Chapter 8 Power Tools 207
Copyright Goodheart-Willcox Co., Inc.
cutting depth. See Figure 8-39. Portable routers are
versatile tools, capable of performing jobs traditionally
completed by a variety of other, less effi cient hand and
power tools. Routers are used for shaping the edges of
lumber and other materials, cutting grooves or slots,
creating rabbets or dados, and carving designs into the
surface of wood.
The three main types of routers are fi xed base,
plunge, and trim routers. “Fixed base” is a slight
misnomer because the base can be adjusted, but it
remains fi xed in position while in use. Plunge routers
allow the bit to be smoothly lowered into the work
surface for cutting that does not extend to the edge
of the board. Trim routers are smaller machines well
suited to trimming the edges of laminate countertops
or working in areas with limited clearance.
Router Bits
Bits for routers range from large bits 3 1/2″ in
diameter to tiny bits less than 1/16″ in diameter.
Routers operate at speeds from 12,000 rpm to
24,000 rpm. Higher rpm speeds limit the size of
bit that may be used safely.
Unlike drill bits, which are designed to cut
down and bore a hole, router bits are designed to cut
sideways. The fl utes of a router bit are its cutting edges.
Bits are available in 1/4″ and 1/2″ shanks and are
attached to routers using a collet-type chuck. Collets
are interchangeable on some routers, while others only
accept a single size shank, usually 1/4″. Router bits with
1/2″ shanks are more stable and produce less vibration.
Bits with larger shanks, or otherwise increased mass,
dissipate heat better than bits of lighter construction.
Reducing heat buildup prolongs the sharpness and longevity of the bit.
The profi le, or shape, of a router bit determines the
shape of the wood remaining at the edge of the cut. A
bit with straight fl utes will leave a straight-walled cut
surface. A convex shape created on the edge of a cut is
done using a bit with concave fl utes. See Figure 8-40.
Some bits are equipped with pilot bearings that guide the
bit evenly along the edge of a surface to ensure that the
cut is uniform in depth for the entire length of the work.
One of the most useful bits for agricultural
purposes is a simple roundover bit. It is used to
produce safe, rounded corners on the edges of lumber
used in the construction of feeders and other livestock
equipment and facilities.
B
Photoexpert/Shutterstock.com
Figure 8-39. A—A fixed base router. B—A router
equipped with a plunge attachment.
Motor
Plunge
depth gauge
Plunge lever Collet
Base
Collet
Motor
Base
A
Robert Hale/Shutterstock.com
Pilot bearing
Jeffrey B. Banke/Shutterstock.com
Figure 8-40. A few of the most common edge-
forming router bits. The shape of a router bit is the
reverse of the material it will remove. Note the pilot
bearing used on each bit.