TM 9-243
TYPES AND USES
THICKNESS (FEELER) GAGES
Thickness (feeler) gages are made in many shapes and
sizes; usually 2 to 26 blades are grouped into one tool
and graduated in thousandths of an inch.
Most thickness blades are straight, while others are bent
at the end at 45 degree and 90 degree angles. Some
thickness gages are grouped so that there are several
short and several long blades together. Thickness
gages are also available in single blades and in strip
form for specific measurements. For convenience,
many groups of thickness gages are equipped with a
locking screw in the case that locks the blade to be used
in the extended position.
These gages are fixed in leaf form, which permits the
checking and measuring of small openings such as
contact points, narrow slots, and so forth. They are
widely used to check the flatness of parts in straighten-
ing and grinding operations and in squaring objects with
a try square.
CENTER GAGE
The center gage is graduated in 14ths, 20ths, 24ths, and
32nds of an inch. The back of the center gage has a
table giving the double depth of thread in thousandths of
an inch for each pitch. This information is useful in
determining the size of tap drills. Sixty-degree angles in
the shape of the gage are used for checking Unified and
American threads as well as for older American National
or U.S. Standard threads and for checking thread cut-
ting tools.
16-2
