Chapter 8 Power Tools 197
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Circular saws typically are powered using standard 120-volt AC
current. However, the development of more reliable rechargeable batteries
has increased the popularity of cordless models. At one time, a pneumatic-
powered circular saw was produced for the military and was capable of
cutting timbers while submerged in the water. Another type of circular
saw uses gear reduction to slow the rotational speed of its blade for cutting
structural steel and metal roofi ng materials.
Circular Saw Blades
Blades for circular saws vary based on the
materials they are intended to cut. Most blades are
classifi ed by the size, number of teeth, and material
used to construct the blade. See Figure 8-24.
Blades for ripping, or cutting with the grain, have
fewer and larger teeth that remove wood quickly.
Crosscutting blades are designed to cut across the grain
of lumber, as in cutting a board to length. Crosscutting
blades have more teeth and shallower gullets. A gullet
is the space between saw teeth that allows for waste
removal. Using a blade with more teeth results in a
smoother cut and a slower cutting speed.
Combination blades combine groupings of smaller
teeth with periodically spaced deep gullets to achieve
acceptable effi ciency for both crosscutting and ripping.
Plywood blades are set up with a large number of very
small teeth to reduce splintering and produce a very
smooth cut. Attempting to use a plywood blade on
framing lumber usually results in a slow cutting speed,
burned lumber at the cut from friction, and possible
damage to the blade from excessive heat.
B
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Figure 8-23. Two saw types are commonly used by building carpenters. A—This sidewinder
saw drives the blade directly using a motor oriented perpendicular to the blade. B—The
motor of this worm-drive saw is parallel to the blade and transfers energy through a gearbox.
A
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Goodheart-Willcox Publisher
Figure 8-24. Circular saw blades are configured
to accommodate the variety of materials they are
designed to cut. Note the size, shape, and number
of teeth on each of these blades.