751 
APPENDIX IT 
Use of the NOL Crusher Gauge 
[Adapted from Navy Department, 
Budrd (Re2c) Technical Note No. 15.] 
Arrangement of the gauge: The gauge when ready for operation, consists of 
the following pieces: 
1. The base, consisting of (a) the anvil against which the copper ball 
is pressed, (bh) a stud by means of which the gauge is screwed into the mount-— 
ing block, and (c) a steel or brass body in which these two pieces are 
mounted. In some versions of the gauge these pieces are combined into one 
unite 
2e The copper ball, which should measure 0.375 in. in diameter. 
3. A rubber centering washer for the copper ball. 
. The piston, a mushroom shaped piece of steel, which is used to de-= 
form the copper ball, 
5. A small spring, somewhat like a section of a corkscrew, which is 
designed to fit around the smaller portion of the piston and, by pressing 
against the piece described next (6), to hold the piston lightly against the 
copper ball. 
6. A brass head for the gauge, into which the piston, spring, ball, 
and washer may be inserted as described below, which is screwed into the base, 
completing the assembly of the gauge. 
7. A spacing ring, for use with gauges in which a 0.375—in. copper 
ball is used. 
Preparing gauges for use: 
1. Copper spheres of 3/8—in, or 5/32-in, diameter should be obtained 
from a lot which has been sampled and tested for wniformity of hardness. 
Spheres should be within =0,0003 in. of the mean diameter of the spheres in 
the particular lot, and their out-of-roundness should not exceed 40,0003 in. 
2. Determine the number of gauges to be used in the test. Procure 
that number of each of the (7) pieces described above. Be sure that all 
parts of the same gauge bear the same serial number. : 
Check the gauge with a sphere in place to be sure the piston (and 
spacer ring, if 3/8-in. balls are used) is of the proper dimension so that 
the face of the piston is flush with the face of the gauge. 
The piston must be free moving, without side play, in the body of the 
gaugee 
easier 
