TB 9-5210-209-35
(1) Rotate thimble of micrometer depth gages through its full range; the thimble
should move freely and easily without backlash. Backlash may be checked by holding the
base and observing that there is no movement when the thimble is pushed and pulled
laterally.
(2) Main scales (blades) of vernier depth gages should move freely in their base
section.
(3) The rod of dial indicating depth gages should move freely and return to stop
position without hesitation.
a. Performance Check
(1) Turn thimble of TI counterclockwise until 0 to 1 inch rod recedes beyond
working face of base (fig. 1).
(2) Place TI on triangular base component of gage block set.
(3) Turn thimble clockwise until rod makes contact with triangular base, or for
three clicks of ratchet.
NOTE
Use light pressure to advance thimble so that the base of the TI
is not lifted off gaging surface. The rod should be raised and
lowered several times to insure that it has not overrun proper
reading.
(4) The TI should indicate 0 0.0003 inch (with vernier) or 0 0.001 inch (without vernier).
(5) Check zero settings of rods other than 0 to 1 inch by placing appropriate size
gage block between base of TI and triangular base.
NOTE
To change rods, remove knurled cap from end of thimble and
clean and insert rod through hole in thimble assembly.
Replace and tighten cap.
b. Adjustments. Position adjusting nut on rods in accordance with manufacturers'
instructions for zero indications. Special wrenches are supplied with micrometer depth
gages.
