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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