Lesson 2/Learning Event 2
CALIPERS
Outside
These calipers are used in one of two ways. Either the caliper is set to
the dimension of the work and the dimension transferred to a scale, or the
caliper is set on a scale and the work machined until it checks with the
dimension set on the caliper.
To adjust an outside caliper to a scale
dimension, one leg of the caliper should be held firmly against one end of
the scale and the other leg adjusted to the desired dimension, Figure 26,
Part A.
FIGURE 26.
USING OUTSIDE CALIPERS (A AND B)
To adjust the outside caliper to the work, open the legs wider than the work
and then bring them down to the work. A sense of feel must be acquired to
use calipers properly.
This comes through practice and care in using the
tool to eliminate the possibility of error.
Always position the caliper
properly on the axis of the work, Figure 26, Part B.
NOTE.
Never set a caliper on work that is revolving in
a machine.
The
contact of one leg of a caliper on a revolving surface will
tend to draw the
other leg over the work because of the friction between the
moving surfaces.
Only a slight force is necessary to spring the legs of
a caliper thus
measurements made on moving surfaces are never accurate.
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