AN INTRODUCTION
TO
MACHINE DRAWING
AND
DESIGN
BY
DAVID ALLAN LOW
(WHITWORTH SCHOLAR), M. INST. M.E.
HEAD MASTER OF THE PEOPLE'S PALACE TECHNICAL SCHOOLS, LONDON
AUTHOR OF 'A TEXT-BOOK ON PRACTICAL SOLID OR DESCRIPTIVE GEOMETRY'
'AN ELEMENTARY TEXT-BOOK OF APPLIED MECHANICS' ETC.
FOURTH EDITION
LONDON
LONGMANS, GREEN, AND CO.
AND NEW YORK: 15 EAST 16th STREET
1890
PRINTED BY
SPOTTISWOODE AND CO., NEW-STREET SQUARE
LONDON
PREFACE.
It is now generally recognised that the old-fashioned methodof teaching machine drawing is very unsatisfactory. Inteaching by this method an undimensioned scale drawing,often of a very elaborate description, is placed before thestudent, who is required to copy it. Very often the studentsucceeds in making a good copy of the drawing placed beforehim without learning very much about the object representedby it, and this state of matters is sometimes not much improvedby the presence of the teacher, who is often simply an artmaster, knowing nothing about machine design. It is relatedof one school that a pupil, after making a copy of a particulardrawing, had a discussion with his teacher as to whether theobject represented was a sewing machine or an electricalmachine. Evidently the publisher of the drawing example inthis case did not adopt the precaution which a backwardstudent used at an examination in machine design: he put ona full title above his drawing, for the information of hisexaminer.
Now, if machine drawing is to be of practical use to anyone, he must be able to understand the form and arrangementof the parts of a machine from an inspection of suitable drawingsof them without seeing the parts themselves. Also heought to be able to make suitable drawings of a machine orparts of a machine from the machine or the parts themselves.[Pg iv]
In producing this work the author has aimed at placingbefore young engineers and others, who wish to acquire theskill and knowledge necessary for making the simpler workingdrawings such as are produced in engineers' drawing offices, anumber of good exercises in drawing, sufficient for one session'swork, and at the same time a corresponding amount of informationon the design of machine details generally.
The exercises set are of various kinds. In the first andsimplest certain views of some machine detail are given, generallydrawn to a small scale, which the student is asked to reproduceto dimensions marked on these views, and he is expectedto keep to these dimensions, and not to measure anything fromthe given illustrations. In the second kind of exercise thestudent is asked to reproduce certain views shown to dimensionsgiven in words or in tabular form. In the third kind ofexercise the student is required to make, in addition to certainviews shown to given dimensions, others which he can onlydraw correctly if he thoroughly understands the design beforehim. In the fourth kind of exercise the student is asked tomake the necessary working drawings for some part of amachine which has been previously described and illustrated,the dimensions to be calculated by rules given in the text.
The illustrations for this work are all new, and have beenspecially prepared by the a