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MECHANICAL DRAWING

FOR

SECONDARY SCHOOLS

FRED D. CRAWSHAW, B.S., M.E.

PROFESSOR OF MANUAL ARTS, THE UNIVERSITY OF WISCONSIN
AND

JAMES D. PHILLIPS, B.S.

PROFESSOR OF DRAWING AND ASSISTANT DEAN COLLEGE OF ENGINEERING,
"" THE UNIVERSITY OF WISCONSIN

SCOTT, FORESMAN AND COMPANY
CHICAGO NEW YORK

BY
SCOTT, FORESMAN AND COMPANY

PREFACE

Mechanical Drawing is recognized today as an important part
of a secondary education. For all classes of pupils it serves
as an important means of developing visualization, strengthen-
ing the imagination, and forming habits of careful observation
and perception. For those who will make use of it commercially,
mechanical drawing is the accepted means of creating a con-
ventional picture of objects.

This book analyzes mechanical drawing upon the basis of
its elements, or natural divisions, such as Perspective Sketch-
ing, Orthographic Sketching, Pencil Mechanical Drawing, Ink-
ing, Tracing, and Reproducing. Each one of these divisions is
treated separately in a chapter. Each chapter organizes the
division of drawing which it represents. Hence in each chap-
ter there is presented a progressive series of problems in one
of the natural divisions of the subject.

The book contains six chapters and covers the first two years
of mechanical drawing in Secondary Schools. The first four
chapters are designed to occupy the time of a class for the
first year of the two years' course. As there is a large element
of flexibility in the selection of problems, no one individ-
ual is expected to solve all problems. The course may be easily
extended over a period of more than two years, even to three
or four years, depending upon the number of problems solved,
whether a part or all of the chapters are included in the course,
and the time devoted to the subject during each year.

The chapters are arranged in the order in which the divisions
of drawing are dealt with in commercial drawing room practice.
Problems, arranged in groups in each chapter, progress in the
order of their difficulty. Each group of problems is chosen to

436277

•1 MECHANICAL. DRAWING

emphasize the construction of a certain type of line, the use
of particular instruments, and the application of commonly used
conventions. It is believed that such a treatment both retains
and extends all possible educational values attributed to mechan-
ical drawing.

In those branches of vocational education which deal with
industry, mechanical drawing is the means of showing the plan
of construction or the method of assembling constructed parts.
Therefore the authors of this book have taken the view that all
problems presented must represent commercial industrial prac-
tice. They have selected problems which represent several com-
mon industrial materials, and the solutions required represent
the best commercial drawing room practice. Consequently all
abstract problems have been eliminated except in so far as they
relate directly to practical problems. This feature, when coupled
with the one of dwelling upon one division of drawing until a
complete series of problems in it has been solved, makes the
book unique in its presentation of unit courses. All of these
units, when taken together, complete the field of mechanical
drawing, and each one prepares the student for efficient serv-
ice in a particular division of the whole field of drawing.

The course presented in this book has the following subject
matter features:

1. Every problem represents typical industrial material,
commercial construction, and the best drawing room practice.

2. Every chapter presents a complete course in one of the
natural divisions of drawing.

3. All problems are arranged in groups depending upon
the elements in drawing which are involved. The student may
select or the instructor may assign any one or more of several
problems in each group, depending upon student ability and
community interest. This feature of flexibility makes it easy
to adapt the course at any time to any student in a class and
to any class in a community by any one or all of three means :

(a) A selection of problems within a group.

(b) The addition of problems to any group.

PREFACE 5

4. All chapters, when completed in the order in which they
are arranged, furnish a complete course, both in the subject
of mechanical drawing and in the field of industry covered in
secondary education, in which mechanical drawing plays a part.

The course presented in this book has the following method
features :

1. A type problem showing typical conventions and solu-
tions is furnished for each group of problems.

2. Numerous dal;a problems, given in the form of freehand
sketches and finished mechanical drawings, present a standard
in technique.

3. Each division in mechanical drawing is analyzed into
its several elements which are presented in a series of well
graded, practical problems, involving essential theory and its
application.

4 Each division in drawing requires the concentration of
the student upon one thing at a time until he has a fair mastery
of both theory and practice. The next division reviews this
theory and practice in related problems.

5. Each group of problems in each division in drawing is
accompanied by explicit instruction and illuminating reading
for the student, and suggestive demonstration material for the
instructor.

6. Each chapter in the first year's course closes with a series
of review problems and review questions.

In order to cover fully the field of mechanical drawing for
secondary schools and to prepare students for commercial draw-
ing room practice in the several divisions of the subject, the
authors have given special attention in the second year of the
two-year course to such subjects as Sheet Metal Drawing, Archi-
tectural Drawing, and Machine Drawing. The student who com-
pletes the work as outlined for the first year will therefore be
able to devote his attention to any one of these subjects or to all
of them depending upon his needs. This element of latitude of
choice of subject matter makes the book particularly valuable
in schools where drafting is taught for early vocational use.

A Teacher's Manual and an Outline of the Course of
Study are furnished free to teachers using the text. The Manual

6 PREFACE

gives brief but pertinent suggestions to assist the instructor.
The Outline of the Course of Study shows clearly the plan of
the text and indicates possibilities of modifying it to meet local
conditions.

The authors wish to express their appreciation of the co-
operation of H. D. Orth, Assistant Professor of Drawing and
Descriptive Geometry, the University of Wisconsin. From the
very beginning to the end of the book, he has been a co-author
in its production.

THE AUTHORS.

TABLE OF CONTENTS

CHAPTER ONE

PAGE

PERSPECTIVE SKETCHING 9

CHAPTER TWO
ORTHOGRAPHIC SKETCHING 66

CHAPTER THREE
PENCIL MECHANICAL DRAWING 110

CHAPTER FOUR
TRACING AND BLUEPRINTING 159

CHAPTER FIVE

ADVANCED DRAWING .-...• 189

a. Sheet Metal Drawing Problems.

b. Furniture and Cabinet Drawing Problems.

c. Machine Drawing Problems.

d. "Architectural Drawing Problems.

CHAPTER SIX
ISOMETRIC AND CABINET DRAWING 305

CHAPTER SEVEN
GEOMETRICAL CONSTRUCTIONS 319

CHAPTER I

PERSPECTIVE SKETCHING
• PROSPECTUS

It is the aim of this chapter to develop in a condensed but
thorough manner the essential principles upon which perspective
sketching is based. Furthermore, the presentation is intended to
assist the student to develop a fair degree of skill in drawing
perspectives of rectangular, angular, and cylindrical objects.
Upon completion of the work of this chapter, he should be able
to draw objects composed of a combination of these elementary
forms. It is hoped that the student will have gained confidence
in his ability to visualize and represent an object pictorially. If
this has been accomplished he will find a use for perspective as
an interpretation of orthographic drawing which will be treated
in the succeeding chapters.

FIG. 1. SHADED PERSPECTIVE OF TRY-SQUARE

GENERAL PRINCIPLES

A perspective drawing of gfn object shows it as it appears
when viewed from a given position. Fig. 1 is an example of a
perspective drawing. This drawing gives the observer a correct
idea of the form and proportion of the object.

MECHANICAL DRAWING

The shading of the drawing, Fig. 1, while adding somewhat
to its appearance, does not aid greatly in giving the correct
impression of the form and proportion of the object. The shad-
ing may, therefore, be omitted, leaving the simplest kind of
drawing — the outline drawing as shown in Fig. 2. Such draw-
ings will be referred to in this course as perspective sketches.

Perspective sketches are valuable as a means of conveying
information about the forms of objects to those who are not
familiar with the more conventional means of representation
used in mechanical drawing. The student will . find the per-
spective sketch an aid in interpreting mechanical drawing.

FIG. 2. PERSPECTIVE OF TRY-SQUARE

In this course all objects to be drawn in perspective will be
represented as resting on a horizontal plane directly in front of
the observer and below the level of the eye. The try-square is
shown in Fig. 2 as an observer would see it when standing
directly in front of A B with his eye on the same level as S.

In Fig. 2 the line marked horizon represents a line in space
at an infinite distance in front of the observer. The eye of the
observer is on a level with this line and is, consequently, above
the level of the try-square, which rests on a horizontal plane.

The horizon or horizon line is therefore an imaginary horizon-
tal line on a level with the eye of the observer and at an infinite
distance in front of him. The" apparent meeting of sky and
water when one looks over a large body of water is an example of
a horizon. Since the horizon is always on a level with the eye
of the observer, it follows that, as the eye is raised or lowered to

PERSPECTIVE SKETCHING 11

secure a different view of the object, the horizon will be raised
or lowered the same distance.

Direction of Lines in Perspective. Referring again to Fig. 2,
we note that :

1. In a perspective drawing all of the vertical edges of the
object are represented by vertical lines in the perspective.
Example : Lines A B and C D.

2. In a perspective drawing all of the horizontal edges of the
object which are at right angles with the direction of sight of the
observer are represented by horizontal lines in the perspective.
Example: While not an edge of the object, the horizon line,
Fig. 2, is an example of this case.

3. In a perspective drawing all of the horizontal edges which
are parallel to each other, but not at right angles to the direction
of sight of the observer, are represented by lines which converge
to a point on the horizon. Example : Lines A C and B D.

4. Horizontal lines receding to right and left in a perspective,
which make equal angles with the horizon line, meet the horizon
line at points equally distant from the point on the line directly
in front of the observer. Example : In Fig. 2, S is a point on
the horizon line directly in front of the observer. The distance
from S to VR is equal to the distance from S to VL.

4o° Perspective. The angle between the beam and blade of
the try-square is 90°. The try-square is so placed that the angles
which the receding edges to the right and to the left make with
the horizon are equal and must therefore be 45° angles. Because
of this fact the try-square is said to be drawn in 45° perspective.

All of the rectangular objects drawn in this course will be
placed in a similar position to that of the try-square, i.e., in 45°
perspective. This will insure comparative ease in the construc-
tion of perspective sketches, as will appear later.

The points VL and VR on the horizon toward which the hori-
zontal receding edges of the try-square converge are called
vanishing points.

A vanishing point is the common intersection of two or more
converging lines which represent parallel receding edges of an
object.

All parallel horizontal receding lines must converge to the

12 MECHANICAL DRAWING

same paint on the horizon. Example : The horizontal lines of
the try-square converging to the right in its perspective meet in
VR. Likewise all the horizontal lines converging to the left meet
in VL.

Vertical Lengths in Perspective.

1. Eqnal distances on the same vertical edge of an object are
represented by equal lengths in perspective. Example : In Fig.
2 the try-square blade is represented as entering the beam mid-
way between the upper and lower surfaces. The distance from
A to the blade is equal to the distance from B to the blade.

2. Equal distances on vertical edges of an object which are at
unequal distances from the observer are represented by unequal
lengths in perspective. Example : A B and C D represent equal
lengths on the object but are unequal in the perspective.

3. Of two equal vertical distances on an object the one nearest
the observer is represented by the greater length in perspective.
Example : A B and C D which represent equal vertical lengths
on the object are both included between two lines of the drawing
which converge toward VR. On account of the convergence of the
two receding lines C D is shorter than A B.

Horizontal Lengths in Perspective.

1. Equal distances on a horizontal receding edge of an object
are represented by unequal lengths in perspective. Example :
The spaces between the lines representing the one-inch marks on
the try-square blade, Fig. 2, are unequal.

2. Of the equal distances on a horizontal receding edge of an
object, those farthest from the observer are represented by
shorter lengths. Example : In Fig. 2 the spaces between the lines
representing the one-inch marks grow shorter as they are farther
away from the observer.

3 Equal distances on a horizontal receding edge of an object
are represented by lengths which appear equal. Example : The
spaces between the lines representing the one-inch marks on the
try-square blade, Fig. 2, are made to appear equal.

PERSPECTIVE SKETCHING 13

The varying of the lengths of lines representing equal
distances on the object as described above is known as fore-
shortening.

Foreshortening is the process of shortening parts of a perspec-
tive of an object so as to give the impression of true form and
proportion.

The Cube in Perspective. Thus far only a general considera-
tion of perspective has been given. The following is an applica-
tion of the principles thus far developed to the representation of
a one-inch cube.

In this course the cube will be regarded as the "basic form for
all perspective drawing. The one-inch cube will be used as the
unit of measure and therefore it is essential that its proportions
and position with reference to the eye be well in mind. In Fig. 3
the eye of the observer is directly in front of the point S. The
vertical faces of the cube make 45° with the horizon and, also,
with the direction in which the observer is looking. This agrees
with the position of the try-square in Fig. 2 and is said to be in
45° perspective as defined on page 11. In 45° perspective the
distances from the point on the horizon directly above the nearest
point of the object to the vanishing points and to the eye must
be equal. In this course the vanishing points are taken 14" to
the right and left of the point above the nearest corner of the
object.

The edges of the cube are one inch long. The front vertical
edge of the cube will be the longest line in the perspective of the
cube (See 3 under Vertical Lengths in Perspective). It will be
drawn in its true length, one inch.

The principles already developed are applied in the follow-
ing analysis of the perspective of the cube.

Since the side faces are equally inclined to the direction in
which the observer is looking :

1. Angle D A E- angle D'A E'

2. Angle F B H- angle F'B H'.

Such angles will hereafter be referred to as the angles of
inclination.

MECHANICAL DRAWING

The perspective of the corner G is directly above A.

Due to the convergence of A D with B F and A D' with B F' :

Angles F B H and F'B H' are greater than angles DAE
and D'A E'.

TOVL

OVR

FIG. 3. PERSPECTIVE OF ONE- INCH CUBE

Lines D F and D'F' are shorter than A B. D F = D'F'. Due
to the convergence of A D with D'G and A D' with D G :

1. G D and G D' are shorter than A D and A D' ;

2. G C is shorter than C A.

Due to foreshortening:

A D and A D' are shorter than A B.

PERSPECTIVE SKETCHING

RECTANGULAR OBJECTS
PREPARATORY INSTRUCTION FOR DRAV7ING PLATE 1

The following is a list of the materials needed to make the
perspective sketches :

1. Drawing board.

2. High-grade drawing paper similar to Universal —

9"xl2" sheets.

iSH

3. High-grade pencils

4. Pencil pointer.

5. Erasers — Ruby and Flexible gray.

6. Thumb tacks.

7. A straightedge — ruler or triangle.

BORDER LINE

FIG. 4. POSITION OF SHEET ON DRAWING BOARD
\

The drawing board should be made of well-seasoned, straight-
grained, soft wood, free from knots and cracks.

When in use the drawing board should be placed on the desk
with the longer edges parallel to the front edge of the drawing
table. It may be tilted to any convenient angle.

Drawing Paper. In selecting a drawing paper the draftsman
should have in mind the purpose for which it is to be used. For

MECHANICAL DRAWING

freehand drawing, where it is desired to produce a porous, uni-
form line with a soft pencil, a slightly grained surface is satis-
factory. It should stand erasing without injury.

In preparing to make a drawing, a sheet of paper should be
tacked near the upper left hand corner of the board with the
longer edges parallel to the longer edges of the board. Fig. 4.
To fasten the sheet insert a tack in the upper left hand corner ;

CORRECT AVOID

FIG. 5. POSITION OF THUMB TACKS

square the paper with the board, and, stretching it diagonally,
insert a tack in the lower right hand corner. Insert a tack in the
upper right hand corner, stretch the sheet in the direction of the
lower left hand corner, and insert a fourth tack. Press each tack
down vertically until the head is firmly in contact with the paper.
Fig. 5.

Pencils. The lead of the drawing pencil should be of firm,
even grain. To secure the desired effect in the drawing, the
hardness of the pencil must be considered in connection with the
surface of the paper. For freehand drawing a medium soft
pencil should be used on a slightly grained surface. A soft pencil

PERSPECTIVE SKETCHING

is more easily controlled, and consequently there is more freedom
in drawing lines with it than can be secured with a hard pencil.
To sharpen the pencil, grasp it in the left hand as illustrated
in Fig. 6, and with the knife in the right hand, cut the shavings
by drawing the knife toward the body and through the wood

FIG 6. SHARPENING THE PENCIL. WHITTLING AWAY THE WOOD

FIG 7. SHARPENING THE PENCIL. POINTING THE LEAD

only. About one-quarter inch of lead should be exposed, and the
wood tapered back about one inch from the lead. Sharpen the
lead on the surface of a sandpaper pad or file, rotating the pencil
so as to produce a conical point. Fig. 7. The sharpened lead
should be slightly rounded on the end in order that soft lines as
shown in Fig. 8 may be produced. This figure also shows the
sketching pencil properly sharpened.

MECHANICAL DRAWING

The Constructive Stage. In making a freehand sketch all of
the straight lines will first be drawn very lightly with the aid of
a straightedge such as the edge of a triangle or ruler, using
the 5H pencil. Fig. 12.

1. When two points on a line are known the edge of the tri-
angle or ruler should be placed so that its edge passes through
both points. The line may then be ruled lightly.

2. Sometimes only one point on the line and its general direc-
tion will be known. In this case the edge of the rule should be
made to pass through the point with the edge adjusted to the
proper direction.

FINISHING LINt

4
NCH

MEDIUM PENCIL

CONSTRUCTION LINE

HARD PENCIL

FIG. 8. SKETCHING PENCIL PROPERLY SHARPENED

Ruling a Line. In ruling a line along a straightedge the
pencil is held in the hand as indicated in Fig. 13. The line is
drawn with a continuous motion from left to right with the tip
of the fourth finger touching the ruler to steady the hand. The
forearm should always be at right angles with the line being
drawn. The rule should preferably be between the draftsman
and the line being drawn.

The Finishing Stage. When the constructive stage has been
completed all lines which will not appear in the finished drawing
should be erased. The 3H pencil should then be properly sharp-
ened and the lines of the drawing traced over freehand. They
must be uniform in width and grayness of tone.

The Position of the Hand and Pencil in Sketching. In draw-
ing a freehand line the pencil is held firmly, but not rigidly,
between the first two fingers and the thumb as in writing.

In sketching a horizontal line the ends of the third and fourth
fingers should rest upon the board to help support and steady

PERSPECTIVE SKETCHING

the hand. Fig. 9. With the forearm resting on the drawing
board, the hand should be moved from left to right, hinging at

FIG. 9. SKETCHING A HORIZONTAL LINE

me wrist. This will permit only short strokes, about one inch
long, to be taken. To sketch a long line, therefore, one must
join together a series of one-inch lines. The position for each

FIG. 10. SKETCHING A VERTICAL LINE

stroke should be obtained by moving the hand and forearm in the
direction of the line. Each section should be joined to the pre-
ceding one, but not lapped upon it, as the lapping of sections
produces an undesirable sketchy effect.

20 MECHANICAL DRAWING

In sketching a vertical line the hand is placed in the position
shown in Fig. 10. The hand rests upon its side instead of upon
the ends of the third and fourth fingers. The pencil is moved
downward. The strokes are made with a finger movement while
the hand remains stationary. In sketching a vertical line the
forearm should remain approximately in the position of a vertical
line on the sheet.

The Border Rectangle. Before starting the drawing of the
object on the sheet, draw a border line approximately one-half
inch from each edge of the sheet. This may be done in the con-
structive stage by placing the straightedge parallel to each edge
of the sheet at a distance estimated to be one-half inch in from
the edge, and ruling a line lightly. This border rectangle should
be traced over freehand in the finishing stage as are the lines of
the sketch.

DATA FOE DRAWING PLATE 1

Given: The perspective of a cube, Fig. 11.
Required: To make a perspective sketch similar to that
shown in Fig. 11, on a 9" x 12" sheet as explained below.

Instructions:

1. Draw lightly the border rectangle J" from the edge of
the sheet.

2. To locate the perspective of the cube use the 5H pencil with
the ruler as a straightedge.

a. Draw two very light horizontal lines XVR and YZ

dividing the space between the upper and lower bor-
der lines into three equal parts.

b. Draw a vertical line, VW, through the center of the

sheet and SIT midway between VW and the left
border line.

c. From B estimate one inch up on S U, thus locating A,

the upper front corner of the cube.

3. VR is about J" from the right border line.

4. Draw lightly a horizontal line through A and connect A
with VR.

PERSPECTIVE SKETCHING

5. Get the direction of A D' by drawing the angle of inclina-
tion D'A E' equal to angle DAE. This may be accomplished by
placing the ruler so that the edge passes through point A and
adjusting its direction until the angles appear equal. Fig. 12.

6. To obtain the width of a vertical face of the cube, draw
DF so that the figure ADFB appears as a square. Fig. 13
shows the process of locating D F. A ruler or triangle is placed

FIG 11. PERSPECTIVE OF CUBE

with an edge in a vertical position parallel to the line A B. It is
then moved back and forth to right and left until, in the judg-
ment of the draftsman, the figure ADFB appears as a square.

7. Draw D'F' making AE'=AE. Complete the perspective
of the cube by drawing D'VR and D G. Fig. 11.

This completes the constructive stage.

8. All lines not shown in Fig. 11 should now be erased. The
cube and the border rectangle should be traced over freehand
with a well sharpened 3H pencil to produce a line of even weight
and uniform shade. The remaining lines of the drawing should

MECHANICAL DRAWING

be allowed to remain light, as drawn in the constructive stage.
Omit all reference letters.

9. Write the plate number and name in the lower right hand
corner of the sheet as. in Fig. 11. Remove the sheet from the
board, turn it over and, with a knife or other sharp instrument,
press the paper back into the thumb tack holes.

The Method of Developing Lettering in the Course. One of
the most difficult steps in making a drawing is the lettering of
the notes, dimensions, and title. In this course lettering will be
omitted from all drawings until the student has had considerable
practice in forming and spacing the letters and figures. This
practice will be had on small lettering plates. Each drawing
plate should be followed by the lettering plate of the same
number.

FIG. 12. SKETCHING THE ANGLES OF INCLINATION

LETTERING

Modern practice demands that the lettering done on working
drawings be simple, legible, and capable of easy and rapid ren-
dition. The simple Gothic style fulfils these requirements and
is therefore quite generally used.

Form and Proportion. A careful study of the form and
proportion of each letter must be made before the student can
hope to make any considerable progress in lettering. Practice

PERSPECTIVE SKETCHING 23

in drawing the letters will add something to his control of the
media with which he works, but first of all he must have a dis-
tinct knowledge of what he is trying to accomplish.

Strokes. For convenience in forming letters they are divided
into strokes. In most cases the strokes are natural divisions of
the outline of the letter. Three things should be remembered
about the strokes for each letter: (1) the number of strokes,
(2) the order in which they are made, (3) the direction in which
each stroke is drawn. The advantage in knowing and using a
system of strokes lies in the fact that drawing the letters repeat-
edly in the same manner makes the forming of each letter more

FIG. 13. DETERMINING THE WIDTH OF THE FACE OF THE CUBE

nearly automatic. Hence it adds to the ease with which letters
can be produced and aids in securing uniform results.

Spacing. Second only in importance to the forms of the let-
ters is their relation to each other. The best effect is obtained
when the areas included between the letters in a word appear
equal. For the capital letters the area of these spaces should
be equal to the area of a rectangle one-half the normal width
of the II. The space between words should be about three times
that between letters. Words set off by a comma should be spaced
from one to one and one-half times the usual distance. The space
between sentences should be about twice the space between words.

The final test of good spacing is legibility. The letters must
be far enough apart to avoid a crowded effect and yet the spaces
must not be so great that the letters armear scattered. In like

24 MECHANICAL DRAWING

manner words must be separated enough to stand out individ-
ually, but not enough to make reading difficult.

Lettering in Pencil. The pencil used for the freehand work
on a drawing should be softer than the pencil used for the
mechanical work. It should be of such grade that when prop-
erly sharpened a clear gray line can be produced with a single
stroke. It should not be hard enough to cut into the surface of

FIG. 14. CORRECT POSITION OP THE HAND AND PEN FOR LETTERING

the paper, as difficulty is then experienced in controlling the
direction of the line.

The lead should be sharpened to a long taper, conical in
form and rather blunt at the end. With one-quarter inch of
lead exposed, and this tapered back to the wood, the section
of the lead will be so nearly uniform near the end that it will
stand considerable use without resharpening. The pencil should
be held in the hand in the same position as the pen shown in
Fig. 14, with the forearm nearly in the direction of the vertical
stems of letters or, in the case of the inclined letters, nearly in
the direction of the slant. The strokes should be drawn with a
finger movement. The pencil should be turned about its axis

PERSPECTIVE SKETCHING 25

frequently to keep the point round so as to prodrce a line of
uniform weight. All strokes should be made with the hand held
in the same position Shifting the arm to obtain advantageous
positions for drawing strokes in different directions is a habit
which will prevent the acquirement of commercial speed and at
the same time will prevent the development of the professional
type of lettering as distinct from the labored effect produced by
the average novice.

Lettering in Ink. The beginner will find it more difficult to
produce satisfactory results with pen and ink than with the
pencil because of the complications which arise from the nature
of the media. To secure a black line of uniform weight with a
quick drying fluid such as India ink, and with an ordinary
writing pen, presents a problem which usually requires a careful
study of the methods of using these materials and considerable
intelligent practice.

The pen should be held in the hand as shown in Fig. 14.
In drawing a line the points of the pen should be side by side
so that the width of the line can be controlled by the pressure
applied to spread the nibs. The position of the pen in the hand
should not be changed for strokes of different direction, but
rather the weight of line should be kept uniform by varying the
pressure on the pen. In lettering in ink as in lettering with the
pencil, the hand should be held in the same position for all
strokes. This will give a better general effect and will make it
easier to develop commercial speed in forming the letters.

The pen should be filled by applying the quill attached to the
stopper of the ink bottle to the under side of the pen. Enough
ink should be put on the pen to last a reasonable length of time
and to produce a wet line so that when it is dry, enough carbon
will have been deposited to make it black. Overloading the pen,
on the other hand, will cause the corners to fill at intersecting
lines. The pen should be wiped frequently to remove the dry
ink from the surfaces of the pen and between the nibs. Fresh
ink and a clean pen are necessary to produce sharp clean-cut
lines.

Titles. The title contains information by which the drawing
can be identified, such as the name of the part or parts of the

MECHANICAL DRAWING

machine or structure, name of the complete machine or structure,
manufacturer's firm name and address, drawing number, date,
scale, and initials of draftsman, tracer, and checker.

The usual position of the title is in the lower right-hand
corner of the sheet where it does not interfere with the drawing
and at the same time may be read without taking the sheet from
its place in a drawer or file. The relative importance of the
items in the title is shown by varying heights and widths of the
letters or the weight of their stems, or both.

The lines should be balanced, i.e., the middle point of each
line should fall on the same vertical line. To give the best effect

Ntoli/ fionovi

FIG. 15. TITLE MATERIAL DIVIDED INTO GROUPS OF WORDS

the lines should vary in length. The general contour of the title
is very commonly oval or pyramidal in form.

The arrangement of the lines of the title and the determina-
tion of the height of each line present a problem in design for
the solution of which the contour of the title should be kept in
mind.

The space between the lines of letters for the single stroke
capitals should be from three-fourths to one and three-fourths
the height of the smallest adjacent letters.

The style of letter used for the tit/e -should be dignified. For
this reason the capital letters are generally used.

The steps in designing a title should be taken in about the
following order:

1. Assuming that the wording or at least the substance of
the title is stated, write ont the complete title and divide the
words into logical grouDs for the differpjeit lines. Fig. 15.

PERSPECTIVE SKETCHING 27

2. Rewrite, tentatively arranging the lines as they will be
in the printed title. Fig. 16.

3. Decide upon the relative importance of the lines and select
heights of letters accordingly. It may now appear that a re-
arrangement of the lines will give a better outline without affect-
ing the meaning.

i"*

V fyowlg

TlwiMA^^ i"

FIG. 16. TENTATIVE ARRANGEMENT OF LINES OF THE TITLE

4. The title may be balanced by printing each line lightly in
its proper space to obtain the spacing of the letters. Any
adjustment necessary to make the middle point of each line fall
on the center line of the title should be made. The letters should
then be drawn in full weight. This method may be used with

ANNUAL EXHIBIT

WEST DIVISION HIGH SCHOOL
DEPARTMENT OF MANUAL ARTS

MILWAUKEE WISCONSIN

FIG. 17. FINISHED TITLE

success by those who have had considerable experience in letter-
ing. The beginner will obtain better results with but little more
work by lettering the lines first on a trial sheet to get the spacing
and then by using these lines as a guide in balancing the lines
and spacing the letters on the drawing, as described on page 140.
Fig. 17 shows a balanced title.

In drafting offices or business firms where large numbers of
drawings similar in general character are made, the items com-

MECHANICAL DRAWING

mon to all titles are very often printed on the pencil drawing
with a rubber stamp and on the tracing in type. Uniformity in
treatment is thus secured and much' time in lettering is saved.
Fig. 144 illustrates commercial titles. These title forms are
printed on the under side of the tracing cloth. Errors may thus
be corrected and changes made in the lettering done by the
draftsman without erasing the printed lines and letters.

EDGE OF CARD^ = |

BORDER

'-f

FIG. 18. LETTERING CARD

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 1

The Plate. The first ten lettering plates will be in pencil.
Three by five cards of the regular drawing paper, ruled as shown
in Fig. 18, will be used.

The Lettering Pencil. Use the 3H pencil for lettering, sharp-
ened to a conical point as for freehand sketching. Fig. 8.

Number, Order, and Direction of Strokes. Each letter or
numeral is made by one or more strokes. In general, vertical
and inclined strokes are made downward and horizontal strokes

PERSPECTIVE SKETCHING

to the right. Fig. 19 shows the number, order, and direction
of strokes for the numerals 1, 4, 7, and the symbols used for
the foot, inch, and dash. The relative width of numerals is
shown in column 4.

STROKES

__.,,!

WIDTH

4-7"

FIG. 19. ORDER, NUMBER, AND DIRECTION OF STROKES

The Scale of Heights. For convenience in estimating ver-
tical distances the space between the guide lines is divided into
four equal parts. Fig. 19.

A Scale of Widths. The width of the H is taken as the unit
of width. The total letter distance is divided into four equal
parts. Horizontal distances may be estimated by observing
their relation to these divisions. Fie. 19.

30 MECHANICAL DRAWING

Drawing the Strokes. Before starting a stroke, carefully
plan its position and direction. Make each line with one move-
ment of the pencil. A vertical stroke is made by drawing a
line from one point to another directly beloiv it. In case a stroke
or letter is unsatisfactory it should be erased and redrawn.

Foot and Inch Marks. A short dash placed to the upper
right of a numeral indicates feet. Two such dashes similarly
placed indicate inches. A horizontal dash is placed between
numerals representing feet and inches. See Fig. 19.

3 1.

II II!

1 1

1 1 1

INN

111 =

444

141

144 z

777

7 7

147

I747f

7' 4 4

47'

7" 74"

17" 41'Z

~7'-

47-7"

174-4"

471-7"

714-7"

44-l"Z '

FIG. 20. LETTERING PLATE 1. 1; 4, 7
DATA FOR LETTEKING PLATE 1

Given: Plate 1 to reduced size, Fig. 20.
Bequired: To make the plate to an enlarged scale.

Instructions:

1. Fasten the card to the board either with thumb tacks or
by inserting its corners in diagonal slits cut in a larger piece
of paper which is tacked to the board. Fig. 18.

2. Draw the numerals and symbols, using the number, order,
and direction of strokes shown in Fig. 19.

3. Write in the plate number, followed by the name at the
top of the sheet as indicated in Fig, 20.

PERSPECTIVE SKETCHING 31

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 2

Plate 1, page 21, gave practice in making a perspective of
the unit of measure and basic form in perspective — the cube.
The one-inch cube will be used in the following plates as a
means of constructing and proportioning the perspective sketches
of more complex objects.

A Scale of Levels. Fig. 21 shows a horizontal square at dif-
ferent levels in perspective. At the left in Fig. 22 the horizontal
square is used as the top of a cube, represented at levels one-half
inch apart. It will be noticed that in each of these figures the

FIG. 21. VAKiAfioN CF AREA WITH LEVEL

area of the figure representing the square and the angle of
inclination increase with the distance below the level of the eye.
The distance below the level of the eye of the front corner of
each square, Fig. 22, is indicated by the numerals at the left of
the figure. In this course the student will be aided in determin-
ing the level for the perspective of an object by referring to this
scale. To the right of the scale is shown its application in repre-
senting a cube at different levels.

Vertical Measurements. Under, "Vertical Lengths in Per-
spective/ ' page 12, the general facts regarding these measure-
ments are given. In making vertical measurements in per-
spective the following rule must be observed.

All vertical distance's on an object must be measured in per-
spective on the line representing the front vertical edge of the
object. This is true for the following reasons :

MECHANICAL DRAWING

1. The front vertical edge is drawn full length. In Fig. 23,
AB is greater than the vertical line through I. To secure this
length, one would determine AB and draw the vanishing lines.

HORIZON

FIG. 22. SCALE OP LEVELS

2. In general, equal vertical distances are equal in perspective
only when measured on the same vertical edge. Example:

PERSPECTIVE SKETCHING

MECHANICAL DRAWING

Horizontal Measurements. Under, ''Horizontal Lengths in
Perspective," page 12, the general facts regarding horizontal
measurements are given. In making horizontal measurements in
perspective the following method should be used :

Whenever possible, horizontal distances on an object should
be measured in perspective by drawing the faces of a series of
receding one-inch cubes so that they appear to be squares. In
Fig. 23, lengths A D, D E, E G, G H, and H 1, representing equal
horizontal distances, are measured by making faces 1, 2, 3, 4, and
5 appear as squares.

FIG. 24. ENCLOSING SOLID

The Enclosing Solid. In using the methods of making hori-
zontal and vertical measurements given above, one of the impor-
tant steps in the construction of the perspective sketch will be
the drawing of a rectilinear solid the edges and surfaces of which,
so far as possible, are coincident with the edges and surfaces of
the object. Fig. 24. This solid will be called the enclosing solid.
This solid should be drawn completely before any attempt is
made to construct the details of the object in perspective.

The Measure Cube. The first step in drawing the enclosing
solid is to draw a one-inch cube with its upper front corner at
the level required for the perspective of the object to be drawn.
This one-inch cube will be at the upper front corner of the enclos-

PERSPECTIVE SKETCHING 85

ing solid. The front vertical edge of the cube serves as the ver-
tical unit of measure and the width of the side fac^s as the hori-
zontal unit of measure. This cube is therefore called the measure
cube.

