Isomatric projections unit 4

ISOMETRIC
PROJECTIONS
 COURSE- Diploma
 SUB- BASICS OF ENGINEERING GRAPHICS
 UNIT-4

H
3-D DRAWINGS CAN BE DRAWN
IN NUMEROUS WAYS AS SHOWN BELOW.
ALL THESE DRAWINGS MAY BE CALLED
3-DIMENSIONAL DRAWINGS,
OR PHOTOGRAPHIC
OR PICTORIAL DRAWINGS.
HERE NO SPECIFIC RELATION
AMONG H, L & D AXES IS MENTAINED.
H
NOW OBSERVE BELOW GIVEN DRAWINGS.
ONE CAN NOTE SPECIFIC INCLINATION
AMONG H, L & D AXES.
ISO MEANS SAME, SIMILAR OR EQUAL.
HERE ONE CAN FIND
EDUAL INCLINATION AMONG H, L & D AXES.
EACH IS 1200
INCLINED WITH OTHER TWO.
HENCE IT IS CALLED ISOMETRIC DRAWING
H
L
IT IS A TYPE OF PICTORIAL PROJECTION
IN WHICH ALL THREE DIMENSIONS OF
AN OBJECT ARE SHOWN IN ONE VIEW AND
IF REQUIRED, THEIR ACTUAL SIZES CAN BE
MEASURED DIRECTLY FROM IT.
IN THIS 3-D DRAWING OF AN OBJECT,
ALL THREE DIMENSIONAL AXES ARE
MENTAINED AT EQUAL INCLINATIONS
WITH EACH OTHER.( 1200
)
PURPOSE OF ISOMETRIC DRAWING IS TO UNDERSTAND
OVERALL SHAPE, SIZE & APPEARANCE OF AN OBJECT PRIOR TO IT’S PRODUCTION.
ISOMETRIC DRAWING TYPICAL CONDITION.

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.
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.
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.
H
A
SOME IMPORTANT TERMS:

ISOMETRIC VIEW ISOMETRIC PROJECTION
H H
TYPES OF ISOMETRIC DRAWINGS
Drawn by using Isometric scale
( Reduced dimensions )
Drawn by using True scale
( True dimensions )
450
300
0
1
2
3
4
0
1
2
3
4
TRUE
LENG
THS
ISOM. LENGTHS
Isometric scale [ Line AC ]
required for Isometric Projection
A B
C
D
CONSTRUCTION OF ISOM.SCALE.
From point A, with line AB draw 300
and
450
inclined lines AC & AD resp on AD.
Mark divisions of true length and from
each division-point draw vertical lines
upto AC line.
The divisions thus obtained on AC
give lengths on isometric scale.

SHAPE Isometric view if the Shape is
F.V. or T.V.
TRIANGLE
A
B
RECTANGLE
D
C
H
L
D
A
B
C D
A
B
D
C
L
H
L
D
L
1
2
3
A
B
3
1
2
A
B
3
1
2
A
B
H
L
D L
1
2 3
4
PENTAGON
A
B C
D
E 1
2
3
4
A
B
C
D
E
1
2
3
4
A
B
C
D
E
ISOMETRIC
OF
PLANE FIGURES
AS THESE ALL ARE
2-D FIGURES
WE REQUIRE ONLY
TWO ISOMETRIC
AXES.
IF THE FIGURE IS
FRONT VIEW, H & L
AXES ARE REQUIRED.
IF THE FIGURE IS TOP
VIEW, D & L AXES
ARE REQUIRED.
Shapes containing
Inclined lines should
be enclosed in a
rectangle as shown.
Then first draw isom.
of that rectangle and
then inscribe that
shape as it is.
1

1
4
2
3
A B
D C
1
4
2
3
A
BD
C
Z
STUDY
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
WHEN IT IS FRONT VIEW.
FOR CONSTRUCTION USE RHOMBUS
METHOD SHOWN HERE. STUDY IT.
2

25 R
100 MM
50 MM
Z
STUDY
ILLUSTRATIONS
DRAW ISOMETRIC VIEW OF THE FIGURE
SHOWN WITH DIMENTIONS (ON RIGHT SIDE)
CONSIDERING IT FIRST AS F.V. AND THEN T.V.
IF TOP VIEW
IF FRONT VIEW
3

