Post on 18-Oct-2020
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Orthographic Projection
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Perspective Projection
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Orthographic Projection:
When the projectors are parallel to each
other and also perpendicular to plane of
projection , the projection is called an
orthographic projection.
There are three important elements of
this projection system,
(1) An object
(2) Plane of projection
(3) An observer.
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Parallel Ortho- rays
(right angle to plane
Of projection)
(Projectors)
ObjectOrthographic
View
or
Projection
Orthographic Projection
Observer
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The object is assumed to be observed
from an infinite distance so that the
rays of sight are parallel to each
other .The lines representing these
rays of sight are known as projectors.
These planes of the object which are
parallel to the plane of projection are
seen as true shape and true size.
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First angle projection system
The object is situated in front of
vertical plane and above horizontal
plane,i.e. in the first quadrant and
then projected it on these planes.
This method of projection is known as
first angle projection method.
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First Angle Method of Projection
Object will be above H.P and
In front of V.P.
II
III IV
ObserverI st quadrant
X
Y
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X
Y
First Angle Method of Projection
X
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First Angle Method of Projection
X
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First Angle Method of Projection
X
F.V.
T.V.
R.H.S.V.L.H.S.V.
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X
YF.V.
T.V.
R.H.S.V.
First Angle Method of Projection
L.H.S.V.
X Y
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The object lies between the
observer and the plane.
In this method, the top view
comes below the front view, the view
of object as seen from left side is
placed to the right side of front view
and vice versa.
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Third angle projection system
The object is situated below horizontal
plane and behind vertical plane, i.e. in
the third quadrant and then projected
it on these planes. This method of
projection is known as third angle
projection method.
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Third Angle Method of Projection
Object will be below H.P
And behind V.P.
(3rd quad.)
II
III Observer
I st quadrant
X
Y
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•The plane lies between the observer
and the object.
• In this method, the top view comes
above the front view, the view of
object as seen from left side is placed
to the left side of front view and right
side view is placed to the right of the
front view.
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X
Y
Third Angle Method of Projection
F.V.
T.V.
L.H.S.V. R.H.S.V.
18Third Angle Method
F.V.
T.V.
L.H.S.V. R.H.S.V.
F.V.
T.V.
R.H.S.V.L.H.S.V.
X Y
First Angle Method
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20
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ALIGNED
SYSTEM(FOR A2 TO A5
SHEET SIZE)
UNIDIRECTIONAL
SYSTEM(FOR LARGE SIZED
SHEETS)
35
20
ARROW HEADS
(H x 3H) 3H H
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(AS PER BUREAU OF INDIAN STANDARDS
FOR ENGINEERING DRAWING.)
SCALING OF A DRAWING
RECOMMENDED SCALES
1. FULL SCALE e.g. 1: 1
In certain cases the engineering components may
be very large or very small for drawing purposes,
hence the corresponding scale may be preferred
from the following
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3. ENLARGED SCALE e.g. 50:1, 20:1, 10:1,
5:1, 2:1
2. REDUCED SCALE e.g. 1:2, 1:2.5, 1:5,
1:10, 1:20,
1:15, 1:100,
1:200, 1:500,
1:1000, 1:2000,
1:5000,
1:10000
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SYMBOLS USED ON ENGINEERING
DRAWING SHEET
FIRST ANGLE METHOD
OF
ORTHOGRAPHIC
PROJECTIONS
THIRD ANGLE METHOD
OF
ORTHOGRAPHIC
PROJECTIONS
M/c. PARTS ARE NEVER ASSUMED IN SECONDOR IN FOURTH QUADRANT, AS THE VIEWSMAY OVERLAP ON ONE ANOTHER ABOVE XYOR BELOW XY RESPECTIVELY.
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(1)Dimensions should be done such that any further calculation or direct measurement from drawing is not necessary.
(2)Every dimension must be given, but none should be given more than once.
(3)A dimension should be placed on the view where its use is shown more clearly.
1. General rules for dimensioning :
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(4)Dimensions should be placed outside the views, unless they are clearer and more easily read inside.
(5)Mutual crossing of dimension lines and dimensioning between hidden lines should be avoided. Dimension lines should not cross any other line
of drawing.
