MICROMETERS is essentially the same except that a
Before putting a vernier gauge away, wipe it
standard must be placed between the anvil and the
clean and give it a light coating of oil. (Perspiration
spindle to get a zero measuring reference. For
from hands will cause the instrument to corrode
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.
Dial indicators and other instruments that have a
mechanically operated dial as part of their measure-
ment features are easily damaged by misuse and lack
setting and adjusted in about the same way as a
of proper maintenance. The following instructions
micrometer caliper; the main difference in the method
apply to dials in general:
of testing is that an accurate micrometer caliper is
required for transferring readings to and from the
As previously mentioned, be sure the dial you
standard when an inside micrometer is being checked.
have selected to use has the range capability required.
When a dial is extended beyond its design limit, some
lever, small gear, or rack must give to the pressure.
periodically for cleaning and lubrication of internal
The dial will be rendered useless if this happens.
parts. When this is done, each part should be cleaned
in noncorrosive solvent, completely dried, and then
Never leave a dial in contact with any surface
given a lubricating coat of watchmaker's oil or a
that is being subjected to a shock (such as hammering
similar light oil.
a part when dialing it in) or an erratic and
uncontrolled movement that could cause the dial to be
Protect the dial when it is not being used.
Vernier gauges also require careful handling and
Provide a storage area where the dial will not receive
proper maintenance if they are to remain accurate.
accidental blows and where dust, oil, and chips will
The following instructions apply to vernier gauges in
not contact it.
When a dial becomes sticky or sluggish in
Always loosen a gauge into position. Forcing,
operating, it may be either damaged or dirty. You may
besides causing an inaccurate reading, is likely to
find that the pointer is rubbing the dial crystal or that
force the arms out of alignment.
it is bent and rubbing the dial face. Never oil a
sluggish dial. Oil will compound the problems. Use
When taking a measurement, use only gentle
a suitable cleaning solvent to remove all dirt and
pressure on the fine adjustment screw. Heavy
pressure will force the two scales out of parallel.