Section 4.1 Measuring and Layout Tools 61
ten millimeters in one centimeter. The best rule
to use for woodworking is a rule that has the
large divisions labeled in millimeters rather than
centimeters; for example, 10, 20, 30, etc. Most of
the project plans that use the metric system will
show measurements in millimeters.
Squares
Squares are an important layout tool. They
are used for making accurate joints, squaring
boards, and general layout work. There are vari-
ous designs, but all squares include two straight
edges that meet at a 90° angle. When using a
square, make sure that the handle is held fi rmly
against the edge or surface of the wood. Accu-
rate 90° angles cannot be formed on the wood
unless this is done.
Three kinds of squares are normally found
in the woodshop.
• The steel square is used to lay out or square
large pieces of stock, Figure 4-7. The steel
square is also called a rafter square, framing
square, or carpenter’s square. In addition to
an accurate rule, it has many useful scales
engraved on the tongue and blade. This
square can be used to perform complex
operations such as laying out rafter lengths
and cuts, stair steps, and multisided cuts.
• The try square is used to lay out and square
smaller pieces of stock, Figure 4-8. A try
square has a rule engraved on the blade.
Some try squares have a 45° miter formed in
the handle for accurate layout of miter cuts.
• The combination square can perform more
functions than the other types of squares,
Figure 4-9. It has a blade that slides in a
handle. This sliding feature allows it to
be used like a marking gauge. The blade
is also a one-foot rule. The handle can be
used to lay out 45° and 90° angles. Many
Metric
Millimeters (mm) Centimeters (cm)
Half millimeters
(0.5 mm)
Line A
Line B
Line C
Line D
1 inch
16/16 15/16 14/16 13/16 12/16 11/16 10/16 1/16 2/16 3/16 4/16
3/4 1/4
5/16 6/16
7/8 5/8 1/8 3/8 8/8 6/8 2/8 4/8
7/16 8/16
1/2 2/2
9/16
4/4 2/4
Figure 4-6. Metric rules are divided into
centimeters and millimeters.
Figure 4-7. Use a steel square and pencil to lay out
large pieces of wood.
Figure 4-5. Customary rules are divided into inches and fractions of an inch.
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Goodheart-Willcox Publisher