Geometric and Engineering Drawing This page intentionally left blank Geometric and Engineering Drawing Third Edition K . MORLING Graduate of the Institution of Mechanical Engineers SI Units AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD • PARIS SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Elsevier 32 Jamestown Road London NW1 7BY 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA First edition by Edward Arnold 1969 Second edition by Edward Arnold 1974 Reprinted by Butterworth Heinemann 2001, 2003 (twice), 2004, 2006, 2007 Third edition 2010 Copyright © 2010 Elsevier Ltd. All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. 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In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. British Library Cataloguing - in - Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN : 978-0-08-096768-4 For information on all Elsevier publications visit our website at www.elsevierdirect.com This book has been manufactured using Print On Demand technology. Each copy is produced to order and is limited to black ink. The online version of this book will show colour figures where appropriate. Contents Preface ix Acknowledgements xi Introduction xiii Part 1 Geometric Drawing 1 1 Scales 3 The Representative Fraction (RF) 3 Plain Scales 4 Diagonal Scales 5 Proportional Scales 8 Exercise 1 8 2 The Construction of Geometric Figures from Given Data 11 The Triangle 14 The Quadrilateral 19 Polygons 22 Exercise 2 28 3 Isometric Projection 31 Conventional Isometric Projection (Isometric Drawing) 31 Circles and Curves Drawn in Isometric Projection 34 Exercise 3 39 4 The Construction of Circles to Satisfy Given Conditions 43 The Greatest Invention of All Time 43 Exercise 4 55 5 Tangency 59 Exercise 5 63 6 Oblique Projection 67 Circles and Curves in Oblique Projection 68 Exercise 6 71 7 Enlarging and Reducing Plane Figures and Equivalent Areas 75 Equivalent Areas 81 Exercise 7 87 vi Contents 8 The Blending of Lines and Curves 91 Exercise 8 97 9 Loci 103 Loci of Mechanisms 105 Trammels 107 Some Other Problems in Loci 109 Exercise 9 112 10 Orthographic Projection (First Angle and Third Angle) 117 Auxiliary Elevations and Auxiliary Plans 122 Prisms and Pyramids 125 Cylinders and Cones 130 Sections 135 Exercise 10 141 11 Conic Sections – the Ellipse, the Parabola, the Hyperbola 149 The Ellipse 150 The Parabola 156 The Hyperbola 159 Exercise 11 161 12 Intersection of Regular Solids 165 Fillet Curves 178 Exercise 12 179 13 Further Orthographic Projection 185 The Straight Line 185 The Inclined Plane 191 The Oblique Plane 193 Exercise 13 196 14 Developments 201 Prisms 201 Cylinders 204 Pyramids 208 Cones 212 Exercise 14 216 15 Further Problems in Loci 221 The Cycloid 221 The Trochoid 224 The Involute 225 The Archimedean Spiral 228 The Helix 229 Exercise 15 232 Contents vii 16 Freehand Sketching 235 Pictorial Sketching 236 Sketching in Orthographic Projection 240 17 Some More Problems Solved by Drawing 245 Areas of Irregular Shapes 245 Resolution of Forces 247 Simple Cam Design 254 Exercise 17 258 Part 2 Engineering Drawing 263 18 Engineering Drawing 265 Introduction 265 Type of Projection 265 Sections 266 Screw Threads 272 Dimensioning 279 Conventional Representations 284 Abbreviations 289 Framing and Title Block 290 Assembly Drawings 294 Some Engineering Fastenings 294 Three Worked Examples 301 Example 1 303 Example 2 304 Example 3 307 Exercise 18 310 19 Postscript – Planning a Design 337 Appendix A Sizes of Isometric Precision Hexagon Nuts, Bolts and Washers 339 Appendix B Sizes of Slotted and Castle Nuts with Metric Thread 341 Appendix C Representation of Threaded Fasteners 343 This page intentionally left blank Preface Our world has become one where computers are used to solve many problems quickly and accurately. We use calculators to solve arithmetical problems, word pro- cessors to check spelling and grammar in texts and computer-aided design (C.A.D.) programs to do much of our drawing for us. However, in the same way that we need to know what ϩ , Ϫ , ϫ and ÷ mean when we press that symbol on a calculator, and we need to be able to write a text before we can ask a word processor to check it, in the same way we need knowledge and understanding