TM 9-243
TYPES AND USES
Ring and snap gages and precision gage blocks are
used as standards to determine whether or not one or
more dimensions of a manufactured post are within
specified limits. Their measurements are included in the
construction of each gage, and they are called fixed
gages. However, some snap gages are adjustable.
Gages are used for a wide range of work, from rough
machining to the finest tool and die making. The accu-
racy required of the same type of gage will be different,
depending on the use.
SNAP GAGE - ADJUSTABLE
RING GAGES
SNAP GAGE - NONADJUSTABLE
The following classes of gages and their limits of accu-
racy are standard for all makes:
Class X - Precision lapped to close tolerances for many
types of masters and the highest quality working
and inspection gages.
Class Y - Good lapped finish to slightly increased toler-
ances for inspection and working gages.
Class Z - Commercial finish (ground and polished, but
not fully lapped) for a large percentage of working
gages in which tolerances are fairly wide, and
where production quantities are not so large.
Class ZZ - (Ring gages only). Ground only to meet the
demand for an inexpensive gage, where quantities
are small and tolerances liberal.
GAGE BLOCKS
The table below lists the tolerances for ring gages in
each class:
TO AND
ABOVE
INCL
X
0.029
0.825
0.00004
0.825
1.510
0.00006
1.510
2.510
0.00008
2.510
4.510
0.00010
4.510
6.510
0.00013
6.510
9.010
0.00016
9.010
12.010
0.00020
Y
0.00007
0.00009
0.00012
0.00015
0.00019
0.00024
0.00030
RING
GAGES
Z
ZZ
0.00010
0.00020
0.00012
0.00024
0.00016
0.00032
0.00020
0.00040
0.00025
0.00050
0.00032
0.00064
0.00040
0.00080
X
Precision lapped
Y
Lapped
Z
Ground or polished (grinding marks may be in evidence),
ZZ Ground only
15-2
