60 Chapter 4 Hand Tools
Before you attempt to use any measuring
tools, you must understand how to read them. In
the United States, rules may be designed for cus-
tomary measurements, metric measurements, or
both, Figure 4-4.
Reading a Customary Rule
The most common customary rules are di-
vided into inches. Each inch is subdivided into
2, 4, 8, 16, 32, or 64 parts. Look at Figure 4-5 and
follow the steps listed here to learn how to read
a customary rule.
1. Look along Line A. You will note the inch
is divided in half. Each of the half marks is
equal to 1/2″.
2. Look along Line B. You will see the inch is
now divided into four equal parts. Each part
is equal to 1/4″. The fi rst mark is 1/4″, the
second mark is 2/4″, or 1/2″, the third mark
is 3/4″, and the fourth mark is 4/4″, which is
the same as 1″.
3. Look along Line C. On this line, you will see
the inch is divided into eight equal parts.
Each small division mark is 1/8″. Two of
these marks equal 2/8″, or 1/4″. Three marks
equal 3/8″. Four marks equal 4/8″ or 2/4″ or
1/2″. Five marks equal 5/8″. Six marks equal
6/8″, or 3/4″. Seven marks are equal to 7/8″,
and eight marks are 8/8″, or 1″.
4. Look along Line D. Now you are looking
at the smallest division on the rule. This
division is 1/16″. Notice that 2/16″ is equal to
1/8″. Next is 3/16″, 4/16″ (2/8″ or 1/4″), and
so on down the line.
Look at any set of working drawings for
projects and you will probably see measurements
in inches and parts of an inch. For example,
suppose a project plan calls for one of the pieces
to be 22 1/4″ long. First locate 22″ on the rule and
then locate the 1/4″ mark beyond the 22″ mark.
On larger projects, the drawing might indicate the
measurements in feet and inches; for example, 3′
4 1/4″. There are 12 inches in one foot, so 3′ equals
36″. You will need to fi nd 36″ on the rule and then
locate the point 4 1/4″ beyond that. On most tape
measures, 36″ will be marked as 3 ft.
Reading a Metric Rule
Most metric rules used for woodworking are
divided into centimeters, with each centimeter
subdivided into millimeters, Figure 4-6. A cen-
timeter (cm) is 1/100 of a meter, and a millimeter
(mm) is 1/1000 of a meter. Therefore, there are
Figure 4-2. Folding rules, also called zigzag rules,
have hinged segments. They are very handy for
taking inside measurements of cabinets and
drawers.
Figure 4-3. Bench rules should be used primarily for
short measurements.
Figure 4-4. This tape measure is marked in both
inches and centimeters.
Goodheart-Willcox Publisher
Goodheart-Willcox Publisher
Goodheart-Willcox Publisher