1. Problem 12.8 : Draw the projections of a circle of 50 mm diameter resting on the HP on point A
on the circumference. Its plane inclined at 45º to the HP and (a) The top view of the diameter AB
making 30º angle with the VP (b) The diameter AB making 30º angle with the VP
The difference in these two problems is in step 3 only.
In problem no12.8(a) inclination of TV of that AB is given, It could be drawn
directly as shown in 3rd step.
While in 12.8(b) angle of AB itself i.e. it’s TL, is given. Hence here angle of
TL(ab2) is taken, locus of b2 is drawn and then LTV I.e. a1 b1 is marked and
final TV was completed.Study illustration carefully. 7’
6’ b’ b1’71’ 72’
5’ 8’ 81’ 82’ 62’
6 1’
9’ 91’ 9 2’
4’ 51’ 5 2’
10’ 101’ 102’
3’ 42’
41’
2’ 11’ 111’ 112’
12’ 31’ 3 2’
1’ 121’
X 45º
21’ 122’ 2 2’
1’ 2’ 3’ 6’ 7’ a’ a1’11’ 1 2’ Y
4’ 5’
a’ 12’ 11’ 10’ 9’ 8’ b’
4 4 3
3 5 3 5 4
1 2 1
1 2 3
1 1 4
2 6 2 6
1 5 11 a1 1
1
a111 1 Ø β 1
1 1
30º 5
6 121
1a 7b 11 a1 b171 121
1
1
6
b171
12 8 121 8 111 1
b2
111
1 8 b1 7
11 9 111 9 101 9 101 1
101 1
9 8
10 1 1 1