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ENGINEERING DRAWING/CADD

CONTENTS

Page No.

Preface………………………………..…………………………………………………… i

Acknowledgement………………………………………………………………………... i

Contents…………………………………………………………………………………... ii

CHAPTER 1 INTRODUCTION

1.1 Drawing………………………………………………………... 1

1.2 Types of Drawing……………………………………………… 1

1.2.1 Artistic Drawing…...………………………………… 1

1.2.2 Engineering Drawing………………………………… 1

1.3 Purpose of Engineering drawing………………………………. 1

1.4 Applications of Engineering Drawing………………………… 2

1.5 Types of Engineering Drawing……………………………….. 2

1.5.1 Geometric Drawing………………………………….. 2

1.5.2 Mechanical Engineering Drawing…………………… 2

1.5.3 Civil Engineering Drawing…………………………… 2

1.5.4 Electrical Engineering Drawing……………………… 2

1.6 Specific Purposes of Studying Civil Engineering Drawing…… 2

1.7 Types of Civil Engineering drawing…………………………... 3

1.8 Elements of Engineering Drawing…………………………….. 3

1.9 Drawing Standards……………………………………………. 3

1.10 Drawing Instruments…………………………………………. 3

Review Questions…………………………………………………. 9

CHAPTER 2 LINES AND SYMBOLS

Objectives………………………………………………………….. 10

2.1 Conventional Lines……………………………………………. 10

2.2 Conventional Symbols………………………………………… 12

2.2.1 Common Geometric Symbols Used in Engineering

Drawing…………………………………………………...

12

2.2.2 Common Symbols Used in Civil Engineering Drawing… 13

2.2.3 Common Symbols Used in Electrical Engineering

Drawing…………………………………………………...