(6)An outline or a centre line should never be used as a dimension line. A centre line may be extended to serve as an extension line.
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(7)Aligned system of dimensioning is recommended.
(8)Distance between object outline and dimension line should be atleast 8 to10 mm.
(9)Distance between two parallel dimension lines should be 8 to 10 mm.
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ISOMETRIC VIEW
OF
FIRST ANGLE METHOD OF PROJECTIONS (FOR L.H.S.V.)
Z1
1
X
Y
Y
X 3
OBJECT IN
FIRST
QUADRANT
(FOR L.H.S.V.)
(i.e. within planes
1,3 &5)
28Fig. 2(c)
X Y
3
T.V.
L
L.H.S.V.
D
5
H
X
1
F.V.
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AIM: Fig. 2(a) shows the Pictorial
(ISOMETRIC) view of a cut
block. Draw its following
orthographic views using Ist angle
method of projections.
I. Front View
II. Top View
III.R. H. S.View
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X
Fig 2(b)
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Z2
1
3
Z2
Fig 2(a)
X
Y
YY
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Fig. 2(c)T.V.
L
F.V.
X YR.H.S.V.
D
H
Z2
Fig 2(a)
X
Y
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AIM: Fig. 3(a) shows the Pictorial
(ISOMETRIC) view of a cut block.
Draw its following orthographic views
using IIIrd angle method of projections.
I. Front View
II. Top View
III. Left Hand Side View
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4
6
X
Y
Z1
X
Y
2
Fig 3(b)
Y
Z1X
Fig 3(a)
Plane 4 turned up(above
plane 2)
Plane 6 turned side
way(towards left side of
plane 2)
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T.V.
4
D
6
L.H.S.V
2
F.V.
L
X Y
Fig.
3(c)
Y
Z1X
Fig 3(a)
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37
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FIGURE SHOWS ISOMETRIC VIEW OF A
SIMPLE OBJECT(WITHOUT DIMENSIONS)
SHOW ITS THREE ORTHOGRAPHIC VIEWS
Use First Angle
Method
1. Front View
2. Top View
3. L.H.S.ViewD
E
A
B
3
C
2
1
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F.V
T.V
L.H.S.V.
E
A
BC
3
2
1
B
3
D
A
C
BD
E
1
2
3
4020
60
R40
X
ISOMETRIC VIEW GIVEN
DRAW F.V.,T.V.,R.H.S.V.
USE FIRST ANGLE
METHOD
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20 20
R40
20
100
80
ø40
80
20
TOP VIEW
FRONT VIEWR.H.S.V
SCALE: 1:1
60
R40
X
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FIGURE SHOWS ISOMETRIC VIEW OF AN
OBJECT(WITHOUT DIMENSIONS) SHOW ITS
THREE ORTHO GRAPHIC VIEWS
Use Third
Angle Method
1. Front View
2. Top View
3. L.H.S.View
1. Front View
2. Top View
3. L.H.S.ViewA
a
b
3 c
2
1
43FRONT VIEWL.H.S VIEW
TOP VIEW
A
ab
3
c
2 1
a
b c
A
1
2
3
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Aim : Figure shows isometric
view, of a simple machine
component.
Draw its following Orthographic
views, & dimension them.
1. Front View
2. Top View
3. R.H.S. View
Use First Angle Method of projection
45Figure, is the isometric view
X
Figure
L = 75+25=100
H = 10+30=40
D=50
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10
10
F.V.
25 75
40
T.V.
F.V L=100H=40
T.V L=100D=50
S.V D=50H=40
X
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30
10
25 SQ
15 SQ
Ø30,Depth 10
40 SQ
ISOMETRIC
ORTHO. VIEWS
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25 Sq
40
15
453535
15 Sq
40 Sq
Ø30
5
10
30
10
510
R.H.S.V.
F.V.
T.V.
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Figure shows the isometric view of a
vertical shaft support.
Draw its all the three views, using first
angle method of projections.
Give the necessary dimensions as per
aligned system.
