Machine drawing : includes AutoCAD

690 Pages·2012·98.408 MB·English

by  Ajeet Singh

M A C H I N E
D R A W I N G
Includes AutoCAD
Second Edition
About the Author
Ajeet Singh graduated in Mechanical Engineering from Jodhpur
University in 1963. While completing his masters degree in Heat and
Power Engineering in 1970, he served as lecturer at Malviya Regional
Engineering College, (which is now known as Malviya National Institute
of Technology (MNIT) Jaipur. From 1970 onwards, he served at MNR
Engineering College, which is now known as Motilal Nehru National
Institute of Technology (MNNIT), Allahabad. He acquired a PhD de-
gree from Allahabad University in 1979 while serving at MNNIT. As
one of the most distinguished faculty members of his college, Dr Singh
also served in various positions like President of Students’ Club, Dean:
Academic, Dean: Research and Consultancy and lastly as Professor and
Head of Mechanical Engineering Department from 1997.
Besides being an academician, Dr Singh has also provided consult-
ing services to many private and public companies like BHEL. He has
published many research papers in national and international journals
and has reviewed the journal of Institution of Engineers in the fi eld of Automobiles and Tribology. He received
the Railway Board prize for his paper on Fuel Injection. He is a fellow member of the Institution of Engineers,
India, and Life Member of ISTE.
Dr Singh has expertise in many programming languages and has wide experience in teaching CAD (Computer
Aided Design) for many years. Experience in using computers, helped him write his previous book, Working
with AutoCAD 2000, published by Tata McGraw Hill, which was widely accepted in India and abroad. He
introduced the unique idea of combining machine drawing with newer methods of drafting using AutoCAD.
His book Machine Drawing, which applied the techniques of AutoCAD 2005, was fi rst published in 2007.
The revised second edition emphasizes on AutoCAD 2010.
Dr Singh also worked as Visiting Professor in foreign countries for 15 years. His fi nal tenure, which lasted
for 10 years, was at Salalah College of Technology, Salalah, Sultanate of Oman, where he completed his books
on AutoCAD 2000 and the present book on Machine Drawing. After enjoying a fruitful and distinguished
academic career for 44 years, and teaching at the undergraduate, postgraduate and doctoral levels, he now
leads a retired life and spends his time reading, writing and travelling.
M A C H I N E
D R A W I N G
Includes AutoCAD
Second Edition
Ajeet Singh
Retired Professor and Head of Mechanical Engineering Department
Motilal Nehru National Institute of Technology
Allahabad
Tata McGraw Hill Education Private Limited
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Dedicated to my wife, Mrs Kanwaljeet
and
Our grandchildren, Gaganjit, Karanjit, Ananya, Neha, Tanvi and Simar

