TOPICS OF “ENGINEERING GRAPHICS” (Mechanical Portion)

( C ) ORTHOGRAPHIC PROJECTIONS FROM GIVEN ISOMETRIC VIEW

( D ) ISOMETRIC VIEW/PROJECTIONS FROM GIVEN ORTHOGRPHIC VIEWS

Without Sections

With Sections

View i.e. drawing Projections

Topic no. Topic Content No. of Lectures

07

05

TYPES OF LINES USED IN

ENGINEERING DRAWING

APPLICATIONS OF LINES ON DRAWING

G2CUTTING PLANE

LINE (IN T.V)

CONTINUOUS THICK

A

A

G1CUTTING PLANE

LINE (IN F.V)G1

B CONTINUOUS THIN (WAVY)

B

C SHORT ZIGZAG THIN

C

DDD CONTINUOUS

THIN

D

ESHORT DASH

MEDIUM (DOTED LINE )

E

F LONG CHAIN THIN (CENTER

LINE)

F

40 30

2515

0

60

Trimmed and untrimmed drawing sheet sizes are commercially designated as A0 (Maximum size), A1, A2, A3, A4 & A5 (Least size).

In Engineering Graphics’ term work, all the 4 sheets will be of A2 (approximately ½ Imperial) size

The following two systems are adopted for dimensioning purposes on orthographic views as well as on pictorial view.

Dimensioning Techniques

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

ORTHOGRAPHIC PREOJECTIONS

(MULTI VIEW REPRESENTATIONS i.e. F.V.,

T.V. & S.V. – L.H.S.V OR R.H.S.V) FROM

ISOMETRIC VIEW

PLANES OF

PROJECTIONSQUADRANTS

VISION

DIRECTIONS

SCALING OF A DRAWING (Full Size 1:1,

Reduced 1:2 or Enlarged 5:1 )

VIEWES

METHODS OF PROJECTIONS WITH

THEIR SYMBOLS

(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

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

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 SECOND OR IN FOURTH QUADRANT, AS THE VIEWS MAY OVERLAP ON ONE ANOTHER ABOVE XY OR BELOW XY RESPECTIVELY.

HP

VP

PP

ISOMETRIC VIEW

OF

FIRST ANGLE METHOD OF PROJECTIONS (FOR L.H.S.V.)

Z1

L.H.S.V.

T.V.

L

F.V.

L

X

F.V. Plane

T.V. Plane

L.H.S.V. Plane

Y

D

H

Y

XH

D

OBJECT IN FIRST

QUADRANT (FOR L.H.S.V.)

Fig. 2(c) shows turning of the planes H.P & P.P with their respective hinges, considering V.P as fixed plane.

b) F.V is within L & H, T.V is within L & D, While L.H.S.V is within H & D.

It may be noted that :-(a) F.V. (X directional view) is on V.P, T.V. (Y

directional view) is on H.P, while L.H.S.V (Z1 directional view) is on P.P

c) The symbol for Ist angle method of projections

is placed as shown on fig. 2(c)

Fig. 2(c)

X Y

H.P

T.V.

L

V.P

F.V.

L.H.S.V.D

P.P

H

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

X

Fig 2(b)

P.P

H

D

R.H.S.V.

Z2

Y

X

V.P

L

F.V.

H.PT.V.

Z2

LD

H

Fig 2(a)

X

Y

YY

Note : Ist angle means, the block is assumed in

front of V.P, above H.P and inside P.P,

as in fig. 2(b) where the F.V. is

projected on V.P, seen in X direction,

T.V. is projected on H.P, seen in Y

direction & R.H.S.V. is projected on

P.P, seen in Z2 direction

It may be noted that :-

a) F.V. (X directional view) is on V.P, T.V. (Y directional view) is on H.P, while R.H.S.V (Z2 directional view) is on P.P

Fig. 2(c) shows turning of the planes H.P & P.P with their respective hinges, considering plane V.P as fixed plane.

b) F.V is within L & H, T.V is within L & D, While R.H.S.V is within H & D.

c) The symbol for Ist angle method of projections is

placed as shown on fig. 2(c)

Fig. 2(c)

H.P

T.V.

