PRECISION MEASURING AND GAGING - OD1642 - LESSON 1/TASK 2
measuring device is very convenient when making keyseat layouts on shafts.
(d) Care.
Rules, like any other measuring tool, must be taken
care of if accurate measurements are to be obtained. Do not allow them to
become battered, covered with rust, or otherwise damaged in such a way that
the markings cannot be read easily.
Do not use them for scrapers; once
rules lose their sharp edges and square corners, their general usefulness is
decreased.
FIGURE 18.
SPECIAL RULES.
(2) Scales.
A scale is similar in appearance to a rule, since its
surface is graduated into regular spaces.
The graduations on a scale,
however, differ from those on a rule because they are either smaller or
larger than the measurements indicated. For example, a half-size scale is
graduated so that 1 inch on the scale is equivalent to an actual measurement
of 2 inches. A 12 inch long scale of
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