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Edging with a Pilot Bit (Figs . 21a and 21b)
The arbor-type bits with pilots are excellent for edge shaping any workpiece edge that is
straight, or is curved at a curvature equal to or greater than the radius of the bit to be used.
The pilot prevents the bit from making an excessively deep cut, and holding the pilot firmly in
contact with the workpiece edge throughout prevents the cut from becoming too shallow.
Top-Edge Shaping
Whenever the workpiece thickness, together with the desired depth of cut (as adjusted by
router depth setting) are such that only the top part of the edge is to be shaped (leaving at
least a 1/16 in. thick uncut portion at the bottom), the pilot can ride against the uncut portion,
which serves to guide it (Fig. 21a).
Whole-Edge Shaping
If the workpiece is too thin or the bit is set so low that there will be no uncut edge against
which to ride the pilot, an extra board must be placed under the workpiece to act as a guide
(Fig. 21b). This “guide” board must have exactly the same contour, “straight or curved”, as the
workpiece edge. If it is positioned so that its edge is flush with the workpiece edge, the bit will
make a full cut (in as far as the bit radius). On the other hand, if the guide is positioned (out
from the workpiece edge), the bit will make less than a full cut, which will alter the shape of the
finished edge.
Fig. 21a
Spindle Lock
Cutter-bit
Pilot
Fixed Base
Sub-base
Work-piece
TOP EDGE SHAPING
Motor Housing
Spindle
Collet/Nut
Fig. 21b
Workpiece
Guide Board
Whole Edge of Workpiece
WHOLE EDGE SHAPING
NOTICE: The size (diameter) of the pilot that is used determines the maximum cut width that
can be made with the pilot against the workpiece edge (a small pilot exposes all of the bit; a
large pilot reduces this amount by 1/16 in.).
Any of the piloted cutter bits can be used without a pilot for edge shaping with guides.
WARNING
Always securely clamp your workpiece and keep a firm grip on the router
base with both hands at all times. Failure to do so could result in loss of
control causing possible serious personal injury.