L

F.V.

V.P

X YR.H.S.V.

D

P.P

H

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

T.V.

H.PHL.H.S.V.

P.P

D

X

Y

Z1

X

Y

V.P

F.V.

L

Fig 3(b)

Y

Z1X

D

H

L

Fig 3(a)

Plane H.P turned up(above V.P)

Plane P.P turned side way(towards left side of plane V.P)

Note : IIIrd angle means, the block is

assumed behind V.P, below H.P and

inside P.P, as in fig. 3(b) where the F.V.

is projected on V.P, seen in X direction,

T.V. is projected on H.P, seen in Y

direction & L.H.S.V. is projected on

P.P, seen in Z1 direction

c) The symbol for IIIrd angle method of projections is placed as shown on fig. 3(c)

b) F.V is within L & H, T.V is within L & D, While L.H.S.V is within H & D.

Fig. 3(c) shows turning of the planes H.P & P.P with their respective hinges, considering plane V.P as fixed plane.

It may be noted that :-

a) F.V. (X directional view) is on V.P, T.V. (Y directional view) is on H.P, while L.H.S.V (Z1 directional view) is on P.P

T.V.

4

D6

L.H.S.V

H

2

F.V.

L

X Y

Fig. 3(c)

AIM: Fig. 4(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.Right Hand Side View

X

Y

X

Y

R.H.S.V.HP.P

D

Z2

Fig. 4(b)

Planes H.P, V.P & P.P are assumed as transparent

Y

Z2

Fig. 4(a)

X

H.P

DL T.V.

V.P HL

F.V.

Note : IIIrd angle means, the block is assumed

behind V.P, below H.P and inside P.P, as

in fig. 4(b) where the F.V. is projected

on V.P, seen in X direction, T.V. is

projected on H.P, seen in Y direction &

R.H.S.V. is projected on P.P, seen in Z2

direction.

b) F.V is within L & H, T.V is within L & D, While R.H.S.V is within H & D.

c) The symbol for IIIrd angle method of projections is placed as shown on fig. 4(c)

Fig. 4(c) shows turning of the planes H.P &P.P with their respective hinges, considering plane V.P as fixed plane.

It may be noted that :-

a) F.V. (X directional view) is on V.P, T.V. (Y directional view) is on H.P, while R.H.S.V (Z2 directional view) is on P.P

YX

H.P

T.V.D

V.P

F.V.

L

Fig. 4(c)

P.P

R.H.S.V.

H

Step by step procedure

Suggested to prepare

Orthographic views (First angle

method) for The simple

component Shown pictorially in

figure

100

20

80

20

20

40

20

60

R40

Ø4

0ISOMETRIC

VIEW X

R40

20

100

80ø40

80

20

TOP VIEW

FRONT VIEWR.H.S.V

SCALE: 1:1

SYMBOL IS NOT MARKED

20 20

R20

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.ViewA

B

a

b

3

c

2

1

F.V

T.V

L.H.S.V.

B

a

bc

32

1

b

3

A

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

FRONT VIEWL.H.S VIEW

TOP VIEW

A

ab

3

c

2 1

Aim : Figure shows isometric view, of a simple machine component.

Draw its following Orthographic views, & dimension them.

1. Front View2. Top View3. R.H.S. View

Use First Angle Method of projection

10

10

Figure, is the isometric view

10

50

75

40

20

R25

30X

Figure

L = 75+25=100

H = 10+30=40

D=50

R2510

10

20

F.V.

5010

40

25 75

40

T.V.

R.H.S.V.

ORTHOGRAPHIC VIEWS

F.V L=100H=40

T.V L=100D=50

S.V D=50H=40

5

5

45

35

35

30

40

15

10

25 SQ

15 SQ

10

Ø30,Depth 1040 SQ

ISOMETRIC

ORTHO. VIEWS

25 Sq

40

15

453535

15 Sq

40 Sq

Ø30

5

10

30

10

51

0

R.H.S.V.

F.V.

T.V.

