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DEDICATION
To our students
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M. B. Shah is a professor of mechanical engineering and the principal of Shah and Anchor Kutchhi Engineering College, Mumbai. He pursued his undergraduate studies in mechanical engineering from Sardar Patel University and obtained his master of engineering degree in machine design from the University of Bombay (now University of Mumbai). After obtaining his Ph.D. from the Indian Institute of Technology Bombay, he joined Veermata Jijabai Technological Institute in 1969 where he taught engineering drawing and machine design until 1998. His research paper, “Magnetic NDT Technique to Evaluate Fatigue Damage,” was published in the Physica Status Solidi.
B. C. Rana was an assistant professor at Veermata Jijabai Technological Institute. He graduated in mechanical engineering from Gujarat University in 1968 and obtained his master of engineering degree from the University of Mumbai. He has taught for nearly thirty years, initially at K. J. Somaiya Polytechnic as a lectu rer and then at Veermata Jijabai Technological Institute.
16.3 Reading Orthographic Projections by Visualizing the Bounding Surfaces 382
16.4 Recognizing the Projections of the Same Plane Surface 383
409
Thinking Exercises 416
Objectives 419
17.1 Introduction 420
17.2 Types of Pictorial Projections 420
17.3 Isometric Projections 420
17.3.1 The Isometric Scale 422
17.3.2 Drawing Isometric Projections of Solid Objects 423
17.3.3 Procedure for Drawing Isometric Projections of an Object 424
17.3.4 The Isometric Projection of a Sphere 430
Exercises 434
Critical Thinking Exercises 438
18Oblique
Parallel Projections and Perspective Projections
Objectives 441
18.1 Introduction 442
18.2 Oblique Parallel Projections 442
18.3 The Oblique Parallel Projections of a Cube 444
18.4 Perspective Projections 451
18.4.1 Terminology 451
18.4.2 Theory of Perspective Projections 452
18.4.3 The Visual Ray Method 452
18.4.4 The Vanishing Point Method 454
18.4.5 Important Points About Perspective Projections 455
Exercises 460 Critical Thinking Exercises 464
19Threaded Fasteners
Objectives 467
19.1 Introduction 468
19.2 Screw Threads 468
19.2.1 The Terminology for Threads 468
19.2.2 The Forms of Screw Threads 469
19.3 Representation of Threads 472
19.4 Bolts, Nuts and Washers 475
19.5 Hexagonal Nuts 476
19.5.1 Orthographic Projections of a Hexagonal Nut 477
19.5.2 Symbolic Views of a Hexagonal Nut 479
19.6 Projections of a Hexagonal-Headed Bolt 480
19.7 Washers 480
19.8 Square Nuts 481
19.9 Types of Nuts 482
19.10 Types of Bolt Heads 483
19.11 Set Screws 487
19.12 Foundation Bolts 487
19.13 Tap Bolts 490
19.14 Stud Bolts 490
19.15 Locking Arrangements for Nuts 492
Exercises 495
Critical Thinking Exercises 496
20Riveted and Welded Joints 497
Objectives 497
20.1 Introduction 498
20.2 Types of Rivet Heads 499
20.3 Riveted Joints 499
20.3.1 Lap Joints 499
20.3.2 Butt Joints 502
20.4 Welding 504
20.5 Types of Welded Joints 504
20.5.1 Types of Welds 504
20.5.2 Welding Drawing 506
20.5.3 Representation of Welded Joints 506
20.5.4 Indication for Plate Preparation 507
20.5.5 Dimensioning Welds 507
20.5.6 Supplementary Symbols 508
20.5.7 Indicating the Welding Process 509
Exercises 509
Critical Thinking Exercises 510
21Computer-Aided Drafting
Objectives 513
21.1 Introduction 514
21.2 Using AutoCAD 514
21.2.1 A Mouse 517
21.2.2 A Keyboard 517
21.2 AutoCAD Command Access 517
21.3 Menus and Toolbars 518
21.4 Toolbars 518
21.4.1 Opening a File 518
21.4.2 Saving a File 519
21.5 Execution of Commands 519
21.5.1 The Donut and Spline Commands 519
21.5.2 The Line Command 521
21.5.3 The Coordinate Systems Command 522
21.5.4 The Polygon Command 524
21.5.5 The Circle Command 525
21.5.6 The Arc Command 526
21.5.7 The Ellipse Command 527
21.5.8 The Hatch Command 527
21.5.9 The Zoom Command 527
21.5.10 The Regen Command 527
21.5.11 The UCS Command 528
21.5.12 The Units Command 528
21.5.13 Drawing Limits 528
21.5.14 The Grid Command 528
21.5.15 The Offset Command 528
21.5.16 The Change Command 529
21.5.17 The Chprop Command 529
21.5.18 The Erase Command 529
21.5.19 The Trim Command 529
21.5.20 The Array Command 529
21.5.21 The Mirror Command 531
21.5.22 The Copy Command 532
21.5.23 The Move Command 532
21.5.24 The Chamfer Command 532
21.5.25 The Fillet Command 532
21.5.26 The Pedit Command 532
21.5.27 The Dimension Command 532
21.5.28 The Extend Command 532
21.5.29 The Lengthen Command 532
