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 Title of Chapter : Isometric Projection

Contents: Introduction to isometric projection, oblique projection and perspective

projection. Draw the isometric projection from the given orthographic views

Unit Objectives

To visualize three dimensional engineering objects and shall be able to draw their isometric
views

Unit outcomes: On completion the students will be able to :

Apply the visualization skill to draw a simple isometric projection from given orthographic
views precisely using drawing equipment

Outcome Mapping: Mapping of PEO,PO, CO, PSO

Books :
Text books used
T1: Bhatt, N. D. and Panchal, V. M., (2016), “Engineering Drawing”, Charotar Publication, Anand, India
T2: Jolhe, D. A., (2015), “Engineering Drawing with introduction to AutoCAD”, Tata McGraw Hill, New Delhi
Reference Books Used
R1: Cencil Jensen et.al, “Engineering drawing and design”, seventh edition
R2: R. K. Dhavan, “Engineering drawing”
R3: T Jeyapoovan, “Engineering drawing and graphics using AutoCAD”, Third edition
 Point of Syllabus

Introduction to isometric projection, oblique projection and perspective projection.

Draw the isometric projection from the given orthographic views
 ISOMETRIC DRAWING TYPICAL CONDITION.
IT IS A TYPE OF PICTORIAL PROJECTION IN THIS 3-D DRAWING OF AN OBJECT,
IN WHICH ALL THREE DIMENSIONS OF ALL THREE DIMENSIONAL AXES ARE
AN OBJECT ARE SHOWN IN ONE VIEW AND MENTAINED AT EQUAL INCLINATIONS
IF REQUIRED, THEIR ACTUAL SIZES CAN BE WITH EACH OTHER.( 1200)
MEASURED DIRECTLY FROM IT.

3-D DRAWINGS CAN BE DRAWN NOW OBSERVE BELOW GIVEN DRAWINGS.

IN NUMEROUS WAYS AS SHOWN BELOW. ONE CAN NOTE SPECIFIC INCLINATION
ALL THESE DRAWINGS MAY BE CALLED AMONG H, L & D AXES.
3-DIMENSIONAL DRAWINGS, ISO MEANS SAME, SIMILAR OR EQUAL.
OR PHOTOGRAPHIC HERE ONE CAN FIND
OR PICTORIAL DRAWINGS. EDUAL INCLINATION AMONG H, L & D AXES.
HERE NO SPECIFIC RELATION EACH IS 1200 INCLINED WITH OTHER TWO.
AMONG H, L & D AXES IS MENTAINED. HENCE IT IS CALLED ISOMETRIC DRAWING

H
H H
PURPOSE OF ISOMETRIC DRAWING IS TO UNDERSTAND
OVERALL SHAPE, SIZE & APPEARANCE OF AN OBJECT PRIOR TO IT’S PRODUCTION.
 SOME IMPORTANT TERMS:

ISOMETRIC AXES, LINES AND PLANES:

The three lines AL, AD and AH, meeting at point A and making
1200 angles with each other are termed Isometric Axes.
A
The lines parallel to these axes are called Isometric Lines.

The planes representing the faces of of the cube as well as

H
other planes parallel to these planes are called Isometric Planes.

ISOMETRIC SCALE:
When one holds the object in such a way that all three dimensions
are visible then in the process all dimensions become proportionally
inclined to observer’s eye sight and hence appear apparent in lengths.

This reduction is 0.815 or 9 / 11 ( approx.) It forms a reducing scale which

Is used to draw isometric drawings and is called Isometric scale.

In practice, while drawing isometric projection, it is necessary to convert

true lengths into isometric lengths for measuring and marking the sizes.
This is conveniently done by constructing an isometric scale as described
on next page.
 TYPES OF ISOMETRIC DRAWINGS

ISOMETRIC VIEW ISOMETRIC PROJECTION

Drawn by using True scale Drawn by using Isometric scale
( True dimensions ) ( Reduced dimensions )

