Basic engineering drawing

ISOMETRIC PROJECTIONS

• A type of pictorial projection in which all the three dimensions of a solid are seen in such a
way that all of them are equally shortened.

• The actual sizes can be measured from them.

, • If a cube is placed on one of its corners on the ground with a solid diagonal perpendicular
the V.P., the front view is the isometric projection of the cube.




d h d
h

f a h

a e c e a g c
g

b g d

f
b f b
c
x y


a' a'


b' b' d'
a' b' c' d'
d' c'
e' c'
e'

f' h'
f' h'

h'
G e' f' g' g' g' L

,a) All the faces of the cube are equally inclined to the V.P. and hence, they are seen as
similar and equal rhombuses instead of squares in the front view.




A



B D



C
E



F H



G

, b) The three lines CB, CD and CG meeting at C and representing the three edges of the
solid right-angle are also equally inclined to the V.P. and are therefore equally
foreshortened. They make equal angles of 120o with each other. The line CG being
vertical, the other two lines CB and CD make 30o angle each with the horizontal.




A



B D

120°

C
120° E 120°


F H
60°

30° 30°
G