USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 3/TASK 1
(2) Outside Calipers. Outside calipers (figure 176 on the following
page) are used to measure distances over and around adjacent surfaces, and
to transfer the measurements to a rule. Several types are made in several
sizes to accommodate a wide range in measurement. 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 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 you may spring the legs, resulting in an inaccurate
Never set a caliper on work that is revolving in a
The contact of one leg of a caliper on a
revolving surface will tend to draw the other leg over
the work because of the friction between the moving
surfaces. Only a slight force is necessary to spring
the legs of a caliper so that measurements made on
moving surfaces are never exact.