Eg unit 1 1

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
Manual
Drawing
Computerized
Drawing

Allocation of Internal Marks
Content Weightage Nos. Marks
Test - - -
Experiments 5 12 60
Quiz - - -
Assignment - - -
Presentation - - -
PBL - - -
Mini Project - - -
Total 60

Lettering
Lowercase Slanted
Numbers Slanted

Lettering
Standard writing format for universal understanding
3mm
3mm
7mm
10
mm
10 mm 3 mm
Cap Line
Waist Line
Base Line
Drop Line

Line Types – Sample Drawing
Thick Lines
– Visible
Edges
Thin Lines –
Construction
Lines
Dashed Lines –
Hidden Edges
Thin Chain –
Axis Line

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.
1. Dimension Line
2. Extension Line
3. Leader Line
1
2
3
2

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
two dimension lines
Dimensioning within the
drawing
Missing
dimensioning
diameter ø
No gap at the Exension
Line
Misalignment and text
crossed by line

Dimensioning Types
Aligned Dimensioning Unidirectional Dimensioning

Title Block
NAME :
REG. NO. :
YEAR / SEM / SEC. :
DEPT. :
TITLE:
SCALE:
DATE:
MARKS: CHECKED BY:
170
3
10

Folding of A3 Drawing Sheet
1 2

4
3

5 6

Geometrical Construction
Point Line
Curve
Compound Line

Lines and Curves
P1
(x1,y1,z1)
P2
(x2,y2,z2)
Straight
Line
Regular
Curve
Irregular
Curves

Geometrical Shapes
Square
90° 90°
A B
C D
Equilateral Triangle
A B
C
60° 60°

Geometrical Shapes
Pentagon
A B
72°
72°
Method 1 Method 2
A B
72°
E
E
D
C
90°
O
C
D

D
C
Geometrical Shapes
Hexagon
A B
O
C
D
E
F
A B
60°
60°
E
F
Method 1 Method 2

Hexagon
Note:
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.
Case 1:
Distance across
Corners is given
Dia. = Distance = d
Case 2:
Distance across
Sides is given
Dia. = Distance = d

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.

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.
Dividing of a Line in ‘n’ Equal Parts
A B
1 6 7
4 5
2 3
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
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.

Construction of Conics by Eccentricity
Method
Eccentricity, e = distance of the point from the focus
distance of the point from the directrix
Focu
s
Focu
s
Point
Directrix
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.
F
Directrix
50
All dimensions are in mm
Given e = 2/3
Add numerator and
denominator, 2+3 =5
Divide CF into 5 equal parts.
C
From F jump backwards as
many times as numerator,
i.e., From F jump backwards
2 times along FC & mark this
point as Vertex, V
V Axis
D’
D
C’

F
Directrix
50
C V
• Draw a  line at V
• With V as center and
VF as radius, cut two
arcs G and H.
G
H
• Join CG and extend.
Similarly join CH and
extend
Axis
• Divide the axis into
equal parts from F
and name it as 1, 2, 3
and so on.
1 2 3 4 5 6 7 8 9 10
• Draw vertical lines
through points
1,2,3,… and they cut
CG extended line at
1’, 2’,3’ , … and they
cut the line CH at 1’’,
2’’, 3’’, ….

F
Directrix
50
C V
• With 1-1’ as
radius and F as
center, cut arcs
in the 1’-1” line.
G
H
Axis
1 2 3 4 5 6 7 8 9 10
1’
2’
3’
4’
5’
6’
7’
8’
9’
10’
1’’
2’’
3’’
4’’
5’’
6’’
7’’
8’’
9’’
10’’
• The arcs cut
line 1-1’ at P1’
and 1-1’’ at P1’’.
P1
’
P1’’
• Repeat this
process and get
points P2’ &
P2’’, P3’ & P3’’,
...
• Join all these
points with a
smooth curve.

To draw Tangent & Normal to Ellipse
F
Directrix
C V Axis
• Choose a random
point, P on the
ellipse.
P
• Join points F & P.
• Draw a  to FP
@ F and it will
intersect the
directrix at Q.
Q
• Join QP and
extend. This is
the tangent to the
ellipse at point P.
Tangent
• Draw a  to this
tangent passing
through point P.
This is the
Normal to the
ellipse at point P.
Normal
N
T

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.

Construction of Conics –
Parabola
F
Directrix
60
C V
• Eccentricity e = 1.
G
H
Axis
1 2 3 4 5 6 7 8 9
1’
2’
3’
4’
5’
6’
7’
8’
9’
1’’
2’’
3’’
4’’
5’’
6’’
7’’
8’’
9’’
• So CF should be
divided into two
parts or bisected
because fore to be
‘1’ the Numerator
and Denominator
are same.
P1
’
P1’’
• Repeat the
same steps
used for ellipse
to finish the
parabolic curve.
• Repeat the
same steps
used to draw
the tangent and
normal to the
parabolic curve.

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.

Construction of Conics –
Hyperbola
F
Directrix
70
C V
• Eccentricity e =
4/3.
G
H
Axis
1 2 3 4 5 6 7 8 9
1’
2’
3’
4’
5’
6’
7’
8’
9’
1’’
2’’
3’’
4’’
5’’
6’’
7’’
8’’
9’’
• So CF should be
divided into 7
equal parts.
P1
’
• Repeat the
same steps
used for ellipse
and parabola
• Repeat the
same steps
used for ellipse
and parabola to
draw the
tangent and
normal.

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.
20
15
50
15
10
a.
b.
25
25
25
25
5
10
c.
60
20
20
20
5
20
d.
30 10
20
20
10
50
R?
?
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.
directrix and the eccentricity is 1 Also draw a tangent and

Assignment 3
directrix and the eccentricity is 1. Also draw a tangent and
5. Construct a hyperbola whose focus is 60 mm from the

Rough Draft
Major
Axis
Minor
Axis

Dividing a straight line into ‘n’ equals
parts
60
mm

Rough Draft
A B
72° 72°
72° 72°

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