Depth Of Cut; Direction Of Feed And Thrust - Craftsman 315.17560 Owner's Manual

OPERATIO
DEPTH OF CUT DIRECTION OF FEED AND THRUST
As previously mentioned, the depth of cut is impor-
tant because it affects the rate of feed which, in turn,
affects the quality of a cut (and, also, the possibility
of damage to your router motor and bit). A deep cut
requires a slower feed than a shallow one; and a too-
deep cut will cause you to slow the feed so much
that the bit is no longer cutting; is scraping, instead.
Making a deep cut is never advisable. The smaller
bits -- especially those only 1/16 inch in diameter
are easily broken off when subjected to too much
side thrust. A large enough bit may not be broken off,
but if the cut is too deep a rough cut witl result m
and it may be very difficult to guide the bit as
desired. For these reasons, we recommend that you
do not exceed 1/8 inch depth of cut in a single pass,
regardless of the bit size or the softness or condition
of the workpiece. See Fig. 7.
DEPTH
OF CUT
_a_- WIDTH
OF CUT
Fig. 7
To make deeper cuts it is therefore necessary to
make as many successive passes as required, lower-
ing the bit 1/8 inch for each new pass. In order to
save time, do all the cutting necessary at one depth
setting, before lowering the bit for the next pass.
This will also assure a uniform depth when the final
pass is completed. See Fig. 8.
2HD. PASS
¢-_ tST, PASS
+°+It/
j!,, 7;Ty/
Fig. 8
GUIDE OUTSIDE GUIDE INSIDE
=_ IIOIA,ION, _" _ L _ BUSY
--:'_ ++. I-H. U $+_ ' + FI[O - ' GUIO| "-'_ FlieD
_+ eOTAIION Iu$I
ROTA,IO.('_ " " GUlOl
Fig. 9
The router motor and bit revolve in a clockwise direc-
tion. This gives to the tool a slight tendency to twist
(in your hands) in a counterclockwise direction,
especially when the motor revs up (as at starting).
Because of the extremely high speed of bit rotation
during a "proper feeding" operation, there is very Iito
tie kickback to contend with under normal condio
tions. However, should the bit strike a knot, hard
grain, etc. that would affect the normal progress of
the cutting action, there will be a slight kickback
sufficient to spoil the trueness of your cut if you are
not prepared. Such a kickback is always in the direc-
tion opposite to the direction of bit rotation.
To guard against such a kickback, plan your set-up
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. In short,
the thrust should be in a direction that keeps the
sharp edges of the bit continuously biting straight
into new (uncut) wood.
ROUTING
Whenever you are routing a groove, your tool travel
should be in a direction that places whatever guide
you are using at the right-hand side. In short, when
the guide is positioned as shown in the first part of
Fig. 9, tool travel should be left to right and
counterclockwise around curves. When the guide is
positioned as shown in the second part of Fig. 9,
tool travel should be right to left and clockwise
around curves. If there is a choice, the first set-up is
generally the easiest to use. In either case, the
sideways thrust you use is against the guide.
Whenever you are shaping an edge, the feed should
always be clockwise when working on an outside
(convex) edge; but should be counterclockwise
when working on an inside (concave) edge. See Fig.
10. The reason for this is that, when traveling the
tool as instructed, the bit will have a "chopping ae-
tion" _ but will have a "gouging action" if you
reverse the travel direction. "Chopping" is much
preferable to "gouging" as there is less danger of
ripping out chips by tearing the wood grain.
.OT . FK --_mO
_X ROTATION "="T _ }' + "_,-_"
GUIDE ,E ,NGX, V
__T::_::_ r "OUTS;DE EDGE THRUSTIf_
_ INSIDE"_ ROTAT|ONd_ " .E,4_
FEED _'( /_
LEADING EDGE ROTATION
ROT AT,ON
i/
_ TH RUST'/l_;"_ _/"1
.OTAT,O. -_.. ,_.,://,/
A "CHOPPING" ACTION A "GOUGING" ACTION
// Fig. 10
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