) 69

miscellaneous 113

modern application of v 3

new English type of universal limit 77

Newall working 77

parallel vernier 154

permanent snap 135

piston thread 120

planer 88, 137

planer, a new system of 51

plates for models, boring master 38

plates for watches, making master 39

practice i

practice at works of Lwdw. Loewe & Co 30

practice in Austrian iron works 18

preparation of emery for lapping 6

rebabbitting journals 83

remarkable surface 188

renewing of thread 9

ring 14.

INDEX 239

PAGE

Gages, scratching lines on chalked surfaces 57

set of simple shop 56

setting points in 8

slots in boring machine tables 57

standard exact inch 22

surface 88

Swedish 229

system, limit 19

systems, laid out 20

systems, shops in which they are unknown 2

taper seats of crank brackets 87

testing and laying out fine work, hight 156

testing centers on lathe work on face-plate 101

testing cutter teeth 99

testing dovetail slides 51

testing size and parellelism of holes 17

testing truth of planing table 85

textile machine work 138

thread 113

thread , German 117

thread testing 1 1

three-quarter cylindrical 70

tools for rolling sheet metal 75

tooth, a gear with micrometer 215

type 121

universal 88

universal indicator and the R. R 109

universal indicator, decimally graduated 90

use on milling machine 82

variation in size of work due to type of 18

vernier gage for testing snap 154

wall thickness, inspection of 48

when threading, measuring 8

width of dovetail channel 50

work 113

Gaging double-head valves 27

fixture, a rod 136

fly-wheel segments 26

pin for bottom of holes 15

small taper-holes 92

taper holes 27

the recess in bored work 16

wheel joints for shrink fits 27

Gear tooth, gage for 113

Geometrical methods for laying out right angles 164

German shop custom in gages 1 1 7

Graduated disks, vernier plate instead of 3^

240 INDEX

PAGE

Graduated gage for dovetail slide inspection, decimally 51,52

universal indicator, decimally Q0

Grinding machine, indicator for setting I08

straight work, gages for ' ^8

Hair lines on type faces, gage for measuring 78

Handy thread, worm, and depth gage 115

Hardened cylinder as test block !66

test block with knife straight-edge 166

Hauer, Charles E 92

Heads for special gages, micrometer 82

Hight and vernier gages and attachments 152

gage, a micrometer 103

gage for testing and laying out fine work 156

gage, six-inch I58

gage, square used as 1 73

gage, the R. R. universal indicator and 109

gage, vernier transformed into 152

How to make a knife-edge square 167

to make a large micrometer 200

to produce a correct square 161

Index making another accurate 44

plate making, use of page and indicator in accurate 40

plates, locating and swinging 44

plates, testing gage for ' 44

Indicator, a lathe x 105

and hight gage, the R. R. universal 109

and holder, test 102

and inclinometer 104

attached to straightening press 109

attachments for the vernier and dial test 152

for setting grinding machine 108

for setting work in shaper or planer 102

for testing round pieces 107

for testing up index plates 44

for thread gages 10

lathe and planer 92

sensitive to 1.200000 part of an inch 106

test IDT , 106

used as a depth gage 90

Indicators, as applied to milling machine 99

for testing work, use of test 107

in jig and fixture work, use of gage and 32

INDEX 241

PAGE

Indicators, in accurate index plate making, use of gages and 40

lathe 88

planer 1 88

special 48

surface 88

their construction and use 88

universal 88

Indicating gage for use on milling machine 32

Inexpensive lathe indicators 88

Inside gage 147

micrometer 143, 145

micrometer 150

micrometer caliper 144, 150

micrometer for 4-inch holes and under 149

micrometer for gaging bored holes 150

micrometer gage for making shrink fits 145

micrometers, outside and 210

Inspecting duplicate work 48

Inspection, gage for wall thickness 48

gages 48

graduated gage for dovetail slide 51

tools 48

Instruments, interchangeability and measurements 3

sensitive attachments for measuring 71

Instrument for internal hole measurement 21

Interchangeability vs. measurement instruments 3

