TB 9-5210-205-40
(c) Interpret flatness errors from fringe patterns (B, fig. 1) and record four
results from each block (two from each wringing surface).
(2) The TI will not exceed the applicable flatness value listed in table 1.
NOTE
Since the majority of gage blocks under 0.100 inch (2.5 mm) in
length are not precisely flat, the test for parallelism is
considered sufficient. The interferometer will be used to
examine blocks under 0.100 inch (2.5 mm) in length for
scratches, dents, or other damage that would prevent accurate
calibration or usage. Blocks showing such damage will be
rejected.
10. Parallelism and Size Measurement
a. Performance Check
(1) Arrange TI and gage blocks (hereafter called master block) side by side
according to size on soaking area.
(2) Allow sufficient time for normalizing of TI. Observe such factors as elapsed time
between handling and stability of room temperature.
NOTE
Handle blocks with forceps. Gloves may be used for blocks over
4 inches.
(3) Place master block on anvil of comparator and align master block so that
gauging head contact tips of comparator will contact reference point for length
measurement.
(4) Zero the comparator.
(5) Remove master block and insert TI.
NOTE
Copies of the calibration worksheet located in Appendix A
may be used to record values and facilitate calculations.
(6) Record meter reading (in.) at reference point A (fig. 1) with proper signs and
algebraically add reading to test reported deviation for master block. Record value on
calibration worksheet as the length deviation of the TI.
(7) Remove TI and insert master block to ensure that proper setting of instrument
was maintained during measurement; remove master block and re-insert TI.