[Illustration]
“_LEARN TO DO A THING BY DOING IT._”--_OLD PROVERB_
SELF-HELP
MECHANICAL DRAWING
_AN EDUCATIONAL TREATISE_
[Illustration]
BY
N. HAWKINS, M. E.
_Author of Handbook of Calculations, etc._
_New York_: THEO. AUDEL & CO., Publishers
1902
_Copyrighted
by
Theo. Audel & Co.
New York
1902_
_This work
is
most kindly and
respectfully dedicated to
THE COMING MAN
who at the present time
is undoubtedly devoting
a goodly share of
his spare time to
the study of
drawing._
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[Illustration: INTRODUCTION]
Preface.
_It is because of a personal and practical experience of the advantage
to be gained by the possession of a knowledge of drawing, that the
author is prompted to undertake the rather pleasant task of producing a
self-help book relating to the subject._
_Since the days of youthful endeavor, the author has passed through an
extended experience of mechanical life, and scarcely ever without chalk,
pencil or instrument in hand, to illustrate by sketch or drawing, the
tools to be employed, or to picture the finished product; accordingly,
throughout this work, words of explanation and the drawings will go
together to aid the diligent student._
_It has been said by an eminent writer, that “one workman is superior to
another--other circumstances being the same--directly in proportion to
his knowledge in drawing, and those who are ignorant of it must in many
respects be subservient to others who have obtained that knowledge.”_
_It has been also said that no man is fitted to be foreman of a shop who
cannot draw, and it is generally true that no one will be appointed to
that position, except temporarily, who does not possess some knowledge
of the art, either “freehand” or instrumental._
_It is a question how far a good working knowledge of drawing can be
attained without a teacher; it is true that but few have become
proficient without such aid, but it is equally true that “self-help” has
been the key note to all advancement._
_The author received personal instruction in several ways and times, at
home, in school, in an architect’s office, and under an experienced
mechanical engineer, but it was in the early morning hours of a bright
summer time--lang syne--that he made his first serious attempt to master
the art of mechanical drawing. It was a struggle and a battle to hold
himself down to “the board” to the finish, but it was a victory--one,
won over slothfulness and impatience, and of such a nature as to warrant
the use of the term “self-help” to the encouragement of others._
_In conclusion two sentiments may be added; if a good working knowledge
of drawing is “worth the while” then, 1, the student should be
thoroughly in earnest in acquiring it; 2, he should be willing to take
sufficient time and give much hard study to gain the skill necessary for
success._
_This persistence is not irksome. It carries its own reward, and the
results are definite and sure._
“_One step and then another, and the longest walk is ended;
One stitch and then another, and the largest rent is mended.
One brick upon another, and the highest wall is made;
One flake upon another, and the deepest snow is laid._”
Introduction.
Drawing is one of the arts; art relates to something to be done, and art
in the industrial and mechanical sense aims chiefly at utility, and is
governed by exact rules; hence mechanical drawing--so-called--tends
first to be useful and helpful, and second to accuracy in execution,
including most minute details; it aspires to the perfection of nature in
adaptability of the means to the end.
Drawing constitutes a universal language, to acquire which is a matter
of importance, for by its use one is able to illustrate the form and
dimensions of an object, device, or utility, in very much less time, and
far more clearly, than by a verbal description.
To a person who may not be able perfectly to understand the language of
a country, to be able to draw is an aid and a safeguard; to use the
words of Sir Joshua Reynolds, “the pencil speaks the language of every
land.”
In extensive iron works and metal-working establishments the designer
and draughtsman is always in demand. His services are indispensable and
his position is a highly responsible one. It becomes his special
province to design improvements, to furnish sketches and to make
finished drawings; to calculate strains, strength, power, motion,
weight, friction and durability. All this and much more is the
professional draughtsman’s work.
In “directory” classification, he who accomplishes such comprehensive
results as above described is termed a “Draughtsman,” but the word has
as wide a meaning as “Engineer,” which takes in civil, mechanical,
naval, sanitary, steam and other engineering specialists. So, in
drafting, it includes the office boy employed in making blue prints, it
embraces the copyists, tracers and assistants, as well as the head
draughtsman and chief engineer.
Consequently the range is wide, and the line hard to draw between
draughtsmen who work with their hands, and those who work with their
brains. It may be added that the best men are too frequently
undervalued, owing to the unavoidable difficulty in distinguishing the
difference in true worth, between the two widely separated classes.
It may be remarked that they only draw well who draw intelligently;
aptness in this, as in many other virtues, is a matter of slow growth,
“here a line and there a line”--it’s the proper direction, not the rate
of progress, that counts in the end.
There are several methods of drawing--1, Free-hand; 2, Instrumental; 3,
Geometrical; 4. Perspective. In the first the work, also termed
sketching, is executed by pencil, pen, crayon, or even paint-brush; in
the second the result is attained by the use of rule, tee-square,
drawing pen, etc.; this method is also denominated mechanical drawing,
and suggests the title of this volume.
The great usefulness, not to say necessity, of readiness in executing
accurately, drawings “to scale,” is emphasized by the fact that now,
more than ever, is all machinery designed, and it may almost be said, is
“built,” in the draughting room--this is a valuable hint relating to
“reading” drawings.
It is wise, as well as easy, to begin at the beginning of things; thus,
it is altogether the good part to mount a ladder by the first and second
rounds rather than to attempt it by taking the third, sixth, ninth,
etc.--especially are first and second rounds the very best to start
upon; “Chalk-work,” is the first subject introduced, next, that of
“Free-hand.” These are the first steps leading upward in this most
agreeable attainment--skill in illustrating and designing of objects,
tools, and utilities.