Internal hole measurement, instrument for 21

Jig and fixture work, use of gages and fixtures in 32

Jigs, button method of placing holes in 32

Johansson combination gages 229

Kearsarge, U. S. S 54

Keyseats, gages for locating 57

Knife-edge bevel 17°

squares 161

squares with handle 17°

straight-edge 17°

straight-edge i72

tools, a set of 17°

Lapping a male plug gage, grinding and 6

gages, preparation of emery for 6

plate of vcast iron I^9

242 INDEX

PAGE

Large micrometer caliper at the British Westinghouse works 203

micrometer test caliper for engine liners 53

Lard oil used with emery 6

Last cuts on thread gages 7

Lathe and planer indicator 92

attachments for cutting of thread gages 7

bed templet for planing 134

gages 88

indicator 105

indicator, inexpensive 88

indicator, universal 89

micrometer attachment for the 217

Laying out fine work, hight gage for testing and 156

Length, testing and comparisons of end standards of 61

Limit gage practice at the works of Ludw. Loewe & Co 30

gage system 19

gage, English type of . 77

Loewe & Co., limit gage practice of work Ludw 30

shops, Berlin, Germany 30

Locating and swinging index plates 44

keyseats, gages for 57

parts, making a templet for 130

work on milling machine, vernier method for 36

Ludw. Loewe & Co., limit gage practice at works 3o

Machine, description of measuring 62

indicators as applied to milling 99

material used in measuring 66

tools, with a micrometer caliper, testing. . 219

work, gages for textile 138

Making a real square 175

a small inside micrometer gage 141

a snap gage 184

a taper plug and ring gages 4

a templet for locating parts 130

an armature templet 125

and using gages for manufacturing mechanism 12

another accurate index plate 44

master gage plates for watches 39

Male plug gage, grinding and lapping 6

Marbach, Medina, Ohio, Frank G 210

Marine engine liners, large micrometer caliper for 53

Manufacturing mechanisms, making and using gages for 12

Master gage plates for models, boring 38

gage plates for watches, making 39

square, one form of 164

INDEX

243

PAGE

Materials used in machine 66

Manchester works of British Westinghouse Co 203

Measuring bar gages with flat ends 66

cylindrical gages 71

external screw threads with the micrometer 197

gages with threading 8

hair lines on type faces 78

instruments, sensitive attachments for 71

machine 48

machine, description of 62

machine, materials used in 66

methods at work of Westinghouse Machine Co 22

Measurement instruments, interchangeability and 3

Method for construction correct square 163

for testing a flat square, simple 166

for testing try-squares 165

of locating work on milling machine 36

testing of and adjusting try-squares 164

Mechanism, making and using gages for manufacturing 12

Meter, micron the millionth part of 68

Micrometer a 6-inch beam 200

a shop set of 207

an inside and outside 210

attachment for the lathe 217

beam, any mechanic can make 200

Brown and Sharpc 122

caliper, a 10x12 inch 200

caliper at the British Westinghouse works 203

caliper for measuring the radius of spindle 217

caliper for testing gages 73

caliper, testing a machine tool with a 219

depth gage 122

equating 199

for 4-inch hole under, inside 149

for screw threads 196

for testing dovetail 49

gage for large work - 146

gage for making shrink fits 145

gage on stand and leg 198

gages, making small inside I41

gear tooth gages 215

heads for special gages 82

hight gage 193

how to make a large 200

inside 141, i43> T4S

measuring external screw thread with the 197

of English design *99

244 INDEX

PAGE

Micrometer outside 196

practical shop use of 208

scales 212

scribing block 211

stop 218

test caliper for marine engine liners 53

testing a drill press with 200

testing a lathe of face-plate 228

testing a machine vise 221

testing hight and centers 227

testing tail and head centers with 226

testing the accuracy of a lathe 224

Micron, the millionth part of meter 68

Miller, John C. Bloomfield, N. J 105

Millimeter gage (25) 69

gage (150) 69

Milling machine, indicators as applied to 99

machine table, vernier and scale for fire adjustment in

