It’s designed for a beam type rip fence patterned on the Biesemeyer design. You can make two of these – one for cutting straight tenons and the other for cutting angled tenons at 45º (simply by mounting the arm at 45º). You can, of course, incorporate both these features on a single jig. The jig also cuts half lap and bridle joints. And best of all, you can make the jig from leftover pieces of 3/4″ sheet stock. Essentially the jig rides over the rip fence. Obviously, if you’ve added enhancements to your fence you will have to remove them to use this jig. The waste pieces cut from the cheeks are quite thin and can easily fall into the gap between the saw blade and the mouth of the table saw insert. For this reason, consider using a zero clearance insert on the table saw.

Making the Jig

• It’s important in making this jig that the tall side (closest to the blade) is exactly parallel to the saw blade. So cut all your parts carefully. Pre-drill and countersink all the screws. The bottom of the arm, against which the stock rests, should be at least 1/4″ above the maximum extended height of your saw blade. To avoid chipping, screw a sacrificial backer board to the arm – replacing the board when it gets chewed up.
• Before you begin construction measure the height and width of your rip fence. You want the jig to ride smoothly over the rip fence without wiggling. If the jig wiggles too much on the fence try adding some low friction (UHMW) tape to the inner sides of the jig where they contact the fence. Also, leave a 1/16″ gap between the base of the jig and the table saw top.
• The length of the jig is not crucial – 6″ to 8″ is sufficient. However you do want to make it tall enough to support long stock. A 14″ high jig will accommodate stock up to 32″ with ease. Make your jig to accommodate the size of tenons you cut.

Using the Jig

This jig is very easy to use. You only need to mark the location of the tenon on one end of your stock. Cut the cheeks on the face side of each piece, flipping the stock end-to-end. Then re-set the rip fence to cut the cheeks on the edge. Again, flip each piece end-to-end. You can clamp the stock to the arm if you wish. However, it’s just as easy (and quite safe) to hold the stock tightly against the arm, ensuring that the stock is flush against the side of the jig. Don’t push the arm to move the jig, you’ll likely cause the jig to wobble. Instead push the part of the jig that sits over the rip fence.

After you cut the cheeks with this jig you cut the tenon shoulders by hand or on the table saw. If you have only a couple of tenons to cut, its just as quick to cut them with a crosscut saw.