Exercise :-
50
Ø40
Ø64
24
50
ISOMETRIC
VIEW
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14
14
48
70
24
10
Ø40
50
Ø64
30
140
L.H.S.VFRONT VIEW
TOP VIEW
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Isometric view of a rod support is
given.
Draw its all the three orthographic
views, using first angle method of
projections.
Give all the dimensions.
Exercise :-
53ISOMETRIC VIEW
16
20
R22
40
X
54
TOP VIEW
R22
2040
10
FRONT VIEWRIGHT SIDE VIEW
1402
0
80
SCALE: 1:1
3030
66
26
30
55
10
20R20
R8
30
ISOMETRIC
56
45 3
0 820 25
16
R8
R20
30
20
10
100
FRONT VIEW
TOP VIEW
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ISOMETRIC VIEW OF AN OBJECT SHOWN HERE
DRAW, ITS 1) FRONT VIEW 2)TOP VIEW
& 3) LEFT HAND SIDE VIEW
NOTE : ASSUME
L = 120
H = 55
& D = 70
USE FIRST
ANGLE METHOD
OF PROJECTIONS
FOR THE
EXCERCISE
EX-1
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AIM – ISOMETRIC VIEW OF AN OBJECT SHOWN
DRAW ITS
1) FRONT VIEW
2)TOP VIEW
& 3)LEFT HAND SIDE VIEW
NOTE : ASSUME
L = 100
H = 70
& D = 50
USE FIRST ANGLE METHOD
OF PROJECTIONS FOR THE
EXCERCISE
EX-2
59EX-3
AIM : ISOMETRIC VIEW OF AN OBJECT SHOWN
DRAW, ITS 1) FRONT VIEW 2)TOP VIEW
& 3) RIGHT HAND SIDE VIEW
NOTE : ASSUME
L = 100
H = 60
& D = 40
USE THIRD ANGLE
METHOD
OF PROJECTIONS
FOR THE
EXCERCISE
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AIM : ISOMETRIC VIEW OF AN OBJECT SHOWN
DRAW, ITS 1) FRONT VIEW 2) TOP VIEW
& 3) RIGHT HAND SIDE VIEW
NOTE : ASSUME
L = 120
H = 60
& D = 50
USE FIRST ANGLE
METHOD
OF PROJECTIONS
FOR THE
EXCERCISE
EX- 4
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ISOMETRIC VIEW OF AN OBJECT SHOWN HERE
DRAW, ITS 1) FRONT VIEW 2) TOP VIEW
& 3) RIGHT HAND SIDE VIEW
NOTE : ASSUME
L = 120
H = 60
& D = 80
USE THIRD ANGLE
METHOD
OF PROJECTIONS
FOR THE
EXCERCISE
EX- 5
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ISOMETRIC VIEW OF AN OBJECT SHOWN
DRAW ITS
1) FRONT VIEW
2)TOP VIEW
& 3)LEFT HAND SIDE VIEW
NOTE : ASSUME
L = 80
H = 70
& D = 50
USE FIRST ANGLE METHOD
OF PROJECTIONS FOR THE
EXCERCISE
EX - 6
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AIM – ISOMETRIC VIEW OF AN OBJECT SHOWN
DRAW ITS
1) FRONT VIEW
2)TOP VIEW
& 3)LEFT HAND SIDE VIEW
NOTE : ASSUME
L = 100
H = 50
& D = 50
USE FIRST ANGLE METHOD
OF PROJECTIONS FOR THE
EXCERCISE
EX- 7
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65
66
67
68
69
70
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X
Y
First Angle Method of Projection
X
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First Angle Method of Projection
F.V.
T.V.
R.H.S.V.L.H.S.V.
X Y
73
30
10
25
SQ
15
SQ
Ø30,Dept
h 10
40
SQ
74
25 Sq
40
15
453535
15 Sq
40 Sq
Ø30
5
10
30
10
510
R.H.
S.V.
F.V.
T.V.
75
X
Y
F.V.
T.V.
L.H.S.V. R.H.S.V.
Third Angle Method of Projection
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F.V.
T.V.
L.H.S.V. R.H.S.V.
Third Angle Method of Projection
77
10
20R20
R
8
30