machine, use of indicating gage 32

machine, vernier method of locating work on 36

Miscellaneous gages 113

Models, boring master gage plates from 38

Mott Street Factory of the Singer Company 188

New English type for universal limit gage 77

New system of gages for the planer 57

Newall working gages 77

Outside and inside micrometer 210

Parallel ends, bar gages with plain 61

testing 46

vernier gage 154

Perfect square 161

Permanent snap gage 135

Pin gages, different forms of 15

gage for bottom of hole 15

Piston-rod, thread gage 120

Plain parallel ends, gages with 61

Planer, a new system of gages for the 57

gage 137

gages 88

indicator, lathe and 42

table gages for 85

INDEX 245

PAGE

Planing a lathe bed, templet for 134

Plate making, use of gages and indicator in accurate index 40

Plates, testing gage for index 44

Plug and ring gage, making a taper 4

gage, grinding and lapping a male 6

gage usually made first 6

Points in gage setting 8

Practical shop use of micrometer 208

Pratt & Whitney 22

measuring machine 22

Precision square 185

Preparation of emery for lapping gages 6

Produce a correct square, how to 161

Producing perfect, true try-squares 161

Real square, the making of a 175

Remarkable surface gage 188

Renewal of thread gages 9

Reversible parallel for testing a square 46

Ridlon tools, Roach & 109

Ring gage, making a taper plug and 4

gages . 14

gages, grinding out small 5

Roach & Ridlon tools 109

Rod gaging fixture 136

Roll gage 75

Rollers, test gage for large duplicate 54

Scale and vernier for fine adjustment of milling machine table in

Scales, micrometer ^ 212

Screw-testing gage 12

Screw threads, micrometer for 196

threads with micrometer, measuring external 197

Scribing block micrometer 211

Sensitive attachments for measuring instruments 71

Set of knife-edge tools 170

of micrometer calipers, a shop 207

of simple shop gages 56

Setting gages, points in 8

Shaw, P. E. of England 62

Shop gages, set of simple 56

set of micrometer calipers 207

use of micrometers, practical 208

Shops in which gaging system? ar- unknown • 2

246 INDEX

PAGE

Simple and inexpensive lathe indicator 88

method for testing a flat square 166

Singer Company, Mott Street, Factory of 188

Six-inch hight gage 158

Sizing blocks, test and 161

block, adjustable 173

Slide inspection, decimally graduated gages for dovetail 51

Slocomb micrometer calipers, set of twelve 207

Slocomb & Co., J. T. of Providence, R. 1 82

Small inside micrometer gages 141

Snap gage, adjustable 208

gage, a permanent 135

gage, making of a 184

gage, vernier gage for testing in lapping 154

Special gages, micrometer heads for 82

indicators 48

Sphere or bar with spherical end 62

Spherical end gage 20

ends, sphere or bar with 62

rod end gages 18

Spiral gear tooth gage 113

Squares, a device for testing 80

and squares 161

combination 1 61

commercial hardened 161

corrected when slightly out 81

knife-edge 161

method of testing and adjusting try 164

perfect 161

try .v 161

Square, a precision 185

best manufactured 175

gage, a remarkable 188

how to make a knife-edge 167

how to produce a correct 161

knife-edge with handle 170

making, templet for 162

method for constructing correct 163

simple method for testing flat 166

standard for constructing a perfect 162

testing 46

the making of a real 175

used as hight gage 173

used in making molds 168

using test blocks in place of 165

Standard exact inch gages 22

Standards of length, testing and comparison of end 61

INDEX 247

PAGE

Steel, question of 4

Stop, a micrometer 218

small defect in 4

that can be depended upon 4

that will not shrink or warp excessively 4

to use for gage work 4

Straight-edges, knife-edge 170

edges 161

edges, a knife-edge 172

edges, English razor as 170

edges, hardened block with knife 166

Straightening press with indicator attached 109

Surface gage and indicator , 96

plate, small hardened 165

Surface gage 88

gage, a cheap 96

gage, to adjust the needle of a 94

gage, with micrometer adjustment, universal in

System limit gage 19

of gages for the planer, a new 57

Taper gage 121

