Textbook of Engineering Drawing, Second Edition

_____ Orthographic Projections 5.11

x

-:-_...,b

o

'"

.--b'

X-_..l.-....1.....-!:o---Y

(b)

Fig. 5.12 Point in II Quadrant

4. To draw the orthographic projections; draw xy line on which a projectior is drawn at any
   point. Mark on it bl 30 nun above xy on this projector.


5. Mark b 40 nun above xy on the same projector.

Problem : A point C is 40 mm below HP and 30 mm behind v.P. Draw its prujc('tim1<:.

Sulution : (Fig.S.13) The point C is in the ill Quadrant

1. C is 40 nun below H.P Hence cl is 40 nun below xy.


2. Draw xy and draw projector at any point on it. Mark cl 40 nun below xy on the projector.

c

o (')

X-;-:-::::-I-=-+--H.P Y

v.p 0

c'

Fig. 5.13 Point in III Quadrant

3. Cis 30 nun behind v.P. So cl is 30 nun behind xy. Hence in the orthographic projections

mark c 30 nun above xy on the above projector.

Problem: A point D is 30 mm below HP and 40 mm in front of v.P. Draw its projeciton.

Solution: (F ig.S .14) The point D is in the IV Quadrant.

1. Dis 30 nun below H.P. Hence, dl, is 30 nun below xy. Draw xy line and draw a projector
   perpendicular to it. Mark dl 30 nun below xy on the projector.


2. Dis 40nun in front ofV.P; so dis 40 nun in front ofxy. Therefore, mark d 40 mm below xy.