USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 3/TASK 1
3 The frame may be in the form of a base so that the gage can
be used as a bench micrometer.
4 The frame may have a wooden handle and may be of extra
heavy construction for use in a steel mill for gaging hot sheet metal.
(c) The spindle and anvil may vary in design to accommodate special
physical requirements. For example:
1 The spindle and anvil may be chamfered so that the gage can
slide on and off the work easily, as when gaging hot metal.
2 The ball-shaped anvil is convenient
in
measuring
the
thickness of a pipe section of small diameter.
3 The V-shaped anvil is necessary on the screw thread
micrometer caliper to mesh properly with the screw thread. The spindle of
the screw thread micrometer is cone shaped.
This micrometer measures the
pitch diameter.
4 Interchangeable anvils of various lengths make it possible
to reduce the range of the caliper. A micrometer having a range from 5 to 6
inches can be changed to one having a 4 to 5, or 3 to 4 inch range by
inserting a special anvil of the proper length.
(2) Inside Micrometers.
Inside micrometers are used to measure
inside dimensions. The minimum dimension that can be checked is determined
by the length of the unit with its shortest anvil in place and the screw set
up to zero.
It consists of an ordinary micrometer head, except that the
outer end of the sleeve carries a contact point attached to a measuring rod.
The typical inside micrometer set (figure 191 on the following page) has a
range that extends from 2 to 10 inches. The various steps in covering this
range are obtained by means of extension rods. The micrometer set may also
contain a collar for splitting the inch step between two rods. The collar,
which is 1/2 inch long, extends the rod another half-inch so that the range
of each step can be made to overlap the next. The range of the micrometer
screw itself is very short when compared to its measuring range. The
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