Contact Cylinders—Ceramic contact cylinders of the
same material as the specimens to be tested shall be used
between the bearing plates and the test specimen to aid in
distributing the load and to minimize detrimental “end effects.”
These contact cylinders shall be 1⁄2 in. (12.7 mm) high and 5⁄8
in. (15.9 mm) in diameter. The contact faces shall be flat and
parallel to within 0.0005 in. (0.013 mm) total indicator reading.
Two new contact cylinders should be used for each specimen to
prevent a damaged contact cylinder failing prematurely and
thereby giving an erroneous reading. By using contact blocks
made of the same, or similar, material as the test specimen
itself there is less deformation and less frictional resistance at
the interfaces.