732 
- 26- 
(a) Description. — (i) For 5/32-in, spheres. The gauge (Fig. 20) 
consits of a base of 1.5—in, diameter which includes the anvil agsinst 
which the copper sphere is pressed, a stud by which the gauge is screwed 
into the mounting block, and a steel or brass body in which these two 
pieces are mounted, In some versions of the gauge these pieccs of the base 
are made as one unit. The upper part of the base is threaded to accept the 
brass head (cap and piston guide in Fig. 20) of the gauge (also 1.5-in. 
diameter). The center hole of the brass head accepts the piston of the 
gauge, which is 0.5 in. in diameter and 0.5 in. long. The base of the pis- 
ton, which rests against the copper sphere, has a 0.625-in, diameter ridge 
to allow a bearing surface for the small spring that holds the piston in 
contact with the copper sphere at all times, The copper sphere is placcd 
in a rubber centering washer and inserted between the piston and anvil be- 
fore the head is screwed on to the base of the gauge. When completcly 
assembled the gauge is 1+3/ in, in over-all length. 
(ii) or 3/8-in. spheres, This same gange may be uscd with 3/8-in. 
spheres by inserting an adapter ring of 0,218-in. thiclmess between the 
head and the base before assembling. This allows the larger sphere to be 
inserted, and at the same time keeps the piston flush with the outcr face 
of the gauge. 
(b) Measurement of sphere deformation. -- The deformation of the 
copper spheres may be obtained from micrometer measurements of the diameter 
before deformation and the distance between the two flat faccs after de- 
formation. Since the-oriexatation of the copper sphere within the gauge can 
not be controlled, these sphores must have an out-of-roundness which is less 
than the desired precision of the measured deformations. Another factor 
affecting the reproducikility of the results is the hardness of the spheres; 
all spheres must be annealed dead soft. The Paes was checked for all 
spheres uscd at UERL with a drop test machine 2 
Because of the Jarge number of 3/8—in. spheres uscd on each shot, it 
was found convenient to set up a standard measuring procedure for theme 
The spheres were first subjectcd to one hundred percent inspection with go- 
no go gauge to keep any variations in out-of-roundness and diameter to with= 
in 0,0003 in. of the average diameter for the particular lot of spheres 
being used. This inspection made it unnecessary to measure and record the 
diameter of cach individual sphere and identify cach sphere with a particular 
gougee After the spheres were deformed they were placcd in envelopes marked 
to identify them With the giuge and its position during the shot. The de- 
formation was measured by means of a benchetype dial gauge set to read zoro 
deformation for a sphere of average diameter for the particular lot. The 
deformations of the damaged spheres were read directly from the dial. The 
uncertainty in this measurement was the tolerance allowed in the average 
diameter and resulted in somewhat lower precision in the results. However, 
the efficiency gained in servicing the gauges by this procedure made it 
possible to greatly increase the number of gauges that could be uscd on 
each shote 
10/550 Appendix VIL, . 