15

Exercise and Assignments…………………………………………. 16

Review Questions…………………………………………………. 16

CHAPTER 3 LETTERING AND NUMBERING

Objectives………………………………………………………….. 17

3.1 Letter Styles……………………………………………………. 17

3.2 Classification of Letters………………………………… 17

3.2.1 Extended and Condensed Letters…………………….. 17

3.2.2 Light Face and Bold Face Letters…………………….. 18

3.3 Technique of Lettering………………………………………… 18

3.4 Guide Lines……………………………………………………. 18

3.4.1 Guidelines for Capital Letters……………………….. 18

3.4.2 Guidelines for Lower-Case Letters………………….. 18

3.5 Single Stroke lettering…………………………………………. 18

3.6 Order of Strokes……………………………………………..... 18

3.7 Spacing of Letters……………………………………………… 22

3.8 Lettering in Maps……………………………………………… 22

3.9 Summary of ISO Rules for Lettering…………………………. 22

Exercise and Assignments…………………………………………. 24

Review Questions…………………………………………………. 24

iii

CHAPTER 4 GEOMETRIC CONSTRUCTION

Objectives………………………………………………………….. 25

4.1 Introduction……………………………………………………. 25

4.2 Geometric Nomenclature……………………………………… 25

4.2.1 Points in Space………………………………………... 25

4.2.2 Lines…………………………………………………... 25

4.2.3 Angle………………………………………………….. 25

4.2.4 Triangles………………………………………………. 26

4.2.5 Quadrilateral…………………………………………... 26

4.2.6 Polygon………………………………………………... 26

4.2.7 Circle………………………………………………….. 27

` 4.2.8 Solids………………………………………………….. 27

4.3 Techniques of Geometric Constructions………………………. 27

4.3.1 How to Bisect a Line or an Arc……………………….. 28

4.3.2 How to Divide a Line into a Number of Equal Parts….. 28

4.3.3 How to Bisect an Angle……………………………….. 29

4.3.4 How to Draw an Arc or Circle (Radius) through Three

Given Points……………………………………………

29

4.3.5 How to Transfer an Odd Shape (Triangular)………….. 30

4.3.6 How to Transfer Complex Shapes……………………. 30

4.3.7 How to Draw a Pentagon (5 Sides)…………………… 31

4.3.8 How to Draw a Hexagon (6 Sides)……………………. 31

4.3.9 How to Draw an Octagon (8 Sides)…………………… 31

4.3.10 How to Draw any Sided Regular Polygon…………… 32

4.3.11 How to Locate the Center of a Given Circle………… 33

4.3.12 How to Draw Arc Tangent to a Straight Line and a

Curve…………………………………………………

34

4.3.13 How to Draw Arc Tangent to Two Arcs of Different

Radius………………………………………………...

34

4.3.14 How To Draw an Ogee Curve………………………. 35

4.3.15 How to Draw Straight Tangent to Two Arcs of

Different Radius………………………………………

36

4.3.16 How to Draw an Ellipse (Four-centered Approximate

Method)……………………………………………….

