Our world has become one where computers are used to solve many problems quickly and accurately. We use calculators to solve arithmetical problems, word processors 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 , , 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 drawing, 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 latest recommendations in BS 308, the British Standards Institution publication about engineering drawing practice.
There is a new Appendix C, which shows the recommendations 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. Howevercarefully one checks a manuscript, errors creep through. I shall be very grateful if any readers who find errors let me know through the publishers.
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. Iespecially 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. Mythanks 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 proceed with the third edition and to my wife, Jennifer, for her help and support in the preparation of this edition.
Using the Equipment
First fix the paper to your board, using clips or tape. Then sharpen your pencils, either to a point using a pencil sharpener, or to a chisel shape using the emery board and use this shape for drawing lines, drawing from the ends of each line to meet in the middle. Use the emery board to sharpen your compass leads to a chisel point too. Finally, draw a frame on your paper if required (see Fig. 18.26). Now you are ready to start drawing. Here are some exercises.