Related Resources: Design and Engineering General

Engineering Drawing Communication and Design

Engineering Applications and Design
Drafting and Design

Engineering Drawing Communication and Design

Premium Membership Required to view Document/Book

Open:

Engineering Drawing Communication and Design

There is an old practical joke in which a group of people who are "in the know" ask a newcomer to describe a spiral staircase. Very often the newcomer does as expected and traces out the locus of the stairs with a finger whilst saying "It's a staircase that goes round like this". The rest of the group are prepared for this and can laugh at his predictable behavior. The trick works because some objects are very difficult to describe in words and most people resort to pictures or models when they have to deal with them in detail.

The engineering designer has to cope with this problem throughout most of his professional life. In order to communicate ideas and instructions he uses sketches and drawings as well as written and spoken words. There are many books on engineering drawing and on the various aspects of engineering design but little has been written which shows the relationship between the two activities. Surely this is a very strange state of affairs? Engineering drawings and sketches are the engineering designer's special method of communicating his ideas to other people but why should the study of this communication be isolated from the process which uses it? In this book I have attempted to treat the basic topic of drawing and sketching and then to show how they may be used in the synthesis of a new product.

The earlier chapters cover most of the essential engineering drawing background required by most students of engineering. They can be used either as a text or as a self-instruction manual. To facilitate the latter, solutions are provided for many of the exercises. Whenever possible the exercises are design-orientated: students choose the most suitable views of a given object rather than being told exactly what to draw. The units used are SI throughout.

The last eight chapters illustrate the design process. It is extremely difficult to present a realistic project in a book; only in an industrial environment are there real constraints on the designer which could be easily appreciated. However, I believe that the unusual and, frankly, experimental scripted case-history approach will prove stimulating to most readers . My own experience with this technique has been most encouraging and I hope that other students of engineering design will find it interesting and informative.

1 ORTHOGRAPHIC PROJECTION
First and Third Angle Projection • 7
Lines and Dimensions • 7
Pictorial and Orthographic Drawings • 7
Clarity in Engineering Drawings • 9
2 VISUALIZATION
Engineering Practice and Visual Noise • 15
Intersection of Planes and Curved Surfaces • 19
3 SECTIONS
Other Types of Sectional Views • 25
Ribs • 25
Exceptions and Conventions • 27
Special Section Lining • 27
4 THE USE OF DRAWING INSTRUMENTS AND EQUIPMENT
Materials • 29
Supporting the Drawing Material • 29
Marking the Drawing Material • SI
Removing Marks • S3
Other Drawing Instruments • S3
At the Drawing Board • 33
The Use of Springbows and Compasses • 35
Arc Blending • 35
5 DIMENSIONING
General Principles • 39
Arrangement of Dimensions • 41
Circles^ Radii and Holes • 41
Dimensioning for Manufacture and Function • 43
6 AUXILIARY PROJECTIONS
Circles • 55
Double Auxiliary Projection • 57
Surfaces with All Sides Foreshortened • 59
Circles in Double Auxiliary Projection • 63
Projective Geometry • 63
Isometric Projection • 65
7 DEVELOPMENTS 69
Modified Cylinder • 71
Right Cone • 71
Oblique Cone • 75
Triangulation • 77
8 PICTORIAL DRAWINGS 79
Isometric Projection • 79
Isometric Drawing • 79
Sloping Surfaces • 81
Circles • 83
Blended Arcs • 85
Small Circles • 8 5
Dimetric Projection • 85
Dimetric Drawing • 85
Trimetric Projection • 88
Trimetric Drawing • 88
Methods of Producing Dimetric and Trimetric Drawings • 88
Oblique Drawing • 88
9 MATING PARTS 89
Tolerances 3 Deviations and Limits • 89
Selection of Fits • 95
British Standard 4500:1969 • 95
Fits for General Engineering Products • 96
Typical Applications of Hole Basis Fits • 96
Other Manufacturing Tolerances • 96
10 ENGINEERING DRAWINGS IN INDUSTRY 99
General Arrangement Drawings • 99
Assembly and Sub-assembly Drawings • 99
Detail Drawings • 99
Conventions in Assembly Drawings • 101
Fasteners • 101
Surface Texture • 103
Modifications to Detail Drawings • 103
11 SKETCHING 109
Sketching Circles • 109
Pictorial Drawings - Oblique Sketches • 113
Pictorial Drawings - Isometric Sketches • 113
The Sketching of Ideas • 115
12 INTRODUCTION TO SYNTHESIS 118
13 PROBLEM DEFINITION 119
Phase 1 - Discovering the true nature of the problem posed • 119
14 PROBLEM ACCEPTABILITY 123
Phase 2 - Determining whether the task is one that the organization will be able
to carry out • 123
15 DESIGN FACTORS 128
Check List of Design Factors • 128
Phase 3 - Examining the factors that will influence design • 129
Specification for Automatic Toothbrush • 133
16 PROBLEM SOLVING 135
Phase 4 - Finding possible solutions and selecting the most suitable one • 135
17 SOLUTION DIVISION 142
Phase 5 - Preparing an overall design and dividing up the work that it will entail • 143
18 SOLUTION DEVELOPMENT 147
Phase 6 - Making decisions on items of increasing detail 3 in consultation with the other people affected • 149
19 SOLUTION EXECUTION 160
Phase 7 - Directing the manufacture of the required quantity • 161