Attention should be given to tracking
the jig tightly in the groove and
ensuring that it is square in both
dimensions. A small clamp is used to
secure the workpieces before cutting
with a smooth, firm continuous
action.
way. The bearing is fitted on the
arbor followed by a shim. The cutters
are then fitted with a spacer between
each. Always stagger the teeth of
each cutter to balance
and lighten the impact load when
cutting. A nut and washer secure the
assembly on the arbor, using the
routers spindle lock to grip the cutter
shank while tightening the nut.
Cutting the comb joint
fibre break out is more likely to
occur when clamping several
members of a box together in the jig
for cutting at the same time.
Assembling the cutter
It is easier to set up the cutter
assembly with the router mounted in
the table. It is helpful to follow the
instructions supplied with the cutter
set. First the arbor shank is inserted
into the 1/2” collet and tightened in
the
normal
The Comb Joint cutter set
comprises five three winged 4mm
kerf TCT grooving cutters which
are mounted with spacers on an
arbor. The spacing between each is
precisely the same as the kerf. The
cutter assembly is self guiding, one
of three interchangeable bearings
supplied with the set has been fitted
on the arbor to suit the thickness of
the timber.
Prepare the wood to size, checking
that the pieces of each pair of sides
or ends are equal in length and the
ends are square. Remember to
prepare extra material for making
several trial pieces. To reduce
breakout, prepare a backing piece to
lie against the face of the sliding jig.
Fit the cutter set into the router
collet ensuring that at least three
quarters of it’s length is held in the
collet. Adjust the height of the
cutter above the table,
preferably with a fine height
adjuster. Set the cutter off
against a piece of the
work and align the
bottom of the cutter
with the bottom edge
of the workpiece.
Using a steel rule,
align the guide
bearing face with
the fence faces.
Mount the two trial pieces
on the jig with the backing piece
against the jig face (clamping them
there with a small clamp). Make sure
that the locking bar of the clamp will
be clear of the cutter path.
Check that all adjustments and the
two trial pieces are secured before
switching on the router and allowing
it to reach full speed.
Grip the jig firmly, keeping fingers
away from the cutter and make a pass
across the cutter face keeping the
trial piece tight to the fence face.
Switch off the router after the work
has cleared the cutter.
Check the fit of the
two pieces, turning
one edge over to leave
the top and bottom
edges flush when
interlocked.
Clamp the sides and
ends of the box
aligning one end of
each against the fence
face. Cut end profile
in one pass before
turning the pieces around, aligning the
opposite ends against the fence, and
cutting those. Remember to fit the
backing piece each time and replace it
if it becomes ragged.
Dry assemble the jointed box (frame
or carcass) to check the joints before
cutting the grooves to take the top
and bottom. Remember the
grooves will appear on both
sides or the front and back,
unless stopped grooves are
cut o