A single word of advice before introducing the elementary work connected
with mechanical drawing: if the student should experience difficulty in
mastering the diagrams and curves abounding in this book, let him
consult an experienced draughtsman or teacher, who, by a few strokes of
a lead pencil, can easily make them plain; that knowledge--which cannot
be printed or self-taught--termed _the Craftsman’s Art_, is communicated
largely by personal telling and showing, from man to man; in drawing,
this help should be thankfully availed of, when necessity arises.
NOTE.--Sketching is often in demand because there is no time for
finished or careful drawings, and the one who can draw a few lines in
a moment to let a sudden necessity be known, is the man of the hour.
All candidates for First Class Engineer’s Certificates in marine
service in the navy have to undergo an examination in rough drawing;
this is intended not so much as a proof of the applicant possessing
the capability of a draughtsman, but in the event of any injury to the
engines in his charge, so that he may be able to send to his
Superintendent a rough drawing of the particular part, properly
dimensioned, so that it could be worked from, and time saved on the
arrival of the ship at the port where the repairs are to be done.
[Illustration]
[Illustration: PLAN OF THE WORK]
“_No matter how thorough our education may have been at the first,
rules and formulas will slip from the memory, and every day’s
experience gives additional evidence of the truth of the old adage
that_ ‘THE KEY THAT RESTS, RUSTS.’”--SIMPSON BALLARD.
The Plan of the Work.
The purpose or scope of this work may be briefly stated: It is to aid
the aspiring student in making the first advance towards a thorough and
useful knowledge of drawing in its several divisions, as elsewhere
defined.
The method to be followed in presenting the subject will be the natural
order clearly and simply defined, as “from the less to the greater.”
The first subject to be discussed comes under the heading of chalk-work,
_i. e._, such drawings as can be executed on a blackboard, a floor, or
even on more primitive surfaces, such as a smooth stone or board.
This is indeed a lowly beginning, but the author is quite confident it
will awaken as much interest as any part of the book--even in the most
experienced in the art of drawing, as to them it will revive the
ambitions and first crude attempts made in the golden days of their
youth.
Let it be clearly understood by all, and especially by those who wish to
learn drawing, that the study of this delightful art does not require
any special qualification. We need only ask one question: Have you
learned to write? If so, be assured you may learn to draw, but to all
the same rule applies, first the elements of the art, and afterwards the
more advanced study.
It is not expected that all should exhibit a decided taste for drawing,
for the possession of this is rather a gift of nature than the result of
education; but a knowledge of principles and a certain amount of
executive ability may be obtained by every one of average capacity, and
whatever the natural power may be, it will be increased and developed by
exercise; if the progress is steady and continuous and in the right
direction, success is sure to crown the work.
The second division of the book will be free-hand drawing, _i. e._, that
which is executed without instruments. Nothing to instruct has been
spared in this important step in the path of advancement.
The illustrations accompanying the two opening sections have been made
designedly elementary, for there are many who have a taste for drawing
and who have a desire to learn, who from place of residence or other
circumstances have not the opportunity of receiving the assistance of a
master. To such this book presents itself as a friend directing to the
right road, talking, reasoning, and explaining by the way.
The “chalk-work” and “free-hand” sections of the book relate to the
foundations upon which all must rest who seek the aid to be derived from
the art; hence, the following pages are written with a view to encourage
all, and those who are prepared to follow the directions given in them
may look forward to the possession of sufficient drawing power to add to
their usefulness in after life.
At this point of attainment there arises a need to know the meaning of
many words and phrases used by draughtsmen; these are grouped
alphabetically from A to Z under the heading of,----
Useful Terms and Definitions: Memorizing these few pages will be of
benefit, as an intimate knowledge of the language of the drawing office
stamps a man as worthy of a hearing, and assures attention to anything
which he may write or say pertaining to the art.
After the Definitions the subject explained will be the Instruments and
Materials used in mechanical drawings; following in due course appear
Geometrical and Mechanical Drawing, Gearing, Linear Perspective,
Projection, Shading, Tracing, Lettering, Drawing Office Rules, Reading
Drawings, Useful Tables and a General Index, to which the student is
referred. A careful reading is requested to the following helpful note.
Grateful acknowledgment is made to George Perrott, Esq., M. E., for
practical and technical assistance throughout the work, and to Theo.
Lucas, Engineer, for text and illustrations in the portions of the book
relating to Linear Perspective and Projection.
NOTE.--In MACHINERY Prof. Chas. H. Benjamin says, referring to
drawing, under heading “How and what to study,” “... I have so far
said nothing about drawing, for I do not think it of much use to learn
that, until you know what you want of it. All this time that you have
been studying mechanism you should have had a sketch book or pad of
note paper, and made free hand sketches of mechanical movements which
interested you and of various machine details. You should accustom
yourself to use drawing as a means of expressing ideas, just as you
use written words, so that it becomes a second nature to you to sketch
anything you wish to remember or describe. If you work from
blue-prints in the shop, or if you can borrow some to study, this will
help you to understand how a drawing is made. You can get some drawing
instruments at any time and begin to practice on drawing straight
lines and circles, so as to become familiar with the instruments. And
here it will be of great benefit to you if you can attend an evening
drawing school for one night in the week at least.
“When you have become sufficiently familiar with the principles of
drawing, a book on mechanism will tell you how to draw gear teeth and
cams, and how to design various link motions. Make up your own
problems from what you see in the shop and make your drawing a means
to an end and not the principal thing; it is of little use to be able
to make a nice drawing unless you know what to draw and why.
“Drawing is a convenient tool as an aid in expressing to others the
ideas which you wish to convey; in all cases take the problems and the
ideas from your every-day work and that which is around you; your
success will depend upon the close connection which you keep at all
times between your acquired knowledge and your practical work.”
General List of Contents.