PRECISION MEASURING AND GAGING - OD1642 - LESSON 1/TASK 2
provided for that purpose.
Bring the spindle into contact with the anvil
and rotate the sleeve into alignment with the zero mark on the thimble.
After alignment is made, back the spindle away from the anvil, and retighten
the barrel sleeve locking nut. Recheck for zero setting to be sure that the
thimble spindle relation was not disturbed while the locking nut was being
tightened.
(c) To set zero on the adjustable-anvil type, bring the thimble to
a zero reading.
Lock the spindle, if a spindle lock is available, and
loosen the anvil lock screw. After the lock screw is loosened, bring the
anvil in contact with the spindle making sure that the thimble is still set
on zero. Tighten the anvil setscrew lock nut slightly, unlock the spindle,
and back the spindle away from the anvil; then lock the anvil setscrew
firmly. After locking the setscrew, check the micrometer for zero setting
to make sure that the anvil was not moved out of position while the set
screw was being tightened.
(d) The zero check and methods of adjustment apply directly to
micrometers that will measure to zero.
The procedures for larger
micrometers is essentially the same, except that a standard must be placed
between the anvil and the spindle in order to get a zero measuring
reference.
For example, a 2 inch micrometer is furnished with a 1 inch
standard. To check for zero setting, place the standard between the spindle
and the anvil and measure the standard.
If zero is not indicated, the
micrometer needs adjusting.
(e) All micrometers should be disassembled periodically for
cleaning and lubrication of internal parts.
When this is performed, each
part should be cleaned in a noncorrosive solvent, completely dried, then
given a light coat of watchmaker's oil or a similar light oil.
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