Orthographic Projection · Orthographic Projection Observer. 6 The object is assumed to be observed...

1

Orthographic Projection

2

Perspective Projection

4

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.

5

Parallel Ortho- rays

(right angle to plane

Of projection)

(Projectors)

ObjectOrthographic

View

or

Projection

Orthographic Projection

Observer

6

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.

7

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.

8

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

9

X

Y


X

10


X

11


X

F.V.

T.V.

R.H.S.V.L.H.S.V.

12

X

YF.V.

T.V.

R.H.S.V.


L.H.S.V.

X Y

13

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.

14

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.

15

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

16

•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.

17

X

Y


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

19

20

35

ALIGNED

SYSTEM(FOR A2 TO A5

SHEET SIZE)

UNIDIRECTIONAL

SYSTEM(FOR LARGE SIZED

SHEETS)

35

20

ARROW HEADS

(H x 3H) 3H H

20

(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

21

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

22

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.

24

(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 :

25

(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.

26

(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.

27

5

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.

29

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

30

X

Fig 2(b)

7

Z2

1

3

Z2

Fig 2(a)

X

Y

YY

31

Fig. 2(c)T.V.

L

F.V.

X YR.H.S.V.

D

H

Z2

Fig 2(a)

X

Y

32

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

33

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)

34

T.V.

4

D

6

L.H.S.V

2

F.V.

L

X Y

Fig.

3(c)

Y

Z1X

Fig 3(a)

38

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

39

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

41

20 20

R40

20

100

80

ø40

80

20

TOP VIEW

FRONT VIEWR.H.S.V

SCALE: 1:1

60

R40

X

42

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

44

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

46

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

47

30

10

25 SQ

15 SQ

Ø30,Depth 10

40 SQ

ISOMETRIC

ORTHO. VIEWS

48

25 Sq

40

15

453535

15 Sq

40 Sq

Ø30

5

10

30

10

510

R.H.S.V.

F.V.

T.V.

49

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

51

14

14

48

70

24

10

Ø40

50

Ø64

30

140

L.H.S.VFRONT VIEW

TOP VIEW

52

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

57

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

58

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

60

AIM : ISOMETRIC VIEW OF AN OBJECT SHOWN

DRAW, ITS 1) FRONT VIEW 2) TOP VIEW


NOTE : ASSUME

L = 120

H = 60

& D = 50

USE FIRST ANGLE

METHOD

OF PROJECTIONS

FOR THE

EXCERCISE

EX- 4

61

ISOMETRIC VIEW OF AN OBJECT SHOWN HERE

DRAW, ITS 1) FRONT VIEW 2) TOP VIEW


NOTE : ASSUME

L = 120

H = 60

& D = 80

USE THIRD ANGLE

METHOD

OF PROJECTIONS

FOR THE

EXCERCISE

EX- 5

62

ISOMETRIC VIEW OF AN OBJECT SHOWN

DRAW ITS

1) FRONT VIEW

2)TOP VIEW


NOTE : ASSUME

L = 80

H = 70

& D = 50



EXCERCISE

EX - 6

63

AIM – ISOMETRIC VIEW OF AN OBJECT SHOWN

DRAW ITS

1) FRONT VIEW

2)TOP VIEW


NOTE : ASSUME

L = 100

H = 50

& D = 50



EXCERCISE

EX- 7

71

X

Y


X

72


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.


76

F.V.

T.V.

L.H.S.V. R.H.S.V.


77

10

20R20

R

8

30

Orthographic Projection · Orthographic Projection Observer. 6 The object is assumed to be observed...

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