Mechanical Drawing Self-Taught Comprising instructions in the selection and preparation of drawing instruments   By: Joshua Rose

COMPRISING

INSTRUCTIONS IN THE SELECTION AND PREPARATION OF DRAWING INSTRUMENTS,

ELEMENTARY INSTRUCTION IN PRACTICAL MECHANICAL DRAWING ;

TOGETHER WITH

EXAMPLES IN SIMPLE GEOMETRY AND ELEMENTARY MECHANISM, INCLUDING SCREW THREADS, GEAR WHEELS, MECHANICAL MOTIONS, ENGINES AND BOILERS.

BY JOSHUA ROSE, M.E.,

AUTHOR OF "THE COMPLETE PRACTICAL MACHINIST," "THE PATTERN MAKER'S ASSISTANT," "THE SLIDE VALVE"

ILLUSTRATED BY THREE HUNDRED AND THIRTY ENGRAVINGS.

PHILADELPHIA: HENRY CAREY BAIRD & CO., INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS, 810 WALNUT STREET.

LONDON: SAMPSON LOW, MARSTON, SEARLE & RIVINGTON, CROWN BUILDINGS, 188 FLEET STREET. 1887.

Copyright by JOSHUA ROSE. 1883.

PHILADELPHIA.

COLLINS, PRINTER

PREFACE.

The object of this book is to enable the beginner to learn to make simple mechanical drawings without the aid of an instructor, and to create an interest in the subject by giving examples such as the machinist meets with in his every day workshop practice. The plan of representing in many examples the pencil lines, and numbering the order in which they are marked, the author believes to possess great advantages for the learner, since it is the producing of the pencil lines that really proves the study, the inking in being merely a curtailed repetition of the pencilling. Similarly when the drawing of a piece, such, for example, as a fully developed screw thread, is shown fully developed from end to end, even though the pencil lines were all shown, yet the process of construction will be less clear than if the process of development be shown gradually along the drawing. Thus beginning at an end of the example the first pencil lines only may be shown, and as the pencilling progresses to the right hand, the development may progress so that at the other or left hand end, the finished inked in and shaded thread may be shown, and between these two ends will be found a part showing each stage of development of the thread, all the lines being numbered in the order in which they were marked. This prevents a confusion of lines, and makes it more easy to follow or to copy the drawing.

It is the numerous inquiries from working machinists for a book of this kind that have led the author to its production, which he hopes and believes will meet the want thus indicated, giving to the learner a sufficiently practical knowledge of mechanical drawing to enable him to proceed further by copying such drawings as he may be able to obtain, or by the aid of some of the more expensive and elaborate books already published on the subject.

He believes that in learning mechanical drawing without the aid of an instructor the chief difficulty is overcome when the learner has become sufficiently familiar with the instruments to be enabled to use them without hesitation or difficulty, and it is to attain this end that the chapter on plotting mechanical motions and the succeeding examples have been introduced; these forming studies that are easily followed by the beginner; while sufficiently interesting to afford to the student pleasure as well as profit.

NEW YORK, February, 1883 .

CONTENTS.

CHAPTER I.

THE DRAWING BOARD.

The T square 18

The triangles 19

Curves 21

Selecting and testing drawing instruments 22

Lead pencils 23

Mixing India ink 25

The drawing paper 26

Tracing paper 29

The ink 30

Testing and selecting India ink 30

Draftsmen's measuring rules 33