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64 Part II: Metrology
Part II.A.2
Figure 7.7 A digital micrometer.
Courtesy Fred V. Fowler Company, Inc.
micrometer shown in Figure 7.4 represents one instrument of this type for use in
measuring to a resolution of 0.01 mm. The instrument shown in Figure 7.7 has a
digital readout with a resolution to 0.001 inch. When equipped with vernier scales,
the resolution may be increased to 0.001 mm (commonly 0.0001 inch in the case of
an inch-reading device).
Micrometer Calipers
The micrometer caliper, or mike as it is often called, is an end-measuring instrument
for use in measuring outside dimensions. Although the mike is fairly easy to
apply, the accuracy it provides depends on the application of the proper amount
of torque to the thimble. Too much torque is likely to spring the frame and cause
error. Thus, it is important that personnel using these instruments be trained in
their use, and also that they be periodically required to check their measurements
against a standard to minimize errors. The indicating micrometer in Figure 7.8
has a built-in dial indicator to provide a positive indication of measuring pressure
applied. The instrument can be used like an indicating snap gage.
2. ATTRIBUTE GAGES
Identify and use attribute gages, including
snap, plug, and thread gages, gage blocks,
pins, etc. (Application)
Body of Knowledge II.A.2