The Table Line. When an object rests on a horizontal sur-
face its position with reference to that surface is shown by a
horizontal line called the table line. The position of this line as
shown in Fig. 27 is taken arbitrarily. In its relation to the
perspective it should represent the object as resting in a pleasing
position on a horizontal plane. The table line should be drawn
freehand.

DATA FOR DRAWING PLATE 2

•

Given: The dimensioned perspective of a sandpaper block,
Fig. 27.

Required: To make a sketch of the sandpaper block, full
size in perspective, omitting all dimensions and lettering, or any
similar problem assigned by the instructor.

Instructions:

1. Draw the border rectangle as in Plate 1, page 21. Here
and throughout the constructive stage use the 5H pencil.

2. To locate the center of the sheet proceed as follows : Place
the ruler on the sheet with one edge in the position of one of the
diagonals of the border rectangle. Rule a light, short line
through the approximate center of the sheet. In like manner
draw a part of the other diagonal. The intersecting lines will
locate the center of the sheet.

3. With the aid of the ruler draw the measure cube with its
upper front corner A at the center of the sheet and 3£" below
the level of the eye. Fig. 25. Refer to the angle of inclination
in Fig. 22 for the required level. Reproduce this angle as
illustrated in Fig. 12.

4c Complete the enclosing solid by drawing the lines in the
order indicated * by the numerals. Fig. 25. Measure vertically
ind to the right and left as previously described under, " Vertical
Measurements ' ' and, ' ' Horizontal Measurements ' ' respectively,
pages 31 and 34.

MECHANICAL DRAWING

5. To sketch the open space through the sandpaper block
which is to be occupied when the block is in use by a block of the

FIG. 25. CONSTRUCTIVE STAGE. ENCLOSING SOLID

same dimensions as the open space which holds the edges of the
sandpaper, locate B, %" below A, and draw line 10 converging

14-

FIG. 26. CONSTRUCTIVE STAGE. COMPLETE

with line 3, Fig. 26. Lay off from A on line 3 a distance repre-
^uting1 %". The principle of foreshortening applied here will
make this distance slightly greater than one-half of the width

PERSPECTIVE SKETCHING

of the face of the cube. Draw line 11. In the same manner lo-
cate and draw line 12. Draw lines 13, 14, and 15 converging
with lines 2 and 6. Draw line 16 vertically from the intersection
of lines 7 and 13. Draw line 17 converging with lines 3 and 7.
This completes the constructive stage.

6. Erase all lines except the outline of the figure and trace
over the sketch freehand with a carefully sharpened 3H pencil.
Draw a table line as in Fig. 27.

FIG. 27. SAND PAPER BLOCK

7. Write the plate number and name in the lower right hand
corner of the sheet and press the paper back into the thumb tack
holes as directed in Plate 1, page 21.

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 2

Curved Strokes. In making the curved strokes of the 5 and
the 2 the student should have in mind the form of the complete
oval.

The Dimension Form. The dimension form consists of the
numerals designating feet and inches, the foot and inch marks,
the dash, the dimension and extension lines, and the arrowheads
as arranged in Fig. 77.

It will be seen that the arrowheads are placed on the dimen-
sion lines with their points touching the extension lines. They

MECHANICAL DRAWING

are composed of two slightly curved lines symmetrical with
respect to the dimension line. The length of the arrowhead
should be about -J" and the width -f-/'. Fig. 77. Fig. 28 shows
strokes for arrowheads pointing in different directions.

STROKES

WIDTH

FIG. 28. LETTERING PLATE
DATA FOR LETTERING PLATE 2

Given: Plate 2 to reduced size, Fig. 29.
Required: To make the plate, to an enlarged scale.
Instructions: Proceed as in Plate 1, page 30, following care-
fully the number, order,, and direction of strokes.

PERSPECTIVE SKETCHING

DATA FOR EXTRA DRAWING PLATE

Given: A dimensioned perspective sketch of a clamping
plate for lathe tail-stock.

55555
22222

122-5"-

\415 545 75457=
425 5272 27527=

TTTTTTTTTr=

475- 2— >\ [—- 2'-

FIG. 29. LETTERING PLATE 2

Required: To make a sketch of the clamping plate full
size, omitting all dimensions.

FIG. 30. CLAMP FOR TAIL STOCK

The upper front corner of the enclosing solid is in the center
of the sheet and 3J" below the level of the eye.

MECHANICAL DRAWING

ANGULAR OBJECTS
PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 3

To Center a Perspective Sketch on a Sheet. For the pre-
ceding plates definite instructions have been given to center the
sketch, on the sheet. For the sake of appearance a sketch should
be centrally located. The student should use considerable care,
therefore, in locating the upper front corner of the enclosing
solid. It cannot always be located at the center of the sheet.
The following suggestions will be of value in locating the upper
front corner of the enclosing solid.

A close approximation can be made to the correct position of
the front vertical edge of the enclosing solid to right or left of
the center of the sheet by referring to Fig. 23.

FIG. 31. ENCLOSING SOLID

1. On this figure the distance to be measured to the right and
to the left of the front vertical edge of the enclosing solid may
be marked off. If the horizontal distance ^between the extreme
points is divided into two equal parts the division will come at
the point in the perspective which should be at the center of the
sheet.

2. The distance from A B, Fig. 32, to this middle point is the
distance which the front vertical edge of the enclosing solid
must be to the right or left of the center of the sheet.

In locating the upper front corner of the measure cube after
the position of the front edge is determined, the length of the
front edge of the enclosing solid and the distance of the back
corner of the upper surface above the front corner of the enclos-

PERSPECTIVE SKETCHING

ing solid must be estimated. Half the sum of these two distances
should fall above and half below the center of the sheet.

DATA FOR DRAWING PLATE 3

Given: The dimensioned perspective sketch of a cord- wind
with the upper surface 3" below the level of the eye. Fig. 33.

Required: One of the two solutions as stated below.

1. To draw the cord-wind, full size, with the upper surfaces
5" below the level of the eye. Omit all dimensions and letters
.from the finished sketch.

FIG. 32. CONSTRUCTIVE STAGE COMPLETE

2. To draw the cord-wind full size with the upper surface 5"
below the level of the eye, and turned so that the longer edges
vanish toward the left instead of toward the right.

3. To draw any similar object assigned by the instructor.

FIG. 33. CORD-WIND

Instructions:

1. Locate the upper front corner of the measure cube A as
directed under, "To Center a Perspective Sketch on a Sheet,"
page 40.

MECHANICAL DRAWING

2. Complete the enclosing solid as in Plate 2, page 35, taking
care to secure the necessary convergence. As it is the aim that
the student should learn to make perspective sketches entirely
freehand he should now draw as many as possible of the lines of
the constructive stage without the use of a straightedge.

3. To locate the lines representing the cut in the near end
of the cord-wind lay off A F and D E, Fig. 32, to represent one

FIG. 34. LETTERING PLATE

inch and H F and E I to represent one-half inch. From H and I
draw lines converging with A N and D M to the right. Lay off
A K to represent two inches and draw a line from K converging
with A D. This line meets the lines from H and I in L and TT
respectively. Connect E 0 and F L. From 0 draw a vertical
line and from P a line converging with K 0. These lines inter-
sect in Q. Draw R Q.

By a similar method make the construction for the cut at the
farther end of the cord wind.

4. Erase unnecessary lines and finish the sketch in the usual
manner.

PERSPECTIVE SKETCHING 43

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 3

Curved Strokes. The oval of the numeral 0 is the basic form
for the 6 and 9. In making the outline strokes of these numerals
the student should have in mind the form of the complete oval.

Whole Numbers and Fractions. The whole number in a
dimension will be made -J" high.

The total height of the fraction should be twice the height
of the whole number with a clear space between each numeral
and the division line. Fig. 141. To check these heights mark
off an eighth inch and a quarter inch space on the edge of a card
and use it as a scale. Fig. 78.

00000 104 520 500 214 1
66666 460 506 672 276=
99999 690 269 795 926=

:1 ' . JL £ i! 11 Q! c5 1^1 ppZ L5— •

4 ? 64 16 64 16 y2 DI6 IU2 ^^16 I6~

H 62-9^"— HH— |6-o{— H Z

FIG. 35. LETTERING PLATE 3. 0, 6, 9

DATA TOR LETTERING PLATE 3

Given: Plate 3 to reduced size. Fig. 35.
Required: To majse the plate to an enlarged scale.

MECHANICAL DRAWING

DATA TOR EXTRA DRAWING PLATE

Given: The dimensioned sketch of a wall bracket, Fig. 36,
with the upper surface of the enclosing solid 3J" below the level
of the eye.

Required: To draw the wall bracket full size, with the
surface as shown 3J" below the level of the eye, but with the
longer horizontal edges receding toward the left instead of toward
the right.

FIG. 36. WALL BRACKET

CYLINDRICAL OBJECTS
PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 4

The Vertical Measure Cylinder. As stated before, the cube
is the basic form for the perspective sketching in this course. To
secure a measure unit for cylindrical objects a cylinder is in-
scribed in a measure cube as shown in Fig. 37. The cylinder is
therefore one inch in diameter and one inch long. The principle

PERSPECTIVE SKETCHING

of foreshortening makes the axis of the cylinder and the major
axis of each of the ellipses representing its bases slightly less
than one inch. In sketching, these differences may be ignored.
In Fig. 38 these distances are one inch in length.

The following is an analysis of a cylinder which will be
referred to as the vertical measure cylinder:

1. The distance between the centers of the ellipses is equal
to their major axes or one inch. A B = C C' = D D'. Fig. 38.

2. The major axes C C' and D D' of the ellipses are at right
angles with the axis of the cylinder. These lines do not con-

IE'

FIG. 37. VERTICAL CYLINDER IN-
SCRIBED IN A MEASURE CUBE

FIG. 38. VERTICAL MEASURE
CYLINDER

verge, since they represent lines at right angles to the direction
of sight of the observer. See, "Direction of Lines in Perspec-
tive," page 11.

3. The minor axes E E' and F F' are coincident with the line
representing the axis of the cylinder.

4. Due to the difference in level of the upper and lower bases
the minor axis F F' of the lower base is greater than the minor
axis E E' of the upper base. The minor axis of the upper base
"nay be determined for any level from the scale of levels discussed
in the following paragraph.

The half length of the minor axis of the lower ellipse may be
determined by drawing F H' through D', converging with E H.

A Scale of Levels. The left half of Fig. 39 is a scale of levels
showing the upper base of a measure cylinder at levels one-half

46 MECHANICAL DRAWING

inch apart. It is evident that the area and minor axis of the
ellipse increase with the distance of the ellipse below the level of
the eye. The distance below the level of the eye of the center of

HORIZON

FIG. 39. SCALE OF LEVELS

each circle, Fig. 39, is indicated by the numerals at the left of the
figure. In this course the student will be aided in determining
the level for the perspective of a cylindrical object by referring

PERSPECTIVE SKETCHING

to this scale. To the right of the scale is shown its application in
representing a cylinder at different levels.

To Draw and Test an Ellipse Representing a One-Inch Circle.

1. Draw light indefinite lines at right angles to each other to
represent the axes of the ellipse.

FIG. 40. TESTING AN ELLIPSE

2. On the line representing the. major axis lay off on either
side of the intersection of the axes one-half the diameter of the
circle.

3. Refer to the scale of levels ; estimate and lay off the minor
axis.

4. Sketch the ellipse lightly and freely, drawing correspond-
ing parts in consecutive order, i.e., draw the long sides of the

FIG. 41. CONCENTRIC CIRCLES IN PERSPECTIVE

ellipse and then the ends. Compare the form thus secured with
the corresponding ellipse in the scale of levels. Care should be
taken to avoid sharp or blunt ends.

5. Ordinary defects in the form of the ellipse should be de-
tected by examining it as follows :

a. Turn the sheet to the right, to tne left, and upside
down, and view the form carefully when the sheet is in
each of these positions.

48 MECHANICAL DRAWING

b. Locate two points as A and B, Fig. 40, on the axis
equidistant from 0. The vertical distances from these
points to the ellipse should be equal. Compare these dis-

FIQ. 42. SPLIT CORE Box — Axis VERTICAL

tances and make the necessary corrections. x Likewise lo-
cate C and D equidistant from 0 and compare the vertical
distances from these points to the ellipse. Make the nec-
essary corrections as before.

CONCENTRIC CIRCLES IN PERSPECTIVE

The problem of drawing two concentric ellipses is more diffi-
cult than that of drawing a single ellipse.

PERSPECTIVE SKETCHING

Fig. 41 shows two concentric ellipses inscribed in concentric
squares shown in perspective. The ellipses therefore represent
circles. ' On account of foreshortening, the axes of the ellipses do
not coincide with the line representing the diameter of the circles
or with each other. In most cases the difference is so slight that
it may be ignored. For very large ellipses, however, the construc-
tion shown in Fig. 41, where the major axis of the larger ellipse is

FIG. 43. SPLIT CORE Box — Axis HORIZONTAL

slightly in front of the major axis of the smaller ellipse, must
be used.

In Figs. 42 and 43 the major axis C F is laid off equal to the
diameter of the circle, as in the case of the ellipse representing
a one-inch circle. Fig. 38. A one-inch ellipse should be drawn
first and tested. In cases where the major axes of the ellipses are
made to coincide, the half length of the minor axis of a larger or
smaller ellipse may be determined as shown in Figs. 42 and 43.
C D is drawn through C parallel to A B. In cases where the axes
do not coincide the line corresponding to C D should be made to
converge slightly with A B.

MECHANICAL DRAWING

DATA FOR DRAWING PLATE 4

Given: The dimensions ef a split core box for standard
one-inch cores, which consists of a hollow cylinder split into
halves; outside diameter 2", inside diameter V, length 3".

Required: A perspective sketch of the split core box with
its axis vertical and the upper base 3" below the level of the eye,
Fig. 42, or any similar object assigned by the instructor.

STROKES

WIDTH

Ml!"

FIG. 44. LETTERING PLATE 4

Instructions:

1. Draw through the center of the sheet a vertical line to
represent the axis of the cylinder. All lines should now be drawn
freehand.

2. Through points 1-J" above and below the center of the sheet
draw horizontal lines as the major axes of the ellipses represent-
ing the ends of the bushing. The minor axes will coincide with
the axis of the cylinder. Care should be taken to make the angle
between these axes a right angle.

3. Draw the ellipse representing the smaller circle in the
upper end of the core box at the required level. Refer to the
scale of levels tojestimate the major and minor axes of the ellipse.
Draw the ellipse with these axes and test it as described under,
"To Draw and Test an Ellipse," page 47.

4. Lay off the major axis and determine the length of the
minor axis of the larger ellipse as described under, "Concentric
Circles in Perspective," page 48.

PERSPECTIVE SKETCHING . 51

5. Only one-half of the larger ellipse representing the lower
end of the bushing will be seen. The length of the minor axis
of this ellipse may be found by the method illustrated in Fig. 42.
H G is drawn through G converging with E F. While only the
lower half of the ellipse will be needed, the complete ellipse should
be drawn as construction.

6. Complete the constructive stage of the sketch by drawing
the vertical contour elements of the cylinder which join the ends
of the major axes of the large ellipses.

7. Erase all construction lines and complete the sketch in the
usual manner.

= 88888 418- 698 785 829 =
= 33333 136 983 568 3921 =

*-*H j j n

>'-2^"— H H- I69'-0|"H JL_ JL J_:

FIG. 45. LETTERING PLATE 4. 8, 3

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 4.

The combination of ovals in the 8 serves as a basic form for
the 3. In making the curved strokes of these numerals the stu-
dent should have in mind the form of the complete oval.

DATA FOR LETTERING PLATE 4

Given: Plate 4 to reduced size. Fig. 45.
Required: To make the plate to an enlarged scale.

MECHANICAL DRAWING

DATA FOR EXTRA DRAWING PLATE

Given: The dimensions of a picture frame as shown in
Fig. 46.

Required: To draw the picture frame as though it were
lying on a table, with its upper surface 4" below the level of the
eye. At this level a portion of the bottom of the hole will be
visible.

P-Sfr

FIG. 46. PICTURE FRAME SECTION

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 6

The Horizontal Measure Cylinder. Fig. 47 shows a horizontal
cylinder inscribed in a measure cube. This cylinder is therefore
one inch in diameter and one inch long. Due to foreshortening,

FIG. 47. HORIZONTAL CYLINDER IN-
SCRIBED IN A MEASURE CUBE

FIG. 48.

HORIZONTAL MEASURE
CYLINDER

the major axis of the nearer base is slightly less than one inch,
and the axis of the cylinder is shorter than the line representing
the horizontal edge of the measure cube.

These differences are so slight that they will be disregarded
in the following analysis of the cylinder, which will hereafter be
referred to as the horizontal measure cylinder. Fig. 48.

PERSPECTIVE SKETCHING

Figs. 49 and 50 are similar to Figs. 47 and 48, respectively,
but show a horizontal cylinder at a different level, with its axis
receding to the right instead of to the left.

1. Since the axis of a horizontal cylinder in 45° perspective
always extends toward a vanishing point, the inclination of the
axis indicates the level at which the cylinder is drawn. Figs. 48
and 50.

2. The major axis of the bases are perpendicular to and the
minor -axis coincident with, the axis of the cylinder as in the
vertical measure cylinder.

FIG. 49. HORIZONTAL CYLINDER
INSCRIBED IN A MEASURE CUBE

FIG. 50. HORIZONTAL MEASURE
CYLINDER

3. The major axis of the nearer base is equal in length to the
diameter of the cylinder, or one inch. The major axis of the .far-
ther base is shorter, on account of the convergence of the contour
elements of the cylinder.

4. The distance between the centers of the bases is equal to
the horizontal receding edge of the measure cube, which is ap-
proximately three-fourths of the front vertical edge of the cube.
Since the major axis of the near base is drawn equal to the front
vertical edge of the measure cube, or one inch, the distance
between the centers of the bases may be taken as three-fourths
the length of the major axis of the near base. This ratio remains
constant for all ordinary levels.

5. It will be noticed in Figs. 48 and 50 that the minor axes
of the nearer bases are practically equal to the distance between
the centers of the bases or three-fourths of the major axis of the

54 MECHANICAL DRAWING

nearer base. When the nearer ellipse is drawn, the half length
of the minor axis of the farther ellipse may be determined by
drawing a line CD through D, converging with AB. Fig. 48.
These lines do not converge toward a point on the horizon line.

DATA FOE DRAWING PLATE 5

Given: The Split Core Box represented in Plate 4. Fig. 43.

Required: To draw the Core Box in a horizontal position
with its axis 4|" below the level of the eye, or any similar object
assigned by the instructor.

Instructions:

1. Draw through the center of the sheet a line in the direction
of one of the vanishing points, to represent the axis of the cyl-
inder at the required level. The angle of inclination may be
obtained from Fig. 22.

2. Refer to Fig. 23, estimate, and lay off three foreshortened
inches on tne axis. One-half of this length should fall on either
side of the center of the sheet to locate the drawing centrally on
the sheet.

3. Draw through the points thus determined the major axes
of the bases at right angles to the axis of the cylinder.

4. Draw the ellipse representing the nearer end of the Core
Box as shown in Fig. 43. C F is made equal in length to the
outside diameter of the Core Box, 2". D is determined by draw-
ing C D through C parallel to AB. Test each ellipse as described
under, "To Draw and Test an Ellipse," page 47.

5. From the ends of the major axis of the larger ellipse draw
contour elements converging with the axis of the cylinder to
determine the ends of the major axis of the farther base.

6. The half length of the minor axis of the farther base may
be determined as shown in Fig. 43. H G is drawn through G
converging with EF. EF and HG do not converge toward a
point on the horizon line. While only one-half of the farther
ellipse will show in the finished drawing, a better result will be
obtained by drawing the complete ellipse as construction.

7. Erase all construction lines, including the axes of the
ellipses, and finish the sketch in the usual manner.

PERSPECTIVE SKETCHING

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 5

Horizontal and Vertical Strokes. As stated under Plate 1
vertical strokes are usually made downward and horizontal
strokes to the right.

HIT

FIG. 51. SPACING OF ADJACENT VERTICAL STEMS

The direction of horizontal and vertical strokes must be exact.
The relative width of the letters is shown in column 4. Fig. 52.

STROKES

Illli

I ! Ill

— rrfrl

rfrrrr

Pic. 52. LETTERING PLATE

Spacing. In this and the following plates practice in mak-
ing individual letters will be followed by practice in making

56 MECHANICAL DRAWING

words. In order that the lettering may present a good appear-
ance, it is as important that the letters be well spaced as that
they be properly formed.

Correct spacing depends more on the judgment of the drafts-
man than on any rule which might be given. However, it may
be said that as a rule the letters should appear to be equally
spaced.

= 11111 I I I I I 1234567890 847 z
zLLLLL ILI LIL ILLI ILI LILz
zTTTTT LIT TILT TILL LIT =
zHHHHH HIT LITH THILL ITz

I HILT LITH THILL TILT HIT TILL HILL

FIG. 53. LETTERING PLATE 5. I, L, T, H

For this style of letters adjacent vertical strokes should be
a distance apart equal to one-half the width of the H. Example :
H and I, Fig. 51. Letters of irregular form should be placed
at such a distance that the space appears equal to that between
the H and I. Example : I and T, Fig. 51.

When spacing a letter the beginning of the first stroke should
be carefully located.

DATA FOR LETTERING PLATE 5

Given: Plate 5 to reduced size. Fig. 53.
Required : To make the plate to an enlarged scale.

PERSPECTIVE SKETCHING

DATA FOR EXTRA DRAWING PLATE

Given: The dimension of a picture frame as shown in
Fig. 46.

Required: To draw the picture frame as though it were
hanging flat against a vertical wall, with its center 3" below the
level of the eye.

EXTENSION OP PERSPECTIVE THEORY
PREPARATORY INSTRUCTIONS TOR EXTRA DRAWING PLATES

The Measure Cube in New Positions. In the preceding plates
the measure cube was drawn at different levels, but always with
its side faces at 45° with the horizon.

135

45°

PIG. 54. DRAWING A CUBE AT ANY ANGLE

If the measure cube is turned with its side faces making other
angles with the horizon, the number of positions in which an
object may be drawn will be increased.

Fig. 54 shows a method of constructing a measure cube at
any level and with its side faces at any desired angle. The steps
in the construction are as follows :

1. Draw an ellipse representing a two-inch circle at the
required level.

MECHANICAL DRAWING

2. Draw a semi-circle of the same diameter as the circle
represented by the ellipse, with its center at the center of the
ellipse.

3. Mark off on the semi-circle the angles which the faces of
the cube are to make with the horizon. These angles should be
90° apart.

4. Vertical lines through these points intercept the ellipse
in the ends of the nearer edges of the upper face of the cube.
These edges meet at the center of the ellipse which is the upper
front corner of the cube.

FIG. 55.

CYLINDER INSCRIBED IN A
MEASURE CUBE

FIG. 56. MEASURE CYLINDER

5. Make the front vertical edge one inch long as in 45°
perspective.

6. Complete the cube by drawing the remaining edges con-
verging so as to give the faces of the cube the appearance of
squares. It will be noted that the farther edges of the upper face
intersect on the line making 45° with each of the side faces.

The Measure Cylinder in New Positions. Fig. 55 shows a
horizontal cylinder inscribed in a measure cube with its side
faces at other than 45° to the horizon. This cylinder is there-
fore one inch in diameter and one inch long. Due to foreshort-
ening, the major axis of the nearer base is slightly less than one
inch and the axis of the cylinder is shorter than the line rep-
resenting the horizontal edge of the measure cube. These differ-
ences are so slight that they will be disregarded in the following
analysis of the measure cylinder. Fig. 56.

PERSPECTIVE SKETCHING

1. The distance between the centers of the bases is equal to
the horizontal receding edge of the measure cube. This distance
will be shorter as the angle of the axis of the cylinder to the
horizon increases.

2. The major axes of the bases are perpendicular to, and the
minor axis coincident with, the. axis of the cylinder.

3. The major axis of the nearer base is equal in length to
the diameter of the cylinder, or one inch. The major axis of
the farther base is shorter on account of the convergence of the
contour elements of the cylinder.

x.v-—

FIG. 57.

CYLINDER INSCRIBED IN A
MEASURE CUBE

FIG. 58. MEASURE CYLINDER

4. The'length of the minor axis of the nearer base will depend
upon the angle that the axis of the cylinder makes with the
horizon. Fig. 56 illustrates the case in which the minor axis is
lengthened, due to the axis of the cylinder making an angle
greater than 45° with the horizon.. Pig. 58 illustrates the case
in which the minor axis is shortened, due to the axis of the cylin-
der making an angle less than 45° with the horizon. The length
of the minor axis for other positions may be estimated by using
Figs. 56 and 58 as guides. For any angle the axis of the cylinder
makes with the horizon the length of the minor axis will remain
the same for all levels. When the nearer ellipse is drawn, the
half length of the minor axis of the farther base may be deter-
mined by drawing a line C D through D, converging with A B.
Figs. 56 and 58.

60 MECHANICAL DRAWING

DATA FOR EXTRA DRAWING PLATE
Given: The objects shown in Figs. 59, 60, 61, and 62.

FIG. 59. CONCRETE BLOCK

Required: To draw one or more of the above objects in
positions selected from the following table by the instructor.

FIG. 60. NAIL Box

The level at which the object is drawn may be assumed by the
student.

PERSPECTIVE SKETCHING

The right vertical face of the enclosing solid makes one of
the following angles with the horizon :

1. 15°. 2. 30°. 3. 60°. 4. 75°.

The objects should be centered on the sheet as in previous
problems.

FIG. 61. BROOM HOLDER

REVIEW QUESTIONS

1. (a) What is the horizon? (b) How is it represented?
(c) What is its relation to the eye?

2. (a) What is a vanishing point? (b) Where is it located?

3. Where do parallel horizontal lines appear to meet in per-
spective ?

4. Do vertical lines appear to converge in perspective ?

5. (a) What is meant by foreshortening? (b) Are the per-
spectives of equal lengths on the same vertical edge equal?
(c) On the same horizontal edge? (d) Are the perspectives of
equal vertical lengths at different distances from the observer
equal ?

6. (a) What is the angle of inclination? (b) How does it
vary?

MECHANICAL DRAWING

7. (a) In what position on the drawing board is the paper
fastened? (b) How is it fastened?

8. Describe in detail how the pencil should be sharpened for
sketching.

9. (a) What is the position of the hand and pencil in sketch-
ing horizontal lines? (b) Vertical lines? (c) What is the

FIG. 62. BIRD HOUSE (DIMENSIONED PERSPECTIVE)

essential difference? (d) What movements are made to produce
the line ?

10. (a) What is meant by constructive stage? (b) Finish-
ing stage ?

11 In what way does a scale of levels assist in making a
perspective of a rectangular object ?

12. (a) Where are all vertical measurements laid off in per-
spective? (b) Why?

PERSPECTIVE SKETCHING

13. How are horizontal measurements made ?

14. Explain what is meant by enclosing solid.

FIG. 63. BOOK BACK (DIMENSIONED PERSPECTIVE)

15. (a) What is a measure cube? (b) Why is it called a
measure cube ?

FIG. 64. FORM FOR TESTING CONCRETE PRISMS

16. Of what use is the table line 1

17. (a) How do you proceed to locate the drawing centrally
on the sheet?

64 MECHANICAL DRAWING

18. How are the perspectives of the inclined lines located?

FIG. 65. TOOTH BRUSH HACK

FIG. 6G. PEN RACK

19. (a) Give the proportions of the vertical measure cylinder,
(b) The major axes of the bases are at what angle with the axis
»of the cylinder?

PERSPECTIVE SKETCHING 65

20. How does the difference in level affect the appearance of
a horizontal circle in perspective?

21. Of what assistance is a scale of levels in drawing a vertical
cylinder?

22. How is the ratio of the minor axes of two ellipses repre-
senting concentric circles determined ?

23. (a) Give the proportions of a horizontal measure cylin-
der, (b) The major axes of the bases are at what angle with the
axis of the cylinder? (c) What is the relative length of the
major and minor axes of the nearer base ?

DATA FOR EEVIEW DRAWING PROBLEMS

^-^__
Given: The objects shown in Figs. 63, 64, 65, 66.

Required: To draw one or more of the above objects in 45°
perspective. The level at which the object is drawn may be
assumed by the student.

CHAPTER II

ORTHOGRAPHIC SKETCHING
PROSPECTUS

In this chapter the work of the preceding chapter will be
continued in order that the value of the perspective sketch as an
aid in interpreting orthographic views may be apparent. At the
same time more general application will be made of perspective
principles and additional skill acquired in representing objects
pictorially.

It is the chief aim of this chapter to familiarize the student
with the method of representation generally used in working
drawings. By the time the work of this chapter is finished the
student should be able to read drawings of ordinary complexity
as well as to make freehand orthographic sketches with a con-
siderable degree of skill and confidence.

PEEPAEATOEY INSTRUCTION FOE DEAWING PLATE 6

Views. In perspective sketching the object is viewed from
one position, so chosen as to show its three general dimensions in
one view. Such a means of representation does not show the prin-
cipal surfaces of an object in their true form and proportion or
the principal edges in their true lengths.

In order to represent the principal surfaces of an object in
their true form and proportion and the principal edges in their
true length, the object is usually viewed in two or more direc-
tions, viz. : from directly in front, directly above, or directly from
the right or left. Each view thus secured will give the exact
form and proportion of the surfaces and the true lengths of the
edges toward which one is looking perpendicularly. Views thus
secured are known as orthographic. In mechanical drawing
orthographic views are generally used.

ORTHOGRAPHIC SKETCHING

Fig. 69 shows two views of a bench stop. The view marked
TOP represents orthographically what is seen from directly
above the object and the view marked FRONT represents what is
seen from directly in front of the object. The top view shows
two general dimensions in horizontal directions, viz. : the dimen-
sion from left to right and the one from front to back. The front

FIG. 67. TYPE PROBLEM. PERSPECTIVE OF BENCH STOP

view shows the horizontal dimension from left to right and the
vertical dimension. Thus the three general dimensions are given
in the two views and the proportions of the object are determined.
Relation of Top and Front Views. It should be clear from
the above statement that, one of the general dimensions, viz.:
the horizontal dimension from left to right, is common to the
front and the top views. For this reason as a matter of con-
venience in making and interpreting the drawing it is essential
that the top view always be placed directly above the front view.

MECHANICAL DRAWING

Under this condition all distances from left to right may be
projected from one view to the other.

"Reading" the Drawing. To form a mental image of an
object the relation of its surfaces, edges, and corners as repre-
sented must be studied. This process is called reading the draw-
ing and is illustrated under the four following headings: (The
present discussion is confined to rectangular solids.)

FIG. 68. TYPE PROBLEM.

CONSTRUCTIVE STAGE OF THE ORTHOGRAPHIC
SKETCH

Plane Surfaces. Fig. 69 represents an object having plane
surfaces.

1. When the observer is looking perpendicularly at a surface
it appears in its true form and proportion. Example: The
rectangular top surface A B C D of the bench stop, Fig. 69, is
represented in its true form and proportion in the top view.

2. When the observer is looking edgewise at a plane surface
it appears as a straight line. Example : Line E F is the front
view of the top surface A B C D. Fig. 69.

ORTHOGRAPHIC SKETCHING

Straight Edges.

1. A straight edge viewed at right angles to its length shows
as a line in its true length. Example : The front edge of the
top surface of the bench stop shows in its true length in line A B
in the top view and in line E F in the front view.

2. A straight edge viewed endwise appears as a point. Exam-
ple : Point F is the front view of the edge B C. Fig. 69.

-JO

.i-E

FRONT

FIG. 69. TYPE PROBLEM. FINISHED SKETCH OF BENCH STOP

Corners. A corner appears as a point when viewed from any
direction. Example : The upper front corners at the left of the
bench stop are represented by A in the top view and E in the
front view.

Invisible Edges. Hidden edges or hidden surfaces viewed
edgewise are represented by dotted lines to distinguish them from
visible edges or surfaces. Example: GH in the top view.
Fig. 69.

MECHANICAL DRAWING

PROBLEMS AND QUESTIONS ON ORTHOGRAPHIC PRINCIPLES

The student should test his knowledge of the orthographic
principles just stated by answering the following questions:
See Fig. 70.

1. (a) Where is the front view of the horizontal surface 9,
10, 15, 16? (b) Of 10, 12, 13, 15? (c) Of 9, 11, 14, 16?

2. (a) Where is the top view of the horizontal surface 5, 4?
(b) Of 8,1?

9 10 II

TOP

FRONT

FIG. 70. REVIEW PROBLEM

3. (a) Where is the top view of the front vertical surface
1, 2, 3, 4, 5, 6, 7, 8? (b) Of the rear vertical surface 1, 2, 3,
4,5,6,7,87

4. (a) Where is the top view of the vertical surface 7, 8?
(b) Of 3, 4? (c) Of 5, 6?

5. (a) Where is the top view of the front horizontal edge
2,3? (b) Of 7, 6?

6. (a) Where is the front view of the rear horizontal edge
15,13? (b) Of 16, 14?

ORTHOGRAPHIC SKETCHING 71

7. (a) Where is the front view of the upper horizontal edge
10,15? (b) Of 12, 13?

8. (a) Where is the top view of the edge 5? (b) Of 6?

9. (a) Where is the front view of the upper front corner 12 ?
(b) Of 9? (e) Of the upper back corner 15?

10. (a) Where is the top view of the front corner 2? (b)
Of 5?

The Type Problem. In each of the following problems pre-
sented for solution the methods to be employed and the results
to be obtained will be illustrated by a type problem. This type
problem will consist of two parts :

1. A drawing of an object similar to, and represented in the
same manner as, the one given for solution.

2. A solution of the problem corresponding to that required
of the student.

Example: Fig. 69 is the type problem for the first ortho-
graphic sketch. Fig. 67 is the perspective of the bench hook
shown in Fig. 69 and corresponds to the kind of a drawing the
student will make from Fig. 71, 72, or 73.

Materials. The materials used for the plates in this chapter
are the same as those used in perspective sketching (see page
15; except that in this case the 5H pencil will be used for both
the constructive and finishing stages.

Perspective Sketches. In this chapter perspective sketches
will be drawn preceding the orthographic sketches as a means of
interpreting the orthographic views and at the same time to
continue the practice necessary to develop skill in representing
objects in perspective.

DATA FOR DRAWING PLATE 6

Given: An orthographic sketch, Fig. 71, 72, or 73.

