TM 9-243
TYPES AND USES - Continued
SCREW PITCH GAGES
SMALL HOLE GAGE SET
Screw pitch gages are made for checking the pitch of
U.S. Standard, Metric, National Form, V-form, and
Whitworth cut threads. These gages are grouped in a
case or handle, as are the thickness gages. The number
of threads per inch is stamped on each blade. Some
types are equipped with blade locks. The triangular-
shaped gage has 51 blades covering a wide range of
pitches, including 11-1/2 and 27 threads-per-inch for
V-form threads.
Screw pitch gages are used to determine the pitch of an
unknown thread. The pitch of a screw thread is the
distance between the center of one tooth to the center of
the next tooth.
Small hole gages are adjustable, having a rounded
measuring member. A knurled screw in the end of the
handle is turned to expand the ball-shaped end in small
holes and recesses. A micrometer caliper is used to
measure the ball end. Maximum measuring capacity is
1/2 inch. This set of 4 or more gages is used to check
dimensions of small holes, slots, grooves, and so forth
from approximately 1/8 to 1/2 inch in diameter.
TELESCOPING GAGES
Telescoping gages are used to gage larger holes and to
measure inside distances. These gages are equipped
with a plunger (1) that can be locked in the measuring
position by a knurled screw (2) in the end of the
handle (3). Maximum measuring capacity is 6 inches.
Measurements must be calipered on the gage by a
micrometer, as in the case of the small hole gages.
They are also used when measurements cannot be
taken with a standard micrometer. Telescoping gages
are particularly adaptable for roughly bored work and
odd sizes and shapes of holes. Compress the plungers
and lock them by turning handle screw.
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