The
other name of slide calipers is venire calipers. Because the Venire’s method is
used
a
graduated rectangular still plate. A metal jaw is fixed at the starting end of
the main
scale,
that is, at the end marked 0 of the main scale. A Jawed small scale is put over
the
body
of the main scale, to measure fraction of the small division of the main scale
accurately.
It is called venire scale.
This
Jawed vernier scale can be moved forward or backward along with the main scale.
There
is screw in it. It can be fixed at any point on the body of the main scale with
this
of
the main scale should coincide with the zero of the vernier scale.
By
using vernier scale fraction of millimeter may be measured accurately.
Vernier
constant of the slide calipers can determine from the above mentioned vernier
scale
chapter.
Measurement of slide calipers : Suppose, the length of rod is to be measured. The rod
is
to be placed between the two jaws of the slide calipers. The jaw connected with
the
vernier
scale is to be pushed forward so that the jaws of the main scale and the
vernier
scale
touch the opposite ends of the object. The rod is placed such that it’s left
end
coincides
with zero (0) mark of the main scale. The vernier scale is moved forward and
backward
to make it coincide with the right side of the rod. Suppose the right end of
the
rod
has crossed M mm mark of the scale and is between M and (M + 1) mm. This extra
distance
beyond M mm is to be determined by using the vernier scale. This length will
be
the vernier reading.
Now
it is to be noted which vernier scale mark coincides with which of the main
scale
mark.
If no vernier mark coincide with a main scale mark then find out the nearest
vernier
mark. The reading of this mark that is the number of vernier scale divisions
from
the
left to this mark, is the vernier scale reading.
Suppose
the Vth vernier
mark coincides with or nearest with any main scale mark. Hence
the vernier
constant of the instrument is VC.