Preface
Any machine part which is produced is fi rst designed and then its drawing is prepared. The industry then
manufactures the part according to the details given in the drawing. Thus, drawing is the only means of com-
munication between the design offi ce and the manufacturing shop fl oors. Hence Engineering Drawing is quite
an important communication tool for engineers.
Engineering drawings were made manually in the past but now they are made with the help of computers,
and are called Computer Aided Drafting (CAD). There are many good books in the market on engineering
drawing but only a few of them cover CAD. Some books give CAD as only a single small chapter in the end,
which does not help a student in correlating the art of drawing with CAD.
There are some good books which focus solely on CAD. They describe the tools available in the software
with a few examples. This book is written as a combination of both manual and computer methods which
run in parallel, chapter by chapter. The idea is that a student who makes a drawing manually, should be able
to create a similar drawing with the help of a computer. It will give a better understanding of the use of the
software for engineering-drawing purposes. The examples selected for AutoCAD cover a majority of the
relevant commands. The software is explained by showing actual toolbars and dialog boxes which appear on
the screen to enhance the understanding of students.
The software adopted in the fi rst edition was AutoCAD 2005. The revised second edition describes
AutoCAD 2010. For more details on the subject of AutoCAD, readers can consult the other book of the
author, Working with AutoCAD 2000.
This book not only gives elaborate drawings, but an effort has been made to describe all the basic knowl-
edge required for each topic. The information given will be quite useful to answer questions asked in the
viva-voce examinations.
The contents of the book are selected to cover the syllabi of various universities/institutions offering machine
drawing. Some chapters like Applied Geometry, Surface Developments, Intersections, Cams, Jigs and Fixtures,
etc., are not given in the book but these chapters will be put on the Internet to make the book comprehensive.
The chapters have been arranged in a logical order for step-by-step mastering of the subject.
The book is suitable for fi rst-year degree courses in Civil, Mechanical and Electrical Engineering and the
second year of Mechanical Engineering courses. The production drawings section of the book on Tolerances,
Limits, Fits, Geometric Tolerances and Surface Finish, etc., is very helpful for practicing engineers as well.
Internet websites given in the Appendix makes the book useful for any person searching information on a
topic concerning machine drawing.
viii Preface
The conventions and terminology used in the book are mostly as per the Bureau of Indian Standards (BIS).
But wherever there are different terms by BIS and AutoCAD, the terms of AutoCAD have been used so that
students do not get confused while using the software.
Explanations are accompanied by many pictorial drawings for better visualization of the concept. The author
has had a long experience of 44 years of teaching this subject and is fully aware of the common mistakes which
students commit. Therefore, these mistakes have been pointed out so that students do not repeat the same.
The book has the following important features:
∑ The book has over 120 solved examples on manual drafting as well as on CAD to give a comprehensive
idea to the students.
∑ Over 500 theory questions help students know as to what type of questions can be asked on the subject.
They also help the teacher to select questions for setting examination papers.
∑ Multiple choice questions (totalling almost 400) are given at the end of each chapter for evaluating
students quickly for short quizzes, etc.
∑ Fill up the blank questions have been so chosen that they check the key knowledge points of the
chapter.
∑ Over 170 unsolved problems for practice are given to create a thorough grasp on the concepts of the
drawing. They also form a good question bank for the teacher to set examination papers. Solutions of
the unsolved problems have not been given intentionally, so that the students do not copy from the book
without understanding.
The contents of the book are divided into six sections:
Section A The fi rst chapter deals with the importance of drawing and Fundamentals of Drawing while
the second chapter is on the general tools available in CAD. The initial settings, and the draw and modify
commands are explained with the help of solved examples. The following chapters are on the materials and
tools used for drawing, standard conventions for lines, lettering, and dimensions.
Section B This is about Projection Methods. Various methods of projections like Orthographic, Isometric,
Oblique, Perspective, etc., are explained to fully describe a 3D object on a 2D sheet. This helps to view an
object from any side and to understand the methods of visualization.
Section C This is about Joints and Couplings. Permanent joints like riveted and welded joints are described.
Temporary joints formed by bolts/nuts, cotter, shaft couplings and pipe joints are also explained. CAD can
be of help in copying a part in rectangular or polar array form. Use of this tool for copying many parts in an
array is explained. How the drawings stored in a graphic library can be used in creating drawings for the joints
and couplings are demonstrated here by examples. Sections A, B and C form the fi rst course on Engineering
Drawing for a majority of the universities/colleges and deal with all the disciplines of engineering.
Section D This concentrates on Production drawings to be used in the shop fl oor. The mating parts have to
be specifi ed by a type of standard fi t required for an application. It is not possible to manufacture any part of
the exact dimensions put on the drawing and hence a certain amount of tolerance is also to be put in addition
to the basic dimensions. The type of machine to be used for manufacturing is decided by the type of surface
fi nish mentioned on the drawing. Geometric tolerances like squareness, fl atness, etc., are sometimes specifi ed
on production drawings. Standard methods to specify materials and all this information is described in this
section. How AutoCAD helps in putting these values very easily on the drawing is explained. This section
and the next few sections are mainly for mechanical engineers and is given in the second course on machine
drawing. This can be useful for practicing engineers as well.
Section E This deals with Machine Parts like springs, belts and pulleys, bearings, and gears to transmit
power. AutoLISP is a programming language to be used in AutoCAD. Fundamentals of this language are
Preface ix
given to create parametric drawings. Once a program is made, it can be used to create a drawing by defi ning
the values of the variable sizes.
Section F This is on Part and Assembly Drawings. Machines are made by assembling different parts.
How the parts are to be joined together are explained here. The main important parts of internal combustion
engines, steam power plants are selected for these drawings. Some parts of the machine tools and hand tools
have also been included. The drawings created as part drawings can be assembled very easily using AutoCAD
to produce an assembly drawing.
Appendix 1 contains some useful Indian Standards. Due to developing Internet facilities, useful websites
for different topics are given in Appendix 2. Appendix 3 lists some commonly used AutoCAD commands.
Appendix 4 shows the display of the icons of the various tabs of the ribbon.
The online Learning Center of the book www.mhhe.com/singh/md2 provides a vast range of supplements.
Instructors can take the advantage of the solution manual and Power Point Slides. Five chapters on Applied
Geometry, Surface Developments, Intersections, Cams, Jigs and Fixtures not included in the book are also
available at the above-mentioned site for the students as well as instructors.
I am sure that the contents of the book will help readers in getting suffi cient profi ciency and knowledge on
machine drawing and CAD for mechanical drawings.
No human being is perfect. Errors and omissions are always possible from any one in spite of the best ef-
forts. I hope the readers will agree with me and inform the publisher/author for improvements and corrections
in the subsequent editions.
Constructive suggestions for the improvement of the book are most welcome at my email address:
[email protected].
Dr. Ajeet Singh
January 2012