Required: To draw a 45° perspective sketch of the object
shown in Fig. 71, 72, or 73 as assigned by the instructor, with
the upper front corner of the enclosing solid 3J" below the level
of the eye or any similar object assigned by the instructor.

p i A
= I

FIG. 71. GAIN JOINT

"^-ICJ

-*— .3"--^

~-irj

~-!N t

^ T*

,^n

&£*&

^/.Je-AwZ)**^

(72)

FIG. 72. SCOURING BOARD

ORTHOGRAPHIC SKETCHING

Instructions :

Use the corner marked A as the upper front corner of the
object. All lines of this drawing are to be made freehand, includ-
ing the light lines in the constructive stage. Omit all dimensions.

iff

-ft*-

k- d

- — Kvl

-ICM

L „ _ _,

ro
!

t ^

FIG. 73. CEMENT FERN JAR

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 6

Inclined Strokes. Before starting an inclined stroke, the stu-
dent should sense its direction, moving the pencil between its
two ends without touching the paper.

DATA FOR LETTERING PLATE 6

Given: Plate 6 to reduced size. Fig. 75.
Required: To make the plate to an enlarged scale.

MECHANICAL DRAWING

PREPAEATOEY INSTEUCTIONS FOE DEAWING PLATE 7

The Constructive Stage. This stage in orthographic sketch-
ing is similar to the constructive stage in Perspective Sketching
described on page 18. It consists of drawing all lines of the
sketch lightly and full. No attempt should be made to make
the lines exactly the right length in this stage. When drawing

STROKES

IE:

WIDTH

"inii"

FIG. 74. LETTERING PLATE

each line it should be made long enough to give all necessary
intersections with other lines.

By this time the student should have gained such facility in
drawing freehand lines that he will not need the rule to draw
straight lines.

If a straightedge is used at all in this chapter it should be
necessary only in ruling long lines in the constructive stage and
in locating one view directly opposite another.

ORTHOGRAPHIC SKETCHING 75

In laying out the views of an orthographic sketch on the sheet,
proceed in the following manner :

1. Referring to Fig. 68, mark off tentatively the position of
the extreme right and left of each view. Shift both marks to the
right or left, if necessary, to make A equal B.

2. In like manner mark off the vertical dimensions of each
view, leaving a space between the two views proportional to that
which is shown in the figure. This distance should be from J"

FFFFF LIFT FIFTH FIT IF z
EEEEE FILLET FILE TELL z
NNNNN FIN NINETEEN FIN z
MMMMM ELEMENT LIMIT z

FEET TENTH MILE NINE LIME FILM Z

FIG. 75. LETTERING PLATE 6

to V. Shift all marks up or down if necessary to make C
equal D.

3. Make any necessary adjustments in the general propor-
tions of the views.

4. In proportioning the details of the views, a comparison of
the dimensions of each detail with the dimensions of the views in
which it appears will aid in securing good results. Example:
In the front view, Fig. 69, the width of the cleats is about one-
sixth of the total length of the bench hook and their thickness is
twice that of the board to which they are fastened.

MECHANICAL DRAWING

Finishing Stage. As in Perspective Sketching, the finishing
stage consists in erasing unnecessary lines made in the construct-
ive stage, tracing over the outline of the drawing, and otherwise
giving it a finished appearance. The student should proceed as
follows :

1. Erase all construction lines and retrace the lines of the
drawing, using a 5H pencil.

2. Represent all invisible edges by dotted lines which are
composed of.-J" dashes with •£$" spaces between them. The ends
of the dashes should be made definite by placing the pencil on the

}

-J

FIG. 76. DOTTED LINES

paper, moving it the required length, and then removing it as
nearly as possible vertically from the paper. Fig. 76 shows the
correct method of joining dotted lines to full lines.

3. Place the dimensions on the sketch as described below
under, " Arrangement of Dimensions."

Arrangement of Dimensions. Dimensions are placed on a
drawing as shown in Figs. 71 and 72 to show the size of the
object represented Only those dimensions are given which are
necessary to determine completely the size of the object.

An over-all dimension is one which shows the distance from
one extreme point to another. Example : The five inch dimen-
sion in Fig. 71. A detail dimension is one which shows the dis-
tance between two points on some part or detail of the object.
Example : The three and one-half or one inch dimension. Fig. 73.

ORTHOGRAPHIC SKETCHING

When detail dimensions and a dimension representing their
sum are given, they should be grouped in parallel lines. The
shorter dimension should be near the outline of the object to avoid
the confusion arising from the crossing of lines. Example : Those
below the front view, Fig. 69, are properly arranged.

The Dimension Form. Fig. 77 shows what is known as the
dimension form. It includes all of the elements of the convention
used in indicating linear dimensions on a drawing. The following
points should be noted :

SPACE

~— |C\J

1 2

A' ^5"

\ E

8 \

\EXTENSION LINE

.DIMENSION LINE

FIG. 77. DIMENSION FORM

1. Horizontal dimensions read from left to right.

2. Vertical dimensions read from the bottom toward the top
of the sheet.

3. Extension lines begin about $V' i'rom the outline of the
object and continue J" beyond the arrowhead.

4. The space between the outline of the object and the nearest
dimension line or between two parallel consecutive dimension
lines is about 1".

5. Arrowheads are placed on the dimension lines at their
extreme ends.

6. Arrowheads are composed of two slightly curved lines sym-
metrical with respect to the dimension line. The length of the
arrowhead should be about i" and the width Ty. Fig. 77. The

78 MECHANICAL DRAWING

strokes for arrowheads pointing in different directions are shown
in Fig. 28.

7. The whole number in the dimension figure will be made
4" high.

8. The total height of the fraction in the dimension figure is
twice that of the whole number with a clear space between each
numeral and the division line.

FIG. 78. SHOWING ACTUAL HEIGHTS OF WHOLE NUMBER AND FRACTION

To check these heights of numerals in a dimension figure, mark
off an eighth-inch and a quarter-inch space on the edge of a card
and use it as a scale. Fig. 78.

9. The dimension figure is generally located centrally in the
dimension line, which is broken sufficiently to admit it.

DATA FOR DRAWING PLATE 7

Given: Orthographic sketches, Figs. 71, 72, and 73.

Required: To make an orthographic sketch of the object
shown in Fig. 71, 72, or 73 ; or any similar object as assigned by
the instructor, on a 9"x 12" sheet.

Instructions:

1. Draw a border line as in perspective sketching.

2. The rectangles shown about the drawing in Figs. 71, 72,
and 73 are proportional to the size of the 9"x 12" sheet and the
border rectangle. The over-all lengths of the view of the sketch

ORTHOGRAPHIC SKETCHING

:$:

STROKES

-v/

WIDTH

FIG. 79. LETTERING PLATE

KKKKK KILN KEEL KINK
YYYYY KEY FLY KNEEL
ZZZZZ MIZZEN ZENITH
AAAAA FALL LATHE LAY

LAZY METAL KENT KNIFE KINK KEY

FIG. 80. LETTERING PLATE 7. K, Y, Z, A

80 MECHANICAL DRAWING

should bear the same ratio to the dimensions of the sheet as the
corresponding dimensions in the figure bear to the size of the rec-
tangle representing the sheet. With this in mind proportion the
views and locate them centrally on the sheet as previously
explained.

3. Draw in the details and finish the drawing of the views
as usual.

4. Draw in the extension lines, dimension lines, arrowheads,
and numerals following the directions given under, "Arrange-
ment of Dimensions," page 76.

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 7

As stated under Plate 6, the student should sense the direc-
tion of an inclined stroke before drawing it.

The spacing between irregular letters should appear equal
to the area of one-half the H. Fig. 81.

KEY :

FIG. 81. SPACING OF IRREGULAR FORMS

DATA FOR LETTERING PLATE 7

Given: Plate 7 to reduced size. Fig. 80.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 8

It is customary to draw the top and front views of an object
when these views will show the form and proportions satisfac-
torily and when only two views are needed. Some objects are of
such a form, however, that a front view and a view from one
side are needed to determine completely the form of the object.
The particular side view is selected which will represent the
object by the use of the least number of dotted lines. Fig. 82
represents an object which would be well defined bv the nap

ORTHOGRAPHIC SKETCHING

of a front view and one side view. The right side view would
be the one chosen in this case. Since the two side views contain
the same information, if one is given the other may be drawn.
As previously explained, an observer sees all vertical dimensions
and the horizontal dimension from left to right in the front
view. All vertical dimensions and the horizontal dimensions
from front to back are seen in the side view.

A right side view is always placed directly to the right and a
left side view directly to the left of the front view. This is done
both for the sake of convenience in making and reading a draw-

LEFT SIDE.

fRONT

FIG. 82. BEVELER

RI6HT SIDE

ing and because an observer, when viewing an object, would,
after obtaining the front view, naturally step to the right for
a right side view or to the left for a left side view. To secure
the front view after the side view is drawn, or to secure the side
view after the front is drawn, all vertical distances may be
projected from the first of the two views drawn. Fig. 82 shows
the front view and the two side views of an object in their
proper relative positions.

Inclined Surfaces. Any surface which is at right angles to
the line of sight, when an object is being viewed, will show
in its true form and size. A surface which makes other than a
right angle with the line of sight is called an inclined surface.
Such surfaces do not show in their true form and size. Fig. 82
represents an object having inclined surfaces. If one surface is

MECHANICAL DRAWING

rectangular and two of its edges are at right angles to the direc-
tion in which it is inclined, as in the case of the surface C D E F,
Fig. 82, the vertical dimension of the rectangle representing the
surface in the front view is less than the actual width of the
surface.

The inclined surface C D E F is represented by the inclined
line G H in the left side view. G H is equal to the true width of
the surface. G'H', representing the same surface in the right
side view, is also equal to the true width of the surface. It must
be evident from a study of Fig. 82 that in representing any rec-
tangular inclined surface which has two of its edges at right
angles to the line of sight, the dimension represented by these

FIG. 83. CONSTRUCTION FOR ANGLES AND HIDDEN CORNERS (PERSPECTIVE)

edges will show in its true length. C D and E F, perpendicular
to the direction of sight in the front view, show the true length.
of the rectangle in this view.

The end edges, GH and G'H' of the surface C D E F, are
perpendicular to the direction of sight in the side views and
therefore show the true width of the surface in these views.

Inclined Edges. A straight edge which is not at right angles
to the direction in which it is viewed is represented by a line
shorter than the actual length of the edge. Example : The end
edges of the surface C D E F are represented in the front view,
Fig. 82, by lines C E and D F. These lines are shorter than
the actual lengths of the edges, as shown by lines GH and
G'H' in the side views.

In sketching an angle where the direction of the edge is given
by dimensions locating two points on the edge, the line represent-

ORTHOGRAPHIC SKETCHING

ing the edge should be determined by laying off the dimensions
given to locate the points on the line. Where the dimension is
given in degrees the ends of the inclined lines should be located
by estimating the lengths of the legs of the right triangle of
which the inclined line is the hypotenuse. Example : The length
of the lines A B and A C, Fig. 83, are laid off to determine the
direction of B C. For a 45° angle A B and A C represent equal
distances. For a 60° angle AB is roughly T% of AC.

In determining the position of a line passing through an
invisible corner, such as E F, Fig. 83, make a construction for
the invisible corner by drawing lines B E and E G.

The student should test his knowledge of the orthographic
principles just stated by answering the following questions:

LEFT SIDE FRONT

FIG. 84. REVIEW PROBLEM

PROBLEMS AND QUESTIONS IN ORTHOGRAPHIC PRINCIPLES
Refer to Fig. 84.

1. Where is the side view of the inclined surface 1, 2, 7, 8?

2. (a) Is line 1, 2 equal to the true width of the inclined
surface? (b) Where is its true length shown? (c) Why?

3. Where is the inclined edge 1, 8 shown in its true length ?
Why?

4. (a) Is the vertical surface 11, 15 on the front or back of
the object? (b) Why? (c) Where is it shown in the front view?

5. Where is the vertical surface 14, 13 shown in the front
view ?

84 MECHANICAL DRAWING

6. Where is the horizontal surface 13, 16 shown in the front
view?

7. Where is the horizontal surface 6, 7 shown in the side view T

8. Where is the vertical surface 4, 9 shown in the side view ?

'?— H

FRONT

RIGHT END

FIG. 85. TYPE PROBLEM. HARDIE. GIVEN VIEWS

DATA FOR DRAWING PLATE 8

Given: Orthographic sketches, Figs. 88 and 89, 90 and 91.

Required: To draw a 45° perspective sketch of the object
shown in Fig. 88, 89, 90, or 91, or any similar object as assigned
by the instructor.

The upper front corner of the enclosing solid is 2J" below
the level of the eye. Use the point marked A as the upper front
corner of the measure cube. All lines of this sketch including
the constructive stage should be made entirely freehand. Omit
all dimensions.

FIG. 86. TYPE PROBLEM. HARDIE. PERSPECTIVE SKETCH

— I(M

FIG. 87. TYPE PROBLEM. HARDIE. BEQUIRED VIEWS

(85)

A A

FIG. 88. SHEET METAL HOPPER

4- *1

-N-

(86)

FIG. 89. KNIFE AND FORK Box

-3-6"

Fia. 00. BENCH

3MC

FIG. 91. BOOK RACK

(87)

STROKES

ii:

Eli-

\ \

WIDTH

FIG. 92. LETTERING PLATE

zVVVVV VALVE LEVEL LEVEL
zWWWWW WYE WHEEL FEW
zXXXXX LYNX FIX EXTENT
zUUUUU MINIMUM MAXIMUM
= JJJJJ AJAX JAM FAULTY

(88)

Fio. 93. LETTERING PLATE 8. V, W, X, U, J

ORTHOGRAPHIC SKETCHING 89

DATA FOR LETTERING PLATE 8

Given: Plate 8 to a reduced size. Fig. 93.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 9

Dimensioning Angles. The inclination of an edge or surface
is commonly determined by giving dimensions which fix two
points on the line, usually its ends. Example : The wedge end
of the hardie. Fig. 85. In some cases it is desirable to give the
inclination of an edge or surface in degrees. In this case the
dimension line is an arc with its center at the intersection of the
two lines forming the angle. ' Example : The 45° angle in the
end of the bench. Fig. 90.

Solution of the Problem. Attention is called to the fact that
in the following "problems the student is required to draw dif-
ferent views from those given. Read the statement of the
problem carefully before starting to draw.

DATA FOR DRAWING PLATE 9

Given: Orthographic sketches, Figs. 88, 89, 90, and 91,
showing the front and left side of each of the objects.

Required: To draw the front and right side views of the
object shown in Fig. 88, 89, 90, or 91, or any similar object as
assigned by the instructor.

Instructions:

1. Block in the views of the object as described on page 75
and as carried out in Plate 7, so that they are in the center of the
sheet.

2. Complete the details of the views in light lines.

3. Trace over the lines as explained on page 76, making them
the proper weight.

4. Draw in the dimension lines and put in the arrowheads
and figures in the order given on page 77.

MECHANICAL DRAWING

5. Write in the plate number and name as usual. Press the
paper back into the tack holes.

Tdb

FIG. 94. SPACING OF CURVED FORMS

STROKES

WIDTH

Q:
b:

FIG. 95. LETTERING PLATE

PEEPAEATORY INSTRUCTIONS FOE LETTEEING PLATE 9

The letter 0 is wider than the numeral 0.

The forms of the Q, C, and G are based on the oval of the 0.

ORTHOGRAPHIC SKETCHING 91

Spacing Curved Stroke Letters. As stated in the instruc-
tions for Plate 5, the area included between the contour of two
adjacent letters should appear equal to the area of one-half of
the H. When a vertical stroke and a curved stroke are properly
spaced the clear distance between them is slightly less than one-
half the width of the H. Example: The I and 0. Fig. 94.

The clear distance between two curved strokes will be less
than that between vertical and curved strokes. Example: The
0 and 0 in Fig. 94.

zOOOOQ ONYX AVIATION | =

fOQQQQ QUAIL ANTIQUITYz

zCCCCC CHEQUE CONNECTION z

zGGGGG ENGINE GAUGE r-s^'z

zDDDDD LADLE HEAD FLOAT z

FIG. 96. LETTERING PLATE 9. 0, Q, C, G, D

When spacing a letter having a curved outline the begin-
ning of the first stroke should be carefully located. In planning
the letter, the clear space between it and the previous letter should
be held in mind.

DATA FOE LETTERING PLATE 9

Given: Plate 9 to reduced size. Fig. 96.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 10

Objects thus far sketched for which orthographic views were
drawn have had plane surfaces. In Plate 10 an object having
cylindrical surfaces is to be represented orthographically.

MECHANICAL DRAWING

Cylindrical Surfaces. In Fig. 97 an object having cylin-
drical surfaces is represented by orthographic views.

1. The outline of the front view represents cylindrical sur-
faces when viewed at right angles to their axes.

2. A simple cylinder, when viewed in this direction, appears
as a rectangle.

FIG. 97. TYPE PROBLEM. GIVEN VIEWS OF A SHAFT COUPLING

3. The straight lines representing the bases of the cylinder,
A B and C D, Fig. 97, are equal in length to the diameter of the
cylinder and represent the bases of the cylinder viewed edgewise.

4. The straight lines representing the contour elements of the
cylinder AC and BD are the elements of the cylinder which
divide the visible part of the surface from that which is invisible.
They are viewed at right angles to their direction and are there-
fore shown in their true length. See page 81 under "Inclined
Surfaces. ' '

As stated in discussing the representation of plane surfaces,
a surface viewed edgewise is represented by a line. In the case

ORTHOGRAPHIC SKETCHING

of a plane surface the line representing the surface is a straight
line.

When a cylindrical surface is viewed in the direction of its
axis the observer is looking at the surface edgewise and it there-
fore appears as a line, which in this case is a circle. Example :
EFGH, Fig. 97.

FIG. 98. TYPE PROBLEM. PERSPECTIVE OF A SHAFT COUPLING

Circular Edges.

1. A circular edge viewed at right angles to its plane shows
as a true circle. Example : E F G H in Fig. 97.

2. A circular edge viewed in the direction of its plane shows
as a straight line equal in length to the diameter of the circle.
Example : A B and C D in Fig. 97.

The student should test his knowledge of the orthographic
principles just mentioned by answering the following questions :
See Fig. 102.

1. (a) Where is the left end view of the cylindrical surface
3,4,11, 12? (b) Of 1, 2, 13, 14V

MECHANICAL DRAWING

2. Where is the front view of the cylindrical surface 25, 26,
27,28?

3. (a) Where is the circular surface 1, 16, 15, 14, shown in
the end view? (b) Where is the surface 2, 3, 12, 13 shown in
the end view?

4. (a) Where is the circular edge 6, 9 shown in the end view ?
(b) Where is the circular edge 4, 11 shown in the end view?

5. What surface would be crosshatched if a quarter section
were made cutting on the lines 0, 17 and 0, 18 ?

6. What surface would be crosshatched if a half section were
made cutting on the line 17, 19 ?

7. (a) Where is the left end view of the extreme element
3, 4? (b) 11, 12?

FIG 99. HALF SECTION. QUARTER SECTION. ILLUSTRATED IN PERSPECTIVE

DATA FOR DRAWING PLATE 10

Given: Orthographic sketches, Figs. 103 and 104.

Required: To draw a perspective sketch of the object
shown in Fig. 103, 104, or any similar object as assigned by the
instructor, with its axis vertical. The upper end of the object is
2J" below the level of the eye.

FIG. 100. TYPE PROBLEM. CONSTRUCTIVE STAGE OF THE ORTHOGRAPHIC

SKETCH

FIG. 101. TYPE PROBLEM. FINISHED SKETCH OF A SHAFT COUPLING

(95)

MECHANICAL DRAWING

i z

5 6

FIG. 102. REVIEW PROBLEM

DRILL

£><*,

FIG. 103. CYLINDER HEAD

ORTHOGRAPHIC SKETCHING

PEEPAEATORY INSTRUCTIONS FOE LETTEEING PLATE 10

The first two strokes of the P, R, and B are exactly alike.
The basic form of the S is a combination of two ovals. When
drawing the strokes of the S these ovals should be held in mind.

FIG. 104. SPRING CASING

DATA FOE LETTEEING PLATE 10

Given: Plate 10 to a reduced size. Fig. 106.
Required: To make the plate to an enlarged scale.

PEEPAEATOEY INSTEUCTIONS FOE DEAWING PLATS 11

Objects thus far drawn have been shown in their' complete
form. By referring to Fig. 97 it will be noticed that all hidden
contour elements are represented bv dotted lines. When there

MECHANICAL DRAWING

are too many of such lines they tend to confuse the reader of the
drawing.

Half Section. If an object is represented as though a portion
of it has been removed, the drawing can often be made much
clearer because of the reduction in the number of dotted lines.

STROKES

IP.

WIDTH

FIG 105. LETTERING PLATE

A common method of showing a part removed is to imagine the
object cut into two similar parts through an axis of symmetry.
Fig. 99.

The cut is made in a plane at right angles to the line of sight
and the near half of the object is imagined removed. The
observer then sees the cut surfaces of the remaining half in their
true form and proportions. The view thus obtained is called a
half section view. Example : See the front view. Fig. 101.

ORTHOGRAPHIC SKETCHING 99

It should be noticed that a part of the object is imagined re-
moved only in the drawing of one view. The end view, Fig. 101,
represents the complete object.

Quarter Section. Another common method of representing
an object is to imagine it cut on two planes at right angles to
each other in to an axis of symmetry. Fig. 99. One of the cut
surfaces is at right angles to the line of sight and the other is
parallel to it. The quarter of the object included between the

PPPPP PITCH DIAM PATCH z
RRRRR ROD RULE ARMATURE z
BBBBB BEARING BUILDER BINZ
SSSSS SCREW PISTON FOR 4 =
SCOTT & JONES z

FIG. 106. LETTERING PLATE 10

two cut surfaces is considered removed. The observer then sees
the cut surfaces in one plane in their true form and proportions,
and those in the other plane appear as a line. Fig. 101. The
view thus obtained is called a quarter section. It should be
rioted here again that a part of the object is imagined removed
only in the drawing of one view.

Crosshatching. The cut surfaces in the section view are rep-
resented conventionally by crosshatching, which consists of
drawing very fine parallel lines, equally spaced, over a surface
represented as cut. In the student problems the lines should be
drawn about -jV' apart and at an angle of 45° with the hori-
zontal. Both the distance between the lines and the angle at

100 MECHANICAL DRAWING

which they are drawn should be estimated — not measured. It is
suggested, however, that after drawing the first few lines the
student check the spacing with a scale. The angle of the cross-
hatch lines should be carefully checked in a corner where hori-
zontal and vertical boundary lines meet at right angles. When
the distances from the corner to each end of the same Crosshatch
line are equal, the angle is 45°.

Center Lines. A line which represents an axis of symmetry
is called a center line. Center lines may be straight or curved.
Of the straight lines there are two classes, principal and sec-
ondary. A principal center line is one about which the entire
view is symmetrical. Example : A C in Fig. 101. The principal
center lines should extend about -J" beyond the outline of the
view. A secondary center line is one about which only part of
the object is symmetrical. Example : E F, Fig. 101, is the center
line for the hole only. Secondary center lines should extend
about \" beyond the outline of the part of which they represent
the axes.

A circular center line usually passes through the centers of a
number of holes grouped at a certain distance from a central
point. It is not quite a complete circle. Example : See left end
view, Fig. 101.

In general, every circle in a drawing must have two center
lines at right angles with each other. Example : Lines 17, 19 and
Id, 20. Fig. 102. When one of the center lines is circular, as in
the ease of the center line for the drilled holes in the end view,
Fig. 103, the other center line is at right angles to the tangent
of the circular center line, it the center of the hole. This line
is therefore a radial line from the center of the circular center
line.

Dimensioning Cylindrical Surfaces and Circles. The diam-
eter of a cylinder may be given by placing the dimension on a
diameter of the circle representing the cylindrical surface.
Example : See Fig. 101. It may be given between extension lines
drawn from the rectangular view. Example : See Fig. 101. In
this case the dimension figures should be followed by a D or
Diam. to indicate that the dimension is a diameter. A hole to
be drilled, cored, or bored may be indicated by printing the word

ORTHOGRAPHIC SKETCHING 101

showing how it is to be obtained or finished, together with the
dimension and arrow pointing to the hole. The word and the
dimension should be placed in an open area near the hole rep-
resented. The line drawn under the word should be about -fa"
below the letters. Example : See Fig. 101.

To Sketch a Circle.

1. Through the center of the circle draw two light lines at
right angles, and on each lay off points at a distance from the
center equal to the radius of the circle.

2. Repeat this process by drawing another pair of lines which
make 45° with the first pair. In case the circle is large other
similar lines may be drawn which bisect the angles made by the
first lines.

3. Sketch in the circle through the points located on the
several lines. This should be done with great care. The first
lines drawn should be very light.

4. When the circle is complete observe its form carefully and
true it up by erasing and redrawing any portion which is untrue.

5. In the finishing stage the corrected light lines should be
traced over to produce a line of the proper weight.

DATA FOR DRAWING PLATE 11

Given: Orthographic sketches, Figs. 103 and 104, or any
similar problem selected by the instructor, showing the front and
right end views.

Required : To draw the front quarter sectior and left end
views of the objects shown in Fig. 103, 104, or any similar ob-
ject as assigned by the instructor.

Instructions:

1. Proportion the views on the plate.

2. Draw the principal center lines for the circular view.
Draw the circles in the following order: (1) The larger circles.

102 MECHANICAL DRAWING

(2) Circular center line. (3) The circles representing the small
holes.

3. To draw the rectangular view, first determine its vertical
dimensions by projecting from the end view. Complete the view.

4. Retrace the lines as in the finishing stage, giving particu-
lar attention to those affected by the section.

5. Draw in extension and dimension lines and put in the
dimensions. , Finish the sketch by crosshatching the cut surfaces.
Care should be taken to make the section lines parallel to each
other and at 45° to the horizontal.

LETTERING IN INK
PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 11

The following is a list of the materials used in making letter-
ing plates in ink.

1. Tracing Cloth, 4" x 6" sheets.

2. One of the following or any similar pen which will give
satisfactory results may be used:

303 Gillott's

404 Gillott's

XT ., J-Three of each.
Spencerian No. 1

Lady Falcon

3. Penholder.

4. Black waterproof drawing ink.

Square one of the three by five inch cards on the board and
stretch the tracing cloth over it with the dull side up. The sur-
face of the cloth should be prepared for inking by being rubbed
with chalk dust. All superfluous chalk must be removed to
prevent its clogging the pen. The guide lines for the letters
should be drawn on the cloth in pencil. When the plate is
finished a border rectangle should be drawn and the sheet
trimmed to 3"x5". Fig. 18. The space outside the cutting
lines may be used to try the pen on during the process of let-
tering the plate. A pen should be selected which will give a

OKTHOGKAPH1C SKETCHING 103

width of line suited to the height of letters to be made. The
proper width of line should be secured with but little spreading
of the nibs of the pen. Fig. 14 illustrates the position of the pen

ROUGH ROUND RODS
OHIO CORLISS ENGINE

FIG. 107. EXAMPLES OF WORD SPACING

in the hand while lettering. Note that the forearm is nearly
parallel to the vertical strokes. Vertical strokes should be made
with a finger movement. In making the horizontal and curved
strokes this movement is combined with a turn of the wrist.

Z CLAMP TENSION WEIGHING FIXED Z
Z FULL SIZE YOKE BLOCK LOCOMOTIVE Z
Z VALVE MOTION SCALE FULL SIZE Z

Z ANGLE TENSION WEIGHING FIXTURE"
: FULL SIZE CORE REAM PLATE GIRDERZ

FIG. 108. LETTERING PLATE 11

To fill the pen, place the ink on the under side by means of
the quill attached to the stopper of the bottle. The stopper
should be returned to the bottle since the ink dries rapidly.

Composition. In this and the following plates in lettering,
words will be combined into phrases and sentences. The spacing
of words plays an important part in securing a good general

104 MECHANICAL DRAWING

effect in a line of letters. The space between words should appear
equal to three times that between letters or one and one-half
times the width of the H. Adjacent vertical strokes will there-
fore be separated by a space one and one-half times the width of
the H. The clear distance between two words having vertical
strokes adjacent to a curved stroke will be less than one and
one-half times the width of the H. The clear distance between
two words having adjacent curved strokes will be still less.
Example : See Fig. 107.

DATA fOR LETTERING PLATE 11

Given: Plate 11 to reduced size. Fig. 108.

Required: To make the plate to an enlarged scale. In this
plate the wording of the titles for the first pencil mechanical
drawing plates is used. The letters are approximately the height
used in the title.

REVIEW QUESTIONS

1. (a) In what direction does one look at an object in
making its orthographic views? (b) How does this differ from
the way it is viewed in making a perspective of it?

2. (a) How many general dimensions does each orthographic
view show? (b) How many orthographic views are necessary to
show three general dimensions?

3. (a) What is the position of the top with reference to the
front view? (b) Why? (c) Which general dimension is com-
mon in the top and front views ?

4. What is meant by "Reading" a drawing?

5. (a) Under what condition does a surface appear as a line
in a view? (b) When a hidden surface is viewed edgewise how
is it represented?

6. (a) When is a plane surface snown in its true form in one
view and as a straight line in the other? (b) When is a plane
surface shown in less than its true size in one view and as a
straight line in the other?

ORTHOGRAPHIC SKETCHING 105

7. (a) When is a cylindrical' surface represented as a rec-
tangle? As a circle? (b) When is a circular surface repre-
sented as a straight line in one view and as a circle in the other ?

8. (a) When is a straight edge of an object shown in its true
length in two views? (b) When in its true length in one view
and as a point in the other? (c) When in its true length in one
view and in less than its true length in the other ?

9. How are the corners of an object represented ?

10. Describe the process of proportioning the views of an
object and locating them centrally on the sheet.

11. What are the lengths of dashes and spaces in dotted lines ?

12. (a) Illustrate by a sketch how detail and over-all dimen-
sions are grouped, (b) What space is allowed between the out-
line of the object and the nearest dimension line? (c) Between
dimension lines ?

13. (a) Where is the right side view placed with respect to
the front view? (b) Where is the left side view placed with
respect to the front view ?

14. (a) What general dimensions of an object are shown in
the right side view? (b) In the left side view?

15. What determines the choice between a right and left side
view *

16. (a) Why is an object sometimes shown with a part re-
moved? (b) Define quarter-section. Define half -section, (c) Is
the part cut by the section planes shown as removed in both
views ?

17. (a) What is the purpose of crosshatching ? (b) At what
angles are the crosshatching lines drawn ? (c) What is the usual
distance between crosshatching lines?

18. (a) What is a principal center line? (b) A secondary
center line ?

19 (a) When is a straight center line used? (b) Circular
center line ?

20. (a) How many center lines must be drawn for each
circle? (b) At what angle to each other?

21. Illustrate how the two views of a cylinder may be
dimensioned.

FIG. 109. BEARING CAP

-'I

LELFT SIDE

(106)

FIG. 110. VISE

— » —

FRONT

R1C.HT

FIG. 111. TURNING TOOL HOLDER

FIG. 112. • VALVE BONNET

(107)

103

MECHANICAL DRAWING

DATA FOE REVIEW PROBLEMS

Given: An orthographic sketch, Fig. 109.

Required: To -make the orthographic sketch shown in Fig-
109 to an enlarged scale.

Given : An orthographic sketch, Fig. 110, showing the front
dnd left side views of the object.

Required: To draw the front and right side views of the
object shown in Fig. 110.

FJG. 112A. DOVETAIL CROSS SLIDE

Given: An orthographic sketch, Fig. Ill, showing the front
and right side views of the object.

Required: To draw the front and left side views of the
object shown in Fig. 111.

Given: An orthographic sketch, Fig. 112, showing the front
and left side views of the object.

Required : To draw the front quarter section and right side
views of the object shown in Fig. 112.

ORTHOGRAPHIC SKETCHING 109

Given: Orthographic sketches, Fig. 112A, showing the
front and left side of each of the objects.

Required: To draw the front and right side views of the
object shown in Fig. 112A as assigned by the instructor.

CHAPTER in

PENCIL MECHANICAL DRAWING

PROSPECTUS

In this chapter orthographic sketching is continued. A more
general application of the principles of orthographic drawing is
made. This is done principally by introducing problems requir-
ing three views from perspective sketches. It is the chief aim
of this chapter to give considerable practice with some of the
common instruments and materials used in making mechanical
drawings and to fix a standard of technique. When the work of
this chapter is completed, the student should be able to make
neat, accurate mechanical drawings of simple objects. The tech-
nique of the lettering, arrowheads, and figures should be of a
standard comparable with that secured in the mechanical line
work.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 12

Three-view Problems. From the principles developed in
Chapter II it is evident that each view shows two of the general
dimensions of an object and therefore only two views are neces-
sary to obtain all three of the general dimensions of any object.
However, in some cases all of the general dimensions, length,
height, and thickness may be given and still the form of the ob-
ject will not be clearly defined. When this is true a third view is
necessary. A top, front, and side view are drawn with the top
above the front view and the side view to the right or left of the
front view as in the problems of Chapter II.

Example: The front and side views of the part of a Sash
Joint in Fig. 113A do not show the form of the tenon. Hence
a top view is necessary. Also, the front view is necessary to show
the notch in the tenon, and the left side view to show the bead.

As stated under Plate 8, the right and left side views, convey

110

PENCIL MECHANICAL DRAWING

111

the same information and therefore either may be drawn. The
one is usually selected which requires the fewer dotted lines.
Example: Comparing Fig. 113, A and B, the right side view is
preferable for this reason. Ordinarily the right or left side view
is (drawn opposite the front view In some cases, however, a
better arrangement will be secured by placing the side view oppo-

r-1

FIG. 113. RELATION OP FRONT, TOP, AND SIDE VIEWS

site the top view instead of opposite the front view. Fig. 113,
C and D. In this case the views are so related that horizontal
distances from front to back, which are common to the top and
side views, may be projected from one view to the other.

To relate properly the side view to the front view of an object,
attention should be given to the following conditions:

1. In all cases the side views of the front surfaces are adjacent
to the front view of the object. Example : M N and 0 P in
113 represent the side views of the front surface.

112

MECHANICAL DRAWING

2. In securing the views of an object, one should never move
the object but should himself move from the position taken in
securing a front view, viz., to the left, to secure the left side view
or to the right to secure a right side view.

