Tool Test: Powermatic Table Saw Tenon Jig

tenon-jigNo-measure setup delivers precise, repeatable tenons – fast.

If you cut a lot of tenons, the Powermatic Tenoning Jig (PM-TJ) is worth a close look. While it appears a bit complicated out of the box, the PM-TJ is remarkably easy to use and compatible with any standard table saw with a low-profile riving knife.

Set up the jig for your saw and blade using cam-lever stop No. 1, and index the tenon size by referencing stop NO. 2 off the width of your mortise chisel or hollow-chisel mortising bit. Then put your stock between the handle and the second stop, slide the handle flush to the stock and lock it in place.

Raise your table saw blade to the desired height, and you’re ready to cut tenons that perfectly fit the width of the mortises cut with the chisel you used for indexing. (Perhaps obviously, you have to cut the shoulders with the work flat to the saw – this jig is slick, but it doesn’t do everything.)

The initial assembly and setup was easy thanks to the detailed directions, and Powermatic thoughtfully includes the necessary tools.

It took me about 5 minutes to get the miter guide bar attached and square the jig to the blade, to attach the stock clamp (which slides in a T-track), to confirm that the angle guide was at a perfect 90°, and make a few minor adjustments to get everything in perfect working order for dead-on tenons. There are micro-adjust features that make this fine-tuning simple.

It took a little longer (maybe 10 minutes) to cement the tenon setup procedures in my head, but once I ran through the indexing process a few times it all clicked – and I realized just how clever and useful this jig is, particularly for production work.

And the PM-TJ is plenty robust enough for a production environment. It’s well machined, mostly of aluminum and steel, weighs in at 17 pounds and slides smoothly in the miter gauge slot.

The fence is 9-9⁄16″ x 6-1⁄4″ tall – plenty large enough for most work – but there are tapped holes that make it easy to add an auxiliary fence if need be.

The one thing I don’t love is the adjustable clamp (which holds a workpiece up to 37⁄8″ thick); the foot is grabby, so if you’re not careful, it’s easy during tightening to move the workpiece away from the angle guide (which also serves as a backstop for the work). A firm grip is needed to keep the work properly aligned while clamping.

And speaking of that angle guide: While most tenons are cut at 90°, the jig also allows you to make cuts up to a 45° angle.

Do you need a $330 jig if you have only a couple tenons to cut on occasion? Nope. But it’s incredibly fast work to set up for tenons of any width indexing off any chisel, and to center the cut on the stock with no measuring. So if you’re in a production environment, or simply build a lot of projects with mortise-and-tenon joinery, the PM-TJ will quickly pay for itself.
— Megan Fitzpatrick