1. Engineering Graphics 2018-19-I
Lecture 4
TA101A
Engineering Graphics I By
Dr. Mukesh Sharma
Professor
DEPARTMENT OF CIVIL ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY KANPUR
KANPUR , INDIA

2. Class on Saturday ?

4. Quadrant 1 and Quadrant 3 are Used for Orthographic Projections
Above
Above
Front
2nd
1st Quad
3rd Quad
4th
Front
Viewing Direction is same irrespective of quadrant where object is kept
Quadrant 1 and Quadrant 3 are Used for Orthographic Projections
In whatever Quadrant the object is in, viewing directions are same
In what quadrant, so far, we have been keeping the object in?

5. Revisit 3rd Angle Projection Scheme
This is Profile Plane
Here too
Observer – Plane - Object
RECAP of Concept
Object Plane Observer

6. 3rd Angle Projection Scheme contd..
See the positions of Front, top, RS, LS Views
FOR LSV ALSO IT IS TRUE
Object Plane Observer

7. 1st Angle Projection SchemeRS LS
Front
Top
See the positions of Front, top, RS, LS Views
Examine how different these are from 3rd angle projection
And why?
Hinge
Plane Object Observer

8. Concept In 3rd angle Projection Observer – Plane - Object
Position wrt Front view;
top view is above, R-S View on right and L-S view on left
In 1st angle projection
Observer – Object - Plane
top view is below, R-S View on left and L-S view on right

9. Theory of Dimensioning -Techniques and Conventions
Object is made of several parts – Need
Position (P)
Size (S)
Each feature is dimensioned once
For each feature, dimension positioned where its
shape shows
No Redundancy

10. Avoid giving any dimensions inside the drawing.
Extension Lines
Dimension Lines
Arc and Circular Features S S S P S
S(RAD.) S
S: Size
P: Position S P P P S
S Drill, 2 holes
Arrow Dimensions
ALL DIMENSIONS IN MM
(Near Title Block) x 3x
Avoid giving any dimensions inside the drawing.
No two dimension lines cross each other.
Center line can be used as extension line.
x=1mm usually

11. Extension line
Arrowhead
Dimension line
Leader
2 Holes, ø12
Note

12. 45 60
ø40 20 40
ø20
ø60 A B C D
Ø20 Drill

13. Unidirectional System
Aligned System
values read from bottom only
(Preferred when?)
values read from bottom and Right side

14. 16 60 10 30 50
Continuous or Chain Dimensioning 20
Progressive or Parallel Dimensioning
- From Common Base (Preferred)

15. Areas to avoid – Place them so to read conveniently
126
450
100 80
Avoid
Areas to avoid – Place them so to read conveniently

16. CORRECT
INCORRECT

17. Omit unnecessary dimensions.

18. Dimensioning of arcs
Single arrow, inclined, show where true shape
(aligned and unidirectional)

19. Equally spaced holes.

20. Dimensioning in limited spaces6 3 22 19
4.8 5 22
ø26 18
21.5 12
300’ 45”
Dimensioning in limited spaces

21. } Today’s Quiz Drawn in Title Block to indicate type of projection.
Identify the angle of projection }
Drawn in Title Block to indicate type of projection.
Third angle
First angle
Third angle