The student should test his knowledge of the orthographic
principles just stated by answering the following questions:
See Fig. 114.

1. (a) Why is the top view of the object necessary ? (b) The
front view? (c) The right side view?

r-1-

i
-j

FIG. 114. REVIEW PROBLEM

2. (a) Is the right side view preferable to the left side view ?
(b) Why?

3. (a) Where is the near horizontal edge 5, 6, shown in the
top view? (b) In the front view?

4. (a) Where is the vertical surface 5, 8, shown in the front
view? (b) In the top view?

5. (a) Where is the back vertical surface 1, 2, 3, 4, shown in
the side view? (b) In the top view?

6. Draw the right side view opposite the top view.

7. Draw the left side view opposite the front view.

8. Draw the left side view opposite the top view.

PENCIL MECHANICAL DRAWING

113

FIG. 115. TYPE PROBLEM. PERSPECTIVE OF SASH JOINT

In this chapter an orthographic sketch will be required pre-
ceding each mechanical drawing. This freehand practice will

FIG. 116. TYPE PROBLEM. CONSTRUCTIVE STAGE OF PENCIL MECH. DRAWING

•„?'

-J

>>!•*

PENCIL MECHANICAL DEAWING

115

develop further skill in orthographic sketching and will make
the student familiar with the problem. As a result time will be
saved in making the mechanical drawing.

DATA FOR DRAWING PLATE 12

Given: Perspective sketches, Figs. 118, 119, and 120.

Required: To draw a three view orthographic sketch of
the object shown in Fig. 118, 119, or 120, or any similar object
with dimensions, as assigned by the instructor.

FIG. 118. MORTISE

Instructions:

1. This sketch should be drawn entirely freehand. Propor-
tions and distances should be estimated — not measured.

2. Consider the form of the object carefully and select the
views to be drawn.

. 3. Compare the over-all dimensions of each view and block in
the view by drawing a rectangle the sides of which are in the
proportions of the over-all dimensions of the object shown in this
view. Example : In Fig. 117 the over-all dimensions of the object
which are represented in the front view are 3f" and If". The
length of the sides of the rectangle are therefore drawn in the

116

MECHANICAL DRAWING

FIG. 119. MILK STOOL

Fio. 120. CONCRETE FLOWER Box

PENCIL MECHANICAL DRAWING 117

approximate ratio of 3 j :1 j=2 :1, or, in other words, the length
of the rectangle is twice its width. The length of the top view
is equal to the length of the front view. Its width is about
one-fourth of its length. The height of the side view is equal to
that of the front view. Its width is about one-half of its height.
4. The distances from the views to the border line above and
below the views should be equal and the distances from the views
to the border lines at the right and left should be equal. Use the
same principle for placing the views as given for the problems
of Chapter II, page 81.

z FOUNDATION WASHER COREZ

Z ENGINE BED SCALE FULL SIZE BACK Z
Z REST 24 TURRET LATHE SCALED"

z JOURNAL BEARING ELECTRICZ

'RAILWAY MOTOR CAR SCALE HALF SIZE!

FIG 121. LETTERING PLATE 12

5. When the rectangles are properly located, sketch in lightly
the details of each view, proportioning them by eye.

6. Complete the views by retracing the lines.

7. With the advice and suggestions of the instructor, select
the necessary dimensions and then draw extension and dimen-
sion lines, arrowheads, and figures.

DATA FOR LETTERING PLATE 12

Given: Plate 12 to reduced size. Fig. 121.
Required: To make the plate to an enlarged scale.

118 MECHANICAL DRAWING

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 13

The following is a list of materials needed in making the
pencil mechanical drawing in this chapter :

1. Drawing board.

2. High-grade paper similar to Duplex or Cream, 11" x 15"
sheets.

3. T-square.

4. 30°-60° and 45° triangles.

5. High-grade 5H pencil.

6. Scale.

7. Bow compass.

8. 4H compass lead.

9. Pencil pointer.

10. Eraser.

11. Erasing shield.

The Drawing Board. The best boards are designed to pre-
vent warping, various means being used to accomplish this end.
Some are built of narrow strips glued together; others have a
series of saw cuts running lengthwise with the grain to reduce
the transverse strength. Fig. 122. Such boards are made rigid
by cleats of hard wood screwed through oblong slots fitted with
metal bushings to the back of the board. This construction
allows the board to expand and contract, the screws sliding in
the slots.

For accurate work it is necessary that the edge of the board
against which the head of the T-square is placed be perfectly
straight and that the face of the board lie in a plane. To test
the edges of the board, place on each a standard straightedge
or the edge of a T-square blade which is known to be straight.
An edge of the board is straight if, when held up to the light,
the straightedge is in contact at all points.

The surface of the board may be tested in like manner by
placing the straightedge upon it in various positions.

The edges and surface of the board should be kept free from
cuts, scratches, and bruises. The board should not be subjected
to extremes of temperature or moisture.

FE1STCIL MECHANICAL DKAWING

119

Drawing Paper. For mechanical drawing, where a sharp,
fine line is to be produced with a hard pencil, a tough, hard paper
should be used. It should stand considerable erasing without
injury to the surface. It should not become brittle or discolored
from reasonable exposure or age. If freehand lettering is to be
done the surface must be reasonably smooth to secure the best
results. If considerable time is to be spent on a drawing, a

FIG. 122. DRAWING BOARDS

paper should be selected which has an agreeable tint and which
will not soil easily with handling. The paper used for the
mechanical drawings of this course must fulfil these requirements.

The drawing paper should be fastened to the board in the
upper left corner of the board as for sketching. After inserting
the first tack, make the upper edge of the sheet horizontal by
means of the T-square ; stretch the sheet and insert the remaining
thumb tacks in the usual manner.

The T-square is used to draw horizontal lines and to provide
an edge against which the triangles are placed. It consists of a

120 MECHANICAL DRAWING

rule called the blade, attached to one end of which is a cross-
piece called the head. Fig. 123. The head is sometimes fastened
to the blade by means of a swivel, so that the blade may be set
at any desired angle.

T-squares are made of steel, hard rubber, and wood. The
steel blade is the most accurate but tends to soil the drawing.
For ordinary work wooden blades are preferable. They are
usually made of maple, mahogany, or pearwood, and their edges
are often lined with hardwood or celluloid.

FIG. 123. T-SQUARE. PLAIN AND SWIVEL, HEAD

The celluloid edges make it possible to see lines near the one
to be drawn and are therefore quite convenient when joining
lines at corners, etc.

The upper or working edge of tht T-square and the edge of
the head which rests against the drawing should be perfectly
straight. The edge of the blade may be tested as follows :

1. Draw a long line along the edge of the blade.

2. Reverse the ends of the blade with respect to the ruled line,
keeping the same side up and bringing the same edge against the
ruled line.

3. Draw a second line along the edge of the blade. If the
edge of the blade is straight the two lines will coincide. Both
the head and the blade of the T-square may also be tested by
means of a straightedge. Since the T-square is used only for
ruling parallel lines, and as lines at other angles are drawn with
the triangles in combination with the T-square, it is evident that
the accuracy of the angles beween lines drawn with the T-square

PENCIL MECHANICAL DRAWING

121

and those drawn with the triangles does not depend upon the
angle of the blade to the head of the T-square. It is not neces-
sary, therefore, that the edge of the head and blade be exactly
at an angle of 90° to each other.

Care should be taken to preserve the upper edge of the blade
of the T-square from injury. It should never be used as a guide
for the knife in cutting paper. When using the T-square the
head is pressed firmly against the edge of the board with the left

FIG. 124. EULING A HORIZONTAL LINE

hand as shown in Fig. 124. The lines are always drawn along
its upper edge.

The triangles are used in combination with the T-square for
drawing lines at certain angles to the horizontal. They are used
in combination with each other for drawing lines at various
angles with lines which are not horizontal.

Triangles are made of steel, wood, hard rubber, or celluloid.
Steel triangles are used for the most accurate work. Triangles
made of wood are easily injured and are likely to change their
shape. Those made of celluloid have the advantage of being
transparent and are more generally used. For accurate work it
is necessary that the edges of the triangles be straight and that

122

MECHANICAL DRAWING

the angles be true. The edge may be tested by the method given
for testing the T-square.

Assuming that the edge of the T-square has been found to be
straight, the 90° angle of a triangle may be tested as follows :

1. Place the triangle in position D, as shown in Fig. 126, and
draw the line AB.

FIG. 125. EULING A VERTICAL LINE

2. If when the triangle is turned over into position C, the
vertical edge coincides with the line A B, the angle is 90°

3. When the 90° angle of the 45° triangle has been found
true, the 45° angles are true if equal.

Compare the two 45° angles as follows, Fig. 127 :

1. Place the triangle against the T-square and draw a 45°
line.

2. Turn the triangle over so that the other 45° angle comes
into the position previously occupied by the first. If the edges
of the triangle coincide with the line drawn, the 45° angles are
equal.

The 60° angle of a 30°-60° triangle may be tested as follows:

1. Draw a horizontal line, A B, along the T-square. Fig. 128.

2. Draw a 60 6 line, B C, along the edge of the triangle cross-
ing the horizontal line.

3. Turn the triangle over and draw a second 60° line. AC.

PENCIL MECHANICAL DRAWING

123

completing a triangle. If the triangle formed is equilateral, the
60° angle is true.

The lengths of the sides of the triangle may be compared by
means of the dividers. When the edges are straight and the 90°

FIG. 126. TESTING THE 90° ANGLE

O O
O O

FIG. 127. TESTING THE 45° ANGLE
FIG. 128. TESTING THE 30° AND 60° ANGLES

and 60° angles are found to be true, the remaining angle, 30°,
will also be true.

124 MECHANICAL DRAWING

With the 30°-60° triangle, lines may be drawn at 90° to the

FIG. 129. LINES DRAWN

WITH THE 30°, 60°

TRIANGLE

FIG. 130. LINES DRAWN
WITH THE 45° TRIANGLE

FIG. 131. LINES DRAWN WITH A COMBINATION OF THE 30°, 60° AND 45"

TRIANGLE

horizontal and at 30° or 60° with the horizontal to the right and
to the left. Fig. 129. With the 45° triangle, lines may be drawn

PENCIL MECHANICAL DRAWING

125

at 90° to the horizontal and at 45° with the horizontal to the right
or to the left. Fig. 130.

By combining the two triangles, lines may be drawn at 15°
or 75° with the horizontal to the right and to the left. Fig. 131.

Lines parallel to any given line may be drawn by placing the
two triangles in contact and sliding them as one tool until an
edge of one coincides with the given line. Fig. 132. With
triangle A held firmly in place, triangle B may be moved along
it and lines drawn parallel to the given line.

FIG. 132. LINES DRAWN PARALLEL OR PERPENDICULAR TO ANY GIVEN LINK

Lines perpendicular to the given line may be drawn along
the edge of triangle B which is at 90° to the given line.

The direction in which lines should be drawn along the
triangles is shown in Figs. 129 and 130. The forearm should
always make a right angle with the line being drawn.

The edges of the triangles should not be cut or bruised. If
they are allowed to fall on the floor a corner may be blunted and
as a result the angle will not be true. The celluloid triangles
should not be allowed to remain bent for any length of time,
as they will remain permanently so.

Pencils. For mechanical drawing where it is desired to pro-
duce fine sharp lines, a hard pencil should be used on a compara-
tively smooth, hard surfaced paper. The pencil should not be
sharp enough or used with enough pressure to crease the paper.

The 5H pencil should be used for drawing lines mechanically.

126

MECHANICAL DRAWING

For convenience in using the pencil for different purposes, it
should be sharpened at both ends. One end is used for ruling
lines and the other for laying off measurements. The ruling
point is obtained by cutting away the wood to expose about J"
of lead and by rubbing opposite sides of the lead on a sandpaper
pad or file to produce a wedge-shaped point. Fig. 133. This
point is used for ruling continuous lines. The measuring point
is similar to the conical point used in sketching except that the
point is sharper in order that very accurate measurements may
be laid off with it. It is used both for measuring and making
dotted lines.

To insure accuracy in laying off measurements from the scale,
the eye should be directly above the division on the scale from

RULING POINT

MEASURING POINT

FIG. 133. EULING AND MEASURING JOINTS OF THE MECHANICAL DRAWING

PENCIL

which the dimension is to be laid off. Care should be taken to
place the point of the pencil on the paper exactly opposite the
mark on the scale. The pencil should be revolved upon its axis
while in this position without pressing the lead into the paper.
The mark left by the pencil should be a small, round dot just
visible to the eye.

Ruling Horizontal Lines. In ruling horizontal lines the posi-
tion of the hand is the same as for sketching horizontal lines.
In this case, however, the pencil is held leaning slightly forward
with the point in the position shown in Fig. 124. The line is
drawn with a continuous motion to the right with the tip of the
fourth finger touching the T-square to steady the hand. Fig. 124.
The forearm should always be at right angles to the line being
drawn.

Vertical Lines are drawn along the edge of a triangle which
is set against the T-square as shown in Fig. 125. Note that the

PENCIL MECHANICAL DRAWING 127

triangle is to the right of the line. The line should be drawn
away from the T-square with the hand and arm in the same
relative position to the line being drawn as for horizontal lines.
Scales are used for taking measurements and laying off dis-
tances. They are made of paper, steel, and wood. Ordinarily
scales are made of boxwood. There are two general forms, the
flat and the triangular. The flat scale may have from one to four
graduated faces and the triangular scale from four to six gradu-
ated faces. The graduations are placed directly on the wooden
face of the scale or the face is coated with a white compound
which makes the graduation easier to read.

0369

FIG. 134. HEADING THE ARCHITECT'S SCALE

The faces of the scales are graduated as follows:

The Engineer's Scale is divided to 10, 20, 30, 40, 50, and 60
parts to the inch. It is full divided, i. e., the small divisions are
marked off for the full length of the face. -

The Architect's Scale is divided to &, JL, ^ i} a i; . j, i; i^
and 3 inches to the foot. The edges on this scale are open di-
vided, i. e., only the portion of the face representing one foot
is subdivided to read in smaller units. One face of the scale is
usually divided into TV' f°r its full length.

To illustrate the reading of the architect's scale, consider the
edge designated by a figure 1 at the end. Fig. 134. This indi-
cates that one inch on this scale represents one foot. The inch
to the right of the 0 at the right end of the scale is divided into
forty-eight equal parts so that each of the smaller divisions rep-
resents \" and the spaces between the 0, 3, 6, and 9 represent 3"
each. To the left of the 0, the readings 1, 2, etc., are inches, and
therefore represent feet. To measure off 2' — 4£" to the right of
point X, place the 2 opposite the point and read four and one-
half inches to the right past the 0. In case it is desired to lay off

128 MECHANICAL DRAWING

this distance to the left of Y, place the four and one-half inch
mark opposite Y and read past the 0 to the 2.

The Proportional Inch Scale is divided to read one-half or
one-fourth inch to the inch and has one face divided to -fa" for
its full length. The open divided edges are read in the same
manner as the architect's scale. The difference is that in this
case the large divisions represent inches instead of feet. One of
the large divisions is subdivided to read sixteenths.

Drawing Instruments. In beginning mechanical drawing it
is important that the student have a good set of instruments. It
is difficult to define a "good" set of instruments, for the better
grades are extensively imitated. The student should be guided
in his selection either by some experienced draftsman or by the
trademark and the price charged by a reliable dealer.

A good set of instruments differs from a poor one, mainly,
in the quality of materials used, correct tempering, and good
workmanship. The steel of the pens must be properly tempered
so that when once sharpened the points will remain in good con-
dition for a reasonable time. The compass and dividers must be
so made that they will retain their alignment and adjustment
when handled with ordinary care. These qualities can only be
definitely determined after the instruments have been given a
fair trial.

To secure uniformly satisfactory results in drawing it is
necessary to start with a good set of instruments and to keep
them in good condition.

The Compass is used for drawing circles and arcs of circles.
Fig. 135. The better grades are made of German silver. It is
important that a compass be light yet rigid. The most impor-
tant part of the compass is the head which, in the modern instru-
ments, consists of two discs held in contact in a fork by means
of pivot screws. By adjusting these screws the pressure between
the discs is regulated. This pressure should be such that the
legs of the compass may be opened or closed without springing
them. On the other hand, the joint should be tight enough to
retain the setting when the instrument is in use.

The thing of next importance is the socket joint of the remov-
able pen and pencil parts. These are made in various forms.

PENCIL MECHANICAL DRAWING 129

They usually consist of a shank on the pen and pencil parts
which fits into a corresponding socket in the compass leg. The
proper position of the shank in the socket is insured by some
device such as a feather or sharp corner on the shank which is
matched by a corresponding slit or groove in the socket. These
parts are made to clamp together with a thumb screw or else a
bayonet fitting is used.

FIG. 135. DRAWING A CIRCLE WITH THE COMPASS

The legs of the compass should move in the same plane. To
test the compass for alignment:

1. Place the parts in the sockets.

2. Bend the legs out at the head, and

3. Bring the joints together, as shown in Fig. 136. If the
points are exactly together the joints are true.

Before using a compass, the needle point and lead should be
adjusted as follows:

1. Place the pen in the compass and adjust the needle point
so that it projects slightly beyond the nibs of the pen.

2. Remove the pen.

3. Replace the pencil and adjust the head so that it is slightly
shorter than the needle point. The pen and pencil parts are
now interchangeable without adjusting the needle point.

130

MECHANICAL DRAWING

In using the compass proceed in the following manner :

1. Place a 4H lead in the compass and sharpen it to a narrow
wedge, in width about one-half the diameter of the lead.

2. Set the lead so that it projects about one-half the length
of the needle point beyond the shoulder.

3. Draw the center lines of the circle to be drawn at right
angles and lay off the radius on one of them.

FIG. 136. TESTING THE COMPASS

4. Grasp the compass by the handle between the thumb and
first finger of the right hand. Care should be taken to place the
needle point exactly at the intersection of the center lines.

5. Adjust the lead to the exact radius and draw the circle,
rolling the handle of the compass between the thumb and finger.

The large compass should not be used for circles of less than
f " radius. For very large circles the lengthening bar should be
inserted between the leg of the compass and the pen or pencil
point. When this does not suffice a beam compass should be used.

Dividers are similar to compasses in general appearance. The
legs terminate in sharp steel points. The dividers are used for
laying off distances from the scale, for transferring lengths, or
for dividing straight or curved lines into any number of equal
parts.

PENCIL MECHANICAL DRAWING

131

To divide a line into any number of equal parts with the
dividers, proceed as follows: (Assume that the line is to be
divided into three equal parts.)

1. Open the dividers to what is estimated to be one-third the
length of the line.

2. Step off the estimated distance three times on the line.

FIG. 137. STEPPING OFF WITH THE DIVIDERS

3. Adjust the dividers to one-third the error making the dis-
tance between the points larger or smaller as the case may
require.

4. Repeat the process until the third step ends exactly at the
end of the line. In taking the steps the dividers are held by the
handle between the thumb and first finger and swung alternately
first to one side of the line and then the other as shown in
Fig. 137. This avoids rolling the handle in an awkward position
between the thumb and finger.

132 MECHANICAL DRAWING

The Bow Pen, Bow Pencil, and Bow Dividers. The bow pen
and bow pencil are used to describe small circles, and the bow
dividers to lay off small distances. They have the advantage over
the larger instruments that they retain their adjustment. There
are two forms of adjusting devices, as shown in Fig. 138. To
make large adjustments in the instruments having side screws the
pressure on the nut should be relieved by pressing the legs to-
gether with the left hand while the nut is made to spin with the
first finger of the right hand.

FIG. 138. CENTER AND SIDE SCREW ADJUSTMENT OF Bow INSTRUMENTS

The bow compass should be used in the same manner as the
large compass, as described on page 129.

The Eraser. Ordinarily a medium hard eraser such as the
ruby is used for removing pencil lines from a drawing. A soft
flexible eraser is very satisfactory for cleaning a pencil drawing
without erasing the lines. When erasing lines the paper near the
lines to be erased should be held down with the thumb and first
finger of the left hand to prevent it from crumpling.

The Erasing Shield is used to protect the parts of the draw-
ing which are not to be erased. The opening in the shield is
selected which is best suited to expose only the parts to be erased.
The shield is held in position on the drawing with the thumb and

PENCIL MECHANICAL DRAWING 133

first finger of the left hand, while the eraser is applied with the
right. Fig. 139,

STEPS IN MAKING A MECHANICAL DRAWING

The Border Rectangle. To draw the border rectangle, proceed
as follows :

1 Lay off y from the upper and left hand edge of the sheet.

2. Through the points thus located draw the upper and left
hand sides of the border rectangle.

FIG. 139. USING THE ERASER AND SHIELD

3. On these lines, and from their intersection, lay off 14" to
the right and 10" downward.

4. Through the points thus found draw the remaining sides
of the border rectangle.

The Enclosing Rectangle. In mechanical drawing the views
are located centrally by calculating the position of a rectangle
in which they may be inscribed. In this course the distance
between views should not be less than f " or more than 1". The
student's calculation should be made as indicated in Fig. 140.

Accuracy. It is of prime importance that a mechanical draw-
ing be accurate. Accuracy depends both on the quality and con-
dition of the instruments and materials and upon the skill of
the draftsman. All straightedges, angles, etc., should be tested
as just described. When the tools are found to be in good con-
dition the draftsman should take great care to lay off measure*

*-&ordert.j

h
X

PENCIL MECHANICAL DRAWING

merits accurately, and draw the lines exactly through the poinL
located. It is always well to place the point of the pencil in the
located point, bring the straightedge up to the pencil, and then
draw the line, being careful to maintain the same relationship
throughout between the pencil and the straightedge.

Errors multiply with the number of operations involved,
hence, other things being equal, the most direct construction is
the most accurate one.

Constructive Stage. In this stage all measurements are laid
off and lines drawn lightly and of indefinite length. This is what
is sometimes known as the blocking-in stage. When using the
scale make as many measurements as possible. Whenever prac-
ticable, consecutive measurements should be laid off with the
scale in one position. Be as systematic as possible in making
measurements and in using the T-square and triangles. It is a
good plan to draw as many of the horizontal lines as may be
drawn at one time, beginning at the top and moving the T-square
downward. In like manner draw vertical lines, several at a time,
moving the triangle from left to right. The lines should be
drawn long enough so that there will be no need to extend them.

No distinction is made between visible and invisible edges in
this stage. Fig. 116.

Finishing Stage. In this stage the drawing is completed as it
will finally appear. First, erase all lines not needed in the fin-
ished drawing and, second, retrace all required lines with a care-
fully sharpened 5H pencil. All finished lines must be of uniform
width and shade. They must be ended at the proper points.
The lines 'should be drawn in the following order:

1. Horizontal lines beginning at the top of the sheet.

2. Vertical lines beginning at the left of the sheet.

The hidden edges of the object should now be represented
by so-called dotted lines, which in reality are lines made up of
short dashes and spaces. The dashes are -J" long, separated by
sV spaces. Fig. 76. The end of each dash can be made distinct
by keeping the end of the pencil in contact with the paper until
the end of the line is reached. The pencil should be placed upon
the paper, drawn J" on the paper, stopped, and then raised in
making each dash.

136 MECHANICAL DRAWING

Dimensioning. The draftsman's judgment is used more in
dimensioning than in any other part of the drawing. To avoid
mistakes and to facilitate the work of the mechanic, only neces-
sary dimensions should be given. They should be placed in such
a way as to make the drawing easily read. Cases are rare where
it is advisable to repeat the same dimensions on different views.
Repeating dimensions adds to the difficulty in checking them and
when changes are made there is a possibility of making a change
in one place and not in another. This leads to confusion. Plac-
ing dimensions in obscure and out of the way places should be
avoided. "Whenever possible, dimensions should be grouped in
such a way as to make their relation obvious. It should not be
necessary for the mechanic to do any calculating to obtain
necessary dimensions.

No doubt, the best guide to follow, in placing dimensions on
a drawing, is for the draftsman to imagine himself in the me-,
chanic 's place and to consider the operations through which the
object must go to become a finished product. With this idea in
mind most problems in dimensioning will be solved without diffi-
culty. For example, when a machinist drills a hole he sets the
point of the drill at its center ; hence the hole should be dimen-
sioned by referring its center to some surface, line, or point easily
accessible.

In ordinary working drawings, dimensions are usually given
in inches up to twenty-four inches. Above twenty-four inches
they should be given in feet and inches. Examples : 23J", 2'-4J".

For all ordinary work, fractions in dimensions containing
mixed numbers have the following denominators : 2, 4, 8, 16, 32,
64 ; such denominators as 6 or 19 are not used. When very small
fractions of an inch are necessary, as in the case of special fits,
etc., the fractional part of an inch may be expressed in decimals
of three or four places. Example : 5.006" bore.

Extension and Dimension Lines. The extension lines and
dimension lines should be drawn in the order suggested for the
finishing stage of the pencil drawing, i.e., draw all horizontal
lines beginning at the top and moving downward, then draw all
vertical lines beginning at the left and moving toward the right.
As in orthographic sketching, the extension lines should begin

PENCIL MECHANICAL DRAWING 137

about sV" from the outline of the object and continue -J" beyond
the arrowheads. The space between the outline of the object and
the nearest dimension line, or between two parallel consecutive
dimension lines, should be about J". Th3 extension and dimen-
sion lines in pencil should be of the same width and shade, as the

PIG. 141. SHOWING ACTUAL HEIGHTS OF WHOLE NUMBER AND FRACTION

object lines. Center lines may be used as extension lines, but
not as dimension lines.

The Dimension Figures and Notes. If a drawing is to present
a neat appearance, a suitable type of letter and figure should be
used for all notes and dimensions. A very plain letter should be
selected; one that can be drawn with reasonable rapidity and
that will be in harmony with the remainder of the drawing. It
is essential that a standard height be adopted and adhered to for
all notes and figures on the drawing. For this course the stand-
ard height for the whole number is y and the total height of the
fraction J" as shown in Fig. 141. Whenever possible, notes
should be lettered on horizontal guide lines. The letters should
be 5y high. To insure uniform heights for all notes the distance
between the ruled guide lines should be accurately laid off with
the scale or stepped off with the dividers.

As nearly as possible, place the dimension figures in the cen-
ter of the dimension line, leaving a convenient free space for the
figures. Whenever a center line interferes with the dimension
figures, place it near the center line and either to the right or
left of it. In the case of consecutive parallel dimension lines
where the dimension figure in one line would naturally interfere
with the dimension figure in the other dimension line, the dimen-
sion figures should be ' * staggered ' ' ; that is, one dimension figure
should be placed a little to the right and the other to the left of
the center of the dimension line, so that they will not interfere.
Example: Fig. 147.

138

MECHANICAL DRAWING

Information which the dimensioned drawing does not make
clear is put into the form of notes. They usually relate to mate-
rials, finish, number of parts needed, etc. Example : See note
below the view. Fig. 156.

The Title. The views of an object with their dimensions and
notes do not convey all of the necessary information. A title
which supplies the deficiency is therefore added. The title is

M«

NAME

OF OBJECT REPRESENTED

'-I*

PLATE! FILING (STUDENTS! ^rAi F

N'UMBER|NUMBER|lNITIAL5| DCALE.

"n^-4-

!_ »^ l|" ^

FIG. 142. DIMENSION AND POSITION OF ITEMS IN TITLE BLOCK

usually placed in the lower right-hand corner of the sheet so that
it will be easily accessible when the drawing is filed.

-t

/tl TAIL STOCK _^-& J
r-= rf^-i .,

\^Z 12" SPElEp LATHE

I 256I'

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FIG. 143. SHOWING METHOD OF BALANCING THE LINES ix THE TITLE

Various elements may enter into the title, depending upon
the character of the drawing and the use to be made of it. The
following items are usually found in the titles of commercial
drawings of machines or structures:

PENCIL MECHANICAL DRAWING

1. Name of part or parts of machine or structure.

2. Name of complete machine or structure.

3. Manufacturer's firm name and address.

4. Drawing number.

5. Date of finishing drawings.

6. Scale to which drawing is made.

7. Initials of draftsman, tracer, and checker.

139

- |

NOTICE TO SHOP

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FIG. 144. COMMERCIAL TITLES

The titles of the plates given in this chapter will be much
simpler than the ordinary commercial title. Figs. 142 and 143
show two forms of title suitable for this course. The words for
each title in this chapter will be given below the figure from
which the drawing is made.

The relative importance of the items of a title is shown by
the varying heights or weight, or both, of the letters. In some

140 MECHANICAL DRAWING

drafting offices a rubber stamp is used on the pencil drawing to
obtain the words and lines that are common to all drawings. The
same words and lines are often printed on the tracing cloth in
type. Example : Fig. 144. The style of letter used should be
plain and dignified, whether printed in type or drawn freehand.

The Title Block. The title for each mechanical drawing plate
in this course will be placed in a title "block. The dimensions for
this block with the names and position of the items are shown in
Fig. 143. The height of the letters and spaces between lines of
letters are shown in Fig. 143.

Balancing a Title. It is essential to the appearance of a title
that the lines be symmetrical with respect to a vertical center
line. Example : Fig. 143 shows a title properly balanced.

To balance the title proceed as follows:

1. Tack a piece of drawing paper to the board opposite the
lower right hand corner of the sheet. Fig. 143. This will be
referred to as the trial sheet.

2. Draw a line as a continuation of the lower border line on
the trial sheet. This is a base line for measurements.

3. Lay off on the trial sheet the space for the letters as given
in Fig. 143. Extreme accuracy in making these measurements
is necessary, as the width of the letters varies with their height.
A small error in height makes the letter appear much too large
or too small.

4. Rule each guide line on the trial sheet and the drawing
sheet with one setting of the T-square. Care should be taken to
draw exactly through the points located. Check the heights of
the spaces with the scale.

5. Letter each line of the title on the trial sheet, giving
attention to the proportion of the letters and to spacing. Do not
try to balance the lines on this sheet.

6. Locate the middle point of each line on the trial sheet.

7. Draw the vertical center line of the title through the
center of the title rectangle.

8. Cut out each line of letters from the trial sheet and place
it above the space in which it is to be lettered on the drawing
sheet, with its middle point on the center line of the title.

PENCIL MECHANICAL DRAWING

141

9. Letter each line, following the spacing on the trial line.
The result should be a perfectly balanced title.

DATA FOR DRAWING PLATE 13

Given: The orthographic sketch, Plate 12.
Required: To make a pencil mechanical drawing from
Plate 12.

Instructions:

1. Test the drawing board, T-square, and triangles as ex-
plained under the corresponding headings in this chapter.

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FIG. 145. LETTERING PLATE 13

2. Draw the border line as previously explained.

3. Calculate the size of the enclosing rectangle.

4. Lay off as many of the dimensions of the object as possible
at one time. Draw the lines lightly.

5. Check the drawing for accuracy.

6. Erase unnecessary lines and retrace the drawing, taking
care to end the lines exactly at their intersections. Dot the lines
representing hidden edges.

7. Draw extension and dimension lines and put in dimensions.

142

MECHANICAL DRAWING

8. Letter a note, giving the number of parts required and
the material from which they are to be made.

9. Letter the title, using the name of the object given below
the figure from which the drawing was made.

DATA FOR LETTERING PLATE 13

Given: Plate 13 to reduced size. Fig. 145.

Required: To make the plate in ink to an enlarged scale

FIG. 146. TYPE PROBLEM. PERSPECTIVE OF BRACE

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 14

In this plate the student will need to decide for himself the
number of views necessary, and their arrangement, to show the
form of the object. It is suggested that for this purpose he
review the principles given on pages 110 and 111.

PENCIL MECHANICAL DRAWING

143

The methods of dimensioning, particularly those relating to
the dimensioning of inclined lines, should also be reviewed.
Pages 136 and 137.

FIG. 147. TYPE PROBLEM. DETAIL OF BRACE JOINT

FIG. 148. VISE ANVIL

DATA FOR DRAWING PLATE 14

Given: Perspective sketches, Figs. 148, 149, 150, and 151.
Required: To draw an orthographic sketch of the object

FIG. 149. TOWEL HANGER

(144)

FIG. 150. FEED HOPPER

PENCIL MECHANICAL DRAWING

145

shown in Fig. 148, 149, 150, or 151, or any similar object, with
dimensions, as assigned by the instructor.

Instructions: Proceed as for previous orthographic sketches.

FIG. 151. BIRD HOUSE

DATA FOE LETTERING PLATE 14

GiVen: Plate 14 to reduced size. Fig. 152.

Required: To make the plate in ink to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 15

Inclined Lines. Lines at such angles as 15°, 30°, 45°, 60°,
and 75° may be drawn with the T-square and triangles described
on pages 123 and 124. When the inclination of a line is not
given in degrees at least two points on it must be located. The
line is then drawn by placing an edge of a triangle or the
T-square so that it passes through the two points.

Scale. When an object is too large to be drawn full size on
the sheet, it may be drawn to some fraction of the actual size.

146 MECHANICAL DRAWING

Half and quarter sizes are common scales for shop drawings.
The edge of the scale, graduated to read half or quarter size,
should be used instead of dividing the dimensions by 2 or 4.
See page 127 for a description of the method of using the scale.

BASE PLATE FOR CABLE REEL z

MOTOR I WANTED -CAST IRON SCALE"
QUARTER SIZE MANHOLE FORZ
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FIG. 152. LETTERING PLATE 14

DATA FOE DRAWING PLATE 15

Given: The orthographic sketch, Plate 14.
Required: To make a pencil mechanical drawing from
Plate 14.

Instructions:

1. Draw the border line and calculate the size of the enclosing
rectangle as in plate 13.

2. Lay off the dimensions of the object and complete the con-
structive stage.

3. Check carefully each dimension for accuracy.

4. Retrace the object lines, drawing (1) horizontal lines,
beginning at the top; (2) vertical lines beginning at the left;
(3) inclined lines.

5. Draw extension and dimension lines and put in dimensions.

6. Letter a note, giving the number of parts required and the
material from which they are to be made.

PENCIL MECHANICAL DRAWING 147

7. Letter the title, using the name of the object given below
the figure from which the drawing was made.

= CLUTCH BRACKET PRESSUREZ

Z TUNNEL HOISTING CAGE 2 WANTED Z,
Z CAST IRON SCALE - QUARTER SIZE Z'

z MOTOR BRACKET FOR VALVEZ

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FIG. 153. LETTERING PLATE 15
DATA FOR LETTERING PLATE 15

Given: Plate 15 to a reduced size. Fig. 153.