21.6 Three-Dimensional Modelling 540
21.6.1 The Wire Frame Model 540
21.6.2 The Surface Model 540
21.6.3 The Solid Model 540 Exercises
ABBREVIATIONS, SYMBOLS AND NOTATIONS
ABBREVIATIONS
AFV auxiliary front view
AGP auxiliary ground plane
AIP auxiliary inclined plane
ATV auxiliary top view
AV axis of vision
Aux auxiliary
BIS Bureau of Indian Standards
CAD computer-aided drafting
CP central plane or cutting plane
CV centre of vision
Dia diameter
DOO direction of observation
FV front view
GL ground line or ground level
GP ground plane
GR ground
HL horizon line
HP horizontal plane
HRP horizontal reference plane
HT horizontal trace
IS Indian standard
ISO International Organization for Standardization
LHSV left-hand-side view
OSNAP object SNAP
PP pro ile plane
PPP picture plane for perspective projection
RF representative fraction
RHSV right-hand-side view
RP reference plane
S station point
Sect sectional
SFV sectional front view
SQ Square (represents the side of a square)
SRHSV Sectional right-hand-side view
SSV sectional side view
STV sectional top view
SV side view
TL true length
TS true shape
TV top view
VP vanishing point or vertical plane
VT vertical trace
XY ground line
SYMBOLS AND NOTATIONS
A, B, …object points
a, b, …top views of object points A, B, …
a ′ , b′, …front views of object points A, B, …
a ″ , b″, …side views of object points A, B, …
a1, b1, …auxiliary top views of points A, B, … on projectors perpendicular to X1, Y1
a1 ′ , b1 ′, …auxiliary front views of points A, B, … on projectors perpendicular to X1, Y1
ht′ , ht front and top views of point HT
vt′ , vt front and top views of point VT
A′ , B′ , C′ …perspective views of object points A, B, C, …
a0, b0, c0 …points at which the top views of visual rays meet top view of PPP; they are top views of perspective views of A′ , B′ , C′ , …
α apparent angle of inclination of a line with the HP or angle of inclination of the front view of a line with the XY line
β apparent angle of inclination of a line with the VP or angle of inclination of the top view of a line with the XY line
θ angle of inclination made by object line with the HP
φangle of inclination made by object line with the VP or diameter
Φ, φ diameter (alternative)
D, d diameter
e eccentricity of a conic curve
r, R radius
OV central axis
Abbreviations, Symbols and Notations
In the more than forty years that we have been teaching enginee ring drawing, we have seen a dramatic increase in the number of engineering colleges in India and a corresponding increase in the number of books on this subject. We have observed, however, that students ind it very dif icult to master the subject from these books since the majority of them cover just the basic theory, examples, and their solutions. Practically none of them discuss the logic behind the solutions. We have attempted to give the logical reasons for the questions as well as the analysis underlying the solutions. This emphasis on understanding—rather than relying on memory alone—is just one of the reasons that make this book unique.
The main purpose of this book is to provide students with a clear and thorough presentation of the theory and applications of engineering drawing. To achieve this objective, this edition has been shaped by the comments, suggestions and reviews from numerous students, instructors, and professionals. Using a step-by-step approach, the book covers the syllabi of irst-year engineering courses as well as diploma courses of major universities and technical boards. It will also be useful to students preparing for professional courses offered by the Institution of Engineers, the Institution of Mechanical Engineers, and the Institution of Electronics and Telecommunications Engineers.
NEW TO THIS EDITION
Signi icant improvements have been made to this second edition. The following is a list of some of the important ones:
Updated Content
All the drawings have been updated and are based on the latest BIS standards. Based on market research as well as reviewer feedback, a new chapter on scales has been added. The chapter on computer-aided drafting has been updated to cover the latest version of AutoCA D.
1.2.15
FLEXIBLE CURVES
tch various plotted points that are not on a straight line (see Figure 1.14). In the bent position it can be utilized to guide a pencil or an ink pen to draw oft metallic rod to strengthen it.
1.2.16 TRACING PAPER
A tracing paper is a semi-transparent paper, which is used to trace an existing pencil or ink drawing. This is then used to draw blueprints.
