20MEGO1 – Engineering Graphics

Prepared by:
M. Sundra Pandian, M.E., M.B.A.
Assistant Professor, Department of Mechanical Engineering,
Sri Ramakrishna Institute of Technology, Coimbatore - 10
 Course Objective

The objectives of this course are to impart

knowledge to interpret engineering drawings and to
enable the students to communicate the concepts,
ideas, and basic designs through graphical
representations as per related engineering
conventions and standards. 
 Course Outcome
CO1: Ability to interpret and construct geometric
entities, orthographic projection of engineering components
CO2: Ability to construct orthographic views of points
and straight lines
CO3: Ability to apply orthographic principles to
construct views of planes and solids
CO4: Ability to build orthographic projection of section
of solids and develop the lateral
surfaces of solids
CO5: Ability to develop isometric and perspective
projections of solids
 Syllabus
Curve Constructions and Orthographic Projection (Module 1)

Lettering – Types of lines – Dimensioning – Conics- Construction

of ellipse, parabola and hyperbola by eccentricity method-
Construction of cycloid- Construction of involutes of square and
circle- Drawing of tangents and normal to these curves. Principles of
Orthographic projection – Layout of views Orthographic projection
of simple Engineering components using first angle Projection.
Drawing of multiple views from pictorial views of objects.
 Syllabus
Projection of Points, Lines and Plane Surfaces (Module 2)
Projection of points – Projection of straight lines (only First angle
projections) inclined to both the principal planes – Determination of
true lengths and true inclinations by rotating line method and
trapezoidal method and traces – Projection of planes (polygonal and
circular surfaces) inclined to both the principal planes by rotating
object method.
 Syllabus
Projection of Solids (Module 3)
Projection of simple solids like prisms, pyramids, cylinder, cone
and truncated solids when the axis is inclined to one of the principal
planes by rotating object method and auxiliary plane method.
 Syllabus
Projection of Sectioned Solids and Development of Surfaces
(Module 4)
Sectioning of above solids in simple vertical position when the
cutting plane is inclined to the one of the principal planes and
perpendicular to the other – obtaining true shape of section.
Development of lateral surfaces of simple and sectioned solids –
Prisms, pyramids, cylinder and cone. Development of lateral surfaces
of solids with cut-outs and holes.
 Syllabus
Isometric and Perspective Projections (Module 5)
Principles of isometric projection – isometric scale – isometric
projections of simple solids and truncated solids – Prisms, pyramids,
cylinders, cones – Perspective projection of simple solids prisms,
pyramids and cylinder by visual ray method and vanishing point
method.
 References
1. Bhatt N.D. and Panchal V.M., “Engineering Drawing”, Charotar
Publishing House, 53rd Edition, 2014.

2. Gopalakrishna K.R., “Engineering Drawing” (Vol. I&II combined),

Subhas Publications, Bangalore, 2017.
3. Jolhe, D. A., Engineering drawing, Tata McGraw Hill, 2017.
4. Shah, M. B. and Rana, B. C., Engineering Drawing, Pearson
Education, 2009
5. K.V. Natarajan, A text book of Engineering Graphics,
Dhanalakshmi Publishers, Chennai, 2016.
 References
6. Venugopal K. and Prabhu Raja V., “Engineering Graphics”, New
Age International (P)Limited, 2018.

7. Luzzader, Warren.J. and Duff,John M., “Fundamentals of

Engineering Drawing with an introduction to Interactive Computer
Graphics for Design and Production, Eastern Economy Edition,
Prentice Hall of India Pvt. Ltd, New Delhi, 2015.
8. Sekkilar.S.M., “Engineering Graphics” Alpha Science International
Ltd, 2018.
 Introduction

Why Engineering Graphics?

We, Engineers communicate differently with fellow
engineers, than we communicate with non technical
people.
We talk with drawings, codes, symbols, etc. and for
easy and confusion free communication, we need to
standardize our non verbal communication.
 Engineering Graphics

The graphical representation of objects used to

communicate the design to the manufacturer.
The designs are earlier manually drawn, then a trial
product is made and tested. This cycle is continued
until the final design is arrived.

Nowadays, modern software aids not only in

designing by also in analyzing the design for
optimum working.
 Engineering Graphics

Computerized
Drawing

Manual
Drawing
 Allocation of Internal Marks

Content Weightage Nos. Marks

Test - - -
Experiments 5 12 60
Quiz - - -
Assignment - - -
Presentation - - -
PBL - - -
Mini Project - - -
Total 60
Standard Code
BIS Code
Drawing Tools

A3 size
Drawing Sheet Dimensions
Drawing Sheet Dimensions
Drawing Sheet Dimensions
Drawing Sheet Dimensions
 Lettering
Uppercase Vertical
 Lettering
Lowercase Vertical
 Lettering

Numbers Vertical
 Lettering
Uppercase Slanted
 Lettering
Lowercase Slanted

Numbers Slanted
 Lettering

Standard writing format for universal understanding

10 mm 3 mm
Cap Line
3mm

10 Waist Line
mm 7mm
Base Line
3mm
Drop Line
Lettering
Line Types
 Line Types – Sample Drawing
Thick Lines Thin Chain –
– Visible Axis Line
Edges

