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 position.
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 sliding table.
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 clean.
Close up view of the machined tenon.
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 considerable stiffness.
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 board.
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.