Care
Micrometers are precision instruments. They
must be used and maintained with great care.
Note the following:
1. Store micrometers in protective cases or separate
padded drawers in a toolbox.
2. When in storage, make sure the spindle and anvil
faces do not contact each other or any other objects.
If they do, temperature changes and corrosion may
damage the contact faces.
3. Do not clean a micrometer with compressed air.
Dirt forced into the tool will cause wear.
4. Lubricate micrometers with WD-40 to prevent
corrosion.
Telescoping and Small Bore Gauges
Use telescoping gauges (
Figure 33
) and small
bore gauges (
Figure 34
) to measure bores. Neither
gauge has a scale for direct readings. An outside mi-
crometer must be used to determine the reading.
To use a telescoping gauge, select the correct size
gauge for the bore. Compress the movable post and
carefully insert the gauge into the bore. Carefully
move the gauge in the bore to make sure it is cen-
tered. Tighten the knurled end of the gauge to hold
the movable post in position. Remove the gauge,
and measure the length of the posts with a microme-
ter. Telescoping gauges are typically used to mea-
sure cylinder bores.
To use a small-bore gauge, select the correct size
gauge for the bore. Carefully insert the gauge into
the bore. Tighten the knurled end of the gauge to
carefully expand the gauge fingers to the limit
within the bore. Do not overtighten the gauge, as
there is no built-in release. Excessive tightening can
damage the bore surface and damage the tool. Re-
move the gauge and measure the outside dimension
(
Figure 35
). Small bore gauges are typically used to
measure valve guides.
Dial Indicator
A dial indicator (A,
Figure 36
) is a gauge with a
dial face and needle used to measure variations in
dimensions and movements. Measuring brake rotor
runout is a typical use for a dial indicator.
Dial indicators are available in various ranges
and graduations. They use three basic types of
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CHAPTER ONE
33
34
35
36
