Lesson 2/Learning Event 1
The accuracy of the vernier caliper depends on the fit of the sliding jaw
and the wear and distortion in the measuring surfaces.
The sliding jaw
should move easily and still not have play. It may be adjusted by removing
the gib in the sliding jaw assembly and bending it.
The gib holds the
adjustable jaw against the inside surface of the blade with just the right
pressure to give it the proper friction.
Wear on the jaws of the vernier caliper is mostly at the tips where most
measurements are made.
A certain amount of this wear may be taken up by
adjusting the vernier scale itself.
This scale is mounted with screws in
elongated holes. This permits slight adjustments to compensate for wear and
When the error exceeds 0.0002 inch, either in parallelism or
flatness, the caliper should be returned to the manufacturer for
Wear on the jaws can best be checked visually or by
measuring rolls or rings of known dimensions.