TM 1-1500-204-23-9
Figure 3-35. Inside Micrometer
Figure 3-36. Depth Micrometer
Figure 3-37. Extension Rods for Inside and
Depth Micrometers
Figure 3-38. Using Inside Micrometer
c. Use. The following paragraphs discuss the basic
use of the outside and inside micrometers.
(1) Outside micrometer. As shown in figure 3-
39, the micrometer is held in one hand and the stock in
the other. The thimble is turned until the anvil and
spindle just touch the stock. The micrometer is then
read for an accurate measurement.
(2) Inside micrometer. The normal procedure in
using an inside micrometer is to set it across a diameter
or between the inside surfaces, remove it, and then read
the dimension. For this reason, the thimble on an inside
micrometer is much stiffer than on a micrometer caliper
it holds the dimension well. It is good practice to verify
the reading of an inside micrometer by measuring it with
a micrometer caliper.
(a) Technique. Figure 3-40 shows an inside
micrometer with extension rod being used to check the
diameter of a bored hole. Note the arrows which
indicate the direction the operator is feeling for the
largest
dimension
horizontally
and
the
smallest
dimension vertically. Inside micrometers have spherical
contact points which require more practice to feel the
full measurement of the diameter. One contact point is
generally held in a fixed position and the other rocked in
different directions to
3-15