of geometric and engineering drawing before we can use computers to help us with design. These understandings can come through studying and using this book. This third edition starts with and introduces the tools needed for technical draw- ing, with some basic exercises that will help you to practise these skills. Part 1 is almost unchanged from earlier editions. It shows specific drawing solutions to many geometric problems. Part 2, engineering drawing, has been updated to the lat- est recommendations in BS 308, the British Standards Institution publication about engineering drawing practice. There is a new Appendix C, which shows the recom- mendations given in BS 308 for the simplified representation of threaded fasteners. Finally there is a chapter that lists the types of questions that need to be asked when creating a design. It then lists the questions that can be answered in this book and guides you to the appropriate chapter. However carefully one checks a manuscript, errors creep through. I shall be very grateful if any readers who find errors let me know through the publishers. K . Morling February 2010 This page intentionally left blank Acknowledgements I express my thanks to the following examination boards for giving their permission to use questions from past papers. I am particularly grateful to them for allowing me to change many of the questions from imperial to metric units. Certificate of Secondary Education Associated Lancashire Schools Examining Board East Anglian Regional Examinations Board Metropolitan Regional Examinations Board Middlesex Regional Examining Board North Western Secondary School Examinations Board South-East Regional Examinations Board Southern Regional Examinations Board West Midlands Examinations Board General Certificate of Education Associated Examining Board Local Examinations Syndicate, University of Cambridge Joint Matriculation Board University of London School Examinations Oxford Delegacy of Local Examinations Oxford and Cambridge Schools Examination Board Southern Universities ’ Joint Board I especially thank the West Midlands Examinations Board, the Associated Lancashire Schools Examining Board and the Southern Universities ’ Joint Board for allowing me to draw solutions to questions set by them (Figs. 18.37, 18.39 and 18.41). The extracts from BS 308, Engineering Drawing Practice, and BS 3692, ISO Metric Precision Hexagon Bolts, Screws and Nuts, are taken from a number of recent British Standards Institution Publications who have given their permission for the reproductions. Copies of the complete standards are available from BSI, 2, Park Street, London W1A 2BS. My thanks to S. Pagett for checking the manuscript of the original publication, Terry Cosgrove, Leverhulme, Professor of Physical Chemistry, Bristol University, for his advice with computer applications, David W. Auckland, Professor Emiritus, University of Manchester, CEO Innovations Lab Ltd, for his encouragement to pro- ceed with the third edition and to my wife, Jennifer, for her help and support in the preparation of this edition. K . Morling This page intentionally left blank Introduction Basic Tools A draftsperson needs some basic tools to draw. These should include the following: ● A range of pencils ● Ruler ● Set squares ● Rubber ● Compasses ● Dividers ● Drawing board ● T-square ● Clips or tape ● Emery board or fine sandpaper Pencils : You will need a selection of pencils. A hard leaded pencil (6H) can be used for light lines, a softer pencil (2H) for the outlines and an even softer pencil (HB) for printing. (More than one pencil of each grade will save you from frequent re-sharpening.) Ruler : It is advisable to have a transparent ruler. Set squares : You will need at least two set squares: a 60 ° and a 45 ° set square. It will be also useful to have an adjustable set square, which will enable you to set the angle on the set square to anywhere between 0 ° and 90 ° . If you have an adjustable set square you can manage without the other two. Rubber : Choose a good quality rubber, one that does not smudge. Compasses : You will need at least two compasses: a small spring bow compass for small circles and one for larger circles. Dividers : A pair of dividers is essential.