Lesson 2/Learning Event 1
Learning Event 1
IDENTIFY VARIOUS TYPES OF CALIPERS AND DIVIDERS
Calipers are devices for determining the dimensions of machine parts.
Calipers are not usually precision instruments but are sufficiently accurate
for the fabrication of many parts. Simple calipers consist of two movable
legs joined at one point with the separation between them controlled by a
spring-loaded screw.
The ends of the legs of inside calipers turn outward to measure widths of
grooves, interior diameters, and similar dimensions. Outside calipers have
curved legs with turned-in ends suited to measuring outside diameters.
Scribes are calipers with straight legs and sharp points used for marking
off distances on flat surfaces.
Hermaphrodite (hur maf re dit) calipers
have one straight scribing leg. They are used to scribe a line parallel to
a curved shoulder. In simple calipers, the opening must be placed against a
scale to read the dimension.
Vernier calipers incorporate a scale plus a vernier and are capable of
precise measurement.
They are shaped something like an adjustable wrench
with points at the end of the jaws. These points are suited to both inside
and outside surfaces.
CALIPERS
Outside
Outside calipers, Figure 18, are used to measure distances over and around
adjacent outside surfaces. They are also used to transfer the measurements
to a rule. Several types and sizes are made to accommodate a wide range of
measurements. The size of the caliper is expressed in terms of the maximum
dimension it is capable of measuring. A 3-inch caliper, for example, will
measure a distance of 3 inches.
Actually, the maximum capacity of the
caliper will be greater, often as much as one-third.
This means, for
example, that a 3-inch caliper will actually measure up to 4 inches. It is
not recommended that you use a 3-inch caliper to measure 4 inches, since
that could spring the legs resulting in an inaccurate measurement.
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