CIRCLE
HEXAGON
SEMI CIRCLE
ISOMETRIC
OF
PLANE FIGURES
AS THESE ALL ARE
2-D FIGURES
WE REQUIRE ONLY
TWO ISOMETRIC
AXES.
IF THE FIGURE IS
FRONT VIEW, H & L
AXES ARE
REQUIRED.
IF THE FIGURE IS
TOP VIEW, D & L
AXES ARE
REQUIRED.
SHAPE IF F.V. IF T.V.
For Isometric of Circle/Semicircle use Rhombus method. Construct Rhombus
of sides equal to Diameter of circle always. ( Ref. topic ENGG. CURVES.)
For Isometric of
Circle/Semicircle
use Rhombus method.
Construct it of sides equal
to diameter of circle always.
( Ref. Previous two pages.)
4

D
L
1
2
3
4
A
B
C
D
E
D L
1
2
3
4
A
B
C
D
E
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.
Z
STUDY
ILLUSTRATIONS
5

H
L
1
2
3
4
A
B
C
D
E
Z
STUDY
ILLUSTRATIONS
ISOMETRIC VIEW OF
PENTAGONALL PRISM
LYING ON H.P.
ISOMETRIC VIEW OF
HEXAGONAL PRISM
STANDING ON H.P.
6

Z
STUDY
ILLUSTRATIONS
CYLINDER LYING ON H.P.
CYLINDER STANDING ON H.P.
7

Z
STUDY
ILLUSTRATIONS
HALF CYLINDER
LYING ON H.P.
( with flat face // to H.P.)
HALF CYLINDER
STANDING ON H.P.
( ON IT’S SEMICIRCULAR BASE)
8

Z
STUDY
ILLUSTRATIONS
ISOMETRIC VIEW OF
A FRUSTOM OF SQUARE PYRAMID
STANDING ON H.P. ON IT’S LARGER BASE.
40 20
60
X Y
FV
TV
9

ISOMETRIC VIEW
OF
FRUSTOM OF PENTAGONAL PYRAMID
40
20
60
STUDY
ILLUSTRATION
1
2 3
4
y
A
B
C
D
E
40 20
60
x
FV
TV
PROJECTIONS OF FRUSTOM OF
PENTAGONAL PYRAMID ARE GIVEN.
DRAW IT’S ISOMETRIC VIEW.
SOLUTION STEPS:
FIRST DRAW ISOMETRIC
OF IT’S BASE.
THEN DRAWSAME SHAPE
AS TOP, 60 MM ABOVE THE
BASE PENTAGON CENTER.
THEN REDUCE THE TOP TO
20 MM SIDES AND JOIN WITH
THE PROPER BASE CORNERS.
10

Z
STUDY
ILLUSTRATIONS
ISOMETRIC VIEW OF
A FRUSTOM OF CONE
STANDING ON H.P. ON IT’S LARGER BASE.
FV
TV
40 20
60
X Y
11

50
Z
STUDY
ILLUSTRATIONS
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
12

a
b
co
p
p
a
b
c
o
Z
STUDY
ILLUSTRATIONS
PROBLEM: A TRIANGULAR 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.
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.
13

Z
STUDY
ILLUSTRATIONS
50
50
30 D
30
10
30
+
FV
TV
PROBLEM:
A SQUARE PLATE IS PIERCED THROUGH CENTRALLY
BY A CYLINDER WHICH COMES OUT EQUALLY FROM BOTH FACES
OF PLATE. IT’S FV & TV ARE SHOWN. DRAW ISOMETRIC VIEW.
14

Z
STUDY
ILLUSTRATIONS
30
10
30
60 D
40 SQUARE
FV
TV
PROBLEM:
A CIRCULAR PLATE IS PIERCED THROUGH CENTRALLY
BY A SQUARE PYRAMID WHICH COMES OUT EQUALLY FROM BOTH FACES
OF PLATE. IT’S FV & TV ARE SHOWN. DRAW ISOMETRIC VIEW.
15

Z
STUDY
ILLUSTRATIONS
X
Y
30 D50 D
10
40
20
40
FV
TV
F.V. & T.V. of an object are given. Draw it’s isometric view.
16

P
r
R
R
r
P
C
C = Center of Sphere.
P = Point of contact
R = True Radius of Sphere
r = Isometric Radius.
R
r
Iso-Direction
P
r
R
C
r
r
ISOMETRIC PROJECTIONS OF SPHERE & HEMISPHERE
r
R
450
300
TO DRAW ISOMETRIC PROJECTION
OF A HEMISPHERE
TO DRAW ISOMETRIC PROJECTION OF A SPHERE
1. FIRST DRAW ISOMETRIC OF SQUARE PLATE.
2. LOCATE IT’S CENTER. NAME IT P.
3. FROM PDRAW VERTICAL LINE UPWARD, LENGTH ‘ r mm’
AND LOCATE CENTER OF SPHERE “C”
4. ‘C’ AS CENTER, WITH RADIUS ‘R’ DRAW CIRCLE.
THIS IS ISOMETRIC PROJECTION OF A SPHERE.
Adopt same procedure.
Draw lower semicircle only.
Then around ‘C’ construct
Rhombus of Sides equal to
Isometric Diameter.
For this use iso-scale.
Then construct ellipse in
this Rhombus as usual
And Complete
Isometric-Projection
of Hemi-sphere.
Z
STUDY
ILLUSTRATIONS
Isom. Scale
17

