Dovetail Jig

Start With a Sandwich Begin by sandwiching three pieces of wood. This part is made from two pieces of 3/4″ x 6″ x 36″ plywood with a piece of 1″ x 1″ x 36″ solid wood centered between. Use a spacer to index the center precisely in the middle of the larger panels. Glue and nail the sandwich together.

Years ago when I first learned to cut dovetails, my first joints weren’t things of beauty. Sometimes there were more shims than pins. Over time, my work got better and faster. But despite the improvement in my skills, I still had trouble cutting tails or pins consistently, especially if I got out of practice.

This jig allows you to make great dovetails on your first day. The idea came to me when I was building a Shaker stepstool using hand-cut dovetails. I made a jig that fit over the end of a board to guide my saw through the cut and provide a perfect tail. The jig didn’t cut pins and only worked on 3/4″-thick boards. I guess I wasn’t thinking big that day.

A few weeks later it came to me: Why not build a jig that cuts both tails and pins and is adjustable to a variety of thicknesses? So I made this jig. From the first joint I cut using it, I got airtight joints. It was very cool.

This jig uses a 9-degree cutting angle. Woodworking books say that 9 degrees is intended more for soft woods than hardwoods (which use a 7-degree angle) but I thought it a good compromise. You can build this jig entirely by hand, but I cheated and used a table saw for a couple of the precise angle cuts. Let your conscience be your guide.

Cutting the Angles Set your saw’s blade to 9 degrees and crosscut the end of the sandwich while it’s flat on the saw. Next, tilt the blade back to square and set the miter gauge to 9 degrees as shown (above). You can use the angled end of the sandwich to set your miter gauge. Lay out a center line down the middle of the sandwich and mark from the end of the line about 3-1/2″. Use a sliding t-bevel to transfer the angle to the flat side. This yields a jig that will let you cut dovetails in material as narrow as 3″ wide. Any narrower and you’ll have to shorten the jig. Lay the extrusion flat on the saw table and cut to the line. The jig will be a little narrower on the other side but that’s OK.

One of this jig’s peculiarities is that you’ll sometimes have to cut right on the pencil line. As designed, this jig works best with Japanese-style Ryoba saws on material from 3/8″ to 3/4″ thick. Use the saw’s ripping teeth when making your cuts. You could modify this jig to accommodate Western saws, but you’d have to take a lot of the set out of the teeth so you didn’t tear up the faces of the jig. The set of a saw’s teeth basically allow you to “steer” a blade through a cut. This jig does all the steering. You just have to press the gas. PW

Click here to download the PDF for this article.

Jim Stuard is a former associate editor for Popular Woodworking.