Rate-Of-Feed; Too Slow Feeding - Craftsman 315.174921 Owner's Manual

OPERATION
RATE.OF-FEED
IMPORTANT: The whole "secret" of professional
routing and edge shaping I_es in making a careful
set-up for the cut to be made and in selecting the
proper rate of feed
FORCE FEEDING
Clean, smooth routing 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 your router is forced to
move forward too fast, the RPM of the bit becomes
slower than normal in relation to its forward move.
ment As a result, the bit must take bigger bites as tt
revolves "Bigger bites" mean btgger chips, and a
rougher finish Bigger chips also require more
power, which could result in the router motor
becoming overloaded
Under extreme forcefeedtng 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 workplece See
Figure 6.
Your Craftsman Router is an extremely high-speed
tool (25,000 rpm no-load speed), and wil! make clean,
smooth cuts tf allowed to run freely without the
overload of a forced (too fast) feed. Three things that
cause "force feeding" are bit size, depth-of-cut, and
workptece characteristics The larger the bit or the
deeper the cut, the more slowly the router can be
moved forward If the wood is very hard, knotty, gum-
my or damp, the operation must be slowed still
more
You can always detect "force feeding" by the sound
of the motor Its hlgh-pitched whine will sound lower
and stronger as _t loses speed, Also, the strain of
holding the tool will be noticeably Increased
TOO FAST
TOO SLOW
Fig 6
TOO SLOW FEEDING
it Is also possible to spoil a cut by moving the router
forward too slowly When tt is advanced Into the
work too s!owly a revolving bit does not dig Into new
wood fast enough to take a bite; instead, it simply
scrapes away sawdust-like particles Scraping pro-
duces heat, which can glaze, burn, or mar the cut --
in extreme cases, can even overheat the b_t so as to
destroy its hardness
In addition, it is more difficult to control a router
when the bit ts scraping instead of cutting With
practically no load on the motor the bit will be revolv-
ing 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 produc-
ed may have rippled, instead of straight sides See
Figure 6
"Too-slow feeding" can also cause your router to
take off in a wrong direct{on from the intended line
of cut Always grasp and hold your router firmly with
both hands when routing.
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
PROPER FEEDING
The right feed ts neither too fast nor too slow It Is
the rate at which the bit ts being advanced firmly and
surely to produce a continuous spiral of uniform
chips -- wtthout hogging into the wood to make
large Indlvidua! chips 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 Is
a large one, the cut is deep or the wood is hard to
cut, the proper feed may be a very slow one Then,
again, a cross-grain cut may require a slower pace
than an _dentlcal with grain cut in the same
workpiece
There is no fixed rule. You will learn by experience .....
by listening to 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 workplece wood
beforehand
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