This jig will help create clean and accurate tenons on the table saw, with a replaceable strip to save the backstop from damage.
The cleanest way to cut tenons on a table saw is with workpieces standing vertically. To do it safely, you need a tenoning jig that holds parts upright and securely as you run them through the blade. The jig should also offer precise adjustability so you can cut tenons of many sizes and then trim them for a perfect fit in the mortise. This jig satisfies both goals in spades. Its upper carriage slides back and forth across the base on a pair of beveled guides, and the lateral travel is simple to fine-tune with a carriage bolt and knob in back. A toggle clamp and backstop anchors the workpiece. To save the backstop from blade carnage, I’ve added a replaceable strip that fits onto a sliding dovetail. All in all, it’s a must-have jig for any shop, so here’s how to build one for your saw.
Assembling the Base and Carrier Plate
Screw a guide to the base, then slip two paper shims between the second guide and carrier plate to ensure smooth sliding.
Cut the base, carrier plate and guide strips (pieces 1 through 3) to size, following the Material List at right. Plow a 3/8″-deep dado along the length of the base that matches the width of your saw’s miter slots exactly — it will house a runner, later, that guides the jig. Drill a 5/16″-diameter bolt hole through the base at its centerpoint.
Rout a 2-1/4″ long slot through the carrier plate to install the hold-down bolt with a 4/16″ diameter bit, raising the bit up about 1/8″ each pass you make.
Now, switch back to your standard blade, and tilt it to 20°. Bevel-cut the short ends of the carrier plate and one long edge of both guides. The complementary bevels on these parts form a big sliding dovetail joint that holds the carrier plate against the base. Screw the guides to the base with the carrier plate in place, then shift the carrier over so one edge is flush with the edge of the base; we’ll call this the “front” edge. Extend the bolt hole in the base up through the plate. You’ve now created a starting point for routing a 2-1⁄4″-long slot toward the back of the carrier plate. The slot will house a carriage bolt and hold-down knob (pieces 4 and 5) that lock the carriage in place during tenoning operations. Step to your router table and complete that slot. Then, drill a 3/4″-diameter shallow counterbore into the bottom of the base to recess the carriage bolt head.
For the tenoning jig diagrams and material list in PDF format, click here.
Next, follow the Drawings to make and attach two fence braces (pieces 6) to the carrier. Their 7-1⁄2″-long edges should be flush with its front edge. Slide this carriage assembly back onto the base. Cut and fasten the fence (piece 7) to the fence braces; align its bottom edge with the bottom of the base.