1.2.17
Artwork
The artwork has been enhanced by a two-colour presentation that provides the reader with a more realistic and understandable sense of the material. Particular attention has been given to the rendering of each igure so that the views and dimensions can be easily understood.
OBJECTIVES
After studying this chapter, you will be able to
>> Divide a line into equal parts
>> Draw regular polygons
>> Draw lines and arcs tangent to each other
>> Draw the curves used in engineering practice such as conics, cycloids, involutes and spirals
>> Draw normals and tangents to a given engineering curve
>> Draw the path of a point on a selected part of a machine that undergoes ect of another part
Organization and Approach
Each chapter is organized into well-de ined sections that contain an explanation of speci ic topics with illustrative examples. The topics within each section are differentiated using distinct styles and titles. This presents a structured approach that enables quick understanding as well as a convenient review.
(a) Lines inclined to both the VP and the HP
Chapter Contents
A bulleted list of the chapter contents states the learning goals of the chapter. Each chapter also begins with an introduction section that presents an overview and explains the importance of the material within the chapter.
Example5.2 A straight line AB of 40 mm length has one of its ends, A, at 10 mm from the HP and 15 mm from the VP. Draw the projections of the line if it is parallel to the VP and inclined at 30° to the HP. Assume the line to be located in each of the four quadrants by turns.
Analysis: Based on Table 5.3, we can conclude that
(i) As the given line AB is parallel to the VP, the front view will be of the true length, that is, 40 mm, and inclined to XY at α where α θ, the angle at which the given line is inclined to the HP (30° in the present case).
(ii) The top view will remain parallel to the XY line.
(iii) The position of point A is given. Hence, depending upon the quadrant, aʹ and a front view can then be drawn.
(iv) The top view is then projected as a line parallel to the XY line.
Solution (Figures 5.12 to 5.15):
(i) Draw a ʹ 10 mm above XY and a 15mm below XY angle projection draw both the points above XY; for the third-angle projection draw a above XY and aʹ below XY XY for the fourth-angle projection.
Improved Pedagogy
Clarity throughout the text has been improved, new examples have been provided, and many new problems have been added. Also, each example has a new “analysis” section that aids in problem solving and review.
(a)
Review Material
Problem sets have been revised so that readers can select from a wide range of dif iculty. Partial solutions and answers to selected problems are given, aiding students with further applications of the theory. The material has been classi ied into the following:
Exercises
Exercise problems have been provided at the end of the chapter that help gauge the understanding of the concepts discussed in the chapter.
EXERCISES
1
A straight line AB has an end point A, which is nearer to the HP and the VP, 15 mm above the HP and 20 mm in front of the VP. The front view of the line is inclined at 30° to XY and is of 40 mm length. Draw the projections of the line if the top view is inclined at 45° to the XY line. Draw an auxiliary front view on a ground line X1Y1, which tion of the line with the HP.
2
A straight line PQ has its FV inclined at 45° to XY and is of 40 mm length. The end point P is 10 mm above the HP and 20 mm in front of the VP. If the line is inclined at 30° to the VP, draw the projections of the line PQ. Draw an auxiliary top view on a plane inclined at 45° to the HP.
CRITICAL EXERCISES
1
Four lamp posts, each of 10 m height, are erected at the corners of a rectangular plot 10 m 5 m. Each pair of posts that are diagonally opposite has a rope with one end tied at 1 m from the top of one post and the other end at 1 m from the base on the ground of the other post. Assuming the length of the plot to be 10 m and parallel to the VP, draw the projections of the lamp posts and the true length of the ropes. The diameters of the lamp posts and the ropes may be neglected and they may be represented by lines only.
Critical Thinking Exercises
2
A room of 5 m 4 m 3 m dimensions has a fan suspended from the centre of the ceiling 0.5 m from the ceiling. A cable connects a switch directly to the fan at the centre of the ceiling. If the switch is located at one of the corners of the room, at a height of 1.5 m, draw the projections of the cable assuming the 5 m 3 m wall to be ews.
Hints
Hints to the dif icult problems of both kinds of exercises have been provided, encouraging students to try these without giving away the whole solution.
HINTS FOR SOLVING EXERCISES
ataDstniHrofnoituloS
Q.1 aʹ a α 30° aʹbʹ 40 β 45° ? AFV on X1Y1 parallel to ab ? ? θ
Challenging problems based on actual applications have also been provided in a separate section to illustrate the concepts and tie them to the real world.