36

Exercise and Assignments…………………………………………. 37

Review Questions…………………………………………………. 37

CHAPTER 5 DIMENSIONING

Objectives………………………………………………………….. 38

5.1 Purpose of Dimensioning..……………………………………. 38

5.2 General Conditions for Dimensioning….…………………….. 38

5.3 Elements of Dimension System………………………………. 38

5.4 Rules for Dimensioning………...……………………………... 38

5.4.1 General Rules for Dimensioning….………………….. 38

5.4.2 Rules of Extension Lines…………………………….. 39

5.4.3 Rules of Dimension Lines…………………….….…... 39

5.4.4 Rules of Arrowhead…………………………………... 39

5.4.5 Rules of Leaders………………………………………. 40

5.5 Direction of Dimensions………………………………………. 40

5.6 Technique of Dimensioning…………………………………… 41

5.7 Dimensioning in Limited Space………………………………. 41

5.8 Dimensioning of Angles………………………………………. 42

5.9 Dimensioning of Arcs…………………………………………. 43

5.10 Dimensioning of Chord length, Arc length and Angle………. 43

5.11 Dimensioning of Round Holes……………………………….. 44

5.12 Dimensioning of Blind Holes………………………………… 44

iv

5.13 Dimensioning of Chamfer……………………………………. 44

5.14 Common Mistakes in Dimensioning…………...…………….. 45

5.15 Worked-out Examples of Dimensioning……………………... 48

Exercise and Assignments…………………………………………. 51

Review Questions…………………………………………………. 53

CHAPTER 6 SCALES

Objectives………………………………………………………….. 54

6.1 Scale…………………………………………………………… 54

6.2 Uses of scale…………………………………………………… 54

6.3 Sizes of Scales…………………………………………………. 54

6.4 Classification of Scales………………………………………... 55

6.4.1 Plain Scale……………………………………………… 55

6.4.2 Diagonal Scale…………………………………………. 55

6.4.3 Comparative Scale…………………………………….. 55

6.4.4 Vernier Scale………………………………………….. 55

6.4.5 Chord Scale……………………………………………. 55

6.5 Necessity of Construction of Scale on Drawing……………… 55

6.6 Information Necessary for Construction of a Scale…………… 56

6.6.1 The Representative Fraction (R.F.)……………………. 56

6.6.1.1 Worked out Examples of R.F. calculation……….. 56

6.6.2 Units of Measurement………………………………….. 57

6.7 Construction of Plain Scale……………………………………. 57

6.7.1 Worked-out Examples of Plain Scale Construction…… 58

6.8 Principle of Diagonal Scales…………………………………... 61

6.9 Construction of Diagonal Scales………………………………. 62

6.9.1 Worked-out Examples of Diagonal Scale Construction... 63

Exercise and Assignments…………………………………………. 70

Review Questions…………………………………………………. 71

CHAPTER 7 PROJECTION

Objectives………………………………………………………….. 72

7.1 Introduction……………………………………………………. 72

7.1.1 Projection……………………………………………… 72

7.1.2 Picture Plane/Plane of Projection……………………… 72

7.1.3 View…………………………………………………… 72

7.1.4 Projector……………………………………………….. 72

7.2 Types of projection…………………………………………….. 73

7.2.1 Orthographic Projection……………………………….. 73

7.2.2 Pictorial Projection…………………………………….. 74

7.2.2.1 Axonometric Projection………………………….. 74

7.2.2.2 Oblique Projection……………………………….. 74

7.2.3 Perspective Projection………………………………….. 75

7.3 Details of Orthographic Projection……………………………. 75

7.3.1 The Glass Box method………………………………… 75

7.3.2 The Six Principal Views……………………………….. 77

7.3.3 Arrangement of Views…………………………………. 78

7.3.3.1 Glass Box Concept for 1st Angle Projection…...… 79

7.3.3.2 Glass Box Concept for 3rd Angle Projection…...... 80

7.3.4 Orthographic Projections of Parallel, Inclined and

Oblique Surfaces………………………………………..

81

7.3.5 Orthographic Projections of Hidden Surfaces…………. 82

7.3.6 Orthographic Projections of Curved Surfaces and Holes 82

7.3.7 Precedence of Lines…………………………………… 82

7.3.8 Method of Obtaining Views…………………………… 83

7.3.9 Methods of projecting views…………………………… 84

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7.3.10 Spacing between the Views………………..………… 84

7.3.11 Steps for Projecting Views by Diagonal Line Method.. 85

7.3.12 Worked-out Examples of Orthographic Views………. 87

7.3.13 Limitation of Multi View Projection…...…………….. 91

7.4 Details of Isometric Projection………………………………… 91

7.4.1 Principle of Isometric Projection………………………. 91

7.4.2 Isometric Scale…………………………………………. 92

7.4.3 Lines in Isometric Projection…………………………... 93

7.4.4 Isometric Drawing……………………………………... 93

7.4.5 Method of Constructing Isometric Drawing…………… 94

7.4.5.1 Box Method……………………………………… 94

7.4.5.2 Off-set Method…………………………………... 94

7.4.6 Isometric Drawing of Planes…………………………... 95

7.4.6.1 Isometric Drawing of Rectangular Plane……….. 95

7.4.6.2 Isometric Drawing of Pentagonal Plane………… 95

7.4.6.3 Isometric Drawing of a Circular Plane………….. 96

7.4.7 Isometric Drawing of Solids…………………………... 96

7.4.7.1 Points to be Remembered for Isometric drawing... 96

7.4.8 Steps for drawing Isometric View…………………….. 96

7.4.9 Worked-out Examples of Isometric Drawing…………. 99

Exercise and Assignments…………………………………………. 102

Review Questions…………………………………………………. 109

CHAPTER 8 SECTIONING

8.1 Introduction……………………………………………………. 110

8.2 Terminology…………………………………………………… 110

8.2.1 Sectioning……………………………………………… 110

8.2.2 Sectional View………………………………………… 110

8.2.3 Cutting Plane…………………………………………… 111

8.2.4 Cutting Plane Line……………………………………... 111

8.2.5 Section Lining…………………………………………. 112

8.3 Types of section……………………………………………….. 112

8.3.1 Full Section…………………………………………….. 113

8.3.2 Offset Section………………………………………….. 113

8.3.3 Half Section……………………………………………. 114

8.3.4 Broken-out Section…………………………………….. 114

8.3.5 Revolved Section………………………………………. 115

8.3.6 Removed Section………………………………………. 117

8.4 Special Consideration for Section of Ribs, Spokes and

Lugs…………………………………………………………..

118

8.5 Parts that Should Not Be Sectioned…………………………... 119

8.6 Worked-out Examples of Sectioning………………………….. 120

Exercise and Assignments…………………………………………. 123

Review Questions…………….……………………………………. 125

Bibliography ……………………………………… 126