Required: To make the plate in ink to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 16

In a freehand or mechanical drawing where a straight line is
tangent to an arc, the arc should be drawn first. In the con-
structive stage the arc should be drawn long enough so that it
will extend beyond the point of tangency when the line is drawn.
A straightedge may then be laid tangent to the arc and the
straight line drawn in. Before the drawing is finished the
unnecessary part of the arc is erased. Fig. 155.

Centers for rounded corners, fillets and other arcs of circles,
which do not have their centers on any line of the drawing, are
located by what is called the "trial and error" method. The
compass should be first adjusted to the proper radius. To locate
the center of the arc, set the lead on the tangent line at A, Fig.

148

MECHANICAL DRAWING

FIG. 154. TYPE PROBLEM. PERSPECTIVE OF BEARING

FIG. 155. TYPE PROBLEM. CONSTRUCTIVE STAGE OF MECHANICAL DRAWING

150 MECHANICAL DRAWING

157, estimating A C as nearly as possible equal to the radius of
the arc. Set the needle point at B opposite A and bring the lead
around to D. Move the needle point parallel to A C an amount
equal to the error. The compass should then be again rotated
back to A to test for accuracy, and if necessary further adjust-
ment should be made before drawing the arc.

•4-

FIG. 157. TRIAL AND ERROR METHOD OF LOCATING CENTERS

Radius Dimensions. The dimension form for radius dimen-
sions is shown in Fig. 189. When the distance between the arc
and its center is great enough to admit the figures and arrow-
heads the form is as shown in Fig. 189. Sometimes a small cir-
cle is drawn around the center in place of an arrowhead. This
circle should be made freehand and about TV' in diameter. When
the distance between the arc and its center is short the center,
as shown by the J" radius, is not indicated. Fig. 189.

DATA FOB DRAWING PLATE 16

Given: Perspective sketches, Figs. 158, 159, and 160.

Required: To draw an orthographic sketch of the object
shown in Fig. 158, 159 or 160, or any similar object, with dimen-
sions, as assigned by the instructor. The student should decide
what views are necessary to show the form of the object.

Instructions: In drawing the circles and arcs, sketch in the
center lines and lay off the radii on each, as in Plate 10.

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 16

Composition. This and the following plates will be devoted
to the practice of notes which frequently appear on the drawing
to give information not shown by the views.

PENCIL MECHANICAL DRAWING

151

FIG. 158. STUFFING Box GLAND

FIG. 159. STATIONERY AND INK STAND

152

MECHANICAL DRAWING

DATA FOR LETTERING PLATE 16

Given: Plate 16 to reduced .size. Fig. 161.

Required: To make the plate in ink to an enlarged scale.

FIG. 160. CLAMP

DATA FOR DRAWING PLATE 17

Given: The orthographic sketch, Plate 16.
Required: To make a pencil mechanical drawing from
Plate 16.

Instructions:

1. Draw the border line and enclosing rectangle.

2. Locate and draw two center lines at right angles to each
other for each arc or circle.

PENCIL MECHANICAL DRAWING 153

3. Draw the arcs of indefinite length so they extend beyond
the points of tangency.

4. Draw the straight lines tangent to the arcs.

5. When the constructive stage is complete^ retrace the lines
in the following order : (1) circles and arcs ; (2) horizontal lines,
beginning at the top of the sheet; (3) vertical lines, beginning at
the left of the sheet; (4) inclined lines.

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FIG. 161. LETTERING PLATE 16

6. The center line may be produced and used as an extension
line where appropriate.

1. Letter a note, giving the number of parts required and
the materials from which they are to be made.

8. Letter the title.

DATA FOR LETTERING PLATE 17

Given: Plate 17 to reduced size. Fig. 162.

Required: To make the plate in ink to an enlarged scale.

154 MECHANICAL DRAWING

REVIEW QUESTIONS

1. (a) What determines the number of views of an object?
(b) When are more than two views necessary?

2. Where is the front surface of an object represented in the
side view?

3. (a) What dimension is common to the top and side views?
(b) If only the top and side views were drawn how should they
be related ?

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FIG. 162. LETTERING PLATE 17

4. What are the requisites of a good drawing board ?

5. (a) Describe a method for testing the surface and working
edge of a drawing board, (b) What care should be taken of
the surface and working edge of a drawing board ?

6. Give requisites of a good T-square and explain its uses.

7. Is it necessary for the head of a T-square to be at right
angles to the blade ? Why ?

8. Describe a method for testing the working edge of a
T-square for straightness.

9. (a) Describe the position of the T-square for drawing
horizontal lines, (b) How is it held? (c) Illustrate by a sketch
the position of the pencil in ruling a line along the T-square.

PENCIL MECHANICAL DRAWING 155

10. Describe the process of squaring and fastening the paper
on the board for a mechanical drawing.

11. What is the advantage of the celluloid triangle over tri-
angles made of other materials ?

12. (a) For what are triangles used? (b) For what angles
are they usually cut ?

13. Describe a method of testing the accuracy of a 90° angle
of a triangle.

14. Describe a method of testing the accuracy of a 45° angle
of a triangle.

15. Describe a method of testing the accuracy of a 30° and
60° angle of a triangle.

16. (a) Show by a sketch how to construct an angle of 15°
with a horizontal line by means of the T-square and triangles,
(b) What angle does this make with a vertical line?

17. (a) Show by a sketch how to construct an angle of 75°
with a horizontal line by means of the T-square and triangles,
(b) What angle does this make with a vertical line ?

18. When using the triangle against the T-square in which
direction should the line be drawn? (b) Show different cases
by sketching.

19. Show by a sketch how to draw a line parallel to any given
line using only two triangles. Perpendicular,

20. (a) Describe the positions of the T-square and triangle
for drawing a vertical line, (b) In which direction is the line
always drawn ?

21. (a) What is the shape of the ruling point of the pencil?
(b) How is it obtained? (c) How does the measuring point of
the mechanical drawing pencil differ from the point of the
sketching pencil ?

22. What are the uses of a scale in laying out a drawing ?

23. Show by a sketch how to lay off a distance of 16' -3£",
using the architect's scale \" to I'-O".

24. How are the legs of the compass set for describing circles ?

25. (a) What is the shape of the point of the lead used in
the bow compass? (b) How should it be set with reference to
the needle point ?

26. (a) What is the range of the bow compass? (b) How

156 MECHANICAL DRAWING

are the circles drawn which are too large for the ordinary
compass ?

27. Show by a sketch how to divide a line into five equal parts
by means of the dividers.

28. Illustrate by a sketch and show calculations for deter-
mining the size of an enclosing rectangle.

29. Describe the process of drawing the border rectangle for
a mechanical drawing sheet.

30. (a) Define the constructive stage of the mechanical draw-
ing, (b) How are hidden edges shown in this stage ?

31. In what order are the lines drawn in the finishing stage ?

32. (a) What space is left between the outline of the object
and the end of the extension line? (b) How far should the
extension line run beyond the arrowhead? (c) How far should
the nearest dimension line be from the outline of the object?
(d) How far apart should dimension lines be placed?

33. (a) What is the height of the whole number in a dimen-
sion? (b) The total height of the fraction?

34. What is the purpose of notes on a drawing ?

35. What is the title block?

36. Describe the steps taken in balancing two or more lines
in a title.

37. What dimension forms are used in showing the inclination
of a line ?

38. In what order are the lines drawn when an arc and a
straight line are tangent to each other?

39. (a) Show two ways of dimensioning a radius, (b) Under
what condition is each used?

DATA FOE REVIEW PROBLEMS

Given: A perspective sketch, Fig. 163.
Required:

1. To make an orthographic sketch of the object shown in
Fig. 163.

2. To make a pencil mechanical drawing from the ortho-
graphic sketch.

Given: A perspective sketch, Fig. 164.

PENCIL MECHANICAL DRAWING

157

Required:

1. To make an orthographic sketch of the object shown in
Fig. 164.

2. To make a pencil mechanical drawing from the ortho-
graphic sketch

Given: A perspective sketch, Fig. 165.
Required :

1. To make an orthographic sketch of the object shown in
Fig. 165.

FIG. 163. KEYED MORTISE AND TENON

2. To make a pencil mechanical drawing from the ortho-
graphic sketch.

158

MECHANICAL DRAWING

FIG. 164. FOOT STOOL

FIG. 165. DASH POT ARM

CHAPTER IV

TRACING AND BLUEPRINTING

PROSPECTUS

The pencil mechanical drawing of Chapter III is continued
in this chapter to develop further skill in the use of instruments
and to improve the technique in both the mechanical and free-
hand elements of the drawing. It is the chief aim of this chap-

FIG. 166. TYPE PROBLEM. DRAWING BOARD

ter to familiarize the student with the instruments, materials,
and methods used in inking and to fix a standard for the ink
drawing. As a result of the work of this chapter the student
should be able to make neat tracings with proper width of lines,
good joints, and uniform spacing in crosshatching. The tech-
nique of the lettering, arrowheads, and figures should be com-
parable with that secured in the mechanical line work.

159

TRACING AND BLUEPRINTING

161

The tracing of the pencil mechanical drawing on tracing cloth
with ink is usually the last step in the production of a drawing
for the shop or for other purposes where a number of copies of
the drawing are desired. The tracing is made on a transparent
cloth or paper in order that the blueprints may be made from it
as described later. The use of the blueprint makes it possible te
have several copies of the drawing and at the same time preserve
the original tracing from which other copies may be made at
any time.

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FIG. 168. EEVIEW PROBLEM

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 18

Inasmuch as the drawings of many objects require the use of
sections, the student should review both the half and the quarter
sections discussed in Chapter III, pages 98 and 99, and test
his knowledge of the orthographic principles involved in making
sectional views by answering the following questions. See Figs.
99 and 168.

162

MECHANICAL-DRAWING

1. Where is the surface 1, 6, shown in the side view ?

2. (a) Does the rectangle 20, 21, 22, 23 in the side view
represent an opening or a solid part of the object? (b) Why?

3. Where is the surface 7, 4 shown in the side and top views ?

4. Make a front view of the object when cut on A B.

5. (a). Is the side view affected by the section? (b) Top
view?

FIG. 169. INSTRUMENT CASE

Bach tracing in this chapter will be preceded by a pencil
mechanical drawing. The pencil drawing is made to give the
student additional practice in the handling of the instruments
already used, to introduce the use of new instruments, and to
provide drawings for the tracings.

DATA FOR DRAWING PLATE 18

Given: Orthographic drawings, Figs. 169, 170, 171.

Required: To make a pencil mechanical drawing of thei
object shown in Fig. 169, 170, or 171 as assigned by the in-
structor. The views given and required may be obtained from
the following statements. Any similar problems may be substi-
tuted by the instructor.

TRACING AND BLUEPRINTING

163

Given : Fig. 169. The front, top, and right side views.
Required: To draw the front, top, and left side half section

views.

FIG. 170. MEDICINE CABINET

Given: Fig. 170. The front and right side views.
Required: To draw the front and left side half section
views. •

Given: Fig. 171. The front and right side views.
Required: To draw the front, and left side half section.

Instructions:

Proceed as for the mechanical drawing plates of Chapter III.

164

MECHANICAL DRAWING

DATA FOR LETTERING PLATE 18

Given: Plate 18 to reduced size. Fig. 172.
Required: To make the plate to an enlarged scale.

Tow

Bur/ap? —
Laced Webb/,

$ecf/on showing construction
of cushion

FIG. 171. FOOT STOOL

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 19

The following is a list of the instruments and materials needed
to make tracings and reproductions of mechanical drawings :

1. Tracing cloth.

2. Tracing paper.

3. Blueprint paper.

4. Black waterproof ink.

5. Ruling pen.

6. Compass.

7. Bow pen.

TRACING AND BLUEPRINTING 165

Tracing Cloth is a thin, firm cloth sized to hold ink and to
make the cloth transparent. It is generally used when drawings
are to be reproduced by the blue, black, or brown printing proc-
ess. Drawings made on tracing cloth may be kept indefinitely
if the cloth is kept dry and handled carefully. Changes may be1
made on the drawings and new prints made from time to time.

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zORDERS BOTH NEW AND z
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FIG. 172. LETTERING PLATE 18

One side of the cloth is glazed and the other is dull.- Either
side may be used for inking. The glazed side will admit of the
.most erasing, but when inking is done on this side the cloth will
curl. For work where penciling is to be done on the cloth, for
drawings to be used for photographic reproduction, and for
tinting, the dull side should be used. For the tracings of this
chapter use the dull side.

Sometimes the ink does not adhere readily to the surface of
the cloth, particularly when the glazed side is used. To over-
come this difficulty powdered chalk may be rubbed into the sur-
face with a soft cloth. The chalk should be thoroughly removed
before beginning inking.

The cloth is fastened to the board with the same thumb tacks
used to hold the pencil drawing. In order to avoid shifting this

166

MECHANICAL DRAWING

drawing, the cloth should be spread over the sheet and one tack
at a time removed and inserted through the cloth into the hole
from which it came.

Tracing Paper. For temporary drawings, especially where
some portion of a drawing already made can be traced and used
as part of a new drawing, a thin, transparent paper called
tracing paper may be used with considerable saving of time. It
should not be used for a permanent drawing or one which requires
much handling.

FIG. 173. BLUEPRINTING FRAME

Blueprint Paper. Instead of sending the tracing into the
shop where it would soon be injured or worn out, prints are
made, usually on blueprint paper. This is a white paper covered
with a solution which after being exposed to light, turns blue.

The Blueprinting Process. To make prints, the inked side of
the tracing is placed against the glass of a printing frame. The
sensitized side of the blueprint paper is then placed against the
tracing cloth and held firmly in contact with it. The contact is
secured by means of clamps attached to the back of the board
of the printing frame which holds both the tracing and the blue-
print paper in place. Fig. 173.

The printing frame should be placed in a direct light. If
sunlight is used the exposure should be made during the middle
of the day. The length of exposure to the light depends on the
intensity of the sunlight or plpntrie light and upon the " speed"

TRACING AND BLUEPRINTING 167

of the blueprint paper. After removing the paper from the
frame it should be washed by turning it over several times in a
basin of water. This removes the chemical on the sensitized side
of the paper which was covered by the lines of the drawing on
the tracing cloth and leaves the white paper exposed, forming
the outline of the blueprint drawing. The result is a reproduc-
tion of the drawing in white lines with a blue background. After
the blueprint has been washed it should be hung vertically by one
edge or over a horizontal stick to drain, and allowed to remain
until it is dry.

Black Ink will be used for all lines on the plates of this chap-
ter. Black drawing ink is composed of finely divided carbon
held in suspension in a liquid. When a line is drawn with this
ink the liquid dries and leaves the carbon deposited on the paper
or cloth. It is important that enough ink be left on the line so
that when the ink is dry the amount of carbon deposited will be
sufficient to make the line black. Thin ink gives brown lines.
The liquid used in drawing ink evaporates quickly. The carbon
therefore dries quickly, permitting one to work rapidly while
tracing. The rapid evaporation of the ink necessitates keeping
the stopper always in the bottle to prevent the ink from becoming
too thick.

The Ruling Pen is used more than any other instrument in the
draftsman's outfit and should therefore be carefully selected.
The steel of which the pen is made should be properly tempered
and of such quality as to retain a smooth sharp edge. The blades
should be of the same length, the inner one sufficiently stiff to
resist a light pressure against the ruling edge. The nibs should
be of the same width, equally rounded and directly opposite one
another. The ends of the nibs should be narrow enough to give
control in starting and ending lines, but broad enough to hold
a reasonable amount of ink. When the nibs are too narrow the
ink is drawn from the points by capillary attraction, making it
difficult to start the ink at the beginning of a line.

Filling and Using the Pen. The ruling pen should be ad-
justed, filled, and used in the following manner :

1. Adjust the pen by turning the thumb screw to approxi-
mately the proper width of line.

168

MECHANICAL DRAWING

2. Fill the pen by inserting the quill, attached to the stopper
of the ink bottle, between the nibs of the pen. The pen should
be filled to a height of about \" . Care should be taken to avoid
getting ink on the outside surfaces of the nibs.

3. Set the pen to give the exact width of line required, testing
it on the margin of the drawing or on a separate sheet. It should
be tested on the same kind of surface as that on which it is to be
used and by ruling along a straightedge — not freehand.

FIG. 174. EULING A HORIZONTAL LINE

4. Hold the pen in the hand, as shown in Fig. 174, with the
first finger above the thumb screw and the second finger against
the right side of the pen. It should be held in a vertical plane,
but may be allowed to lean slightly in the direction of motion.
In this position both nibs will touch the cloth with equal pressure,
which is essential to the production of smooth, sharply defined
lines.

5. Draw rather slowly with a movement of the hand and arm,
the forearm remaining perpendicular to the line being drawn.
There should be no wrist movement, as the pen must not be
rotated upon its axis. The tips of the third and fourth fingers
should slide on the surface of the T-square or triangle to steady
the hand. As the end of the line is approached the motion of
the hand and arm should cease and the line should be completed
with a finger movement. The center of the ink line on the tracing
should be directly over the pencil line on the drawing being

TRACING AND BLUEPRINTING 169

traced. Care must be taken to set the pen exactly at the begin-
ning of a line. At the end of a line the pen should be lifted
vertically in order that the ink will not run out and cause the
line to overrun. In drawing dotted lines, the pen must be set
down vertically, the dash drawn, and the pen then lifted ver-
tically so as to make both ends of the dash square.

The spacing of section lines is done entirely by eye. In order
to avoid varying the spaces the pen should be placed against the
ruling edge and the perpendicular distance from the point of
the pen to the last line drawn made equal to the perpendicular
distance between any two sequential preceding lines.

When starting the crosshatching in a corner, there is a ten-
dency to space the lines too closely, the spaces increasing as the
lines become longer. The student should practice crosshatching
rectangular areas on a scrap of tracing cloth before attempting to
work on the drawing.

Cleaning the Pen. The pen should be cleaned frequently by
inserting a cloth at the side and pulling it out between the nibs.
This should be done frequently while the pen is in use. The pen
should not be laid away until the surfaces are thoroughly cleaned,
as ink will corrode steel. If the ink does not start readily at the
beginning of a line, squeeze the nibs of the pen together slightly
to draw the ink down to the point. If the ink has been allowed
to stand for some time, the pen should be cleaned and refilled.
Do not touch the pen to the hand or a cloth to start the ink.

Sharpening the Pen. The nibs of the pen should be as sharp
as they can be made without producing the sensation of cutting
when the pen is in use. They should not scratch the paper when
drawing a line. This occurs if they are sharpened to a point
instead of a rounded edge, or if the point is rough or notched.
The length and condition of the points may be tested by holding
the pen up to the light and bringing the nibs together slowly.

In case the pen becomes broken or dull from use it should be
sharpened as follows :

1. Provide a close grained oilstone.

2. Close the nibs until they just touch each other.

3. Hold the pen on the stone as in drawing a line and move
it back and forth, revolving it slowly in the plane of motion until

170

MECHANICAL DRAWING

the nibs are evenly rounded and of the same length. Fig. 175.
This will dull the nibs.

4. Separate the nibs and sharpen them by rubbing the outside
on the oilstone, giving at the same time a slight rotary motion

FIG. 175. SHARPENING THE PEN. EVENING THE NIBS

FIG. 176. SHARPENING THE PEN. GRINDING THE NIBS

to the handle, which is held at a small angle with the face of the
stone. Fig. 176. The point of the pen should be examined fre-
quently and the process continued until the nibs are sharp. If
a burr is produced on the inside of a nib it may be removed by
placing the inside surface flat against the oilstone and rubbing
it lightly.

The Compass. When using the compass for either penciling
or inking, the legs should be adjusted so that the pen or pencil

TRACING AND BLUEPRINTING 171

part and the needle point are perpendicular to the drawing
board. With the legs in this position, the compass revolves about
the needle point as an axis and the two nibs of the pen bear
with equal pressure, thus producing sharply defined Jines. The
compass is held by the handle, between the thumb and first finger
of the right hand. It is rotated by rolling the handle between
the thumb and finger. Fig. 177. If the compass is allowed to
lean very slightly in the direction of motion, sufficient pressure
may be put on the pen or pencil to hold it firmly in contact with
the paper or cloth without danger of the needle point being lifted
from the center.

FIG. 177. DRAWING A CIRCLE WITH THE COMPASS

The pen of the compass is filled, adjusted, cleaned, and sharp-
ened in the same manner as the ruling pen.

The Bow Pen should be used for all circles and arcs of f "
radius or less. The pen should be filled and adjusted in the same
manner as the ruling pen.

Line Notation. In inking, the object lines are drawn notice-
ably heavier than all other lines except the border line. The dif-
ference in width produces a sharp contrast between classes of
lines which makes the drawing easy to read and gives it a good
appearance. In small drawings or those containing intricate
detail the width of the object lines is slightly reduced.

No system of line notation has ever been universally adopted.
In this course a simple one conforming to average commercial
drafting room practice will be used. All lines except the dotted
line used to represent invisible edges are solid. The widths of

172 MECHANICAL DRAWING

lines to be used in this course are given in Fig. 178. All widths
as indicated in Fig. 178 should be estimated by the student. As
far as possible all lines of the same width should be drawn while
the pen is set for that width. Before starting to ink a group of
lines of the same width a sample line should be drawn on the edge
of the sheet. This may be used as a guide in setting another
instrument to give the same width of line. For instance, when
the compass is used in drawing circles a sample of the width of
line should be drawn to aid in estimating the setting of the ruling
pen which will be used later. In case the pen must be reset for
a particular line the estimated width should be determined by
drawing lines near the sample until the proper width of line
is secured.

CENTEELINE .......... *]

EXTENSION LINE ...... I t „ WTT,..-, _

DIMENSION LINE ...... P"» W1LUJJ

CEOSSHATCHING LINE.

FULL -&' WIDE
DOTTED -

T r\nrQ
'S

BORDER LINE ............ . -&' WID

FIG. 178. LINE NOTATION FOR INK DRAWINGS

Order of Inking the Drawing. The drawing should be inked
in the order given below to secure economy of time and effort.

1. Object lines.

a. Circles and arcs of circles.

b. Horizontal lines (beginning at the top).

c. Vertical lines (beginning at the left).

d. Inclined lines.

2. Center lines (same order as object lines).

3. Extension and dimension lines (same order as object lines).

4. Arrowheads.

5. Dimension figures and notes.

6. "Crosshatching lines.

7. Title.

8. Border line.

In inking the title and notes, pencil guide lines on the tracing

TRACING AND BLUEPRINTING 173

cloth will be found of great assistance in keeping the letters
uniform in height. In no case should letters and figures be
penciled on the tracing cloth over those which appear on the
pencil drawing, before they are inked. The pencil drawing
should serve as a copy for inking figures, letters, and arrowheads
as it does for all mechanical lines. All freehand inking should
be done with the writing pen as described under, "Preparatory
Instruction for Lettering Plate 11," page 102.

Erasure. On ink drawings erasures must be carefully made,
especially if inking is to be done over the erased areas. It will
be found that if the ruby eraser is used for removing ink lines
the drawing surface will be left in good condition for re-inking.
In case a blot occurs the ink should not be allowed to soak into
the tracing cloth. As much of the ink as possible should be.
taken up with a blotter or cloth and the remainder allowed to dry
before erasing. The erasing shield should be used to protect the
parts of the drawing which are not to be erased, as described on
page 132.

Trimming the Tracing Cloth. When the tracing is finished
lay off one-half an inch from each corner of the border rectangle
to make a one-half inch margin. Place the tracing on the back
of the drawing board. With a 'sharp knife running along the
edge of the T-square blade not used for ruling, trim the sheet to
the rectangle determined by the eight pencil points. In this
process the T-square blade should be placed over the finished
portion of the sheet. The drawing will then be held firmly and
will be protected from the knife in case it should slip.

DATA FOB DRAWING PLATE 19

Given: The pencil mechanical drawing, Plate 18.
Required: To make a tracing of Plate 18.

Instructions:

1. Fasten the tracing cloth over the mechanical drawing and
prepare the surface for inking as previously described under,
"Tracing Cloth," page 165.

2. Ink the drawing, following the steps outlined under,

of Inking the Drawing," page 172.

174 MECHANICAL DRAWING

DATA FOB LETTERING PLATE 19

Given: Plate 19 to reduced size. Fig. 179.
Required: To make the plate to an enlarged scale.

:END OF STUD TO BE FLAT€
TENED AND CAST IN -PARTz

: USE FILLERS 513 TO- ALLOW GEARS TOZ
'MESH PROPERLY. CROSS HEAD PIN ASZ

SHOWN CROSS HEAD PIN

FIG. 179. LETTERING PLATE 19

DATA FOR DRAWING PLATE 20

Given: Orthographic drawings, Figs. 182, 183, 184, and 185.

Required: To make a pencil mechanical drawing of the
object shown in Fig. 182, 183, 184, or 185, as assigned by the
instructor. The views given and required may be obtained from
the following statements. Any similar problem may be substi-
tuted by the instructor.

Given: Fig. 182. The front and left side views.

Required: To draw the front and right side views.

Given: Fig. 183. The front and left side views.

Required : To draw the front and right side views.

Given: Fig. 184. The front and left side views.

Required: To draw the front and right side views.

Given: Fig. 185. The front and left side views.

Required : To draw the front and right side views.

WER GIRTH 3-eX.g"

SILL 2-

CONCHETE FOUNDATION

FIG. 180. TYPE PROBLEM. BARN FRAMING. GIVEN VIEWS

FIG. 181. TYPE PROBLEM. BARN FRAMING. I'INISHFD DRAWING

(175)

176

MECHANICAL DRAWING

Bere/

fo coyer

FIG. 182. CAMP STOOL

FIG. 183. STEP LADDER

TRACING AND BLUEPRINTING

177

y A

5-0"

Al/wa//s Z± fh/ck

FIG. 184. FORMS FOR CONCRETE DOG KENNEL

•r
1

.1.

'T'

65r™~ -

(

•*

-2

f-o0 >.
-3*

•f

— ^

FIG. 185. SAW BUCK

178 MECHANICAL DRAWING

DATA FOB LETTERING PLATE 20

Given: Plate 20 to reduced size. Fig. 186.
Required: To make the plate to an enlarged scale.

Z2'-l|"xl9f ROUGH ROUND RODS ~ DRILL Z

= I4-24JFLAT_HEAD_SCREW=

Zf-ll BOLTS -6g" LONG WITH NUT AND Z
ZCHECK^NUT |"-I6 ROUND HEAD BOLTZ

zCONNECTING ROD BEARINGz

FIG. 186. LETTERING PLATE 20

DATA FOE DRAWING PLATE 21

Given: The pencil mechanical drawing, Plate 20.
Required: To make a tracing of Plate 20.

Instructions:

1. Fasten the tracing cloth over the mechanical drawing and
prepare the surface for inking.

2. Ink the drawing, following the steps outlined under
"Order of Inking the Drawing," page 172.

3. Trim the sheet and press the cloth back into the tack holes.

TRACING AND BLUEPRINTING 179

DATA FOR LETTERING PLATE 21

Given: Plate 21 to reduced size. Fig. 187.
Required: To make the plate to an enlarged scale.

2 FILLER PLATES" -5x9'x2-4'/ REAM!
2 PIN PLATES INSIDE {xHx2'-6* JIG!

2 HINGE PLATES OUTSIDE ^xlO"x2"
LATERAL PLATE . |x 20Bxr-o|* ALL

HOLES £ COUNTERSUNK g RIVETS
FIG. 187. LETTERING PLATE 21

FIG. 188. TYPE PROBLEM. RESERVOIR CAP. GIVEN VIEWS

PEEPABATORY INSTRUCTIONS FOR DRAWING PLATE 22

(ft

TRACING AND BLUEPRINTING

181

DATA FOR DRAWING PLATE 22

Given: Orthographic drawings, Figs. 190, 191, 192, and 193.

Required: To draw the views of the object shown in Fig.
190, 191, 192, or 193, as assigned by the instructor, from the
following statements. Any similar problem may be substituted
by the instructor.

FIG. 190. BOOK BACK

Given: Fig. 190. The front and right side views.
Required: To draw the front and left side views.

Given: Fig. 191. The front and left side views.
Required: To draw the front half section and right side
views.

Given: Fig. 192. The front and left side views.
Required: To draw the frjont half section and right side
views.

Given: Fig. 193. The front and left side views.
Required: The front half section and left side views.

182

MECHANICAL DRAWING

FIG. 191. COUNTER SHAFT PULLEY FOR 12" WOOD LATHE

— •hr1
?

U*-

FIG. 192. HAND WHEEL FOR 12" WCOD LATHE

DATA FOR LETTERING PLATS 22

Given: Plate 22 to reduced size. Fig. 194.
Required: To make the plate to an enlarged scale.

FIG. 193. LEG FOR 12" WOOD LATHE

4 CHANNELS. I2'xl4'-8f" ROOF TRUSSZ
I COAT OF_ GRAPHITE PAINT DRILL Jz
12 HOLES EQUALLY SPACED TO FIT Z

PIECE NO, ii7 PISTON FOR 10 z
HP, HORIZONTAL ENGINE z

FIG. 194. LETTERING PLATE 22

(183)

184 MECHANICAL DRAWING

I^EPARATORY INSTRUCTION FOR DRAWING PLATE 23

• Locating Points of Tangency. To secure perfect joints where
lines are tangent in the tracings, the exact points of tangency
should be located and marked in pencil on the tracing cloth.
The method of locating the tangent points depends upon the geo-

FIQ. 195. METHOD OF LOCATING POINTS OF TANGENCY

metrical principle that a line perpendicular to a tangent at its
point of contact passes through the center of the circle.

To locate a point of tangency, place the hypotenuse of eitheb
triangle against any edge of the other triangle, as shown in
Fig. 195. Move both triangles as one tool until a side of the
triangle A is coincident with the tangent line. "With triangle B
held firmly in place, slide triangle A into the position marked
A' where the side at right angles to the tangent line passes
through the center of the arc. A short dash should be drawn
across the tangent line to mark the point of tangency.

The point of tangency between two arcs may be located by
drawing the straight line joining their centers. This line passes
through their point of contact. Fig. 195.

TRACING AND BLUEPRINTING 185

DATA FOR DRAWING PLATE 23

Given: The pencil mechanical drawing, Plate 22.
Required: To make a tracing from Plate 22.

Instructions:

1. Fasten the tracing cloth and prepare it for inking.

2. Locate the points of tangency.

Locate the points of tangency.

Ink the drawing in the usual order.

Trim the sheet and press the cloth back into the tack holes.

A DRAWING/ THE" MECHANICAL PART Z

OF WHICHJS WELL EXECUTED MAY Z

HAVE ITS~APPEARANCE SPOILED BY Z
POOR LETTERING MAKE THE LAST Z
PLATE THE BEST OF ALL"~I 2 34 5 61.

FIG. 196. LETTERING PLATE 23

DATA FOR LETTERING PLATE 23

Given: Plate 23 to reduced size. Fig. 196.
Required : To make the plate to an enlarged scale.

KEVIEW QUESTIONS

1. (a) What is the difference between the two sides of the
tracing cloth? (b) Which side is used in this course?

186

MECHANICAL DRAWING

2. (a) Describe the process of fastening the cloth over the
pencil drawing, (b) How is the cloth prepared for inking?

3. Describe the process of making a blueprint from a tracing.

" -— .

^S-f*

4 j

FIG. 197. GOVERNOR SUPPORT

4. (a) How is the ruling pen held for ruling lines ? (b) How
is it adjusted to the proper width of line? (c) How is it filled?
(d) How cleaned?

5. (a) "What precautions are taken in beginning and ending
a line? (b) How does the pen approach and leave the paper
in drawing dotted lines?

6. How are the spaces between crosshatching lines estimated ?

7. (a) Why are the needle point and the pen and pencil
points of the compass set at right angles to the plane of the
drawing paper? (b).How is the compass held when drawing a
circle? (c) How is it rotated?

TRACING AND BLUEPRINTING

187

8. (a) In inking, why are the object lines made wider than
the other lines? (b) Give the standard width of inked object,
extension, dimension, and center lines, and the border line.

9. In what order are the different kinds of lines inked?

FIG. 198. PLANING JIG FOR ROD BRASSES

10. (a) In what order are the object lines inked? (b) Cen-
ter lines? (c) Extension and dimension lines?

11. How is ink removed from a drawing ?

12. How is the tracing trimmed to the required size ?

13. (a) Upon what geometrical principle does the method of
finding the point of tangency between an arc and a straight line
depend? (b) Give the steps in the construction necessary to
locate a point of tangeuoy.

188

MECHANICAL DRAWING

DATA FOB REVIEW PROBLEMS

Given: The top, front, and right side views of an object,
Fig. 197.

Required: To draw the top, front half section, and right
side views of the object shown in Fig. 197. Scale, full size.

Given: The top, front, and right side views of an object.
Pig. 198.

Required: To draw the top, front, and left side views of
the object shown in Fig. 198. Scale, half size.

DRILL T"

FIG. 199. STUFFING Box GLAND

Given: The top and right side views of an object. Fig. 199.
Required: To draw the top and front half section views of
the object shown in Fig. 199. Scale, half size.

CHAPTER V
ADVANCED DRAWING

PROSPECTUS

The first year's work outlined in Chapters I, II, III, and IV
are intended to give opportunity for a thorough grounding in
the fundamentals of the theory and practice of drawing. The
second year's work outlined in this and the succeeding chapter
assumes a knowledge of, and skill in, the work of the preceding
year. With this knowledge and skill as a foundation the aim of
this chapter is to furnish applications of principles in a broader
and more general way and to introduce various details such as
conventional sections, screw threads, etc.

SHEET METAL PATTERNS
PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 24

Development of a Surface. The student is familiar with
many articles made of sheet metal — tin, zinc, galvanized iron,
etc. An examination of these objects, such as pails, cups, pans,
etc., will make it clear that some of them were made from metal
cut from flat sheets and rolled or bent into particular forms.
The student will recognize the geometrical solids — prism, cyl-
inder, cone, etc., as the bases for many of these forms. For
example, an ordinary tomato can is in the form of a cylinder.
Before an object of this kind can be cut from a sheet of metal
a pattern must be made which, when rolled up, will give the
correct form.