Draw XY, locate aʹ and a aʹbʹ inclined 30° and aʹbʹ 40 ab inclined at 45°. Draw bʹb vertical line and locate b Draw X1Y1 parallel to ab
Project AFV by drawing projectors through a and b perpendicular to X1Y1 and locate a1 ʹ b1 ʹ at distances equal to the distances of aʹ and bʹ from XY
Example6.2: A straight line AB has one end A 18 mm below the HP and 10 mm behind the VP, while the other end B is 10 mm below the HP and 25 mm behind the VP. If the distance between the end projectors is 35 mm and the line is located in the third quadrant, draw the projections of the line. With the help of s of inclination to the HP and the VP.
Multimedia Package LiveDraw
This unique package is provided along with the book to help readers understand, practice, and master the toughest and the most dif icult-to-visualize concepts of this subject. It comprises text, graphics, animations, and voice-over effects, and demonstrates solutions to select examples from the book. The examples of this type are identi ied by the icon.
SUPPLEMENTS
• To provide readers with suf icient practice, extra problems and solutions are provided as a question bank. These range from easy to dif i cult and help readers learn in a sequential manner.
• A summary of the important points and topics in each chapter, along with the relevant page numbers, are provided to help students review what they read in each chapter.
• Solutions to selected problems are also provided on the companion Web site for review and quick references.
ACKNOWLEDGEMENTS
I am thankful to Thomas Mathew Rajesh and Jonaki Ray of Pearson Education for their help and efforts in completing the work as early as possible. My colleague, Sachin Bhatt, and my younger daughter-in-law, Manasi, helped in updating the chapters. I am also grateful for the numerous suggestions and comments from various teachers in this ield.
M. B. Shah
THE DEVELOPMENT OF THIS BOOK
The second edition of Engineering Drawing has bene ited from an extensive development process. Over 100 faculty reviewers, students, and industry professionals provided feedback about the accuracy and relevance of the content as well as suggestions for its improvements. While we could not incorporate every suggestion from everyone, we do acknowledge that their feedback was invaluable in our attempt at creating the best possible engineering drawing textbook.
CONSULTANT BOARD
The consultant board provided us with a detailed and critical analysis of each chapter and worked with us throughout the development of the book. We would like to thank the following for their time and commitment:
Nitin D. Junnarkar
Tolani Maritime Institute, Pune
Varinder Mittal
Birla Institute of Technology and Science, Pilani
S. Krishnamoorthy
Sri Ramanujar Engineering College, Chennai
N. Leela Prasad
Vignan Institute of Technology and Sciences, Hyderabad
REVIEWERS
The guidance and thoughtful recommendations of many helped us improve this book. We are grateful for the comments and helpful suggestions received from the following reviewers:
R. K. Agarwal
R. G. Engineering College, Meerut
P. Aravindan
Dr. M. G. R. University, Chennai
R. S. Baliah
Saranathan College of Engineering, Trichy
M. M. Butt
National Institute of Technology, Srinagar
M. S. Charoo
National Institute of Technology, Srinagar
K. Duraivelu
Rajalakshmi Engineering College, Thandalam
R. Gnanamoorthy
Indian Institute of Technology, Madras
Swetank Gupta
Indian Institute of Technology, Kanpur
K. B. Kelgandre
K. J. Somaiya Polytechnic, Mumbai
Manish Kewalramani
Birla Institute of Technology and Science, Pilani
N. S. Parthasarathy
Anna University, Chennai
G. Prasanthi
JNTU College of Engineering, Anantapur
K. Prahalada Rao
JNTU College of Engineering, Anantapur
K. Madhava Reddy
G. P. R. Engineering College, Kurnool
Y. V. Mohana Reddy
G. P. R. Engineering College, Kurnool
C. Selvaraj
Government College of Technology, Coimbatore
N. Shanmukha
R. V. College of Engineering, Bangalore
M. Thiruchitrambalam
Mahalingam Engineering College, Coimbatore
A. S. Verma
Apollo Institute of Technology, Kanpur
STUDENT REVIEWERS
We took the help of many students from the DAV Institute of Engineering and Technology, Jalandhar and R. V. College of Engineering, Bangalore. These students class-tested the manuscript, evaluated it for clarity and assessed each feature. Their comments helped us expand the book’s content, improved the pedagogical features, and strengthened the assessment features. We are than kful to the following:
Shreenidhi Acharya
Tarun Arora
Abhinandan Bhatia
Himanshu Chandra
Mani Bhushan Choudhary
Ranvir Singh Gill
Tarun Kumar
Unnat Mahajan
C. S. Sandeep
Sourabh Sehgal
Ashish Sharma
Sagar Trehan
Vinay Varadaraj
1
Basics of Engineering Drawing
OBJECTIVES
After studying this chapter, you will be able to
>> Understand the basics of engineering drawing
>> Get familiar with drawing instruments and learn how to use them in engineering drawing
