Taking Inside Measurements
with the Vernier Caliper
To measure the distance between inside surfaces,
or the inside diameter of a hole, with a vernier caliper,
use the scale marked INSIDE. Figure 2-46 shows the
measuring points in place.
Figure 2-46.—Taking an inside measurement with a
vernier caliper.
Remember that if you are using a vernier caliper
with both metric and English scales, the scales appear
on opposite sides of the caliper and apply only to
outside measurements. Then, to get correct inside
measurements, you add to the actual reading the
measuring point allowance for the size of caliper you
are using. The measuring point allowance is usually
etched on the measuring point of the fixed jaw (refer
to fig. 2-43), or it is contained in the manufacturer’s
instructions. So if the actual reading from the vernier
scale is 1.026 inch and the measuring point allowance
is 0.250 inch, the inside measurement would be 1.276
inch.
DEPTH GAGE
A depth gage is an instrument for measuring the
depth of holes, slots, counterbores, recesses, and the
distance from a surface to some recessed part. The
RULE DEPTH GAGE and the MICROMETER
DEPTH GAGE (fig. 2-47) are the most commonly
used in the Navy.
Figure 2-47.—Types of depth gages.
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