D
4

H 2 C H
4

1 3

2
CONSTRUCTION OF ISOM.SCALE.
0 From point A, with line AB draw 300 and
1
450 inclined lines AC & AD resp on AD.
450 Mark divisions of true length and from
0 300
A B each division-point draw vertical lines
Isometric scale [ Line AC ] upto AC line.
The divisions thus obtained on AC
required for Isometric Projection give lengths on isometric scale.
1 Isometric view if the Shape is
ISOMETRIC SHAPE
OF
F.V. or T.V.
D
PLANE FIGURES H
RECTANGLE D
A D A
AS THESE ALL ARE
C
2-D FIGURES C
WE REQUIRE ONLY TWO A
ISOMETRIC AXES.
B C B B
IF THE FIGURE IS B
H
FRONT VIEW, H & L
TRIANGLE B
AXES ARE REQUIRED. 1
3
B 1 3
IF THE FIGURE IS TOP A A
VIEW, D & L AXES ARE 3
1
REQUIRED.
2 A 2 2
Shapes containing 4
Inclined lines should PENTAGON H E
be enclosed in a 1 E
4 1 D 4
rectangle as shown. D
Then first draw isom. A D A
E

of that rectangle and 1 3

then inscribe that 3 A C
C
shape as it is. 2 B
B C 3 B
2 2
 2

DRAW ISOMETRIC VIEW OF A

CIRCLE IF IT IS A TV OR FV.

FIRST ENCLOSE IT IN A SQUARE.

IT’S ISOMETRIC IS A RHOMBUS WITH
D & L AXES FOR TOP VIEW.
THEN USE H & L AXES FOR ISOMETRIC
WHEN IT IS FRONT VIEW.
FOR CONSTRUCTION USE RHOMBUS
METHOD SHOWN HERE. STUDY IT.
2

A B

3 4

D C

1
 ISOMETRIC SHAPE IF F.V. IF T.V. 4
OF
PLANE FIGURES HEXAGON

AS THESE ALL ARE

2-D FIGURES
WE REQUIRE ONLY
TWO ISOMETRIC
AXES. CIRCLE

IF THE FIGURE IS
FRONT VIEW, H & L
AXES ARE REQUIRED.

IF THE FIGURE IS
TOP VIEW, D & L For Isometric of Circle/Semicircle use Rhombus method. Construct Rhombus
AXES ARE REQUIRED. of sides equal to Diameter of circle always. ( Ref. topic ENGG. CURVES.)

SEMI CIRCLE
For Isometric of
Circle/Semicircle
use Rhombus method.
Construct it of sides equal
to diameter of circle always.
( Ref. Previous two pages.)
Draw isometric view from
given orthographic views
 27
F.V. and S.V.of an object are given.
Draw it’s isometric view.

30 SQUARE
40 20

50

20
10

O 30
60
F.V.
S.V.
O
26

F.V. & T.V. and S.V.of an object are given. Draw it’s isometric view.

ORTHOGRAPHIC PROJECTIONS

FRONT VIEW L.H.SIDE VIEW

20

20

20
x y
O
50

20

30

O
20 20 20

TOP VIEW
 28
F.V. & T.V. of an object are given. Draw it’s isometric view.

FV
40

10
O
30 D 45

10
50
O

80

TV
 29
F.V. & T.V. of an object are given. Draw it’s isometric view.

FV 40

X O 10 Y
100
10
25
TV
10 30 10
25
30 R O
20 D
 30
F.V. & T.V. of an object are given. Draw it’s isometric view.

30

FV
RECT.
SLOT

10 50
35

10
X Y
O
20 D

TV

60 D
30 D

O
 31
F.V. and S.V.of an object are given. Draw it’s isometric view.

10

25 15

25
40 10

25

25

O O
80 25

F.V. S.V.
F.V. & T.V. of an object are given. Draw it’s isometric view.
32

450

30
FV

40

X Y
O
30 D

40 TV

15
O 40
 33
F.V. and S.V.of an object are given.
Draw it’s isometric view.

HEX PART
30
20
20
40
20

O 50
20
15

O 30
100 60
 34
F.V. & T.V. of an object are given. Draw it’s isometric view.

20 40

F.V.
30

10
X Y
O

10

30

10

30
O 80

T.V.
 37

F.V. and S.V.of an object are given.

Draw it’s isometric view.

30 20 10 20

15
10

15

O
15
30

15
X O Y
50
F.V. LEFT S.V.
Thank You