189

190

MECHANICAL DRAWING

To construct this pattern the object is imagined rolled on a
flat surface, such as that of the drawing board, until the entire
surface of the solid has come in contact with the plane surface.
Example : In Fig. 200 the prism was rolled until each of its faces

FIG. 200. EOLLING A PRISM TO
OBTAIN THE DEVELOPMENT OF ITS
LATERAL SURFACE

FIG. 201. ORTHOGRAPHIC VIEWS
AND DEVELOPMENT OF THE LATERAL
SURFACE OF A PRISM

came into contact with the board. The prints of these faces are
shown. If the whole figure a,b, c, d were cut out of the paper
and folded up on the lines representing the edges of the prism
the result would be a prism like the original.

Fig. 201 shows two views of a square prism with the develop-
ment of the lateral surface. It is evident from the orthographic
views that the edges of the bases are at right angles to the lateral
edges. When this is the case each face is a rectangle which is
represented in the development by a rectangle equal to that of
one side of the prism. When these rectangles are joined to-
gether as they are when the surface is imagined unrolled, the
edges of the bases will form straight lines. Example : Line a a.
Fig. 201.

The steps in the construction of the pattern are as follows :

1. Draw two parallel lines at a distance apart equal to the
length of the prism. It is preferable to project these lines from
the orthographic view as in Fig. 201.

2. Lay off with the dividers on one of these lines distances
equal to the widths of the sides of the prism, taken in consecutive

ADVANCED DRAWING

191

order, as ab, b c, c d, d a. Fig. 201. For the square prism these
distances are all equal. For a rectangular prism these distances
would not be equal; hence care must be taken to lay off the dis-
tances in consecutive order

* *

FIG. 202. FURNACE HEAT PIPE

DATA FOR DRAWING PLATE 24

Given: Two orthographic views of a rectangular furnace
heat pipe. Fig. 202.

Required: To draw a pattern, quarter size, from which
this pipe could be made, or any similar object assigned by the
instructor.

Instructions :

1. Draw the two given orthographic views.

2. Make a construction similar to that shown in Fig. 201. In
this case the widths of adjacent faces are not equal. The width
of each face should be transferred to the pattern with the dividers
from the top view starting at one corner and continuing around
the top view until the same corner is reached.

Beginning at this point in the course the lettering plates are
made up of lower case letters and numerals.

192

MECHANICAL DRAWING

SLOPE

STROKES

I UNIT

STROKES

/III!

Illll

Tft=

-L..L

inn

Illll

'111

Illll

7~/r-

Illll

7SY

///-

/7""

/////

lull

illll

HUH

FIG. 203. INCLINED CAPITAL LETTERS

ADVANCED DRAWING

193

-LJ

STROKES

Ill

////

"rr

IIJIJI

1111

'Iflfl

T///7

TmWi

//If/'

Fiu. 204. INCLINED CAPITAL LETTERS

194 MECHANICAL DRAWING

PBEPABATOEY INSTEUCTIONS FOE LETTEBOTG PLATE 24

The Slope of the inclined letters is equal to that of the
hypotenuse of a right triangle, the vectical leg of which is two
and one-half units long and the horizontal leg one unit long.
Fig. 203.

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 =
444444 I4U 4114 441 141 =

777777 174 147 4711 4177 =
222222 1247 1724 22274 =
555555 1572 5522 14725 =

FIG. 205. LETTERING PLATE

Lettering in Ink. The following list of plates will be made
in ink directly on tracing cloth. A list of materials needed and
directions for lettering in ink are given for Plate 11 of the
vertical Gothic letters.

DATA FOR LETTERING PLATE 24=

Given: Plate 24 to reduced size. Fig. 205.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 25

A somewhat more difficult pattern to lay out than the one just
drawn is illustrated by a square pipe cut away at an angle to meet
another pipe to form an elbow. Fig. 206. The edges of the lower
base are at right angles to the vertical edges and will therefore

ADVANCED DRAWING

195

unfold into a straight line. The lengths of these lines may be
taken from the end view of the pipe and laid off on the pattern.
It is evident in this case that not all of the vertical edges are of

FIG. 206. TYPE PROBLEM. DEVELOPMENT OF SQUARE PIPE CUT AT AN ANGLE

the same length. Their true lengths are shown in the front view
and may be transferred to the pattern by drawing horizontal
lines from it to the pattern as shown in Fig. 206. The ortho-
graphic views, also, show that two of the edges of the slanting
base are horizontal and the other two inclined. The lines a b, b e,
c d, and d a are drawn, connecting points a, b, c, d, which should
be located in consecutive order.

r-*

FIG. 207. EECTANGULAR PIPE

DATA FOR DRAWING PLATE 25

Given: Two orthographic views of an elbow for a rec-
tangular pipe. Fig. 207.

Required: To draw a pattern, quarter size, from which
the pipe could be made, or any similar object assigned by the
instructor.

196 MECHANICAL DRAWING

1. Draw two given orthographic views and make a construc-
tion similar to that shown in Fig. 206.

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 25

Curved Strokes. The 6 and 9 have the same cval outline
as the 0. This form should be kept in mind w'.lle drawing the
6 and 9.

Given: Plate 25 to reduced size. Fig. 208.

Required: To make the plate to an enlarged scale.

-000000 1470 7104 20504 =
= 666666 1626 6064 65276 =
= 999999 1929 4956 91979 =

-L5[9I5J_17_5J_ _7 _& J_-
-16 64 64 2 4 16 64 4 16 16 2 -

: 1116 4701 2196 1245 790=

FIG. 208. LETTERING PLATE

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 26

The cylinder is a very common form in sheet metal work.
Many cans, pails, pipes, etc., are cylindrical in form. When the
base of a cylinder is at right angles to its axis, the base will unroll
into a straight line. Fig. 209. The length of this line must be
found by dividing the circle representing the end view of the
cylinder into a number of small parts and stepping off these
lengths with the dividers on a straight line. Each distance
transferred is the chord of the arc between two points. These
divisions must, therefore, be small enough so that the straight

ADVANCED DRAWING

197

line distance between consecutive points is not greatly different
from the distance measured between these points on the circle,
or the arc distance. These divisions are usually made equal so
that one setting of the dividers is sufficient for stepping off all
the lengths.

Z 3 4 S 6 7 8 9 t0 // 1

FIG. 209. TYPE PROBLEM. DEVELOPMENT OF CYLINDRICAL SURFACE

Eight points equally spaced on the circumference are very
easily obtained with the 45° triangle, or twelve points may be
obtained with the 30°-60° triangle as shown in Fig. 210.

Sixteen points equally spaced may be obtained by subdividing
each of the eight divisions with the dividers.

FIG. 210. DIVIDING A CIRCLE INTO 8 OR 12 PARTS WITH TRIANGLES

DATA FOB PLATE 26

Given: Two orthographic views of a bench oil-waste cup.
Fig. 211.

Required: To draw a pattern from which the cup can be
made, or any similar object assigned by the instructor.

Instructions: Draw the two orthographic views and make a
construction similar to that shown in Fig. 209.

198

MECHANICAL DRAWING

PREPARATORY INSTRUCTIONS AND DATA FOR LETTERING

PLATE 26

The two ovals of the 8 have their major axes at 45°. The
same combination of ovals is the basic form for the 3.

FIG. 211. OIL WASTE CUP

= 33333333 323 435 3 36 3
= 88888888 1834 687 585
~ssssssssss/473 386 83

7359 3 11
.SS55SS Q 4 Q ,6 64 4 I6

= 1830 1492 123456789

FIG. 212. LETTERING PLATE 26

Given: Plate 26 to reduced size. Fig. 212.
Required: To make the plate to an enlarged scale.
The strokes for the S are given in Fig. 238.

ADVANCED DRAWING

199

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 27

If a cylindrical object is cut away at an angle, as in the case
of the elbow in Fig. 213, the end which is cut will not roll out
into a straight line. The curved line into which it will unroll
must be determined by locating a number of points through
which it passes. This may be done by drawing lines in the
orthographic view which represent elements or lines in the cyl-
indrical surface parallel to the axis of the cylinder. For con-
venience these lines should be drawn perpendicularly up from
the points located in the base circle. The length of each of these

FIG. 213. DEVELOPMENT OP CYLINDRICAL SURFACE CUT AT AN ANGLE

lines from the base up to the inclined line is the length of a cor-
responding line to be located in the pattern, because it is shown
in its true length.

Vertical lines are drawn in the pattern from the points
stepped off in the base. These lines represent the ones drawn
in the surface of the cylinder. The length of these lines may
be transferred from the orthographic view to the pattern with
the dividers or by drawing horizontal lines across from the
orthographic view as in Fig. 213. Example: Line a 7 in the
orthographic view is equal to a 7 in the pattern. Here again it
is necessary that these lengths be transferred in consecutive
order.

200

MECHANICAL DRAWING

When both ends of the cylinder are cut at an angle as in
Fig. 214, neither end will develop into a straight line. For the
purpose of determining the length of the pattern a line such as
a b must be drawn in to represent an imaginary base which is at
right angles to the axis of the cylinder. The lengths of the
division from the circular view, A, are then stepped off on a

FIG. 214. TYPE PROBLEM. DEVELOPMENT OF CYLINDRICAL SURFACE CUT AT

BOTH ENDS

line representing this imaginary base, c d, Fig. 214. The points
on the curved lines in the development are located by using this
imaginary base to measure from. If the base is centrally located
between the two cut ends, points on both curves, on any one ele-
ment, may be located with one measurement, as in the case shown
in Fig. 214.

DATA FOR DRAWING PLATE 27

Given: Two orthographic views of the objects shown in
Figs. 215, 216, and 217.

ADVANCED DRAWING

. 201

Required : To draw a pattern for one of the objects shown
in Fig. 215, 216, or 217, or any similar object as assigned by the
instructor.

FIG. 215. FLOUR SIFTER

FIG. 216. SCOOP

Instructions: D*aw the orthographic views and make a con-
struction similar to that shown in Fig. 215, 216, or 217.

202

MECHANICAL DRAWING

PREPARATORY INSTRUCTIONS AND DATA FOR LETTERING

PLATE 27

Spacing of Letters. Observe carefully the spacing of the

FIG. 217. FIVE PIECE ELBOW

STRC

)KES

^
^

— //

STRC

)KES

fi~

,£>

"=[&""

FIG. 218. LETTERING PLATE. 1, i, t, v, y

letters in the words. Correct spacing is as essential as correct
forms.

ADVANCED DRAWING 203

Given: Plate 27 to reduced size. Fig. 219.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 28

Another geometrical form commonly found in sheet metal
work is the cone. If the cone were rolled on a flat surface its
surface would come in contact with an area as shown in Fig. 220.

I I I I I I I I I I I I I I I I I I I I J =

/ / / / / / / / / / /// ill ill ill ill ill =
////////// //// //// //// // //// //z
vvvvvvvv liv vilt liv vilt till ~_

y y y y y y y y //// ivy

FIG. 219. LETTERING PLATE 27. 1, i, t, v, y

The vertex would remain at a fixed point. Since all straight
lines drawn in the surface of the cone from the vertex to the base
circle are equal in length, the base circle will unroll into an arc
with a radius equal to the true distance from the vertex to a
point in the base circle. Fig. 220. The length of this arc is
equal to the circumference of the base circle of the cone and may
be laid off by dividing the orthographic view of the base circle
into a number of small divisions as described for the cylinder,
page 197. These lengths are then transferred to the arc with
the dividers.

The pail shown in Fig. 221 is not a complete cone. It is
therefore necessary to draw a second arc to represent the circular
bottom of the pail.

204

MECHANICAL DRAWING

DATA FOR DRAWING PLATE 28

Given: Two orthographic views of the objects shown in
Figs. 222 and 223.

FIG. 220. ROLLING A COXE TO OBTAIN THE DEVELOPMENT OF ITS SURFACE

Required: To draw a pattern for one of the objects shown
in Fig. 222 or 223, or any similar object as assigned by the
instructor.

Instructions: Draw the orthographic views and make a con-
struction for the pattern similar to that shown in Fig. 221.

ADVANCED DRAWING

FIG. 221. TYPE PROBLEM. PAIL

FIG. 222. CREAM DIPPER

206

MECHANICAL DRAWING

DATA FOR LETTERING PLATE 28

Given: Plate 28 to reduced size. Fig. 225.
Bequired: To make the plate to an enlarged scale.

" FIG. 223. FUNNEL

STROKES

STRC

)KES

.. ./....

l.Tj....

= wy

— KM....

£»

/v— '

iiir/xiv."

:".^f"".

:'/

FIG. 224. LETTERING PLATE, w, k, z, x, j, f

ADVANCED DRAWING 207

PREPAEATOEY INSTRUCTIONS FOR DRAWING PLATE 29

The section of a right conical surface cut at right angles to
the axis of the cone will develop into the arc of a circle as shown

I w w w w w will wily wilt twit it ~
z k k k k k k kilt kitty z z z z z t/zl
I.X x x x x x vix xylyl viz xylyl ill f
-////' /'/' jilt Jill Jill jilt JHI jilt // =
^ffffff fizz jiffy flit fizz fifty =

FIG. 225. LETTERING PLATE, w, k, x, j, f

in the case of the bottom of the pail, Fig. 221. When the conical
surface is cut on a slant as shown in Fig, 226, the distances from
the vertex to points on the cut are not equal and therefore the cut
edge will not roll out into an arc of a circle. Points on the
curved line into which this cut edge will develop may be located
by drawing in the elements or lines in the conical surface from
the vertex to points in the base circle. These elements may be
located in the pattern by joining the vertex with points on the
arc of the base corresponding to the points in which these lines
meet the base circle of the cone.

This construction is illustrated in Fig. 227, where the points
in which the elements pass through the cut edge of the cone are
located in the development by finding their true distances on the
elements from the vertex (see horizontal lines in front view) and
transferring these lengths to the corresponding lines in the devel-
opment. This may be done with the dividers or by swinging
arcs with the compass as shown in the figure.

208

MECHANICAL DRAWING

The true lengths of the contour elements of the cone are
shown in the front view, Fig. 227, in oe and od. None of the

QKtt 10 9 6 7 ff S 4

FIG. 226 DEVELOPMENT OF A CONE CUT AT AN ANGLE TO ITS Axis

other elements show in their true length, although they are known
to be equal in length to o e and o d.

ADVANCED DRAWING

209

In order to find the distance from, the vertex to a point such
as a on an element a construction is necessary. The student
should try to fix in mind the principle on which this construction
is made, which is as follows. Since any element o c is equal in
length to o d it may be imagined turned around into coincidence
with o d by keeping the end c always in the base circle. Thus the

c at

FIG. 227. ILLUSTRATING METHOD OF OBTAINING TRUE LENGTHS OF ELEMENTS

point c moves through an arc e d. The point at the other end of
the line o c remains fixed, but any point, such as a between o
and c will move on an arc a b. Thus when o c is brought into
coincidence with o d the true length of o c is shown in o d and the
true length of any part of it, such as o a, is shown in o b. Notice
that the base circle of the cone appears as a straight horizontal
line e d, Fig. 227, and also that the arc a b appears as a straight
horizontal line in the front view of the cone. With this point
clearly in mind it will be evident that to find the length of o a it
is only necessary to draw the horizontal line ab as construction.

DATA FOB DRAWING PLATE 29

Given: The orthographic views of the objects shown in
Figs. 228 and 229.

210

MECHANICAL DRAWING

Required : To draw a pattern for one of the objects shown
in Fig. 228 or 229, or any similar object assigned by the
instructor.

Instructions: Draw the orthographic views and make a con-
struction for the pattern similar to that shown in Fig. 226.

FIG. 228. VENTILATOR PIPE

FIG. 229. SCALE SCOOP

DATA FOR LETTERING PLATE 29

Given: Plate 29 to reduced size. Fig. 231.
Required: To make the plate to an enlarged scale.

ADVANCED DEAWING

STROKES

l£

FIG. 230. LETTERING PLATE, r, h, n, m

211

r r r r r r r kirk vitrify kirts six
h h h h h h hilt whirl whist his
n n n n n n hint lynx hint lynx
m m m m mink hymn milk hint

65'- 4

FIG. 231. LETTERING PLATE 29. r, h, n, m

212

MECHANICAL DRAWING

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 30

If a pyramid were rolled on a flat surface its faces would
come in contact with triangular areas such as shown for the
square pyramid in Fig. 232. In this case there are four triangles.
For a hexagonal pyramid there would be six triangles, etc. The
length of the edges of the pyramid from the vertex to the corner
of the base are all equal. Therefore if an arc of radius equal to
their length were drawn these lines would all end in the arc. The
sides of the base of the pyramid will appear in the pattern as

FIG. 232. ROLLING A PYRAMID TO
OBTAIN THE DEVELOPMENT OF ITS
LATERAL SURFACE

I c

FIG. 233. TYPE PROBLEM. DEVEL-
OPMENT OF A SQUARE PYRAMID

chords of this arc. In the case of the square pyramid as shown
in Fig. 233, none of the edges from the vertex to the base are
shown in their true length. A construction such as that described
for finding the lengths of the elements of the cone must be made
for finding the lengths of these edges. Referring to Fig. 233r
the base of the pyramid is inscribed in a circle which corresponds
to the base circle of the cone. If the edge oc, for example, is
imagined turned as was the element of the cone, into a position
corresponding to the contour element of the cone, it will show
in its true length in the front view, o d, Fig. 233, therefore
represents the true length of the edge o c. With this length as a
radius, an arc may be drawn and the points representing the
lower corners of the pyramid may be located on it by stepping
off lengths equal to the side of the base, such as ec.

ADVANCED DRAWING

213

DATA FOB DRAWING PLATE 30

Given: The orthographic views of the object shown in
Fig. 234.

FIG. 234. END FOE GRAIN CONVEYOR

STROKES

FIG. 235. LETTERING PLATE, n, o, c, e

214 MECHANICAL DRAWING

Required: To draw a pattern for the object shown in Fig.
234 or any similar object as assigned by the instructor.

Instructions : Draw the orthographic views and make a con-
struction for the pattern similar to that shown in Fig. 233.

u u u u u u u hum tumult funny
ooooooo moon form fourth
c c c c c c c lock column corks
e e e e e e e clever come fewer
68 j' 29'-Ol" /3/j" 997' -8

FIG. 236. LETTERING . PLATE 30. u, o, e, e

PEEPAEATOEY INSTETTCTIONS AND DATA FOE LETTEEINO

PLATE 30

Curved Strokes. The major axes of the oval letters of this
plate are in the direction of the slope.

Given: Plate 30 to reduced size. Fig. 236.
Required: To make the plate to an enlarged scale.

PEEPAEATOEY INSTEUCTIONS FOE DEAWING PLATE 31

The true length of the edge of a pyramid cut at a slant is
found as previously described. Finding the true length of the
edges from the vertex to the point where the edge strikes the cut
involves the same theory discussed in connection with the pattern
for the cone, page 209, Fig. 227 The construction is also the
same.

ADVANCED DRAWING

215

DATA FOR DRAWING PLATE 31

A problem for this plate may be supplied by the instructor
if desired.

FIG. 237. DEVELOPMENT OF PYRAMID CUT AT AN ANGLE TO ITS Axis

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 31

Curved Strokes. The major axes of the ovals of this plate
make 45° with the horizontal.

DATA FOR LETTERING PLATE 31

Given: Plate 31 to reduced size. Fig. 239.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 32

Intersection of Surfaces. The objects thus far considered
have been of the form of geometrical solids. There is another
class of patterns which involves the laying out of the line where

216

MECHANICAL DRAWING

STROKES

7/7=

T/7-

STROKES

— /-

FIG. 238. LETTERING PLATE, a, d, q, g, b, p, s

z a a a a a a crank moke chairs ~
z d d d d d d round drain rods at^_
~ q q q q q quail g g g g ground ~
z b b b b b b bearing block blade ~
~ p p p p p p pipe faceplate shapes

FIG. 239. LETTERING PLATE 31. a, d, q, g, b, p, s

the surfaces of two solids meet or intersect. An example of the
intersection of two prisms is afforded in the case of the roof of

ADVANCED DRAWING

217

a house, as shown in Fig. 240. The line of intersection is the line
abc where the roofs meet. It is quite evident that this broken
line abc lies in the surface of the main roof and also in the sur-
face of the dormer roof, or, in other words, it is a broken line
which is common to both roofs. This illustrates the general defi-
nition of a line of intersection, which is as follows : The line of

FIG. 240. ILLUSTRATION OF AN INTERSECTION

intersection behveen two surfaces is the line which lies in both
surfaces. In the following" discussion of the laying but of pat-
terns of objects containing intersecting surfaces, this definition,
if kept clearly in mind, will help in grasping the principles on
which the methods are based.

In Fig. 241 is shown the orthographic view of a cylinder inter-
secting a square prism. In this case the right side view is unnec-
essary for the purpose of laying out a pattern. It is drawn to
show the method of constructing the line of intersection in this
view,. as in some cases it will be necessary to draw a view corre-
sponding to this one. It also gives a better idea of the method
by which the points on the line of intersection are located for
transferring to the pattern.

Development of the Cylindrical Surface. As in Plate 26, the
edge of the upper base of the cylinder which is at right angles
to the axis of the cylinder will develop into a straight line. The
length of this line may be determined, as before, by dividing the

218

MECHANICAL DRAWING

base circle into a number of equal small divisions and stepping
them off with the dividers. To obtain the development of the line
of intersection, elements are drawn in the surface of the cylinder,
preferably from the points already located in the base circle.
Lines are then drawn in the patterns to represent them. Their
lengths may be transferred from the orthographic views by means

Pattern for one-ha/f of cylinder) /

FIG. 241. TYPE PROBLEM. INTERSECTION OF A SQUARE PRISM AND A

CYLINDER

of the dividers or projected by horizontal lines as shown in
Fig. 241.'

The pattern for the entire surface of the prism is laid out as
in Plate 24. The hole opening into the cylinder or the line of
intersection is determined in the pattern as follows : In the front
view the lateral surfaces of the prism are s"een edgewise, and con-
sequently the points in which the cylinder strikes the surfaces
of the prism are seen in the points where the lines representing
these elements cross the lines representing the surfaces of the
prism. Example : b is the point in which the element a b of the

ADVANCED DRAWING

219

cylinder strikes the surface of the prism. If a line is drawn in
the surface of the prism, through point b and parallel to the
lateral edges of the prism, the distance of this line from the edge
of the prism may be located on the pattern. The true

FIG. 242. EOOF CAP AND VENTILATOR

•10 D-

FIG. 243. SOLDERING STOVE

length of this line, which is shown in the top view, may
be transferred to the pattern with the dividers or projected from
the orthographic view as indicated in the drawing. A similar
construction should be made for the other points on the line of
intersection.

DATA FOB DRAWING PLATE 32

Given: The orthographic views of the objects shown in
Figs. 242 and 243.

220 MECHANICAL DRAWING

Required: To draw the orthographic views and construct
patterns for the object shown in Fig. 242 or 243, or any similar
object as assigned by the instructor.

PREPARATORY INSTRUCTIONS FOR LETTERING PLATE 32

Composition. In the following composition plates the spacing
of letters and words should be given as much consideration as the
forms of the letters. The student should strive to produce a good
general effect in the plate,

Drill ^ Ream I" Bore 2" Holes
/0 Suit Motor Used End of stud
/0 be flattened and cast in part
/ Use Fillers 513 to Allow A//
Gears to Mesh Properly Head

FIG. 244. LETTERING PLATE 32

DATA FOR LETTERING PLATE 32

Given: Plate 32 to reduced size. Fig. 244.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 33

The laying out of patterns for the surfaces of two intersecting
cylinders involves the same general principles as described for

ADVANCED DRAWING

221

the intersection of the prism and cylinder in Plate 32. The base
of the smaller of the two cylinders should be divided into a num-
ber of equal parts and its surface developed as before.

The entire surface of the larger cylinder is laid out and the
points in which the elements of the smaller cylinder strike the

FIG. 245. TYPE PROBLEM:. INTERSECTION OF Two CYLINDERS

surface are located by drawing elements of the larger cylinder
through these points. The spacing of these elements is obtained
by stepping off the arcs a b, b c, etc., Fig. 245, between the points
representing these elements in the end view (top view in this
case) of the cylinder.

DATA FOR DRAWING PLATE 33

Given: The orthographic views of the objects shown in
Figs. 246 and 247.

Required: To draw the orthographic views and construct
patterns for the objects shown in Fig. 246 or 247, or any similar
object assigned by the instructor

222

MECHANICAL DRAWING

50-

Ficf. 246. EAVE TROUGH AND DOWN SPOUT

FIG. 247. FURNACE SMOKE PIPE

DATA FOR LETTERING PLATE 33

Given: Plate 33 to reduced size. Fig. 248.
Eequired: To make the plate to an enlarged scale.

ADVANCED DRAWING 223

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 34

In the preceding plates, elements were first drawn in the cylin-
der to strike the surface of the other solid. In the construction
of the intersection line between a cylinder and cone, example,
Fig. 249, elements of the cone are first drawn striking the surface
of the cylinder. This is made necessary by the fact that the cone
has a slanting surface which is not seen edgewise in any view,
consequently it is impossible to tell where elements drawn in the
surface of the cylinder strike the surface of the cone.

-2-IJX/9J Rough Round Rods z
= /-// Bolts- 6^' Long Without z
zM// &. Check Nut Connecting z
z Rod Bearing 14 - 24 Flat Head^
^Machine Screw Graphite Paint~_

FIG. 248. LETTERING PLATE 33

The elements of the cone should first be drawn in the front
view and in such a manner as to divide the circular base of the
cylinder into a number of small parts. It is evident that these
parts cannot all be equal as in the preceding problems.

Draw the top views of these same elements of the cone. This
is done for element ab by projecting from a to the base circle of
the cone in the top view to determine the foot of the element ab
in the top view, and connecting this point with the apex.

Elements should now be drawn in the surface of the cylinder
to pass through the points in which the elements of the done strike
the surface of the cylinder. Example : c in the top view is
projected from the point c in the front view.

224

MECHANICAL DRAWING

The other points on the intersection are located in the top
view in the same manner.

The surface of the cylinder may now be developed following
the usual method. Attention is again called to the fact that the
elements of the cylindrical surface are not equally spaced. It

ADVANCED DRAWING

225

will therefore be necessary to step off each division separately,
taking care to place them in consecutive order in the pattern.
The true lengths of the elements from the base to the line of inter-
section are shown in the top view and may be either transferred
to the pattern with the dividers or projected from the top view
as shown in Fig. 249.

I';G. 250. OIL RECEPTACLE

The entire surface of the arc is laid out in the pattern by
striking an arc of radius equal to the length of the elements of
the cone and stepping off on this arc a distance equal to the cir-
cumference of the base circle. On this arc are located the feet
of the elements on which points on the intersection were found,
by transferring the distances between the feet of these elements
from the top view of the base circle. The points on the line of
intersection are located on these elements by finding the true
lengths from the vertex of the cone to the line of intersection for
each element. The construction for this is described in detail on
page 209.

DATA FOR DRAWING PLATE 34

Given: The orthographic views of the objects shown in
Figs. 250 and 251.

226

MECHANICAL DRAWING

Required: To draw the orthographic views and make a
construction for the pattern of the objects shown in Fig. 250,
251, or any similar object as assigned by the instructor.

Instructions: The fact that the cylinder in Fig. 250 is larger
in proportion to the cone than in the type problem makes no dif-
ference in the principle of the problem or the method used in its
solution. It is only necessary to assume a base for the cone and a
vertex as indicated by the dotted lines.

FIG. 251. EXHAUST HEAD

In the object shown in Fig. 251, the axis of the cylinder is
parallel to the axis of the cone. The elements of the cone should
always be drawn first in the view in which the cylindrical surface
shows as a circle, which in this case is the top view.

DATA FOB LETTERING PLATE 34

Given: Plate 34 to reduced size. Fig. 252.
Required: To make the plate to an enlarged scale.

A Bill of Stock is a tabulated form, such as the bill of mate-
rial, but which gives the rough and sometimes the finished sizes
for each different piece of timber and the number of each size
required, together with a list of all other materials to be used in
the project. Such a tabulated summary makes it possible to cut

ADVANCED DRAWING 227

all stock and to calculate the cost of all materials for any project
in wood. Example : Fig. 267 shows a bill of stock for a table.

Sectional Views, Very often a drawing is not clear because
the interior of the object is complex or because a part of it is
obscured by other lines. In such cases the object may be repre-

z /' 'Drill and Ream Holes for All z
^Pieces. Spring Must Deflect 2" z
~ Factor of Safety 1, 5 Patterns z
z I j Core for Piece No. 640139 =
= j' Chain (277 Links) Material z

FIG. 252. LETTERING PLATE 34

sented more clearly if a portion of it is imagined cut away to
expose the hidden part. The most common examples of this
method of representation are: (1) half -section in which the
object is cut into two similar parts through an axis of symmetry,
and (2) quarter-section in which the object is cut in to the center
on two planes at right angles. These sections are described in
detail on pages 98 and 99 and illustrated on page 94.

Other methods of sectioning may be used, depending upon the
form of the object or part which it is desired to make clear. Fig.
253 illustrates a case where the section is taken on a broken line,
A 0 B. In drawing the section view, the cut surface 0 A is con-
sidered revolved into the same plane with O B. Fig. 254 illus-
trates what is called a partial section. The ragged line indicates
that a part of the shaft has been broken away.

The cross-section of an object is often given by showing a

228

MECHANICAL DRAWING

revolved section in one of the views, Fig. 255 or 265. Where the
section cannot well be revolved a line may be drawn across the
view of the part at the place where the section is taken and the

Section on AOB

FIG. 253. BROKEN LINE SECTION

TIG. 254. PARTIAL SECTION

section drawn in an open space near the view. Reference should
be made to the line on which the section is taken. Fig. 256. Such
parts as spokes or arms of wheels, solid shafts or rods, screws,
bolts, studs, and nuts are not represented as cut when the section
plane passes through their axes. Fig. 257. Ribs and webs are

ADVANCED DRAWING

229

not sectioned when the section plane is parallel to their lateral
faces.

When a section is taken through an assembly, adjacent parts
are crosshatched in different directions to aid in distinguishing
one from another.

FIG. 255. REVOLVED SECTION

Various combinations of lines are used to represent sections of
different materials. No standard section notation has ever been
universally adopted. It is customary to add a note giving the

Section A A

Sec f /on 63

FIG. 256. REMOVED SECTIONS

name of the material unless a local section notation is in use.
Except for a few cases where it is desirable to distinguish between
the metals in adjacent parts, such as the babbit and the casting
of a bearing, nothing is gained by using characteristic section
lines since, in general, a note must be added to insure proper
interpretation. Fig. 258 shows a few sections in common use.

Breaks. Where it is desirable to omit part of a shaft or rod,
either may be broken and the break indicated as shown in Fig.

230

MECHANICAL DRAWING

FIG. 257. SECTION THROUGH RIBS, SHAFTS, BOLTS, ETC.

CAST IRON CAST STEEL WROUGHT IRON BRASS

BRICK

CONCRETE

LEATHER

WOOD

FIG. 258. CONVENTIONAL CROSS-SECTIONING

ADVANCED DRAWING

231

259. The ragged line representing the break is drawn freehand
in both the pencil and the ink drawing.

f?ecfangv/ar Gar

ftecfangu/ar Sec f ton -Weed

found

or Ho/Jovr Shaft

I Bean? Channef Ang/e

FIG. 259. CONVENTIONAL BREAKS

Z-Bar

Wood Screws are made of steel or brass. They have heads of
various shapes as shown in Fig. 260. The size of screws is given
in terms of their number and their length, which is indicated by
giving the gage number. The threads of wood screws are repre-
sented conventionally as shown in Fig. 260.

Furniture and Cabinet Details. Various joints and a few
other common constructions used in furniture and cabinet con-
struction are shown in Figs. 261 and 262.

FIG. 260. CONVENTIONAL EEPRESENTATION OF WOOD SCREWS

FURNITURE AND CABINET PROBLEMS
PEEPAEATOEY INSTEUCTIONS FOE DEAWING PLATE 35

The problems for this plate were selected with the idea of
giving practice in drawing and dimensioning projects in furni-
ture making and also to set before the student typical examples

232

MECHANICAL DRAWING

6/uec/ anct Stocked
FIG. 261. JOINTS

Dade and ffabbef

Dado. Tongue t

ftav/iched M0rf/se ar?d Tenor?

FIG. 262. JOINTS

(233)

-<^M

•*~.9-.g'
te-2 -

I - II II

-.'

Ld
CQ

^Drawer 6 'vide,

_J 2"L_ Section on MN

Qefa/1 of Drawer

MIL

(236)

FIG. 265. MACHINE SHOP BENCH

ADVANCED DRAWING

237

u 1

M H>

'Oetet/of Joint at B

PIG. 266. PHONE TABLE AND CHAIR

238

MECHANICAL DRAWING

BILL: OF STOCK ]

-|CU

-I" ^

*.
, c
L_

4 ^

PCS

"SIZE

NAME

MATERIAL

M".FT.

FE.R.FT

TOTAL

c
tf

I"X 3p'X4ft"

TOP

OAK

^.1E

[jjo

£.\

fx5|x4)£

RAILS

3.5

>! ?

I'xsgxzsf'j •'

2.16

••

,ee

f'x3"xa5|"

, .,

COS

.13

4
Z

|^~|-

SLAT.3

,94

'•"

4k2i«o4-

LEGS

^ ^25" ^

^X4"xa5"

DRAWtR

2.08

.Z5

L^Jl^^±

j"X4uxa41'

J67

.08

fxaa^xgs'

DRAW. BOT.

PINE.

4.80

X»45

:is

oi« ^ \i X 1

Defa/i of Draiver

r'^a'xas"

DftAW. GUIDE

DAX

£9

.ia

IOB-:

;*H. TOTAL COST

3;8e

FIG. 2G7. LIBRARY TABLE

ADVANCED DRAWING

239

of furniture construction. In order to cover this field as thor-
oughly as possible, two type problems of widely different char-
acter are presented. Figs. 263 and 264. The student should fix

Crossbcu

Minge Joftrf of BacA

Defy// ef Jo/nf af A Section of front

jil/y/hf and Corner at Q

FIG. 268. MORRIS CHAIR

in mind the correct proportion of the joints used in these prob-
lems as well as their names and uses by referring to the discussion
and figures on pages 231, 232, and 233.

240 MECHANICAL DRAWING

DATA FOR DRAWING PLATE 35

Given: The perspective sketch of the object shown in Fig
265, 266, 267, or 268.

Required: To draw the orthographic views of the object
shown in Fig. 265, 266, 267, or 268, or any similar problem as
assigned by the instructor.