Thin Lines –
Construction Dashed Lines –
Lines Hidden Edges
 Dimensioning
The dimensioning is an important part of drawing
as it indicates the size and other details of the
components drawn.
The following 3 lines are the components of
dimensioning. 2 2
1
1. Dimension Line

2. Extension Line 3
3. Leader Line
Dimension Line
Extension Line
 Leader Line
Leader Line: A straight inclined thin solid line that
is usually end by an arrowhead, dot or without any
features.
 Arrow Heads

• Arrow heads are the terminators for dimension

lines.
• The standard ratio is 3:1

3 mm

1 mm
 Arrow Heads

• Arrow heads are drawn between extension lines

normally. If space is smaller, it might be drawn
outside as shown.
 Exercise: Identify the dimensioning mistakes.
Narrow spacing between Misalignment and text
two dimension lines crossed by line

Missing
dimensioning
diameter ø

Dimensioning within the No gap at the Exension

drawing Line
Corrected Dimensioning
 Dimensioning Types
Aligned Dimensioning Unidirectional Dimensioning
Dimensioning Nomenclature
 Title Block
10

TITLE:
NAME :
REG. NO. : DEPT. :
YEAR / SEM / SEC. :
3
SCALE:
DATE:
MARKS: CHECKED BY:
170
Folding of A3 Drawing Sheet
1 2
Folding of A3 Drawing Sheet

3 4
Folding of A3 Drawing Sheet

5 6
Folding of A3 Drawing Sheet

7
 Geometrical Construction

Point Line

Curve

Compound Line
 Lines and Curves
Straight
Line
Regular
Curve

P1 P2
(x1,y1,z1) (x2,y2,z2)

Irregular
Curves
Geometrical Construction
Geometrical Shapes
 Geometrical Shapes

C D
C

90° 90°
60° 60°

A B A B

Square Equilateral Triangle

 Geometrical Shapes
Pentagon

D D

C
E C
E O

72° 90°

90°
72° 72°

A B A B

Method 1 Method 2
 Geometrical Shapes

Hexagon

E D E D

F F C
C
O
60° 60°

A B A B

Method 1 Method 2
Note: Hexagon
1. If the distance between the opposite corners / vertices is given, the hexagon is
inscribed in a circle of diameter equal to the given distance.
2. If the distance between the opposite sides is given, the hexagon is circumscribed in
a circle of diameter equal to the given distance.

Dia. = Distance = d Dia. = Distance = d

Case 1: Case 2:
Distance across Distance across
Corners is given Sides is given
Bisections and Dividing of Lines
 Dividing of a Line into ‘n’ Equal Parts
A line segment of known length can be easily divided into
desired smaller line segments if the total length is easily divisible
by the no. of parts to be divided.
For e.g. Dividing a 60 mm line into 6 segments or parts and 75
mm line into 5 equal parts.
Let say, if the 60 mm line is to be divided into 8 equal parts or
100 mm line to be divided into 13 parts.
It will then be difficult (although its not impossible) to divide
by using a ruler or a divider.
So the following method is adopted.
 Dividing of a Line in ‘n’ Equal Parts
Let us divide the following line (of any length) into ‘n’ equal
parts.
If n = 7, then draw a line from ‘A’ at any convenient acute (<
90°) angle of length with length = n * 10 = 7*10 = 70 mm.

1 2 3 4 5 6 7
A B
10

70

C
 Scale
Scales are used when the actual drawing is too large or too small
to be drawn as per the given dimensions.
So the drawing has to be either “zoomed down” or “zoomed up”
according so that it fits the drawing sheet.
Suitable zooming ratio is chosen as twice, thrice bigger of half,
quarter or any other size smaller.
This technique of drawing a bigger object into a smalle version
and vice-versa is known as Scaling and the ratio of zooming in or out
is called Scale.
Scale = Size of Drawing / Actual Size
Scale – Scaled Down
Scale – Scaled Up
 Scale
Scale = Size of Drawing / Actual Size
 Conics

The sections obtained by intersection of a right circular cone by a

plane at different positions relative to the axis is called Conics.
Cut Sections
Construction of Conics by Eccentricity Method
Eccentricity, e = distance of the point from the focus
distance of the point from the directrix
Directrix

Point

Focus Focus

Ellipse, e < 1 Parabola, e = 1 Hyperbola, e > 1

 Construction of Conics - Ellipse
Construct an ellipse which has its focus 50 mm from the directrix and having
eccentricity as 2/3. Draw a tangent and a normal at any point on the curve.
Given e = 2/3
Directrix Add numerator and denominator,
2+3 =5
D
Divide CF into 5 equal parts.

V F Axis
C C’

From F jump backwards as

many times as numerator, i.e.,
50 From F jump backwards 2 times
along FC & mark this point as
D’
All dimensions are in mm Vertex, V
 • Draw a  line at V
• With V as center and
VF as radius, cut two
arcs G and H.
Directrix • Join CG and extend.
Similarly join CH and
extend
• Divide the axis into
equal parts from F and
G name it as 1, 2, 3 and
so on.

