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Depth of cut, Direction of feed and thrust, Operation – Sears 315.17506 User Manual

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OPERATION

DEPTH OF CUT

As previously mentioned, the depth of cut is important

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, it 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 will result—and it may be very difficult to guide and
control the bit as desired. Forthese reasons, we recommend
that you do not exceed 1 /8 i nch depth of cut i n a single pass,

regardless of the bit size or the softness or condition of the

workpiece.

See Figure 12.

To make deeper cuts it is therefore necessary to make as

many successive passes as required, lowering the bit 1/8
inch for each new pass. Irvorder 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 Figure 13.

DIRECTION OF FEED AND THRUST

The router motor and bit revolve in a clockwise direction. This
gives the tool a slight tendency to twist {in your hands) in a
counterclockwise direction, especially when the motor is
starting up.

Because of the extremely high speed of bit rotation during a

“proper feeding” operation, there is very little kickback to

contend with under normal conditions. However, should the
bit strike a knot, hard grain, foreign object, 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
direction 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.

Whenever you are routing a groove, your 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 Figure 14, tool travel should be left
to right and counterclockwise around curves. When the

guide is positioned as shown in the second part of Figure 14
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.

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