3°

~ Groove R in finished face,

ll for • Split Cotter. 1914-15=

= A// Fillets j. R Unless Otherwise^
~ Specified Key for 9" Spur Gear::
- lxQ Stud Bolt Nut, 1915-16=

FIG. 269. LETTERING PLATE 35

The problems for this plate are designed to give practice in
making working drawings for various kinds of cabinet work and
to familiarize the student with typical cabinet construction.

DATA FOR LETTERING PLATE 35

Given: Plate 35 to reduced size. Fig. 269.
Required: To make the plate to an enlarged scale.

DATA FOR DRAWING PLATE 36

Given: The pencil mechanical drawing, Plate 35.
Required : To make a tracing of Plate 35.

ADVANCED DRAWING 241

DATA FCR LETTERING- PLATE 36

Given: Plate 36 to reduced size. Fig. 270.
Required: To make the plate to an enlarged scale.

- Moke Oil Tight Drill for No, I6~

~ Standard Flat Head Machine

I"
z Screw, 3<? Lock Nut Washer z

z These Holes in Piece No, 64181, z
~On/y Drawing No, 166, Piece z

FIG. 270. LETTERING PLATE 36

DATA FOE DRAWING PLATE 37

Given: The orthographic views of the objects shown in
Fig. 273, 274, 275, or 276.

Required: To draw to large scale two views of objects
shown in Fig. 273, 274, 275, or 276, with sections and details of
joints and paneling; or any similar problem assigned by the
instructor.

§1

-./•

~\ r

\ \
\ (
\

\ \

\ \
\ t
\ !

\
\ \

244

MECHANICAL DRAWING

FIG. 273. GLUE BENCH

F.IG. 274. CABINET FOR DRAWING EOOM

f-J

FIG. 275. CABINET FOR CLOT

1 V> I

HES PRESS U /3~ — +•

, > t±

•r T-|lrT— *' f • -11 : - +

^nu+ >"+

-t- 4

4 4

4^
i

^
i

*-V-

"H
c

(1
_s_

>*
i

L
^

4- 4-

< 2~/l " •>•

i-^'rfd

1 •»!•!

FIG. 276. CHIFFONIER

246 MECHANICAL DRAWING

DATA FOR LETTERING PLATE 37

Given: Plate 37 to reduced size. Fig. 277.
Required: To make the plate to an enlarged scale.

~ Round Point Set' Screw -Brass=L

~l Required Top 2 Special ~

Threads per I" Bottom
Spring Plate Brass -Finish -/
Required, Outside Finish All Over

FIG. 277. LETTERING PLATE 37

DATA TOR DRAWING PLATE 38

Given : The pencil mechanical drawing for Plate 37.
Required: To make a tracing of Plate 37.

DATA FOR LETTERING PLATE 38

Given: Plate 38 to reduced size. Fig. 278.
Required: To make the plate to an enlarged scale.

ADVANCED DRAWING 247

MACHINE DRAWING

A Bill of Material may be given on the drawing or on a sep-
arate sheet. It is a tabulated form in which such information as
the following is given :

1. Number of each part required on one complete machine
or structure.

z A careful study of the form
proportion of each letter
be made before the stu- z
can hope TO make any conE.
^siderable progress in lettering

FIG. 278. LETTERING PLATE 38

2. Description or name of piece.

3. Mark or number by which a piece is designated on the
drawing.

4. General drawing number.

5. Shop drawing number.

6. Erection drawing number.

7. Material from which each piece is made.

8. Pattern number if cast.

9. Where used.

10. Estimated weight.

11. Order number.

248

MECHANICAL DRAWING

, Y _ ^ ^ Y

~/"

-p

9 "

< — j2 — >•

•

Swing Arm

-h

CJ.

Shie/d P/ate .

W.I,

Feed Lever Latch Pin

W.I.

Reach ftcd

W.I.

Thumb Latch

C.I.

Feed Lever

C.I.

DETAILS

FOR
OHIO MONARCH SHREDDER

34 | 359 | A.6.S.

SCALE-HALF SIZE

FIG. 279. BILL OF MATERIAL

FIG. 280. CONSTRUCTION OF THE HELIX

The bill of material includes standard parts such as bolts and
screws which are not detailed on the drawings. A simple bill of
material is shown in Fig. 279.

ADVANCED DRAWING

249

$crcw Threads. The curve of the screw thread is the helix.
It is generated by a point which moves on the surface of a cylin-
der and which advances uniformly in the direction of the axis of
the cylinder and at the same time has a uniform motion around

US. STANDARD

SQUARE

ACME.

60°-y Taper^ "per inch of /e firth

•« — 4- Threads
/mperfecf

/? Threads
Ft///af roof

t .8 outside d/am. -t-4.8

Number of threads per inch

Compete threads -F/at tops —Sharp bottoms

BRIGGS STANDARD PIPE THREADS -MODIFIED

FIG. 281. PROPORTION OF COMMON THREAD FORMS

its axis. Fig. 280 shows the construction for the helix. The dis-
tance in the direction of the axis traversed by a point in one revo-
lution is called the pitch. Pitch in the case of a thread is its
advance in the direction of the axis in one revolution.

In Fig. 281 the proportions of the several common thread
forms are shown to a large scale.

250

MECHANICAL DRAWING

The V-thread is shown in Fig. 282 as it would actually appear
with the edges drawn as helices. On account of the difficulty of
constructing and drawing these curves they are usually conven-

FIG. 282. V-THREAD, SHOWING HELICES

tionalized into straight lines as shown in Fig. 283. The method
commonly used for representing screws up to about one inch in
diameter, as measured on the drawing, is still further simplified
by omitting the short inclined lines forming the "saw teeth."

ADVANCED DRAWING

251

Fig. 284. On the pencil drawing no distinction is made in the
weight of the two sets of parallel lines drawn across the screw,
but on the tracing it is customary to make a striking contrast
between the longer and shorter lines as shown.

FIG. 283. V-THREAD. CONVENTIONAL EEPRESENTATION FOR LARGE SIZES

In this course the shorter lines will be made object-line width
and the longer lines center-line width. The angle at which these
lines are drawn is estimated. It remains practically constant for
all sizes of standard screws as the pitch of the thread increases
with the diameter of the screw. It will be noted that the lines in
the section view of the nut make the opposite angle to the hori-
zontal that those on the screw make because of the fact that the

252

MECHANICAL DRAWING

part of the nut shown matches the invisible half of the screw. The
lines are usually spaced by eye. Guide lines should be drawn to
limit the length of the shorter lines.

In the conventional end view of the bolt, the circle represent-
ing the outer edges of the thread is a full line, while one-half of
the circle representing the inner edges of the thread is a dotted
line and the other half is a full line.

FIG, 284, V-THREAD. CONVENTIONAL REPRESENTATION FOR SMALL SIZES

In the conventional end view of the nut, the circle represent-
ing the inner edges of thread is a full line, while one-half of the
circle representing the outer edges of the thread is a dotted line
and the other half is a full line.

A study of the relation of these conventions to the form of
the object should enable the student to fix in mind the principles
on which they are based. With this relation in mind it will be
unnecessary for him to refer to the figures in rendering the
convention.

The United States Standard (U. S. S.) or Sellers thread,
Fig. 281, differs from the sharp V-thread in that the outer and
inner edges of the thread are flattened. The same convention
is used for representing it that is used for the sharp V-thread.

ADVANCED DRAWING

253

The Square Thread is shown in Fig. 285 with the edges drawn
as helices. Fig. 286 is a conventional representation of the screw
and nut in which the helices have been replaced by straight lines.

FIG. 285. SQUARE THREAD. EDGES DRAWN AS HELICES

For small sizes, the' method shown in Fig. 287 is generally
used because of its simplicity. The Acme screw thread is rep-
resented conventionally as shown in Fig. 288. It is convenient
in drawing to make the angle between the faces of the thread
30° instead of 29°.

FIG. 286. SQUARE THREAD. CONVENTIONAL EEPRESENTATION FOR LARGE

SIZES

FIG. 287. SQUARE THREAD. CONVEN-
TIONAL REPRESENTATION FOR SMALL SIZES

(254)

FIG. 288. ACME THREAD. CON-
VENTIONAL EEPRESENTATION

ADVANCED DRAWING

255

Pipe Thread. The basic form of the Briggs standard pipe
thread is that of the V- thread. This thread is 'rounded slightly
at the outer and inner edges. A modified form in which the
threads have flat outer edges and sharp inner edges is shown in
Fig. 289. This form is used by manufacturers because of the
comparative ease with which taps and dies are made for cutting
the threads.

FIG. 289. PIPE THREADS. CONVENTIONAL REPRESENTATION

The threaded portion of the pipe tapers one thirty-second
of an inch in radius for each inch of length.

Pipe threads are represented conventionally as shown in
Fig. 289.

Springs. The curve of the coil spring is the helix. Fig. 290
shows a spring in which the curves are drawn and also the
conventional representation which shows the curves replaced by
straight lines.

Bolts and Nuts. A bolt consists of a rod with a head on one
end and a screw on the other to receive a nut. Fig. 291. What
are known as United States Standard bolts and nuts are shown

256

MECHANICAL DRAWING

in Figs. 292 and 294. The proportions given by the formulae are
those adopted for rough bolts and nuts. The finished nuts are
3JV less in width and thickness than the rough nuts. The fin-

FIG. 290. COIL SPRING SHOWING ACTUAL AND CONVENTIONAL
REPRESENTATION

BOLT CAP 5CBEW STUD STUD BOLT

FIG. 291. COMMON SCREW FASTENINGS

ished heads have the same sizes as the finished nuts. A table of
standard sizes may be found in an engineering handbook.
United States Standard threads are used on these bolts.

h-vH

FIG. 292. ACTUAL PROPORTIONS.
HEXAGONAL HEAD — U. S. STANDARD
BOLTS AND NUTS

FIG. 293. CONVENTIONAL REPRE*
SENTATION. HEXAGONAL HEAD — U.
S. STANDARD BOLTS AND NUTS

FIG. 294. ACTUAL PROPORTIONS. FIG. 295. CONVENTIONAL REPRE-

SQUARE HEAD — U. S. STANDARD SENTATION. SQUARE HEAD — U. S.

BOLTS AND NUTS STANDARD BoLts AND NUTS

(257)

258 MECHANICAL DRAWING

Figs. 293 and 295 show the conventional methods of repre-
senting hexagonal and square bolt, heads and nuts. Hexagonal
heads and nuts are usually drawn to show three faces, whereas
square heads and nuts are drawn to show two faces. When this
is done the hexagonal forms are easily distinguished from the
square forms.

Since the proportions of the head and nut of standard bolts
are fixed, it is only necessary to give three dimensions, viz., the
length of the bolt under the head, the length of the threaded
portion, and the diameter.

A Stud is a rod threaded at both ends. One end is screwed
into a threaded hole. The other end receives a nut. In Fig. 291
a standard nut is used.

A stud placed through two unthreaded holes with a nut at
each end is called a stud bolt. Fig. 291.

Cap Screws are similar in form to bolts. They hold two
parts together by passing through an unthreaded hole in one
and a threaded hole in the other. Fig. 291. Heads of various
forms are used as shown in Fig. 296.

Machine Screws are similar to cap screws in form. They
differ from them by being measured in decimals instead of even
fractions of an inch.

Tap Bolts have the same form as cap screws except that they
are not finished before threading, are threaded for their full
length, and are used for rough work.

Set Screws are used ordinarily to prevent relative motion of
two parts such as a pulley and shaft. The screw is passed
through a threaded hole in one part and the point is forced
against another part. The proportions of the set screws and the
shapes of the different points are shown in Fig. 297.

Multiple Threads. It is sometimes necessary to increase the
distance traversed by a nut in one revolution. If a coarse
enough single thread is used to give the advance required, the
strength of the bolt may be considerably diminished. To obviate
this difficulty, more than one thread may be cut side by side,
The advance for one revolution of a multiple thread is commonly
called the "lead," and the pitch is the distance between corre-
sponding points on two successive threads. Figr. 298. The con-

FLAT FILLISTER OVAL FILLISTER

FLAT COUNTERSUNK OVAL COUNTERSUNK

BUTTON

END FOR ALL

* !

u
u

. 1*

I 1A
1 ift
Hlifl
U U

u k

H
li

H
1A

11
I

H U

,032
.040
,064
.072
.091
.102
.114
.114
.128
.133
.133
.165

lA
H

A|H

AH
i H

tt|U
AH
M-.

L M

,040
,064
072
,102J
114 A
114
128
,133
133
,133

.035&
.051JA

• 072|

.oeiJA
.102! A

•IHJA

ii4ji

-H4!^

•isaA

.133.1

FIG. 296. VARIOUS FORMS OF CAP SCREW HEADS

(259)

260

MECHANICAL DRAWING

ventions for multiple threads are distinguished from those for
single threads by increasing the angle of the cross lines

. cf'O/a at bottom.
-L of rfiread.

Regular tewHead Necked Head/us Cup HatfifOf Round Pivof

FIG. 297. SET SCREW HEADS AND POINTS

Single L.H.

Sing/eftrt ! Double FtH * Doubfe RH. Single U*

FIG. 298. CONVENTIONAL REPRESENTATION OF MULTIPLE THREADS

and by a note indicating the kind of threads as double, triple,
quadruple, etc.

ADVANCED DRAWING

261

Methods of Indicating Finish. Where and how a part is to
be finished may be shown by symbols or notes, or both. In case
a hole is to be bored, drilled, reamed, cored, etc., a note is usually
made in connection with the dimension figure. Fig. 299. A
cylindrical surface to be turned, ground, polished, rough finished,
etc., may have the method of finishing indicated in the same way.
In case all surfaces of the object are to be finished and the method
can be left to the workman's judgment, a note may be made:
FINISH ALL OVER. Where only certain surfaces are to be finished,

FIG. 299. METHODS OF INDICATING FINISH

the character f may be placed across the lines which represent
these surfaces viewed edgewise. Fig. 299.

While the indication of finish is a very small part of a draw-
ing, it is nevertheless a very important detail. The omission of a
finish mark may mean the making of a large number of castings
from a pattern on which no stock has been allowed for finish.

SKETCHING FROM THE OBJECT

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 39

Freehand sketches may be made by a designer to get an idea
of the form of certain parts in working out his design. A
designer or chief draftsman may use them as a means of con-
veying his ideas to a junior draftsman.

262 MECHANICAL DRAWING

In case a machine is broken, time may often be saved by
sketching the broken parts in the shop and having parts made
to replace them instead of sending to the manufacturer of the
machine for repairs. When a change of design is contemplated
and the original drawings are not to be had, sketches of the
parts affected may be made from the existing machine and the
desired changes incorporated in the mechanical drawing made
from sketches. When time permits and it is desirable to have
.a permanent record of the drawing a mechanical drawing should
Jbe made from the sketch, but in an emergency the sketch, if
carefully drawn and checked, may be used as a shop drawing.

In making the orthographic sketches of Chapter II, the fact
that certain views of the object were shown in correct proportion
and were dimensioned made the task of drawing the other views
of the object to larger scale a simple process.

The drawing of orthographic sketches from dimensioned per-
spective sketches, Chapter III, increased the difficulty of selecting
and arranging the views, and to some extent, the dimensions.

Compared to sketching from orthographic and perspective
views the average beginner will find the making of an ortho-
graphic sketch from the object a rather intangible problem. He
will find it difficult to represent in outline an object which to the
eye stands out in relief in light and shadow. At the same time
he must keep in mind the fact that only two dimensions can be
represented in each view. He is, also, confronted with the neces-
sity of establishing center lines, datum lines, etc., which are not
edges of the object but are of prime importance in the drawing.

He must select dimensions to show the proper relation between
the details of the object. These dimensions must also be selected
to show similar distances on parts which are fitted to the object.
He must use his judgment as to the accuracy with which each
measurement should be made, as to the allowance for inaccuracies
of workmanship, inaccuracies inherent in the process of manu-
facture, etc.

Selecting Views. In selecting the views of an object to be
drawn, the principles developed in previous chapters should be
used. In general only necessary views are drawn, but in the
sketch additional views, partial views, sections, etc., may be

ADVANCED DRAWING 263

drawn in preference to complicating the necessary views with
lines.

Methods Used in Drawing. After an inspection of the object
and after a decision has been reached as to what views are to be
drawn, the student should place the object, if it is removable, so
that he can obtain the required views without changing its posi-
tion. Very often the shifting of the object leads to errors in the
relative position of the views, such as placing the left side view
to the right instead of to the left of the front view. With the
object always in the same position and the principles as to rela-
tion of views, developed in former chapters, well in mind, such
errors are not likely to occur. The views should show the object
in as good proportion as can be obtained without scaling it. Time
should not be wasted in taking dimensions at this stage arid
attempting to lay them out to scale.

The first step in the construction of the drawing is to locate
center or other reference lines. Circles should be constructed by
first drawing two center lines at right angles. The radii should
then be estimated from the intersection on these lines, and the
circle drawn through the four points located.

If the object is of cylindrical form, it will usually be found
advantageous to draw the circular view first because of the ease
with which the other views may be drawn by projecting the
diameters from the circular view. In some cases where the views
of the details of the object are interdependent, it will be necessary
to construct two or more views simultaneously.

The use of the coordinate paper greatly facilitates the align-
ment and proportioning of the details in different views. The
student should learn to use the ruled lines merely as a guide
in locating and proportioning the views. The use of the squares
as units of measurement for the purpose of drawing the object
to scale is not to be considered ; for while it is admitted that their
use will aid in proportioning the drawing, it is not one of the
functions of a freehand sketch to show the object in accurate pro-
portion, and the counting of the squares entails a serious waste "of
time.

Selection and Arrangement of Dimensions. When the views
of the object are compete and have been checked carefully to

264 MECHANICAL DRAWING

make sure that they, together with necessary supplementary
notes, fully represent the object, the question of dimensioning
should next be considered.

To dimension an object properly the draftsman must have
some knowledge of the process through which it must go in the
shop to become a finished product. If it be a casting he must
know what dimensions the patternmakers will use in making the
pattern ? if it has finished surfaces he must know with what
machines each is finished and give the dimensions in such a way
that the machinist may use them directly. Example : The diam-
eter of a part to be turned in the lathe should be given rather
than the radius, since the most convenient and accurate method
of measuring a cylindrical surface is by means of the caliper or
micrometer.

Enough dimensions should be given to determine completely
the sizes and relation of the details of the object. When a sketch
is made at some distance from the place at which it is to be used
either to furnish information for a mechanical drawing or as a
shop drawing, the draftsman must be sure that all necessary di-
mensions are given. However, he should guard against giving un-
necessary or useless dimensions in an attempt to avoid omitting
necessary dimensions. All finished surfaces, special fits, etc.,
should be marked in such a way that they cannot be misunder-
stood. The nature of the sketch admits of a freer use of explan-
atory notes than would be tolerated on the mechanical drawing.

Details which are required to be accurately located on the
object should be referred by dimensions to center lines or finished
surfaces. As the dimensions to be given are planned, the exten-
sion and dimension lines should be drawn, but the dimension
figures should not be inserted until all such lines are drawn.

When the extension and dimension lines are drawn the arrow-
heads should be made.

MEASUREMENTS

265

MEASUREMENTS
MEASURING INSTRUMENTS

The following paragraphs contain a short description of the
more common tools used in taking measurements from the object
for the purpose of dimensioning a sketch.

The Folding Rule. Rules are made of various lengths which
may be folded and carried in the pocket. The smallest divisions
are usually -j^" and TV'. Their construction makes the division
into smaller fractions of an inch unwarrantable as these rules
cannot be depended upon to read accurately to smaller units.

FIG. 300. FOLDING RULE

A two-foot rule will be found very serviceable where accuracy is
not required. While convenient in measuring long distances,
they are in general suitable only for rough work. Fig. 300.

The Steel Tape. SteeJ tape may be had in lengths of 3 feet to
200 feet or more. As in the case of the rules, their divisions are
coarse and cannot be used for accurate measurements. Fig. 301.

The Steel Scale. For accurate measurements steel scales are
used. These scales may be had in lengths of 1" to 72", and with
various combinations of graduations on the two edges of each
side. The most common graduations are J", ^", 3*5", ST"» an^
Tfo". Fig. 302.

The Adjustable Square. Fig. 302 shows a square in which
the blade is adjustable in the stock. The blade is an ordinary

266

MECHANICAL DRAWING

steel scale with a groove made to receive a hook which serves to
clamp the blade in the stock. The stock is furnished with a level.
This instrument will be found useful in many ways.

FIG. 301. STEEL TAPE

u ' 01

FIG. 302. ADJUSTABLE SQUARE

Calipers. Calipers are used for obtaining measurements of
length or diameter where the scale cannot be applied directly.
After they are set to the distance which is to be measured they
are placed upon a scale and the distance read. Fig. 303 shows
two forms of calipers, one adapted to outside measurements, such
as diameters of shafts, etc., while the other is best suited to inside
measurements, such as the diameter of holes.

Other Devices, such as the plumb bob, straightedge, and sur-
face gauge, may be of occasional use in taking measurements
from the object.

MEASUREMENTS 267

TAKING MEASUREMENTS

Having drawn the dimension lines, extension lines, and arrow-
heads, there remain the taking of dimensions from the object and
inserting them on the drawing. In doing this, judgment must be
exercised in determining with what degree of accuracy each
measurement should be taken. Examples: Dimensions between
rough surfaces usually need not be given closer than the nearest
•jV or 3*2", while the inside diameter of the bushing in which a

FIG. 303. INSIDE CALIPER. OUTSIDE CALIPEB

shaft is to run would probably be given .003" or .004" larger
than the diameter of the shaft.

Judgment must also be exercised in determining whether
irregularities such as the uneven thickness of castings, lack of
symmetry, apparent discrepancies in spacing of holes, etc., are
intentional and essential to the design and construction of the
object, or whether they are non-essentials which have come about
through natural causes in the process of manufacture or poor
workmanship, and should be eliminated from the drawing.

The problems arising in the taking of measurements from the
object are so varied that no attempt will be made here to discuss
the subject fully. However, a few examples may be given which
will illustrate the use of the measuring instruments and also the
general principles involved in securing dimensions.

268

MECHANICAL DRAWING

The distance between points on the same plane surface such
as the distance between two parallel edges of the surface and the

FIG. 304. MEASURING A LINEAR DISTANCE WITH THE SCALE

FIG. 305. MEASURING A LINEAR DISTANCE WITH THE SQUARE

length of cylinders may be measured directly with the rule or
steel scale, as shown in Fig. 304. This method is only applicable

MEASUREMENTS

269

for accurate measurement when the corners are sharp. When
the corners are rounded, the same dimension may be obtained by
using the square or caliper, as shown in Fig. 305 or 306.

FIG. 306. MEASURING A LINEAR DISTANCE WITH THE CALIPER

FIG. 307. READING THE CALIPER MEASUREMENT FROM THE SCALE

The use of the square here needs no explanation. The caliper
must be set very carefully so that its points touch both surfaces
between which the distance is to be measured, but not with

270

MECHANICAL DRAWING

enough pressure to spring the caliper. The proper adjustment is
obtained by means of the thumb screw on the adjustable caliper
or by tapping the leg against a solid object in the case of the
plain caliper. The distance between the points of the caliper is

FIG. 308. MEASURING THE DIAMETER OF A CYLINDER WITH THE CALIPER

measured with the steel scale, as shown in Fig. 307. Note that
one point of the caliper rests against the end of the scale so that
the operator's attention may be given entirely to reading the
scale division at the other point

FIG. 309. MEASURING THE DIAMETER OF A HOLE WITH THE CALIPER

The outside caliper is used in obtaining dimensions of curved
surfaces. See Fig. 308. It is adjusted and the measurement
taken from the scale as previously described.

The inside caliper is used in measuring the diameters of holes
and the openings between surfaces where the scale cannot be
applied. Fig. 309. Measurements are obtained from the inside

MEASUREMENTS

271

caliper by placing it over the scale, as shown in Fig. 310. Note
that the scale is placed against a smooth surface and at right

FIG. 310. BEADING MEASUREMENTS FROM THE INSIDE CALIPER

FIG. 311. MEASURING THE CENTER TO CENTER DISTANCE OF EQUAL HOLES

angles to it. One point of the inside caliper is placed against the
smooth surface. By this method the scale division opposite the
other point may be easily and accurately read.

272

MECHANICAL DRAWING

When, as is very often the case, it is necessary to locate
centers of holes with reference to each other or with reference to
some finished surface or datum line, a difficulty arises from the

l&fit

Utl-'t u!//'f-R

FIG. 312. TYPE PROBLEM. CYLINDER HEAD. FREEHAND SKETCH

fact that a center line does not exist on the object and must be
established or the dimension obtained in a roundabout way.

In the case of two holes of equal diameter, the center-to-center
distance may be obtained by measuring from the near edge of
one to the far edge of the other. Fig. 311. The center-to-center
distance of holes of unequal diameter may be obtained by meas-
uring from the near edge of one to the near edge of the other and
adding one-half the diameter of each. The distance from an edge
or surface to the center of a hole may be had by adding one-half
the diameter of the hole to the distance from the edge or surface
to the near edge of the hole.

Fig. 311 shows an object the form of which makes it necessary
to use the caliper in measuring the distance between the centers

MEASUREMENTS

273

of the two holes. The corners of cast parts are usually rounded
or filleted. The radii of these curves are not easily measured, but
usually it is unnecessary to measure them accurately. The radii
of small fillets may often be estimated entirely by eye or the
scale held against the object at one point of tangency and the
radius estimated by placing the thumb nail at the division on the

FIG. 313. TYPICAL OBJECTS FOR FIRST DRAWING FROM MODEL

scale opposite the other tangent point. A very satisfactory
method applicable in some cases is to place the object over a sheet
of paper and trace around the corner or fillet with a sharp pencil.
The center of the arc thus obtained may be found by trial with
the dividers and the radius measured.

Checking. Where a number of detail dimensions have been
taken which make up the length of a larger detail or the whole
length of the object, this over-all dimension should be checked
by direct measurement as well as by addition of the detail
dimensions.

DATA FOB DRAWING PLATE 39

Given : A simple machine part or model preferably finished
all over. Fig. 313 shows typical objects for this plate.
Required: To make a freehand orthographic sketch.

274 MECHANICAL DRAWING

Instructions: The following is a brief summary of the steps
arranged in sequential order to be taken in making a sketch from
the object. It is believed that by carefully observing the steps
of this outline the draftsman will be able to make the sketch com-
plete and accurate with a minimum amount of effort, and to do
the work in the least amount of time.

1. Select views.

2. Draw views (proportioning details by eye without taking
dimensions).

8. Plan dimensions — draw dimension and extension lines.

4. Draw arrowheads.

5. Take dimensions from the object and place figures.

6. Mark finished surfaces.

7. Print all notes, including the name of the part drawn, the
number required, and the material from which each part is to be
made.

: For convenience in forming
.the letters they are divided into
.strokes, Three things should be
remembered about the strokes
.for each letter, (I) the number- :

FIG. 314. LETTERING PLATE 39

DATA FOR LETTERING PLATE 39

Given: Plate 39 to reduced size. Fig. 314.
Required: To make the plate to an enlarged scale.

MEASUREMENTS 275

DATA FOB DRAWING PLATE 40
Given: The orthographic sketch. Plate 39.
Required: To make a mechanical drawing from Plate 39.

\of strokes (2) the order in wh/ch
'.they ore made (3) the direction
.in which each stroke is drawn,
: Second only in importance to
.the forms of the letters is their

Fi«. 315. LETTERING PLATE 40

^relation to each other, The finals:
litest of good spacing is legibility. ~
z All strokes should be made z
ZI/K///? the hand and arm in th& ~
"Lsame position. 123456789''.

FIG. •?"*?. LETTERING PLATE 41
DATA ?OE LETTERING PLATE 40
Given: Plate 40 to reduced size. Fig. 315.
Required : To make the plate to an enlarged scale.

276 MECHANICAL DRAWING

DATA FOE DRAWING PLATE 41

Given : The mechanical drawing, Plate 40.
Required: To make a tracing from Plate 40.

Fio. 317. TYPICAL MODEL OF COMPLETE MACHINE

DATA FOB LETTERING PLATE 41

Given: Plate 41 to reduced size. Fig. 316.
Required: To make the plate to an enlarged scale.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 42

The model for this plate should be a complete machine or
some unit of a machine which is composed of several Darts. The

MEASUREMENTS

277

parts of the model then can be divided into several groups and
each group assigned to a student.* Fig. 317 shows a typical
model, the parts of which are divided into groups. Fig. 318. The
detail drawihgs of this model will be used later (Plate 48) in
making an assembly drawing.

FIG. 318. SHOWING GROUPS OF PARTS OF MACHINE FOR ASSIGNMENT

DATA FOR DRAWING PLATE 42

Given : A part or group of parts of a machine.

Required: To make an orthographic sketch of each part
assigned by the instructor.

Instructions: In making the sketches proceed according to
the steps outlined for Plate 39.

More than one part may be drawn on each sheet, provided the
views are not too small or crowded too closely together.

In drawing and dimensioning these objects the student should
check each detail with the parts which are related to it or depend
upon it in any way.

Note should be made of the name of each part, the number
required, and the material from which it is made.

* This plan gives best results when there are from 3 to 6 students
working on each model.

278 MECHANICAL DRAWING

DATA FOR LETTERING PLATE 42

Given: Plate 42 to reduced size. Fig. 319.
Required : To make the plate to an enlarged scale.

z Shifting of the arm to obtain z
^advantageous positions for draw=
^Ling strokes in different direct- z
~/of?s AS a habit which will never z
i lead to rapid production of z

FIG. 319. LETTERING PLATE 42

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 43

When making the mechanical drawing, all of the parts in each
group should be drawn on one sheet if possible. The arrangement
of the views should be such as to make the best use of the space
available, and at the same time produce a pleasing effect for the
sheet as a whole. This will require careful study. The solution
will depend largely on the draftsman 's judgment. In general, it
may be said that the distance between views of different objects
should be greater than that between views of the same object.
The enclosing rectangles for each view may be drawn lightly to
make sure that sufficient space has been allowed for the drawing
of all parts before drawing the views, or better yet, a rectangle
equal in size to the enclosing rectangle for the ^ Jews of each part
may be cut from paper and moved about until the best possible
arrangement is secured.

Before starting to plan the arrangement of the sheet, the areas
occupied by the bill of material and the title block should be laid
out. The bill of material as shown in Fig. 279 contains the

MEASUREMENTS 279

reference figure corresponding to the one placed near the views
of the object, the name of the object, the number required, and
the materials from which it is made. The width of the bill of
material is equal to the width of the title block, and the height
depends upon the number of parts to be listed. See Fig. 279 for
detail dimensions.

In some shops the information referred to above is given for
each part near the views of that part and is called a sub-title.

The title for a sheet containing the drawings of several parts
must be a general one in which the word ' ' details ' ' usually takes
the place of the name of the part drawn. See Fig. 322. It is
often convenient to use different scales for the various objects,
in which case the scale for each should be printed with the views
of that part and the words, " Scales as noted, " printed in the
usual place in the title.

'.— letters and at the same time ~
\it wi.ll prevent the develooment ~
\of the snap and swing which
\gives the character to what is z
\recognized as good lettering.

FIG. 320. LETTERING PLATE 43

DATA FOE DRAWING PLATE 43
Given: The orthographic sketch, Plate 42.
Required: To make a mechanical drawing from Plate 42.

DATA FOE LETTERING PLATE 43
Given: Plate 43 to reduced size. Fig. 320.
Required : To make the plate to an enlarged scale.

280 MECHANICAL DRAWING

DATA TOR DRAWING PLATE 44

Given: The pencil mechanical drawing. Plate 43.

Required: To make a tracing of Plate 43.

Instructions: The width of the top and left sides of the rec-
tangle enclosing the bill of material and the vertical division lines
should be object line width ( ^ ").The horizontal lines between
lines of lettering should be center line width

DATA FOR LETTERING PLATE 44

Given: Plate 44 to reduced size. Fig. 321.
Required: To make the plate to an enlarged scale.

~ A drawing, Ihe mechanical
^Lpart of which is well executed,
^.may have its appearance spoiled^,
^by poor lettering. Lines should^
black and of uniform weight, ~

FIG. 321. LETTERING PLATE 44

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 45

One of the problems of the draftsman is to make detail draw-
ings from the original layout of a machine in which the parts are
shown assembled. On this assembly drawing some important
dimensions may be given, others may be scaled from the drawing,
and the remainder must be supplied by the draftsman himself.
Since this course does not presuppose a knowledge of design, all
necessary dimensions will be given on the assembly drawing from
which the student draws this plate.

MEASUREMENTS

281

CD <

£L.UJ

284

MECHANICAL DRAWING

The reading of the assembly drawing to get the correct form
for each detail will in most cases require careful study. The dif-
ferent parts may be distinguished when in section by various
erosshatching for different metals and by the sectioning of adja-
cent parts at opposite angles. But even with this aid the differ-
ent views must be compared carefully to check the first impres-
sion gained of the form of each part and to make sure that no
detail has been overlooked. Each part of the object must be
dimensioned completely. It is not sufficient to give a dimension
on the views of one part and omit the same dimension on the views
of another part, even though it is evident that the dimension is
the same on both.

FIG. 325. LEVELING SCREW

DATA FOR DBA WING PLATE 45

Given: An assembly drawing of a Leveling Screw, Fig.
325 ; a flap valve, Fig. 326 ; and a letter press, Fig. 327.

Required: To make freehand orthographic detail sketch
of the object shown in Fig. 325, 326, 327, or any similar object
as assigned by the instructor.

MEASUREMENTS

385

286

MECHANICAL DRAWING

FIG. 327. LETTER PRESS

ASSEMBLY
BENCH DRILL PRESS

FIG. 328. TYPE PROBLEM. BENCH DRILL PRESS

(287)

288 MECHANICAL DRAWING

A Flap Valve is used to allow a liquid or gas, such as water
or steam, to flow in one direction through a pipe but not in the
other. Its parts, as designated by figures in circles in Fig. 326,
are named as follows :

1. Body. 2. Cap. 3. Valve. 4. Arm. 5. Cap Screw.

A Leveling Screw is used for leveling up work on a planer.
Its parts, as designated by figures in circles in Fig. 325, are
named as follows :

1. Base. 2. Screw. 3. Cap.

Fig. 327 shows a Letter Press. Its parts, as designated by

figures in circles, are named as follows:

1. Base. 6. Bolt.

2. Plate. 7. Nut.

3. Yoke Support. 8. Clamp.

4. Press Screw. 9. Button Head Screw.

5. Hand Wheel. 10. Yoke.

: Careful attention to detail
.bined with intelligent and per- ~
.sistent practice will do much to z
.offset lack of talent for lettering^
.2357 9861 45309 728695 =

FIG. 329. LETTERING PLATE 45.