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 :-

ISOMETRIC VIEW

140

Ø40

Ø64

24

20

10

4850

25

1414

48

70

24

10

Ø40

50

Ø64

30

140

L.H.S.VFRONT VIEW

TOP VIEW

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 :-

ISOMETRIC VIEW

16

20

4020

20

20

Ø24

R22

140

40

80 60

30

X

TOP VIEW

R22

2040

10

FRONT VIEWRIGHT SIDE

VIEW

14020

80

SCALE: 1:1

3030

66

26

30

108

20R20

100

45

16

20

25R8

10

30

30

ISOMETRIC

ORTHO. VIEWS

4530 8

20 25

16

R8

R2030

20

10

100

SECTIONING OF A

MACHINE COMPONENT

BY ANY ONE SECTION

PLA NE ,OUT OF THREE

FOLLOWING MENTIONED

SECTION PLANES

(1)BY A VERTICAL SECTION PLANE

(PARALLEL TO PRINCIPLE V.P.)

Hence ,

(a)The real or true shape of the section is

observed in its F.V.

(b)Section plane will be seen as a cutting

plane line (similar to center line ,thick at

ends) with corresponding horizontal vision

direction arrows at the center of thick ends in

its T.V. & S.V.

(2)BY A HORIZONTAL SECTION PLANE

Hence,

(a)The real or true shape of the section is observed in

its T.V.

(b) The cutting or section plane will be observed as a

cutting plane line (similar to center line ,thick at

ends) with the corresponding vertically downward

vision direction arrows at the center of the thick

ends in its F.V. and in S.V.

(3) BY A SECTION PLANE , NORMAL TO BOTH H.P. AND V.P.(i.e. parallel to profile plane or side view plane)

Hence,

(a)The real or true shape of the section is observed in

its S.V.

(b) The cutting or section plane will be observed as a

cutting plane line (similar to center line ,thick at

ends) with the corresponding vertically downward

vision direction arrows at the center of the thick

ends in its F.V. and in T.V.

50

50

50

10

3015

6040

30

15

R12.55

15

30

A

B

X

Figure shows isometric view of a machine component. Draw its

(1)Front view, Top view & L.H.S View, using 3rd angle method of projections.

(2)Sectional Front view, Top view & L.H.S.V., using 3rd angle method of projections.

10

50 50

604030

1525

5

30

50

15

Front View

Top View

L.H.S.View

1.

X

Ortho. Views (No sectioning)

A

B

A

B

X

Retained split of the machine parts

XIt will be nearer to V.P. in 1st angle method & against the vertical plane in 3rd angle method.

50 50

604030

1525

5

10

30

Top View

Sectional Front View -ABL.H.S. View

A B

A

B

B

A

2.(With sectioning)

120

28

2020

2860

Ø30Ø20

14

7A

A

X

Figure shows the pictorial view of a machine component. Draw its following views as per First angle method of projections

(1) Front view from X direction.

(2) Sectional top view-AA(3) L.H.S. View

120

28

20

Sketch shows the assumed cut model (retained part of the machine component / split against the observer) due to horizontal section plane passing through AB.

X

120

60

28Ø30, 7deep Ø20

2020

14

F.V.

Sectional T.V.

L.H.S.V.

A AA A

60

20

90

20

40

60

1030

R10

XA

BFigure shows the pictorial view

of a machine components. Draw its following views, using 3rd angle method of projections.

(1) Front view from arrow X

(2) Top View

(3) Sectional R.H.S.V - AB

B

A

Retained split of the machine parts

Retained split, will be nearer to V.P. in 1st angle method & against the vertical plane in 3rd angle method.

No hatching in this area as not contained in the section plane

80

20

20 20

60

90

40

30

A

A

AF.V.

T.V.

SEC.R.H.S.V

HALF SECTION

SPECIALSECIONS

A

C

B

HALF SECTIONAL F.V.-AB HALF SECTIONALLEFT S.V.-BC

TOP VIEW

REMOVED & REVOLVED SECTIONS

SPECIAL SECTIONS

REMOVEDSECTION

REVOLVEDSECTION

REMOVEDSECTION

REVOLVED SECTION

REMOVED SECTION

REMOVED SECTIONS