Shopmade tablesaw tenoning jig
Bob Van Dyke's jig features a thick, laminated plywood bridge that straddles the tablesaw's rip fence, dampening any vibration that could lead to inaccuracy.
Synopsis: This jig cuts all types of tenons equally well, from narrow ones for table aprons to wide ones for breadboard ends to angled ones for chairs. Its main feature is a thick, laminated plywood bridge that straddles the tablesaw’s rip fence, dampening any vibration that could lead to inaccuracy. This bridge allows the jig to be adjustable and to work with the fence on either side of the blade.
I can think of at least half a dozen different ways to make a tenon, and I use them all. Often the best way to cut tenons is at the tablesaw, holding the workpiece vertically in a jig. But I find commercial tenoning jigs, even the old cast-iron monsters, extremely limiting and usually less than accurate.
I prefer this shopmade jig. It is a smaller version of the massive one I learned from my friend Will Neptune. It cuts all types of tenons equally well, from narrow ones for table aprons to wide ones for breadboard ends and angled ones for chairs. The jig’s heart is its bridge, a thick lamination of plywood that straddles the saw’s rip fence. The bridge’s mass helps to dampen any vibration that could lead to inaccurate tenons. Because it straddles the rip fence, the jig is infinitely adjustable, unlike versions that slide in the miter gauge, and its ability to work with the fence on either side of the blade means that the direction your saw’s blade tilts is not an issue.
The bridge is housed between two uprights. The tall one sits perfectly square to the saw table and hugs the rip fence. The short upright helps trap the jig on the fence so it travels with zero side-to-side play, a crucial fit. I have a clever way to sneak up on the fit with an adjustable pressure bar after the jig is assembled, letting you easily fit the jig to your particular saw.
In this video. Bob Van Dyke demonstrates how
he shims his tenon jig to fit any saw.
A carefully built jig makes for accurate tenons
Precision is critical to this build; any inaccuracy in the jig will affect the accuracy of your tenons. So while the jig may look simple, you shouldn’t underestimate the importance of building it well.
The first step is to glue up the five layers of plywood for the horizontal bridge. I used 3⁄4-in. Baltic-birch plywood here, but I’ve used MDF to make this jig before. Both work well. MDF is heavier, but plywood holds screws better, so it’s your call. The finished width of the bridge is the width of your rip fence plus 3⁄4 in. for the phenolic bar, 1⁄4 in. to accommodate the two 1⁄8-in.-deep dadoes in the uprights, and 1⁄16 in. extra for fitting the jig to your saw later.
Make the layers about 3⁄8 in. wider than the finished bridge so there will be plenty of extra width to trim after the glue-up. To bring the glued-up stack to final size, begin by truing one edge of the bridge at the tablesaw. Tack a straight stick to the middle of the stack on one side and reference that against the rip fence. Then reference the cleaned-up edge off the fence to rip the blank to width. If you have a jointer and planer with carbide knives, you can use those too. The plywood will ruin straight knives, though.
From Fine Woodworking #288
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