UNIT V ISOMETRIC PROJECTION

CO 5 - Sketch the isometric sections of solids.

BL – K3

KCG DEPARTMENT OF MECHANICAL 1

 ISOMETRIC DRAWING TYPICAL CONDITION.
It is a type of pictorial projection in which all In 3-d drawing of an object, all three dimensional
three dimensions of an object are shown in axes are maintained at equal inclinations
one view and If required, their actual sizes with each other.( 1200)
can be measured directly from it.

3-d drawings can be drawn in numerous ways

all these drawings may be called 3- Equal inclination among h, l & d axes.
dimensional drawings, or photographic or each is 1200 inclined with other two.
pictorial drawings. here no specific relation hence it is called isometric drawing
among h, l & d axes is maintained.

H
H H
Purpose of Isometric Drawing is to understand
Overall DEPARTMENT
KCGShape, Size & Appearance OF MECHANICAL
of an Object Prior to it’s Production. 2
 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

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

KCG DEPARTMENT OF MECHANICAL 3

 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 G
S
TH 2 C H
L EN 4

RUE
T 1 3

2 THS
NG
. LE CONSTRUCTION OF ISOM.SCALE.
0 OM From point A, with line AB draw 30 0 and
1 IS
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.
KCG DEPARTMENT OF MECHANICAL 4
 SHAPE Isometric view if the Shape is
ISOMETRIC
OF F.V. or T.V.
D
PLANE FIGURES H
RECTANGLE D
A D A L
As these all are L
C D
2-d figures C
which require only two A
isometric axes.
B C B B
If the figure is front B
view, h & l axes are H
TRIANGLE 3 B
required. 1 L
B 1 3
L
If the figure is top view, A D A
d & l axes are required. 3
1
Shapes containing 2 A 2 2
Inclined lines should 4
be enclosed in a PENTAGON H E
E
rectangle . 1 4 1 D 4
Then first draw isom. E
D
of that rectangle and A D A D L
then inscribe that L 1 3
shape as it is. 3 A C
C
2 3 B B
B C 2 2
KCG DEPARTMENT OF MECHANICAL 5
 STUDY
Z
ILLUSTRATIONS

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

B
WHEN IT IS FRONT VIEW.
FOR CONSTRUCTION USE RHOMBUS
METHOD SHOWN HERE. STUDY IT.
2

C
4
A B

3 4

3
A

1
D C

D
1
KCG DEPARTMENT OF MECHANICAL 6
 25 R

DRAW ISOMETRIC VIEW OF THE FIGURE

SHOWN WITH DIMENTIONS (ON RIGHT SIDE)
CONSIDERING IT FIRST AS F.V. AND THEN T.V.
50 MM

IF FRONT VIEW

100 MM

IF TOP VIEW

KCG DEPARTMENT OF MECHANICAL 7

 ISOMETRIC SHAPE IF F.V. IF T.V.
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.)
 STUDY
ILLUSTATIONS ISOMETRIC VIEW OF
PENTAGONAL PYRAMID
STANDING ON H.P.
(Height is added from center of pentagon)

ISOMETRIC VIEW OF BASE OF

PENTAGONAL PYRAMID
STANDING ON H.P.

4
4
D
D E
E
D L D
L
1 3 1 3
A C
A C
B
2
B
2

KCG DEPARTMENT OF MECHANICAL 9

 ISOMETRIC VIEW OF
PENTAGONALL PRISM
LYING ON H.P.

4
H E
1 D

A
L
3
C
B
2
ISOMETRIC VIEW OF
HEXAGONAL PRISM
STANDING ON H.P.
KCG DEPARTMENT OF MECHANICAL 10
 CYLINDER STANDING ON H.P.

CYLINDER LYING ON H.P.

KCG DEPARTMENT OF MECHANICAL 11

 HALF CYLINDER
STANDING ON H.P.
( ON IT’S SEMICIRCULAR BASE)

HALF CYLINDER
LYING ON H.P.
( with flat face // to H.P.)