V F Axis
C
1 2 3 4 5 6 7 8 9 10
H • Draw vertical lines
through points 1,2,3,…
and they cut CG
extended line at 1’,
2’,3’ , … and they cut
50 the line CH at 1’’, 2’’,
3’’, ….

All dimensions are in mm

 10’
9’
8’ • With 1-1’ as
7’ radius and F as
6’ center, cut arcs in
Directrix 5’
4’ the 1’-1” line.
3’
2’ • The arcs cut line
1’
1-1’ at P1’ and 1-
P1’ 1’’ at P1’’.
G

V F Axis
C
1 2 3 4 5 6 7 8 9 10
H • Repeat this
P1’’ process and get
points P2’ & P2’’,
1’’
2’’ P3’ & P3’’, ...
3’’
4’’
50 5’’ • Join all these
6’’
7’’ points with a
8’’ smooth curve.
9’’
10’’
All dimensions are in mm
 To draw Tangent & Normal to Ellipse
N • Choose a random
Directrix point, P on the
ellipse.
• Join points F & P.
Q • Draw a  to FP @
F and it will
intersect the
directrix at Q.

V F Axis
C
• Join QP and
P extend. This is the
tangent to the
Normal ellipse at point P.
• Draw a  to this
tangent passing
through point P.
Tangent This is the Normal
T to the ellipse at
point P.
All dimensions are in mm
Construction of Conics - Parabola

Construct a conics curve where the focus is 60 mm away from the

directrix and the eccentricity is 1. Also draw a tangent and normal at
any point on the curve.
 9’
Construction of Conics – 8’
Parabola 7’ • Eccentricity e = 1.
6’
5’
4’ • So CF should be
Directrix 3’ divided into two
2’
1’ parts or bisected
because fore to be
‘1’ the Numerator
P1’ and Denominator
G are same.

V F Axis
C
1 2 3 4 5 6 7 8 9 • Repeat the same
steps used for
H P1’’ ellipse to finish
the parabolic
curve.
1’’ • Repeat the same
2’’
60 3’’ steps used to
4’’
5’’ draw the tangent
6’’ and normal to the
7’’
8’’ parabolic curve.
9’’
All dimensions are in mm
Construction of Conics - Hyperbola

Construct a conics curve where the focus is 70 mm away from the

directrix and the eccentricity is 4/3. Also draw a tangent and normal
at any point on the curve.
 9’
Construction of Conics – 8’
Hyperbola 7’ • Eccentricity e = 4/3.
6’
5’
4’ • So CF should be
Directrix 3’ divided into 7 equal
2’
1’ parts.

• Repeat the same

steps used for
G P1’ ellipse and
parabola

V F Axis
C
1 2 3 4 5 6 7 8 9
H • Repeat the same
steps used for
ellipse and
1’’ parabola to draw
2’’ the tangent and
70 3’’
4’’ normal.
5’’
6’’
7’’
8’’
9’’
All dimensions are in mm
 Syllabus
Curve Constructions and Orthographic Projection (Module 1)

Lettering – Types of lines – Dimensioning – Conics- Construction

of ellipse, parabola and hyperbola by eccentricity method-
Construction of cycloid- Construction of involutes of square and
circle- Drawing of tangents and normal to these curves. Principles of
Orthographic projection – Layout of views Orthographic projection
of simple Engineering components using first angle Projection.
Drawing of multiple views from pictorial views of objects.
 Assignment 1

Exercise No. 1
Draw the alphabets- uppercase and lowercase and numbers both
in vertical and slanted modes.
 Assignment 2
Exercise No. 1

Draw with neat dimensioning the following diagrams.

a. 15 25
b.
15 10 5 25
20 10
25 25
50

c.
d.
20 ? 10
20
R? 20
20 30 10
5 20
20
60 50 50
 Assignment 3

1. Construct a conics whose focus is 70 mm from the directrix and

the eccentricity is ¾. Also draw a tangent and normal to any point
on the curve.
2. Construct an ellipse whose focus is 60 mm from the directrix
and the eccentricity is 2/3. Also draw a tangent and normal to any
point on the curve.
3. Construct a conics whose focus is 70 mm from the directrix and
the eccentricity is 1 Also draw a tangent and normal to any point
on the curve.
 Assignment 3
4. Construct a conics whose focus is 80 mm from the directrix and
the eccentricity is 1. Also draw a tangent and normal to any point
on the curve.
5. Construct a hyperbola whose focus is 60 mm from the directrix
and the eccentricity is 3/2. Also draw a tangent and normal to any
point on the curve.
6. Construct a conics whose focus is 70 mm from the directrix and
the eccentricity is 4/3. Also draw a tangent and normal to any
point on the curve.
Rough Draft

Minor
Axis

Major
Axis
 Dividing a straight line into ‘n’ equals parts

60
mm
 Rough Draft

72° 72°

72° 72°

A B