USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 3/TASK 1
(d) The micrometer caliper will be accurately set when the inside
tool will just pass between the anvil and spindle by its own weight.
e. Care of Micrometers. To maintain a micrometer in good condition and
to preserve the accuracy of its measurements, observe the following rules of
good practice and adjusting procedures:
(1) Never store a micrometer with its anvil and spindle closed. Flat
surfaces wrung together for any length of time tend to corrode.
Leave a
small gap between the anvil and spindle when storing.
(2) Oil the micrometer in only one place--the micrometer screw; and
only with a very light oil. If storing for long periods of time, cover the
micrometer with a light film of oil and wrap it in oiled paper.
(3) Never roll the thimble along the hand or arm.
This practice,
like holding the thimble and twirling the frame to open or close the
micrometer, will cause excessive wear on the screw.
(4) Before using a micrometer, wipe it off and pull a piece of paper
between the anvil and the end of the spindle.
(5) The micrometer should operate freely with no play in its travel.
If a micrometer has play, or if it binds, it should be returned to the
manufacturer for reconditioning.
This condition is caused by abuse or
uneven wear.
(6) Check the micrometer screw periodically with a precision gage
block in at least four places other than zero to verify its accuracy.
Simply measure a selected group of blocks ranging from 0 to 1 inch.
(7) Clean the micrometer mechanism whenever it
becomes gummy,
contains abrasive grit, or whenever it is to be adjusted.
Use an approved
cleaning agent.
(8) When the faces of the spindle and anvil become worn and they are
no longer flat and parallel to each other, the error should not exceed
0.0002 inch on a micrometer which is graduated to control measurements to a
limit of 0.001 inch, and should not exceed 0.00005 inch on a micrometer
250
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