3 and 4 ) and record the four results from each block (two from
each wringing surface) on a calibration worksheet (see Figure 5).
Note: Record data on worksheet for TI's that exceed the
applicable flatness error listed in Table 6.
(2) The TI will not exceed the applicable flatness value listed
in Table 6.
Note: Blocks with dimensions less than 0.100 inch usually are
warped and will be wrung into perfect contact with the optical
Only the exposed surface of the wrung-on block will be
checked for flatness, since the fringe pattern will indicate the
sum of flatness error at both surfaces.
Therefore, in this
instance, single-flatness entries will be recorded on the
worksheet for width (across) and length (along the length of the
Parallelism and Size Measurement
(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
(3) Using comparator (Figure 7) for blocks up to. 4 inches or
height gage, and surface plate for blocks greater than 4 inches,
measure parallelism and size at five reference points (Figure 3)
on each block.
Note: Handle blocks with forceps. Gloves may be used for blocks
over 4 inches.
(4) Place master block on anvil of comparator and aline master
block so that gaging head contact tips of comparator will con-
tact reference point for length measurement.
(5) Zero the gage head. Remove master block and insert the TI.
(6) Take readings at the five reference points (Figure 3).
(7) Record meter reading in millionths of an inch with proper
signs on calibration worksheet, as observed when gage points were
contacting the designated reference point for length measurement.
calibration worksheet in millionths of an inch with proper signs,
as observed when gage point was oriented at designated positions
across width and along length of TI.
(9) Remove TI and again insert master block to make sure that
proper setting of instrument was maintained during measurement.
(10) Repeat (3) through (9) above for each TI in set being
(11) Compute length deviation of gage block as follows:
(a) Record deviation and proper sign, shown on certificate for
master block on calibration worksheet.
(b) Compute the algebraic sum of values recorded on calibration
Enter the values computed, with proper sign, in
separate area of calibration worksheet.
These entries will be
the calibrated deviations from nominal size of newly calibrated