How to cut accurate tenons on the tablesaw
A dado set on the tablesaw is Charles Durfee's go-to method for cutting tenons.
Synopsis: A dado set on the tablesaw is Charles Durfee’s go-to method for cutting tenons. It’s fast, because it takes only one or two passes on the saw. He cuts the shoulders and cheeks at the same time, and it’s easy to get a perfectly fit, centered tenon. He uses a miter gauge with a hardwood fence to support the workpiece, and employs the tablesaw’s rip fence as a stop. He fine-tunes the fit at the bench.
I’ve tried many techniques for cutting tenons over the years, but the method I’ve settled on uses a dado set at the tablesaw. With the stock flat on the table, I can cut a tenon in one or two passes. It’s fast because I cut the shoulders (the base of the tenon) at the same time as the cheeks. I can dial in the fit and I get a tenon that’s perfectly centered and parallel with the faces of the workpiece. Tenons that are offset or haunched can also be cut this way, but will require a few more setups.
Before you begin
It’s important to start with flat, square stock because all of the faces will be used for reference on the tablesaw top when cutting the tenons. If the stock is not flat, you’ll end up with a wonky tenon. It’s also critical that the end of the stock be square. This will result in shoulders that are square so that the joint comes together without any gaps.
I cut all of the mortises before the tenons, because I find it easier to fit a tenon to a mortise than the other way around. The mortising method isn’t important, but if you use a router, you’ll need to deal with the rounded mortise ends— either squaring the mortise with a chisel, or rounding the tenon when it’s done.
Dado set is the secret. Assemble the outer blades and inside chipper blades to make a wide cut. With this setup, you can cut a tenon in one or two passes.
Install the dado set
I use a standard 8-in. dado set. It consists of two outer blades and a number of chipper blades between them. The blades all have teeth that make a flat-bottomed cut, a must for tenons. Most tenons are longer than the width of my dado set, so I choose a width that allows for a nice overlap from cut to cut, say 5/8 in. for a 1-in. tenon. For short tenons, anything under 3/4 in., I set the dado blade for a wider cut and bury a portion of the blade in a sacrificial fence clamped to my rip fence. This allows me to cut a full-length tenon in a single pass. Once the dado set is installed, square up the miter gauge and adjust the tablesaw’s rip fence to set the length of the tenon.
From Fine Woodworking #283
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by Chris Gochnour