Lesson 1/Learning Event 2
USING INSIDE MICROMETERS
The normal procedure for using inside micrometers is to set them across
diameters or between inside surfaces, remove them, and then read the
dimension.
For this reason, the thimble on an inside micrometer is much
stiffer than the one on a micrometer caliper. Thus, it holds the dimension
better. It is good practice to verify the reading of an inside micrometer
by measuring it with a micrometer caliper.
Figure 13 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 measuring (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 diametral
measurement.
One contact point is generally held in a fixed position and
the other rocked in different directions. This ensures the tool spans the
true diameter of a hole or the correct width of a slot.
FIGURE 13. USING AN INSIDE MICROMETER
WITH AN EXTENSION ROD
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