plug and ring gage, making 4

Tapering steel scales 212

Taps, gaging accuracy of pitch of 29

Templet, for locating parts, making a 130

for planing a lathe bed 134

making an armature 125

with four sides for square making 162

Testing a comparison of end standards of length 61

accurate of pitch taps 29

a flat square, easy method 166

a flat square, simple method for 166

and adjusting try-squares 164

and laying out fine work, hight gage for 156

cutter teeth 99

diameter of balls 15

dovetail, micrometer for 49

gage for index plates 44

gages, a device for • 72

gages, thread 1 1

machine tools with micrometer caliper 219

parallel '. 46

screws 12

size and parallelism of holes 17

square 46

248 INDEX

PAGE

Testing squares, device for 80

the accuracy of a lathe without special tools 224

tool for fine work 73

up index plates 44

work to .0001 or less . 73

work, use of test indicator for 107

Test and sizing blocks 161

block, hardened cylinder as 166

blocks in place of a square, using 165

caliper for marine engine liners, large micrometer 53

gage for large duplicate rollers 54

gage for width of dovetail channel 50

indicator 101, 106

indicator and hight gage, the R. R. universal 109

indicator and holder 102

indicator, attachments for the vernier and dial 152

pieces for gages 48, 49

Thread cutting, disk for ' 7

• gage, German 117

gages, lathe attachments for cutting of 7

gage, piston-rod 120

gages 113

gages, indicator for 10

gages, renewal of 9

leads, overcoming variation in 10

micrometer for screw 196

testing gages 1 1

Thomas, Mr. of Pratt & Whitney, 22

Threading, measuring gages when 8

Threads with micrometer, measuring external screw . . . 197

Tool-makers favored creatures 188

for fine work, a testing for 73

Try-squares 161

method for adjusting and testing 164

Type faces, gage for measuring hair lines on 78

of gage, variation of work due to 18

of universal limit gage, a new English type of 77

United States Watch Factory, Marion, N. J 189

Universal gage • • 88

indicator, decimally graduated 90

lathe indicator 89

limit gage, a new English type for 77

surface gage with micrometer adjustment in

test indicator and hjght gage, the R. R 109

INDEX 249

PAGE

Use of gages and indicators in jig and fixture work 32

of micrometers in accurate index plate making 40

of micrometers, practical shop , 208

of test indicator for testing work 107

of the combination square 172

Using gages for manufacturing mechanisms, making and 12

test blocks in place of a square 165

Variation in size of work due to type of gage 18

in thread leads, overcoming 10

Verifying instruments 4

Vernier and dial test indicator, attachments for 152

for fine adjustment in

gage for testing in lapping snap gage 154

gages and attachments, height and 152

gages, parallel . . 154

method of locating work on milling machine 36

plate instead of graduated disks 36

transformed into a hight gage 152

Wall thickness, inspection gage for 48

Watches, making master plates for 39

Westinghouse Electric Mfg. Co 92

Machine Co 26

Machine Co., gaging and measuring methods of 22

works, large micrometers at British 203

Whitworth plug and ring gage 21

Wincock, George 188

King of toolmakers 188

Work gages 113

Works of Westinghouse Machine Co 22

Workman, essential necessary to the 6

Worm and depth gage, hand thread 115

and spiral gear tooth 113

and spiral gear tooth gage 112

Grinding ^Lapping

TOOLS, PROCESSES AND FIXTURES
By JOSEPH V. WOODWORTH

Author of: " Dies" " Punches, Dies and Tools," " American Tool-Making
and Interchangeable Parts" etc.

162 pages, 6x9, fully illustrated, $2.OO postpaid

\ practical operator's book— written by a practical man.
Mr. Woodworth's books have achieved a real dis-
tinction among practical men. The present one is the
last word on grinding.

It is very briefly and concisely written; its text is
always clear, the style free from obscure technical words
— and the illustrations very numerous and helpful.

Every machinist, tool-maker, die-maker, designer,
foreman and superintendent of machine shop or metal-
working plant should have this book.

THE CONTENTS — IN BRIEF:

Grinding.

