1. ENGN103 Engineering Drawing orthographic projections
Lecture 3

2. What is Orthographic Projection?
Orthographic Projection is a method of representing a three dimensional object on paper using several two dimensional views.
It is the international language of Engineers and Designers

4. Side elevation
Front elevation
Plan – Top view

5. Orthographic Projection- simple shapes
Rectangle of sides 50 x 35 mm resting on HP.
Rectangle of side 50 x 35 mm, with short edge on HP. 10mm away from PP and 5mm away from VP.
Rectangle of side 50 x 35 mm, with short edge on HP. 10mm away from PP and 5mm away from VP. Inclined at 30degree to VP.
Rectangle of sides 50 x 35 mm, with one corner on HP. Making 30degree and 60degree with HP.
Long edge
corner
Short edge

7. Orthographic Projection- simple shapes
Draw the orthographic projections:
Circle of radius 25mm resting on HP, 10mm away from VP and PP.
Triangle of sides 40mm, 15mm and 35mm. 7.5mm away from PP, 10mm away from VP and 7.5mm above HP.
Hexagon of side 25mm. 10mm away from VP.
Rectangle of sides 35mmx60mm lying flat on HP. A square of side 25mm is resting on the rectangle with its corner on the center of the rectangle.

9. DRAW ORTHOGRAPHIC PROJECTIONS:
Cube of side 45mm with a whole of 10mmx10mm in the center of one of the sides.
Triangular Pyramid of sides 30mm and height 55mm.
A cone of base radius 20mm and height 40mm. Resting on the corner
A cylinder of base radius 15mm and length 55mm. Resting on the side.

10. Orthographic Projection of objects
Front elevation
Side elevation
Plan – Top view
Isometric view

11. Height Height Depth Width Width Height Depth Depth Width
SIDE ELEVATION
FRONT ELEVATION
Height
Width
Depth
Depth
Width
PLAN

12. FRONT ELEVATION
SIDE ELEVATION

13. FRONT ELEVATION
SIDE ELEVATION
PLAN

15. FRONT ELEVATION
SIDE ELEVATION
PLAN

16. FRONT ELEVATION
SIDE ELEVATION
PLAN

17. FRONT ELEVATION
SIDE ELEVATION
PLAN

18. Centerlines

19. Precedence of Lines
FRONT ELEVATION
SIDE ELEVATION
PLAN

20. FRONT ELEVATION
SIDE ELEVATION
PLAN