OPERATION
To guard against kickback, plan your setup and direction of
feed so that you will always be thrusting the tool—to hold
it against whatever you are using to guide the cut—in the
same direction that the leading edge of the bit is moving. The
thrust should be in a direction that keeps the sharp edges
of the bit continuously biting straight into new (uncut) wood.
PROPER RATE OF FEED
Professional trimming and edge shaping depend upon
careful set-up and selecting the proper rate of feed.
The proper rate of feed is dependent upon:
the hardness and moisture content of the workpiece
the depth of cut
the cutting diameter of the bit.
When cutting shallow grooves in soft woods such as pine,
use a faster rate of feed.
When making cuts in hardwoods such as oak, use a slower
rate of feed.
Several factors will help you select the proper rate of feed.
Choose a rate that does not slow down the router motor.
Choose the rate at which the bit advances firmly and
surely to produce a continuous spiral of uniform chips
or a smooth trim edge on laminate.
Listen to the sound of the router motor. A high-pitched
sound means you are feeding too slowly. A strained,
lower-pitched sound signals force-feeding.
Check the progress of each cut. Too-slow feeding can
cause the router to take off in a wrong direction from the
intended line of cut. Force-feeding increases the strain
of holding the tool and results in loss of speed.
Notice the chips being produced as you cut. If the router
is fed too slowly, it will scorch or burn the wood. If the
router is fed too fast, it will take large chips out of the
wood and leave gouge marks.
Always test a cut on a scrap piece of the workpiece wood
or laminate before you begin. Always grasp and hold the
router firmly when trimming.
If you are making a small-diameter, shallow groove in soft,
dry wood, the proper feed rate may be determined by the
speed at which you can travel the router along the guide line.
If the bit is a large one, the cut is deep, or the workpiece
is hard to cut, the proper feed may be a very slow one. A
cross-grain cut may require a slower pace than an identical
with-grain cut in the same workpiece.
There is no fixed rule. Proper rate of feed is learned through
practice and use.
TOO SLOW FEEDING
See Figure 12, page 13.
When the router is advanced into the work too slowly, the
revolving bit does not dig into new wood fast enough to
take a bite; instead, it scrapes away sawdust-like particles.
Scraping produces heat, which can glaze, burn, or mar the
cut, and can overheat the bit. Dull bits can also contribute
to scraping and burning.
It is more difficult to control a router when the bit is scraping
instead of cutting. With practically no load on the motor, the
bit will be revolving near top RPM, and will have a greater
than normal tendency to bounce off the sides of the cut,
especially if the wood has a pronounced grain with hard
and soft areas. The cut that results may have rippled sides
instead of straight.
FORCE FEEDING
See Figure 12, page 13.
The router is an extremely high-speed tool (17,000-
30,000 RPMs.), and will make clean, smooth cuts if allowed
to run freely without the overload of a forced feed. Three
things that cause force feeding are bit size, depth of cut,
and workpiece characteristics. The larger the bit or the
deeper the cut, the more slowly the router should be moved
forward. If the wood is very hard, knotty, gummy or damp,
the operation must be slowed still more.
Clean, smooth laminate trimming and edge shaping can be
done only when the bit is revolving at a relatively high speed
and is taking very small bites to produce tiny, cleanly-severed
chips. If the router is forced to move forward too fast, the
speed of the bit becomes slower than normal in relation to
its forward movement. As a result, the bit must take bigger
bites as it revolves. Bigger bites mean bigger chips and a
rougher finish. Bigger chips also require more power, which
could result in overloading the motor.
Under extreme force-feeding conditions, the relative speed
of the bit can become so slow—and the bites it has to take
so large—that chips will be partially knocked off rather than
fully cut off. This will result in splintering and gouging of the
workpiece.
DEPTH OF CUT
See Figure 13, page 14.
Depth of cut affects the rate of feed and the quality of a cut.
Using the proper depth of cut can lessen the possibility of
damage to the router motor and bit.
A deeper cut requires a slower feed than a shallow one.
Making a cut that is too deep will slow the feed so that the
bit is scraping, rather than cutting, and is not recommended.
A too-deep cut can cause smaller bits to be broken off.
Bits that are 1/16 in. in diameter are easily broken off when
subjected to too much side thrust. A larger bit is not as likely
to break, but attempting a cut that is too deep may result in
a rough cut, and may make it difficult to guide and control
the bit as desired.
9 - English