USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 3/TASK 1
This practice can cause damage to scribers and injury to
personnel. Rack properly or stow in a suitable box. Do not use scribers
for purposes other than those intended.
FIGURE 162.
USING THE SCRIBER.
4.
Rules or Scales
a. Purpose. All rules (scales) are used to measure linear dimensions.
They are read by a comparison of the etched lines on the scale with an edge
or surface. Most scale dimensions are read with the naked eye, although a
magnifying glass can be used to read graduations on a scale smaller than
1/64 inch.
b. Types of Rules.
(1) Steel Rules. Steel rules (figure 163 on the following page) are
available from a fraction of an inch in length up to 4 feet or more; in
machine shops, the 6 inch pocket rule is the one most commonly used. There
are also several standard systems of graduations.
In the English system,
rules are graduated in 10ths, 20ths, 50ths, and 100ths; 12ths, 24ths, and
48ths; 14ths, and 28ths; 16ths, 32nd, and 64ths of an inch. In the Metric
system, rules are graduated in millimeters and one-half millimeters. Some
steel rules have four scales, two on each side (one graduated in 32nds
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