DATA FOR LETTERING PLATE 45

Given: Plate 45 to reduced size. Fig. 329
Required: To make the plate to an enlarged scale.

MEASUREMENTS

289

DATA FOR DRAWING PLATE 46

Given: The orthographic sketch. Plate 45.
Required: To make a pencil mechanical drawing from
Plate 45.

DATA FOR DRAWING PLATE 47

Given: The pencil mechanical drawing. Plate 46.
Required: To make a tracing of Plate 46.

FIG. 330A. DETAILS OF BEXCH GRINDER

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 48
An Assembly or General Drawing is made for showing the
position and relation of parts of a machine or structure. Usually
only the most important dimensions are given. Example:
Fig. 328.

290

MECHANICAL DRAWING

DATA FOR DRAWING PLATE 48

Given : The detail drawings of a bench grinder, Figs. 330A
and 330B; screw punch, Fig. 331.

Nut

I Wanted Head/ess ff./f. Cap Screws

Teefffesf

FIG. 330B. DETAILS OF BENCH GRINDER

MEASUREMENTS

291

Section showing I? a// helef
in place by beaded edge
of socket

Ho30 Dr/7/
Vse special ftx>/ Use spec/a/ dri//

locate groore offer assembling

FIG. 331. DETAILS OF SCREW PUNCH

292 MECHANICAL DRAWING

Required: To make a pencil mechanical drawing from the
details of the objects shown in Figs. 330A and 330B or 331, or any
similar problem assigned by the instructor. It is suggested that
an assembly drawing may be made from the student detail draw-
ings of Plate 43.

DATA FOB DRAWING PLATE 49

Given: The pencil mechanical drawing. Plate 48.
Required: To make a tracing of Plate 48.

ARCHITECTURAL DRAWING

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 50

The average man who contemplates building a house for him-
self finds it a great convenience to be able to make scale drawings
of sufficient accuracy to test his ideas of the arrangement of
rooms, dimensions, proportions, general appearance, etc., and as
a means of conveying his ideas to an architect or contractor.
The drawings should consist of floor plans and views of each side
of the house, known as elevations.

The general arrangement of rooms on the first floor will
depend on such things as the nature of the site, the owner 's ideas
of household conveniences, etc. As a general principle, the rooms
which are used the largest percentage of time are given the most
favorable location for light and ventilation. As an example, the
living room is quite frequently arranged to have a south and east
exposure.

In all rooms, the location of furniture, doors, windows, etc.,
should be carefully considered as the plan for the house is pro-
gressing. The kitchen in the average small house is planned to
save steps for the housewife. The sink, stove, table, and cup-
boards should be arranged with a view to convenience.

In the average house, economy of space is a feature worth
striving for, as the cost of the house will range from 15 cents to
22 cents per cubic foot.

The plan of the second floor will depend somewhat on that of
the first floor. The partitions on the second floor should be

MEASUREMENTS

293

FIG. 331A. EXTRA PLATE

FIG. 331B. EXTRA PLATE

294

MECHANICAL DRAWING

Half L op Joinf
in Wrought Iron

Frenf ILeg nof 5horrr? ^
"•T

FIG. 331C. EXTRA PLATE

MEASUREMENTS

295

directly over those on the first floor, as far as this arrangement
can be made. The position of the stairs must be considered and
space enough allowed for steps to reach the second floor. As a

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FIG. 332. FIRST FLOOR PLAN OF HOUSE

guide in laying out stairs, the sum of the tread and rise should
bo about 17" to 17£"T with a tread not less than 9" wide for front
stairs or 8" wide for back stairs.

296

MECHANICAL DRAWING

In locating the bathroom, care must be taken to make it
possible for the pipes and drains to lead down through the walls
of the first floor. In a cold climate there is danger of freezing

FIG. 333. SECOND FLOOR PLAN OF HOUSE

if they are put through an outside wall. Wherever possible,
plumbing should be minimized. It is well, therefore, to have
bathroom, kitchen, and basemeht water and sewer connections in
the same vertical wall.

MEASUREMENTS

297

298

MECHANICAL DRAWING

t
o

£>

$'*
t;\

£«5

MEASUREMENTS

299

A bathroom should not be less than 5' 6" one way with not
less than 49 sq. ft. of floor space. In planning bedrooms, there
should be windows on two adjacent sides, if possible, to provide
light and good ventilation. Bedrooms may be as small as 9' 6"

<fe

FIG. 336. DETAILS OF DOOR AND WINDOW

by 11' 6", if well planned. The spaces for beds, dressers, etc.,
should be considered with reference both to natural and artificial
light and to necessary wall space. All upstairs rooms should be
provided with ample closet room. Other considerations entering
into the problem of planning the upstairs is the type of roof,
position of ehimneys, etc. Electric wiring, especially for outlets,

300 MECHANICAL DRAWING

and pipes for either hot air or for steam or hot water should be
thought out as the plans for the two floors are made.

When the floor plans have been arranged, the elevation and
possibly a perspective of the house should be drawn. If the
appearance is not satisfactory, the plans for the floors may need
altering. It is not uncommon for plans to be worked over a
number of times to meet the needs of both owner and builder.

DATA FOE DRAWING PLATE 50

Given: The two floor plans, the side and front elevations
of a house, with details, as shown in Figs. 332, 333, 334, 335,
and 336.

Required: To rearrange the floor plans, if desired, and to
design the other side elevation and the rear elevation, or any
similar problems assigned by the instructor.

Note. The student may change the elevations shown in Figs.
334 and 335 if his second floor plan demands a different arrange-
ment of windows or changes in the roof.

Instructions: It will be found very convenient to draw the
first floor plan and then lay out the plan of the second floor on
transparent paper stretched over the first floor drawing.

Many measurements are thus copied by tracing ; an accurate
register of all first floor data in comparison with that for the
second floor is thus made, and mistakes are less apt to occur. In
a similar manner the elevations may be drawn over the plans but
of course in this case all the vertical measurements must be made
with a scale. The particular advantage in this method of draw-
ing elevation views is to secure correct horizontal dimensions,
window and door positions, etc.

PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 51

After the construction of a house has progressed until the
walls are covered with plaster on the inside and with siding on
the outside, and after the roof is in place, the framing construc-
tion is not apparent. But in order to build a house which will
stand firm in wind and will not let in the rain, the carpenter

ARCHITECTURAL DRAWING

301

302

MECHANICAL DRAWING

must consider carefully problems of framing construction. Figs.
338, 339, 340, and 341 give in detail typical construction for a
small house.

FIG. 338. PERSPECTIVE OP PARK HOUSE

FIG. 339. PERSPECTIVE OF FRAMING CONSTRUCTION OF PARK HOUSE

MEASUREMENTS

303

DATA FOE DRAWING PLATE 51

Given: The perspective sketches, Figs. 338 and 339; the
plan, Fig. 340 ; and the cornice detail, Fig. 341, for a small park
house.

Required: To draw the orthographic views showing the
framing and details of construction for the park house or any
similar object as assigned by the instructor.

FIG. 340. PLAN OF PARK HOUSE

304

MECHANICAL DRAWING

A. Plate 2x4 .

6. 6/rt 2-ex4.Mrf/sdirrfo posts

C. Frieze

0 Furring strips g x A

£. flfov/d/rra $' *

/" //a/ ting blocks

6 ft/ting, between ratters

D ' Furring strips £"*//'

/£ sa. strips screwed to cap.
postst cind soffit for
fastenings

Oefait of5heath/nq

Det#/l of Sill and foot/rigs

FIG. 341. CORNICE DETAILS

CHAPTER VI

ISOMETRIC AND CABINET DRAWING
PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 52

Isometric Drawing is a mechanical method of representing
objects pictorially. The object may appear somewhat distorted
when drawn by this method, but to one who is not accustomed
to reading orthographic drawings or for one who is unable to
make a good freehand perspective drawing, it serves the purpose
of making clear the general form of the object. By placing

FIG. 342. THE CUBE IN ISOMETRIC

dimensions on it the isometric drawing may be used as a working
drawing.

Fig. 342 shows the isometric of a cube. The cube appears as
shown in this figure when it is viewed (as in orthographic draw-
ing) with a diagonal of the cube coincident to, or parallel with,
the line of sight. When in this position the three edges meeting
in the near corner are represented by lines 120° apart.

The three lines 120° apart are the axes parallel to which all
measurements are made in isometric drawing.

-Non-Isometric Lines. A line which is not parallel to one of
the three axes is a non-isometric line. A non-isometric line is
drawn by referring points on the line to the axes by means of

305

306

MECHANICAL DRAWING

coordinates. Fig. 343 shows a rectangular solid on the top face
of which is a non-isometric line having a curved and a straight
portion. The position of the point D is determined in the
isometric by transferring lengths AB and AC from the ortho-
graphic views with the dividers and drawing lines B D and C D
parallel to the axes. In some cases where a figure containing non-
isometric lines is to be drawn, it is convenient to enclose the figure
in a rectangle. The hexagon in the side face of the rectangular
solid, Fig. 343, and the circle enclosed in a square, Fig. 343, are
illustrations of such cases.

FIG. 343. LOCATING POINTS ON NON-ISOMETRIC LINES USING Two
COORDINATES

When non-isometric lines do not lie in a face of a rectangular
solid, three coordinates are necessary to locate points on each
line. In drawing the isometric of the frustum of the hexagonal
pyramid, Fig. 344, the base is first enclosed in a rectangle and the
points on the top face are located by three coordinates as shown.
The lengths A B, B D, and D E are taken from the orthographic
views and laid off on the isometric in the directions parallel to
each of the three axes, respectively.

Isometric Circles. Circles may be drawn by locating points
as described above, or by the four-center method shown in Fig.
345. Point A, the center of the smaller arc, is located by laying
off AB = BC. The center D for the larger arc is located by
drawing A D through A perpendicular to B E. The other centers

FIG. 344. LOCATING POINTS ON NON-ISOMETRIC LINES USING THREE

COORDINATES

FIG. 345. A FOUR-CENTER METHOD TOR DRAWING CIRCLES IN ISOMETRIC

(307)

FIG. 346. METHODS OF DRAWING CIRCLES AND ARCS

-rn

1 1

J™j!

-t—j

_ staif of 5ecfton on C-O

Corner Construction

FIG. 347. TYPE PROBLEM. STUDY TABLE. ORTHOGRAPHIC VIEWS

(308),

FIG. 348. TYPE PROBLEM. ISOMETRIC DRAWING OF STUDY TABLE

FIG. 349. TYPE PROBLEM. CABINET DRAWING OF STUDY TABLF-

Y309)

310

MECHANICAL DRAWING

are located in a similar manner. The arcs are tangent at the
point F. The four-center method is an approximation and is
usually suitable only for full circles. When an arc is drawn
which must pass through certain points the plotting method is
preferable. Fig. 346.

Defai/of
Corner Construction

f I

FIG. 350. TABORET

DATA FOR DRAWING PLATE 52

Given: The orthographic views of a taboret. Fig. 350.

Required: To make an isometric (or cabinet drawing) of
the object shown in Fig. 350 or any similar object assigned by
the instructor. For cabinet drawing instructions see page 314.

Instructions:

1. Make an orthographic drawing to scale.

2. Draw lines for the isometric drawing in the directions of
the three axes : One vertical, and one each to the right and to the
left, making 30° with the horizontal.

ISOMETRIC AND CABINET DRAWING

311

3. Decide which of the general dimensions of the object is
to be measured in the direction of each axis.

4. Locate a certain point, usually an extreme corner of the
object, at the intersection of the lines drawn as directed in 2.

FIG. 351. TYPE PROBLEM. PLANING JIG FOR &OD BRASS.

VIEWS

ORTHOGRAPHIC

5. Transfer actual lengths from the orthographic drawing
with the dividers, taking care to lay them off in the direction of
the proper axis.

6. Draw the necessary lines through the points located, re-
membering that lines of the object which are parallel to a general
dimension of the object should be drawn parallel to the axis
representing that dimension.

7. All other lines must be determined by locating points as
described on page 306.

FIG. 352. TYPE PROBLEM. ISOMETRIC OF JIG FOR ROD BRASS

(312) pIQ 353^ TYPE PROBLEM. CABINET OF JIG FOR ROD BRASS

ISOMETRIC AND CABINET DRAWING

313

DATA FOR DRAWING PLATE 53

Given: The orthographic views of a crosshead brass.

Fig.

354.

Required: To make an isometric (or cabinet drawing) of
the object shown in Fig. 354, or any similar problem assigned
by the instructor. For cabinet drawing instructions see page 314.

FIG. 354. CROSSHEAD BRASS
Instructions:

1. Proceed in drawing the straight lines as for the preceding
plate.

2. To draw the circles by the four center method, first deter-
mine the center by the method of coordinates.

3. Draw a figure representing a square which just circum-
scribes the circle. Care must be taken to draw this figure so
that it will appear to lie in the same face of the object as the
circle to be drawn. The direction of the sides of this figure will
correspond to those representing one of the faces of the cube.
Fig. 345.

4. Draw the curves by the method given under, "Isometric
Circles/'

314 MECHANICAL DRAWING

CABINET DRAWING
PREPARATORY INSTRUCTIONS FOR DRAWING PLATE 54

Cabinet Drawing is similar to isometric in that measurements
are made parallel to three axes. One of the axes is horizontal,
the second vertical, and the third 45° to the horizontal. Fig. 355.
Actual lengths are measured parallel to the horizontal and ver-
tical axes and one-half the actual lengths are measured parallel

FIG. 355. CABINET DRAWING OF CUBE

FIG. 356.

EXAMPLE OF AN OBJECT WITH CIRCLES AND ARCS PARALLEL TO
ONE PLANE

to the 45° axis. It should be evident that objects which involve
the drawing of irregular shaped figures which are located in or
parallel to the front surface of the object can be represented
more easily by cabinet than by isometric, inasmuch as such
figures will be drawn in their true form in a cabinet drawing.
For example, an object which has a number of circles parallel
to one plane is more easily represented in cabinet than in
isometric, since the circles can be drawn with the compass.
Fig. 356.

ISOMETRIC AND CABINET DRAWING
DATA FOR DRAWING PLATE 54

315

Given: The orthographic views oi a taboret. Fig. 350.
Required : To make a cabinet drawing of the object shown
in Fig. 350, or any similar object assigned by the instructor.

FIG. 357. Am STARTER BEARING

Instructions:

1. Make an orthographic drawing to scale.

2. Draw lines for the cabinet drawing in the direction of the
three axes; one vertical, one horizontal, and one at 45°.

3. Decide upon the general dimension of the object .to be
measured in the direction of each axis.

4. Locate a certain point, usually an extreme corner of the
object, at the intersection of the lines drawn as directed in 2.

5. Transfer actual lengths from the orthographic drawing
with the dividers for the measurements parallel to the horizontal
and vertical axes, and one-half actual lengths for the measure-
ments parallel to the 45° axis.

316

MECHANICAL DRAWING

6. Draw the necessary lines through the points located, re-
membering that the lines of the object, which are parallel to a
general dimension of the object, should be drawn parallel to the
axis representing that dimension.

7. Lines not parallel to the axes must be located by the same
method of plotting points used for the isometric drawing and
described on page 306.

FIG. • 358. TYPE PROBLEM. SPAKKER BODY

DATA TOR DRAWING PLATE 55

Given: The orthographic views of a crosshead brass. Fig.
354.

Required: To make a cabinet drawing of the object as
shown in Fig. 354, or any similar problem assigned by the
instructor.

Instructions:

1. Proceed in drawing the straight lines as for the preceding
plate.

ISOMETRIC AND CABINET DRAWING

317

2. The circles which are in or parallel to the front face of
the object may be drawn with the compass. All others must be
determined by plotting points. The object should be placed, if
possible, so that the circles can be drawn with the compass.

DATA FOR DRAWING PLATE 56

Given: The orthographic views of a sparker body. Fig.
358.

Required: To make a cabinet drawing of the object shown
in Fig. 358, or any similar object assigned by the instructor.

FIG. 359. BOSCH MAGNETO CAM

Instructions:

1. Make an orthographic drawing to scale. Draw lines for
the cabinet drawing in the direction of the three axes; one ver-
tical, one horizontal, and one to the right or the left, making 45°
with the horizontal.

318 MECHANICAL DRAWING

2. Transfer measurements by the same general method used
in isometric, laying off only one-half the actual lengths in the
direction of the 45° axis.

3. Circles or curves in the front face of the object or planes
parallel to the front face should be drawn in their exact size and
form. All other circles and curves must be plotted.

CHAPTER VII

GEOMETRICAL CONSTRUCTIONS
PROBLEM 1

Given: A straight line or arc AB.
Required: To bisect A B. Fig. 360.

FIG. 360. To BISECT A LINE OR ARC

Instructions: With A and B as centers describe arcs inter-
secting at C and D. The line C D bisects the straight line A B
at F and the arc at E.

a b c d

FIG. 361. To DIVIDE A LINE INTO A NUMBER OF EQUAL PARTS

PROBLEM 2

Given: A straight line AB.

Required: To divide AB into any number of equal parts,
as five. Fig. 361.

319

320

MECHANICAL DRAWING

Instructions: Draw line A C at any angle with AB and lay
off on it five equal spaces, using any convenient unit. Draw
5 B and parallels to it through 1, 2, 3, 4. a, b, c, d are the required
divisions.

Note. A line such as AB in Problems 1 and 2 may be
divided by means of the dividers, as described on page 129.

PROBLEM 3

Given : An angle ABC.

Required: To bisect angle ABC. Fig. 362.

FIG. 362. To BISECT AN ANGLE

Instructions: With B as a center, draw an arc AC of any
radius. With A arid C as centers describe arcs of equal radius
intersecting in D. B D bisects the angle ABC.
c

FIG. 363. To TRISECT A EIGHT ANGLE

PROBLEM 4

Given : A right angle ABC.

Required: To trisect angle ABC. Fig. 363.

GEOMETRICAL CONSTRUCTIONS

321

Instructions: First Method. With B as a center, draw an
arc A C of any radius. With A and C as centers and the same
radius, draw arcs B D and B E. The angles thus formed are 30°.

FIG. 364. To TRISECT A EIGHT ANGLE WITH THE TRIANGLE

Second Method. An angle may be divided into any number
of equal parts by drawing an arc such as AC in Problems 3
and 4 and stepping off equal distances on the arc, with the
dividers.

FIG. 365. To CONSTRUCT A SQUARE

PROBLEM 5

Given: The length of the side of a square, AB.
Required: To construct the square. Fig. 365.

322

MECHANICAL DRAWING

Instructions: First Method. Draw arc B D C with A B as a
radius. Bisect arc BDC (Problem 1). AD is now at right
angles to AB. With centers at D and B draw arcs of radius
AB intersecting in the fourth corner of the square.

FIG. 366. To CONSTRUCT A SQUARE WITH THE TRIANGLE

Second Method. The square may be constructed with the
triangles and T-square. Fig. 366. B E and A D are drawn at
right angles to A B and A E at 45° to AB. DE is drawn
through E parallel to AB.

FIG. 367. To CONSTRUCT AN OCTAGON

PROBLEM 6

Given: The length of the side of a regular octagon.
Required: To construct the octagon. Fig. 367.

GEOMETRICAL CONSTRUCTIONS

323

Instructions: First Method. Draw arc BC and AD and
bisect each as with the lines P M and Q N. Bisect the exterior
right -angles and draw A C and B D equal to A B. Connect
C and D. Make FG and EH equal to FE and draw LO
through GH. Make LG, GM, HN, and HO equal to CF or
E D. Connect C, L, M, N, 0, and D.

FIG. 368. To CONSTRUCT AN OCTAGON WITH THE TRIANGLE

Second Method. The octagon may be constructed with the
T-square and 45° triangle, Fig. 368. BD is drawn at 45° to
AB and equal in length to AB. AM and BN are drawn per-
pendicular to A B. C D is drawn parallel to A B. F H is at 45°
to AB and LO parallel to AB. The figure may now be com-
pleted by drawing the following lines in the order given. A C,
CL, DO, LM, ON, MN.

FIG. 369. To CONSTRUCT A HEXAGON

PROBLEM 7

Given: The length of the side of a regular hexagon.
Required: To construct the hexagon. Fig. 369.

324

MECHANICAL DRAWING

Instructions: First Method. With a radius AB and centers
at A and B, describe arcs meeting at C. With C as center and
the same radius, draw a circle. With the same radius set off the
arcs B D, D E, E F, F G, and G A. The side of the hexagon
equals the radius of the circumscribed circle.

PIG. 370. To CONSTRUCT A HEXAGON WITH THE TRIANGLE

•

Second Method. Draw a circle with a radius equal to the
side of the hexagon. Draw a horizontal or vertical diameter A B,
Fig. 370, depending on the position of the hexagon. Draw lines
with the 60° -30° triangle through A and B, striking the circle.
Complete the figure by horizontal or vertical lines, as the case
may require.

FIG. 371. To CONSTRUCT A TANGENT TO A CIRCLE THROUGH A POINT OUTSIDE

THE CIRCLE

PROBLEM 8

Given: A circle and a point outside the circle.
Required: To draw a tangent to the circle through the
point.

GEOMETRICAL CONSTRUCTIONS

325

Instructions: First Method. With a radius A B and center
at A, describe arc B C. With a radius equal to the diameter of
the circle cut the arc at C. The chord B C strikes the circle in D,
the point of tangency. B D is perpendicular to the tangent A D.
Fig. 371.

FIG. 372. To CONSTRUCT A TANGENT TO A CIRCLE THROUGH A POINT WITH

THE TRIANGLE

Second Method. The tangent may be drawn with a straight
edge, as shown in Fig. 372. The point of tangency may be
found as shown in Fig. 195, page 184.

PROBLEM 9

Given: Two arcs.

Required: To draw a line tangent to both arcs.

Instructions: First Method. Make EF equal to AG, Fig.
373, and draw a tangent through A to the small circle C F, as
in Problem 8. Extend B H and draw A G at right angles to A C.
Join GK.

FIG. 373. To DRAW A LINE TANGENT
TO Two ARCS

FIG. 374. To DRAW A LINE TAN-
GENT T6 TWO ARCS WITH THE TRI-
ANGLE

Second Method. The tangent may be drawn with a straight-
edge, as shown in Fig. 374. The points of tangency may be
found, as shown in Fig. 195, page 184.

326

MECHANICAL DRAWING

PROBLEM 10

Given: Two straight lines intersecting at any angle.

Required: To draw an arc of given radius tangent to the
two lines. Fig. 375.

Instructions: First Method. With radius equal to the given
radius, draw arcs from two different points in each line. Draw
tangents to each, pair of arcs. The intersection of these lines, H,
is the center of the tangent arc. Perpendiculars from this point
to the tangent lines locate the points of tangency K, L.

K A

FIG. 375. To DRAW AN ARC TAN-
GENT TO Two INTERSECTING LINES

FIG. 376. To DRAW AN ARC TAN-
GENT TO Two INTERSECTING LINES
WITH THE TRIANGLE

Second Method. Fig. 376. Draw a line at right angles to
each of the intersecting lines with the triangles, as described on
page 125. Lay off B D and E C equal to the radius of arc. Draw
lines DF and EF parallel to AB and AC, respectively, as
described on page 125. F is the center of the arc. The points
of tangency K and L may be located as described on page 184.

•

GEOMETRICAL CONSTRUCTIONS

327

PROBLEM 11

Given: Two circles of different diameters.
Required: To draw a circle of given radius tangent to
both circles. Fig. 377.

FIG. 377. To DRAW A CIRCLE OF GIVEN RADIUS TANGENT TO Two CIRCLES

Instructions: From the center of circle A with a radius
equal to R plus the radius of A, and from the center of B with
a radius equal to R plus the radius of B, draw two arcs inter-
secting at C, which is the center of the required circle. The
points of tangency are found by joining the centers of the circles.

PEOBLEM 12

Given : Two parallel straight lines A B and C D.
Required : To draw arcs of circles tangent to A B and C D
and passing through E. Fig. 378.

A B

FIG. 378. To DRAW ARCS TANGENT TO Two STRAIGHT LINES THROUGH A

POINT

Instructions: Bisect BE and CE and erect perpendiculars
to AB and C D at B and C. F and G are the required centers.
The arcs are tangent at E. This is called a reverse or an 0. Go
curve.

328

MECHANICAL DRAWING

PEOBLEM 13

Given: The length of the major and minor axes of the
ellipse, 0 A and 0 B.

Required: To construct the ellipse.

FIG. 379. TRAMMEL METHOD OF DRAWING AN ELLIPSE

Instructions: Trammel Method. Fig. 379. Mark off on a
card, C D equal to 0 B and C E equal to 0 A. Keep the trammel
with the point D always on the major axis and point E always
on the minor axis. Move the trammel and mark points opposite
C to form the curve.

FIG. 380. CONSTRUCTION METHOD OF DRAWING AN ELLIPSE

Second Method. Fig. 380. Draw circles of radii equal to the
major and minor axes. Draw any radii OC, CD, etc.; draw
C G, D H, etc., perpendicular to 0 A, and E G, etc., parallel
to O A. G, H, etc., are points on the curve.

INDEX

Accuracy, 133

Accuracy of measurements, 267

Acme threads, 253

Adjacent parts, crosshatching, of, 229

Adjustable square, 266

Angle of inclination, 13

Angles

dimensioning, 89
Architect's scale, 127
Architectural drawing, 292
Arrangement of dimensions in ortho-
graphic sketch, 76
Arrangement of views on sheet, 140
Arrowheads, 38
Assembly drawing

purpose of, 289

details from, 280
Axes, derivation of, Isometric, 305

Balancing a title, 27, 140
Bill of material, 247
Bill of stock, 226
Blueprinting, 166
Board, drawing, 15, 118
Bolt, tap, 258
Bolts and nuts, 255
Border line, 172
Border rectangle, 20, 133
Bow dividers, 132
Bow pen, 132, 171.
Bow pencil, 132
Breaks, conventional, 229

Cabinet drawing, 314
Calipers, 267
Cap screw, 258 '
Center lines

circular, 100

principal, 100

radial, 100

secondary, 100
Circle

drawing with bow compass, 171

sketching, 101
Circles

concentric, in perspective, 47

dimensions of, 100

Isometric, 306
Circular edges, 93
Cloth, tracing, 161, 165
Compass, 170

Concentric circles in perspective, 47
Constructive stage

in perspective, 18

of orthographic sketch, 74

of mechanical drawing, 135
Conventional cross-sectioning, 230
Coordinate paper, 263
Corners, representation of, 69
Crosshatching

adjacent parts, 99, 229

conventional, 230
Crosshatch lines, 172
Cube

in perspective, 13

measure, definition of, 34

measure in new positions, 57
Cylinder

measure, horizontal, 52

measure, in new positions, 58

measure, vertical, 44
Cylindrical surfaces

dimensions of, 100

representation of, 92

Development of a surface

prism, 190

cylinder, 197

cone, 203

pyramid, 212
Diameter

measuring inside, 270

measuring outside, 270
Dimension

figure 137

form, 37, 77

line, 136
Dimensions

arrangement of in orthographic
sketch, 76

selection and arrangement, 263
Dimensioning

angles, 89

general principles of, 136

cylindrical surfaces and' circles, 100

radius, 150
Distance

measuring center to center of holes,
271

measuring linear, 268
Dividers, 130
Dotted lines, 171

329

330

INDEX

Drawing

an ellipse, 47

board, 15, 118

cabinet, 314

from the object, 261

Isometric, 305

paper, 15, 119
Drawing instruments

bow dividers, 132

bow pen, 132

bow pencil, 132

compass, 128

dividers, 130

ruling pen, 167

Edges

circular, representation of, 93

inclined, 82

invisible, 69

straight, 69

Ellipse, to draw and test, 47
Enclosing rectangle, 133
Enclosing solid in perspective, 34
Engineer's scale, 127
Eraser, 132
Erasing shield, 132
Extension lines, 136

Fastening paper to board, 15
Figures

and notes, 137

dimension, 137
Filling lettering pen, 103
Finish, methods of indicating, 261
Finishing stage

for mechanical drawing, 135

for orthographic sketch, 76

in perspective, 18
Folding rule, 265
Foot marks, 30

Foreshortening, definition of, 13
Fraction and whole number, 137
Furniture and cabinet problems, 231

General drawing, 289
Geometrical constructions, 319

Heads, arrow, 38
Heights of letters, 137
Horizon, definition, 10
Horizontal lines, ruling, 126

Inch marks, 30
Inclination, angle of; 13
Inclined edges, 82
Inclined surfaces, 81
Ink, black, 167

Inking

order of, 172

Inside diameter, measuring of, 270
Instruments

drawing, 128

measuring, 265
Invisible edges, 69
Isometric drawings, 305

derivation of axes, 305

Isometric circles, 306

Isometric lines, 305

locating points with three coordi-
nates, 307

locating points with two coordinates,
306

non-Isometric lines, 305

Joints, 232, 233

Lead, 258
Lettering

form and proportion of, 22

inclined, lower case, slope of, 192

in ink, 25, 102

in pencil, 24

pencil, 28

plate, 28

position of hand in, 24

preparation of tracing cloth, 102

slope, 194

spacing of, 23

strokes for, 23
Levels

scale of, cylindrical objects, 45

scale of, rectangular objects, 31
Line

border, 172

dotted, 76

invisible, 76

notation, 171

object, 172

table, 35 '

Linear distance, measuring, 268
Line, center

circular, 100

principal, 100

radical, 100

secondary, 100
Lines

Crosshatch, 172 »

extension and dimension, 136

in perspective, direction of, 11

Isometric, 305

non-Isometric, 305

object, 171

Parallel lines, 125
Perpendicular lines. 125

INDEX

331

Machine drawing, 247
Machine screws, 258
Marks, foot and inch, 30
Material, bill of, 247
Measure

cube, definition, 34

cube in new positions, 57

cylinder, horizontal, 52

cylinder in new positions, 58

cylinder, vertical, 44
Measurements

accuracy of, 267

center-to-center of holes, 272

in foreshortening, 13

in perspective, 31

iinear distances, 268

radii, 273

taking of, 267
Measuring instruments, 265
Multiple thread, 258

Notation of lines, 171
Notes, 137

Number and fraction, 43
Nuts and bolts, 255

Object

lines, 172

sketching from, 261
Orthographic

front and side, 81

review, orthographic sketching, 104

sketching, 66

top of front, 67

views, definition, 66
Outside diameter, measuring of, 270

Paper

blueprint, 166

coordinate, 263

drawing, 15, 119

to fasten to the board, 15

tracing, 166
Partial yiew, 228
Pen

bow, 171

care of, 169

filling, 167

ruling, 167
Pencil

drawing, 16

lettering, 28

review questions, pencil mechanical
drawing, 154

to sharpen, 17
Pencils

manipulation, 126

requisites of, 125

Perspective

concentric circles in, 48

direction of lines in, 11

horizontal measurements in, 34

measure cube in new positions, 57

measure cylinder in new positions, 58

measurements in, 31

review questions, perspective sketch-
ing, 61

sketch, definition of, 10

the cube in, 13

the measure cube in, 34

the table line, 35

to center sketch on sheet, 40
Perspective -sketching

constructive stage in, 18

enclosing solid in, 34

finishing stage in, 18

materials for, 15
Pipe threads, 255
Pitch

of thread, 249

Plane surfaces, representation of, 68
Problems

three view, 110
Proportional inch scale, 128

Quarter section, 99

Radii, measuring, 273
Radius dimensions, 150
Rectangle

border, 133

enclosing, 133
Rule, folding, 265
Ruling horizontal lines, 126
Ruling pen

adjustment of, 167

care of, 169

filling, 108

manipulation of, 168

requisites of, 167

sharpening, 169
Ruling vertical lines, 126

Scale

of levels, cylindrical, 45

of levels, rectangular, 31

steel, 265
Scales

architect's, 127

engineer's, 127

proportional inch, 128
Screw

cap, 258

machine, 258

set, 258

wood screws, 231

332

INDEX

Screw threads

acme, 253

pipe, 255

square, 253

TJ. S. Standard, 252

V-Thread, 250
Sectional views, 227

breaks, 229

broken line, 228

half section, 98

partial, 228

quarter section, 99

revolved section, 228

section through ribs, shafts, bolts,
228

separate section, 229
Section lining, 171
Set screws, 258
Sharpening pencil, 17
Shield, erasing, 132
Sketch, perspective

constructive stage, 18

finishing stage, 18

perspective, definition of, 10

to center on sheet, 40
Sketching

a circle, 101

from the object, 261

orthographic, 66
Springs, 255
Square

adjustable, 266

T-, 119

threads, 253
Straight edges, 69
Strokes

curved, 37

horizontal in lettering, 55

inclined in lettering, 189

vertical in lettering, 55
Strokes

in lettering, 23

in lettering, order, number, and di-
rection of, 23, 28
Stud, 258
Stud bolt. 258
Sub-title, 279
Surfaces

cylindrical, representation of, 92

cylinder and cone, 223

development of a surface, definition
of, 189

inclined, 81

intersection of surfaces, 213
plane, representation of, 68
prism and cylinder, 217
two cylinders, 220

Table line, 35
Tacks, thumb, 16
Tangencies

construction of, 325

locating points of, 184
Tap bolt, 258
Thread

multiple, 258

pipe, 255

screw, 249 (See Screw Threads)
Three view problems, 110
Thumb tacks, 16
Title, block, 138
Title, sub, 279
Titles

balance, 27, 140

commercial, 139

contents of, 139

design of, 26

steps in design, 26

trial, sheet, 140
Tracing

cloth, 161, 165

paper, 166

tracing and blueprinting, 185

trimming the, 173
Triangles

use of, 121

combination of, 124

direction of drawing lines, 124

testing, 122

30° to 60°, 122

45°, 122

T-square, 119

U. S. Standard thread, 252

Vanishing points, definition of, 11
Vertical lines, ruling, 126
Views

arrangement on sheet, 140

definition of, 66

partial, 228

relation of front and side, 81

relation of top and front, 67

sectional, 227

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M/W 16 1936

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UNIVERSITY OF CALIFORNIA LIBRARY

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