Engineering Graphics

1. KCE – 151P
ENGINEERINGGRAPHICSANDDESIGNLAB
Department of AS&H
Umar Karimi
Assistant Professor

2. Course Objectives
1. Learn to sketch and take field dimensions.
2. Learn to take data and transform it into graphic drawings.
3. Learn basic engineering drawing formats

3. UNIT-1
TOPICS
• PRINCIPLES OF ENGINEERING GRAPHICS AND THEIR SIGNIFICANCE
• USAGE OF DRAWING INSTRUMENTS
• LETTERING
• SCALES-PLAIN AND DIAGONAL SCALES
• PRINCIPLES OF ORTHOGRAPHIC PROJECTION
• PROJECTION OF POINTS AND LINES

4. It is not always convenient or possible to draw object of its actual size. In
order to draw large or small objects on drawing sheets we use concept of
scaling so that objects can be accommodated on available drawing sheet
with proper clarity.
Scales has been classified on the basis of Size and Type.
Classification according to Size:
1. Full Size Scale
2. Reducing Scale
3. Enlarging Scale
Classification according to Type:
1. Plain Scale
2. Diagonal Scale
3. Vernier Scale
4. Comparative Scale
5. Scale of Chords
Scales

5. 1. Plain Scale
Plain scale is used to represent two consecutive units i.e. a unit and
subdivision of main unit.
Example:
a) meter and decimeter
b) Km and hm
c) Feet and inches, etc.
2. Diagonal Scale
It is used to represent three units i.e. main unit, its sub-unit and
subdivision of sub unit.
Example:
a) Meter, decimeter and centimeter
b) Km and hm
A diagonal scale is used to indicate the distances in a unit and its
immediate two subdivisions.

6. Representative Fraction:
It is the ratio of the drawing size of an object to its actual size.
Mathematically,
R.F. = Length of Drawing / Actual Length of Object
Or R.F. =
(Area of drawing)^ 1/2
(Actual Area)^ 1/2
Or R.F. =
(Volume of drawing)^ 1/3
(Actual Volume)^ 1/3
(Q1) An area of 36 square km is represented by 144 square cm on a
map. What is R.F. ?

7. (Q2) If a 5 cm long line in the drawing represents 3 km length of a
road in engineering scale. What is its R.F.?

8. (Q3) Find the length of scale for R.F. = 1/50 which is long enough to
measure 5 meters.

9. Orthographic Projections
It is a method of producing dimensioned working drawings or blueprints of
3-D Objects using a series of related 2-D views of the object to
communicate the object's length, width and depth.
Principles of Orthographic Projections
1. Top view is directly over the front view.
2. Side view is inline horizontally with either top view or front view.
3. A line parallel to a plane of projection will be projected on that plane as
a line.
4. A surface parallel to a plane of projection will be projected on that plane
5. A line perpendicular to a plane of projection will be projected on that
plane as a point.
6. A surface perpendicular to a plane of projection will be projected on that
plane as line.

11. Conventions of Orthographic Projection:
​There are a number of rules and conventions which must be adhered to
when producing Orthographic Drawings.
1. Heights of objects will remain the same between Elevations including
End Elevations and Auxiliary Elevations.
2. Widths of Objects will remain the same between the main Elevation,
Plan and Auxiliary Plans.
3. Lines & Surfaces parallel to the Vertical Plane will appear as true
lengths/shapes in the Elevation.
4. Lines & Surfaces parallel to the Horizontal Plane will appear as true
lengths/shapes in the Plan.
5. 45° Lines or Arcs should be used to transfer widths between the plan
and End Elevation.
6. Construction lines should be drawn lightly using a H Pencil.
7. Finished lines should be drawn heavily using a B Pencil.

12. Projection of Points
There are basically nine type of projections of point in space:
1. In FIRST Quadrant (Above H.P. , In front of V.P.)
2. In SECOND Quadrant (Above H.P. , Behind V.P.)
3. In THIRD Quadrant (Below H.P. , Behind V.P.)
4. In FOURTH Quadrant (Below H.P. , In front of V.P.)
5. In PLANE (On V.P. , Above H.P.)
6. In PLANE (On H.P. , Behind V.P.)
7. In PLANE (On V.P. , Below H.P.)
8. In PLANE (On H.P. In front of V.P.)
9. In PLANE (On both H.P. & V.P.)

13. A1-
a1’-
a1 -
Point
F.V.
T.V.
Position 1
.a1’ Y
.A1
Y (3D)
.a
X
1
In 2D
Front View Above Reference Line
In 3D
Above H.P.
In front of V.P.
.a ’ X
Top View Below Reference Line
X Y
.a1 (2D)
1

14. A2- Point
a2’- F.V.
a2 - T.V.
Position 2
Y
A2
.
a
.2’
.
a Y
2
(3D)
X
X
.a
In 2D
Front View Above Reference Line
Top View Above Reference Line
In 3D
Above H.P.
Behind V.P. .a2’ (2D)
Y
X
2

15. A3- Point
a3’- F.V.
a3- T.V.
(3D)
Y
Position 3 Y
a
.3
. X
A3
.a3’
In 2D
Front View Below Reference Line
Top View Above Reference Line
In 3D
Below H.P.
Behind V.P. .a
X
Y
(2D)
X
.a3’
3

16. A4- Point
a4’- F.V.
a4- T.V.
Position 4 Y
Y
X a
.4
.
a4’
. (3D)
X
A4
X Y
.a ’
4
.a4
In 2D
Front View Below Reference Line
Top View Below Reference Line
In 3D
Below H.P.
In front of V.P.
(2D)

17. A5-
a5’-
a5 -
Point
Position 5 F.V.
T.V.
Y
.a
A ’
Y (3D)
.a5
X
In 2D
Front View Above Reference Line
Top View On Reference Line
In 3D
Above H.P.
On V.P.
X
A5 .a5’
(2D)
Y
.a5
X
5 5

18. A6- Point
a6’- F.V.
Position 6 Y a6- T.V.
Y
.a6
X
.a6’
A6
X (3D)
.
X Y
a
In 2D
Front View Below Reference Line
Top View On Reference Line
In 3D
Below H.P.
On V.P. A6
.a ’
6
(2D)
6

19. A7 Point
a7’- F.V.
a7 - T.V.
Y
Position 7
Y
(3D)
a
.7’
X
.a7
A7
In 2D
Front View On Reference Line
Top View Below Reference Line
In 3D
On H.P.
In Front of V.P.
X
.a7’
X Y
A7 . (2D)
a7
A7

20. A8- Point
a8’- F.V.
a8 - T.V.
Position 8
Y
.a8
8
A Y
a
.8’
X
A8
.a8
X
(3D)
In 2D
Front View On Reference Line
Top View Above Reference Line
In 3D
On H.P.
Behind V.P.
(2D)
.a8’
X Y

21. A9-
a9’-
a9 -
Point
F.V.
T.V.
Position 9
Y
Y (3D)
a9’
.a9
A9
X
In 2D
Front View On Reference Line
In 3D
On H.P.
On V.P.
X
Top View On Reference Line
.a9’
X Y
(2D)
a9
A9

22. Q1) A point is above 5m from H.P. and 6m in front of V.P. Draw its projection. Assume
R.F. as 1:50