|Cutting Tenons on the KF700
Shaper using dual 220mm Rebate Cutters:
|Shaper hood showing the
restriction of the Aigner fence with the mounting brackets in one
|By moving the mounting brackets
the other direction, the fence can be widened like this. Note that
the fence still restricts the projection of a 220mm rebate head.
|Assuming the crosscut fence is
square to the trajectory of the sliding table, here is one way of insuring
the shaper fence is square to the crosscut fence. I'm using a Polish
machinist square for this, but you could use the end of your stock if it's
wide enough, or a drafting triangle. The idea is to get the shaper
fence square so the stock doesn't bind against the shaper fence, or pull
away from the shaper fence as the stock moves forward with the advancing
|This is one method of setting the
rebate head depth of cut. This is the Aigner Densitometer. The
depth of cut in this case with the Aigner fences as far apart as they will
go is 45mm (about 1 3/4 inches).
|Here is the clamping setup I
prefer for this cut. In this case, the stock is clamped directly to
the sliding table using a pair of the Brian Lamb Big Squeeze air
clamps. Note in this photo the lower 220mm rebate cutter is dropped
into the shaper cavity. With the cutter as low as you can get it
without the bottom of the cutter hitting the dust port bracket underneath,
the lower cutter still projects 3mm above the table surface.
|This is an example of the tenon
cut using stacked rebate cutters and a 5mm spacer between the
cutters. This is not a preferred setup since there is no backer
board to eliminate tear-out of the shoulders as the stock passes through
the cutter. Even without the backer board, the cut is amazingly
|Close up view of the machined
|This is one end of the tenoning
table accessory. You're looking at the underside of the table.
You can see the underside leading edge of the tenoning table is relieved
so that it doesn't drag on the surface of the iron shaper table top.
You can also see the attachment t-nuts that go in the sliding table
t-slots, and the number of channels in the extrusion that provide
|This is the opposite end of the
tenoning table intended for use when doing mitered tenons. This end
is relieved on the underside as well.
|I have replaced the Aigner fence
with the standard Felder aluminum shaper fence so as to get more cutter
projection for a longer tenon. With the tenoning table in use, one
disadvantage is that the cutters have to ride higher. In fact, the
entire spindle is cranked up considerably higher. In this setup, the
bottom rebate head has a 10mm spacer under it, and the entire stack is
within 20mm of maxing out the length of the spindle.
|Another illustration of the
stacked cutters. This is a LOT of steel to be rotating so far above
the surface of the table. I'm more comfortable with this setup using
the tenoning hood instead of the shaper fence, since the tenoning hood
gives additional protection from the spinning cutter set. Be SURE to
run this stacked cutter set on the low speed belt position, and make
doubly sure the cutters are well secured with the top screw. Due to
the mass of these cutters, if the top bolt isn't REALLY tight, the shaper
spindle will spin inside the cutters at startup and spin-weld one or both
cutters to the spindle. Trust me on this - I have done it.
|This is what can happen if the
stock is not clamped securely to the table. In this situation, the
backer board for the stock was not clamped. You can see how this
cutter likes to suck the stock into the shaper hood.
|The forces in this are
considerable. With the backer board being sucked into the rotating
cutter, it also pulled the entire clamped stock away from the crosscut
fence at the inside edge. This is when you hit the deck and
scramble on your belly for the off button.
|This is the backer board that got
away - or what's left of it. I was lucky the stock didn't come
flying back at me, or jamb the shaper cutters into a stall.
|This is perhaps a better clamping
setup for the backer board. In this case, I'm using a backer board
that is the same thickness as the stock being cut, and straddle clamping
them both with the air pressure increased to 80 PSI. If I were doing
this setup for production, I'd put on a separate clamp just for the backer
|The backer board does NOT have to
project out the entire length of the tenon being cut. It's only the
shoulder cuts that have chip-out on the trailing side. The backer
board need only project far enough to serve the shoulder edge.
|This setup illustrates using the
modified stop block to index the depth of cut on the tenon. I'm
using the short crosscut fence with the precision mitering unit. The
modification to the stop block is the shortened flipper finger that is
provided with the tenoning table accessory. This shortened flipper
finger clears the top of the tenoning table.