KCG DEPARTMENT OF MECHANICAL 12

 ISOMETRIC VIEW OF
A FRUSTOM OF SQUARE PYRAMID
STANDING ON H.P. ON IT’S LARGER BASE.

60
FV

X Y

40 20

TV

KCG DEPARTMENT OF MECHANICAL 13

 PROJECTIONS OF FRUSTOM OF ISOMETRIC VIEW
PENTAGONAL PYRAMID ARE GIVEN. OF
FRUSTOM OF PENTAGONAL PYRAMID
DRAW IT’S ISOMETRIC VIEW.

SOLUTION STEPS:
60 60
FV

20
FIRST DRAW ISOMETRIC
OF IT’S BASE.

x y THEN DRAWSAME SHAPE

AS TOP, 60 MM ABOVE THE
E
1 4 BASE PENTAGON CENTER.
A
THEN REDUCE THE TOP TO
20 MM SIDES AND JOIN WITH
TV 40 20 D THE PROPER BASE CORNERS.

40
2 3
C

KCG DEPARTMENT OF MECHANICAL 14

 ISOMETRIC VIEW OF
A FRUSTOM OF CONE
STANDING ON H.P. ON IT’S LARGER BASE.

60
FV

X Y

40 20

TV

KCG DEPARTMENT OF MECHANICAL 15

 PROBLEM: A SQUARE PYRAMID OF 30 MM BASE SIDES AND
50 MM LONG AXIS, IS CENTRALLY PLACED ON THE TOP OF A
CUBE OF 50 MM LONG EDGES.DRAW ISOMETRIC VIEW OF THE PAIR.

50

30

50

KCG DEPARTMENT OF MECHANICAL 16

 c
PROBLEM: A TRIANGULAR PYRAMID
OF 30 MM BASE SIDES AND 50 MM a
LONG AXIS, IS CENTRALLY PLACED o
ON THE TOP OF A CUBE OF 50 MM p a
LONG EDGES. b
DRAW ISOMETRIC VIEW OF THE PAIR.
o c
p

SOLUTION HINTS.
TO DRAW ISOMETRIC OF A CUBE IS SIMPLE. DRAW IT AS USUAL.

BUT FOR PYRAMID AS IT’S BASE IS AN EQUILATERAL TRIANGLE,

IT CAN NOT BE DRAWN DIRECTLY.SUPPORT OF IT’S TV IS REQUIRED.

SO DRAW TRIANGLE AS A TV, SEPARATELY AND NAME VARIOUS POINTS AS SHOWN.

AFTER THIS PLACE IT ON THE TOP OF CUBE AS SHOWN.
THEN ADD HEIGHT FROM IT’S CENTER AND COMPLETE IT’S ISOMETRIC AS SHOWN.

KCG DEPARTMENT OF MECHANICAL 17

 ISOMETRIC PROJECTIONS OF SPHERE & HEMISPHERE

450 r

n
R

io
ct
r

re
r 300 R

Di
r

o-
Is
Isom. Scale
P

C
r r
R C
R TO DRAW ISOMETRIC PROJECTION
R OF A HEMISPHERE
P r
P Adopt same procedure.
C = Center of Sphere. Draw lower semicircle only.
Then around ‘C’ construct
P = Point of contact Rhombus of Sides equal to
R = True Radius of Sphere Isometric Diameter.
r = Isometric Radius. For this use iso-scale.
Then construct ellipse in
TO DRAW ISOMETRIC PROJECTION OF A SPHERE this Rhombus as usual
1. FIRST DRAW ISOMETRIC OF SQUARE PLATE. And Complete
2. LOCATE IT’S CENTER. NAME IT P. Isometric-Projection
3. FROM PDRAW VERTICAL LINE UPWARD, LENGTH ‘ r mm’ of Hemi-sphere.
AND LOCATE CENTER OF SPHERE “C”
4. ‘C’ AS CENTER, WITH RADIUS ‘R’ DRAW CIRCLE.
THIS IS ISOMETRIC PROJECTION OF A SPHERE.
KCG DEPARTMENT OF MECHANICAL 18