TB 9-5210-205-40
NOTE
Zero drift should not exceed approximately 25% of the
tolerance of the gage block being measured.
(8) Take readings at reference points 1, 2, 3 and 4 (fig. 1) avoiding the area of block
0.020″ from edge of the block, back to the edge. Record the four readings in respective
columns on calibration worksheet in millionths of an inch with proper signs. The largest
algebraic difference between any two points 1, 2, 3 and 4 will be within limits found in table
NOTE
Due to size and shape variations among gage blocks, the
location of the reference points mentioned in step (8) above
may vary in order to accommodate the size markings. These
variations will not adversely affect the parallelism verification
provided that the reference points are evenly distributed over
the measured surface.
(9) Repeat steps (3) through (8) above for each TI in set being calibrated.
b. Adjustments. No adjustments can be made.
11. Final Procedure
a. Verify that TI length and flatness deviations recorded on calibration worksheet are
within the tolerances listed in table 1. For out-of-tolerance conditions, perform one of the
following:
(1) If less than 25% of blocks are out-of-tolerance then replace with same size gage
blocks, if available and return unserviceable blocks to unserviceable stock.
(2) If 25% or more of AS-1 gage blocks are out-of -tolerance, downgrade entire set
to lower grade (AS-2) if possible, and affix DA Label 163 annotating new grade designation.
(3) If 25% or more of AS-2 gage blocks are out-of -tolerance then annotate and affix
DA Form 2417 (Unserviceable or Limited use tag) to the entire set.
(4) Individual blocks which deviate more than twice the length, flatness or
parallelism tolerances or which have lost their wringing qualities are to be replaced.
Discard all unserviceable blocks.
b. Transfer individual block identification and length deviation to a test results report.
One copy will be maintained by the calibration facility and one will be packaged with the
TI. Add all pertinent information.