R/T Tenon Jig

[Joe Scharle]

American Woodworker bought this one. Before I got a Woodrat, I used this jig for cutting tenons on door rails and still do if the 'rat is setup for something else. It's just a sled with a base, a mass block and a fence. I use a 1/2" spiral bit set usually 1" high. Pic shows side cut position. Haunches are cut from the back side of the fence.

[McRabbet]

Joe,

If I understand your jig, it is shown without the rail inserted in front of the "mass block", which is used to support the rail as it passes the bit. How do you avoid tearout? When you say "side cut position", do you mean that the rail is set upright on its long edge? If the base is 1/2" thick, then a 1/2" depth cut would be made, right? Further, I assume there is no runner in the miter slot (no screws shown and it doesn't protrude from the back in the second pic), so one must keep the sled against the outfeed block to maintain the proper alignment, right? Maybe another picture or two would clarify this for me and others.

I normally cut tenons on my tablesaw with the rail on a crosscut sled and I use set-out blocks against my fence, too to set a non-binding depth of cut. When I do cope and stick joints on my RT, I also use a set-out block on the infeed and outfeed sides, but secure the workpiece in a coping sled that slides under the exposed bit.

[Joe Scharle]

Rob, the end of the rail rides directly on the R/T top, with the bit set to about an inch (typ). Inserts have to be flush to prevent snag. The piece of scrap you see clamped on the LH side of the fence is from the same stock and provides parallelism due to any variations in thickness.
If I don't trust the grain, I'll make a kissing pass for a clean cheek, then come back for a full cut. The first version did have a miter runner, but proved too restrictive.
The short edge cuts are made with the rail clamped upright to the back. A haunch cut is made by simply standing the tenon on a 1/4" piece of hardboard scrap.
The function of the mass block (any large square scrap) is to give solidarity to an otherwise lightweight jig and to support the cut side high above the newly cut tenon half. It is far simpler in operation than explanation.
In practice, you can complete the cuts for 1 rail in under a minute.
That's probably clear as mud, huh!
Joe