Conditions, Rules, Methods, Processes, Machines and Attachments

for Accurate Grinding.
Use and Preparation of Abrasives.
Laps and Lapping.
Construction and Use of Tools and Processes for Finishing Gages,

Tools, Dies and Machine Parts to Accurate Dimensions.
Construction, Use and Operation of Grinding Fixtures and Jigs for

Finishing Repetition Parts and Articles of Metal, Small

Hardened and Tempered Steel Parts and Special Work.
The Hardening and Tempering of Interchangeable Tool Steel Parts

of Delicate Structure which require to be Ground and Lapped

Afterward.
Percentage of Carbon Crucible Steel Ground Parts and Tools should

Contain.

HILL PUBLISHING COMPANY

505 PEARL ST., NEW YORK. 6 BOUVERIE ST., LONDON, E. C.

The Engineering and Mining Journal — Power — American Machinist

FINISHING BY GRINDING

To meet the great demand for information on pre-
cision grinding, because of the great increase in this
method of finishing, we have imported this book
from England

PRECISION
GRINDING

By H. DARBYSHIRE
162 pages, $y2 x8*4, illustrated, $2.00 postpaid

Finishing parts by grinding has been a subject of
very careful study by Darbyshire, who has been a
regular contributor to the AMERICAN MACHINIST.

Points he touches: — Best Wheels to Use — Causes of
Defective Work — Plain Grinding — Universal Head
—Surface Grinding — Magnetic Chucks — Cutter
Grinding — Laps and Lapping — Measuring Tools
and Gauges — and dozens besides.

Doesn't that sound like $2.00 worth ?

HILL PUBLISHING COMPANY

6 Bouverie St., London, E.G. 505 Pearl St., New York

The Engineering & Mining Journal- Power— American Machinist

The Hill Kink Books

COMPILED BY

F. H. COLVIN AND F. A. STANLEY

Associate Editors of " The American Machinist''''

Each cloth, 4x6, illustrated, 50 cents postpaid

ORDER NOW

PRESS TOOL KINKS

SCREW THREAD KINKS

PATTERNMAKING KINKS

MILLING MACHINE KINKS

REPAIR KINKS

TOOLMAKERS' KINKS

JIG AND FIXTURE KINKS

DRILL PRESS KINKS
DRAWING ROOM KINKS
SCREW MACHINE KINKS

HILL PUBLISHING COMPANY

505 PEARL ST., NEW YORK. 6 BOUVERIE ST., LONDON, E. C.

The Engineering and Mining Journal — Power — American Machinist

USEFUL BOOKS

COMBUSTION AND SMOKELESS FURNACES

By Jos. W. Hays
6x9, illustrated, $1.50 postpaid.

GAS POWER

By F. E. Junge
6x9, illustrated, $5.00 postpaid. (Ready Oct. 1, 1907.)

ENGINE ROOM CHEMISTRY

By Augustus H. Gill
4x6, illustrated, $1.00 postpaid. (Ready Oct. 1, 1907.)

PRODUCER GAS AND GAS PRODUCERS

By S. S. Wyer
6 x 9, $ 4.00 postpaid.

QUESTIONS AND ANSWERS

from the American Machinist. 5x8, $1 .50 postpaid.
STANDARD "POWER" BOOKS

THE POWER CATECHISM, $2.00

THE ELECTRICAL CATECHISM, $2.00

THE STEAM ENGINE INDICATOR, $1.50

CONDENSERS, 50c

CENTRAL STATION EXPERIENCES, 75c
COMPOUND ENGINES, 50c

DIMENSIONS AND WEIGHTS OF PIPE
AND FITTINGS, 50c

HILL PUBLISHING CO.

505 PEARL STREET, NEW YORK

The Engineering and Mining Journal — Power — American Machinist

THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW

AN INITIAL FINE OF 25 CENTS

WILL BE ASSESSED FOR FAILURE TO RETURN
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO $1.OO ON THE SEVENTH DAY
OVERDUE.

APR 25 1940

ADD 2 1&*3

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MAH 6 1942»E

MAR 22 1943

LD 21-100m-7,'39(402s)

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YC 19669

TTII66

VVT

179776

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