Craftsman 315.275061 Owner's Manual page 12

OPERATION
PROPER FEEDING
The right feed is neither too fast nortoo slow. It is the rate at
which the bit is being advanced firmly and surely to produce
a continuous spiral of uniform chips -- without hogging into
the wood to make large individualchips or,on the other hand,
to create only sawdust. If you are making a small diameter,
shallow groove in soft, dry wood, the proper feed may be
about as fast as you can travel your router along your guide
line. On the other hand, if the bit isa large one, the cut is deep
or the wood is hard tocut, the proper feed may be a very slow
one. Then, again, a cross-grain cut may require a slower
pace than an identical with grain cut in the same workpiece.
There is no fixed rule. You will learn by experience from
practice and use. The best rate of feed is determined by
listening to the sound of the router motor and by feeling the
progress of each cut. If at all possible, always test a cut on
a scrap piece of the workpiece wood, beforehand.
SPEED SELECTION
In general, if the material being cut is hard, the cutter size is
large, or the depth of cut is deep (maximum 1/8"), then your
router shouldbe runat slowerspeeds. When these si!uations
exist, turnthe variable speed controlselector until the desired
speed is reached. NOTE: Carbide cutters cut at higher
speeds than steel cutters and should be used when cutting
very hard materials.
FORCE FEEDING
Clean, smooth routing and edge shaping can be done only
when the bit is revolving at a relatively high speed and is
takingvery small bites toproduce tiny, cleanly severed chips.
If your router is forced to move forward too fast, the RPM 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 the router motor becoming overloaded.
Under extreme force-feeding conditions the relative RPM 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), with resulting splintering and gouging of the
workpiece. See Figure 15.
Your Craftsman router isan extremely high-speed tool(25,000
RPM no-load speed), and will make clean, smooth cuts if
allowed torun freely without the overload of a forced (too fast)
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 shouldbe
moved forward. If the wood is very hard, knotty, gummy or
damp, the operation must be slowed still more,
You can always detect "force feeding" by the sound of the
motor. Its high-pitched whine will sound lower and stronger
as it loses speed. Also, the strain of holding the tool will be
noticeably increased.
TOO FAST
TOO SLOW
Fig. 15
TOO SLOW FEEDING
It is also possible to spoil a cut by moving the router forward
too slowly. When it is advanced into the work too slowly, a
revolvingbit does not dig into new wood fast enough to take
a bite; instead, it simplyscrapes away sawdust-like particles.
Scraping produces heat, which can glaze, bum, or mar the
cut -- in extreme cases, can even overheat the bit so as to
destroy its hardness,
In addition, it is more difficultto control a router when the bit
is scraping instead of cutting. With practicallyno load on the
motor the bit will be revolving at close to top RPM, and will
have a much 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), As a result, the cut produced
may have rippled, instead of straight sides. See Figure 15.
"Too-slow feeding" can also cause your router to take off in a
wrong direction from the intended line of cut. Always grasp
and hold your router firmly with both hands when rout-
Ing.
You can detect "too-slow feeding" by the runaway too-highly
pitched sound of the motor;or by feeling the "wiggle" of the bit
in the cut.
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