Textbook of Engineering Drawing, Second Edition

3.10 Textbook of Enginnering Drawing------------------

O.54+2.S=3.34lcm

O.SSkm

o 5 10

LENGTH OF THE SCALE 150 mm

SCAlE:1:40000

Fig. 3.10 Forward Reading Vernier Scale

Problem 9 : construct a vernier scale to read metres, decimetres and centimetres and long

enough to measure upto 4m. The RF of the scale in 1120. Mark on it a distance of 2.28 m.

Solution: (Fig 3.11)

Backward or Retrograde Vernier scale

1. The smallest measurement in the scale is cm.
   Therefore LC = O.Olm


2. Length of the scale = RF x Max. Distance to be measured
   1 1
   = - x 4m = - x 400 = 20 em
   20 20

3

LeastCO\.llt= O.01m

Rf" 1120

Fig. 3.11 Backward or Retrograde Vernier Scale