TM 9-243
SELECTING THE PROPER MICROMETER - Continued
is necessary, therefore, that the mechanic first find the
approximate size of the work to the nearest inch, and
then select a micrometer that will fit it. For example, to
find the exact diameter of a piece of round stock use a
rule and find the approximate diameter of the stock. If it
is found to be approximately 3-1/4 inches, a micrometer
with a 3- to 4-inch range would be required to measure
the exact diameter. Similarly, with inside and depth
micrometers, rods of suitable lengths must be fitted into
the tool to get the approximate dimension within an inch,
after which the exact measurement is read by turning
the thimble. The size of a micrometer indicates the size
of the largest work it will measure.
7 - 3