P
r
R
r
r
50 D
30 D
50 D
50
r
R
450
300
PROBLEM:
A HEMI-SPHERE IS CENTRALLY PLACED
ON THE TOP OF A FRUSTOM OF CONE.
DRAW ISOMETRIC PROJECTIONS OF THE ASSEMBLY.
FIRST CONSTRUCT ISOMETRIC SCALE.
USE THIS SCALE FOR ALL DIMENSIONS
IN THIS PROBLEM.
Z
STUDY
ILLUSTRATIONS
18

a
b c
d
1
2
3
4
o
1’
4’3’
2’
1
2
4
3
X Y
Z
STUDY
ILLUSTRATIONS
A SQUARE PYRAMID OF 40 MM BASE SIDES AND 60 MM AXIS
IS CUT BY AN INCLINED SECTION PLANE THROUGH THE MID POINT
OF AXIS AS SHOWN.DRAW ISOMETRIC VIEW OF SECTION OF PYRAMID.
19

Z
STUDY
ILLUSTRATIONS
X Y
50
20
25
25 20
O
O
20

Z
STUDY
ILLUSTRATIONS
x y
FV
TV
35
35
10
302010
40
70
O
O
21

Z
STUDY
ILLUSTRATIONS
x y
FV
SV
TV
30
30
10
30 10 30
ALL VIEWS IDENTICAL
F.V. & T.V. and S.V.of an object are given. Draw it’s isometric view.
22

x y
FV SV
TV
Z
STUDY
ILLUSTRATIONS
10
40 60
60
40
ALL VIEWS IDENTICAL
24

x y
FV SV
TV
ALL VIEWS IDENTICAL
40 60
60
40
10
Z
STUDY
ILLUSTRATIONS
25

ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
TOP VIEW
L.H.SIDE VIEW
x y
20
20
20
50
20 20 20
20
30
O
O
Z
STUDY
ILLUSTRATIONS
26

40 20
30 SQUARE
20
50
60
30
10
F.V.
S.V.
O
O
F.V. and S.V.of an object are given.
Draw it’s isometric view.
Z
STUDY
ILLUSTRATIONS
27

40
10
50
80
10
30 D 45
FV
TV
O
O
F.V. & T.V. of an object are given. Draw it’s isometric view.Z
STUDY
ILLUSTRATIONS
28

O
FV
TV
X YO
40
10
25
25
30 R
10
100
103010
20 D
STUDY
ILLUSTRATIONS
29

O
O
10
30
50
10
35
20 D
30 D
60 D
FV
TV
X Y
RECT.
SLOT
STUDY
ILLUSTRATIONS
30

O
10
O
40
25 15
25
25
25
2580
10
F.V. S.V.
F.V. and S.V.of an object are given. Draw it’s isometric view.Z
STUDY
ILLUSTRATIONS
31

O
450
X
TV
FV
Y
30 D
30
40
40
40
15
O
Z
STUDY
ILLUSTRATIONS
32

O
O
20
20
15
30
60
30
20
20
40
100
50
HEX PART
Z
STUDY
ILLUSTRATIONS
33

O
O
10
10
30
10
30
4020
80
30
F.V.
T.V.
X Y
STUDY
ILLUSTRATIONS
34

FV LSV
X Y
10
O
FV LSV
X Y
10 10 15
25
25
1050O
Z
STUDY
ILLUSTRATIONS
35
36
NOTE THE SMALL CHZNGE IN 2ND
FV & SV.
DRAW ISOMETRIC ACCORDINGLY.

YX
F.V. LEFT S.V.
30 20 2010
15
15
15
30
50
10
15
O
O
Z
STUDY
ILLUSTRATIONS
37

30
40
10
60
30
40
F.V. S.V.
O
O
Z
STUDY
ILLUSTRATIONS
38

References
• www.cs.unca.edu/~bruce/Spring11/180/isometric
Sketches.ppt
• www.tcd.ie/civileng/Staff/Bidisha.Ghosh/.../isomet
ric.ppt
• www2.cslaval.qc.ca/cdp/UserFiles/File/.../isometr
ic_drawings.ppt
• A text book of engineering graphics- Prof. P.J
SHAH
• Engineering Drawing-N.D.Bhatt
• Engineering Drawing-P.S.Gill

Isomatric projections unit 4

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