How to Make Dovetail Keys
I’ve built a few boxes with mitered splines on the tablesaw, and now I want to try my hand at dovetail splines. I know I can use a jig to cut the slots in my box at the router table, but how do I make the splines?
John Mihalick, Pensacola, FL
The secret to getting the splines to fit is to use the same dovetail bit you used to cut the slots.
Start by cutting the slots in the side of the box with a dovetail bit and a jig. Once all the slots have been cut, raise the dovetail bit about 1/16-in. The extra height makes the splines, also known as dovetail keys, slightly taller than the slot, and easier to trim to fit. Then bury the bit about halfway into a zero-clearance fence on your router table. Make the keys from a piece of stock that’s slightly thicker than the widest part of the dovetail slot, and at least several inches too wide. The extra thickness lets you adjust the fit of the keys, and the extra width makes it easier to grip and to register the workpiece against the fence.
Make one pass with the face of the workpiece against the fence to cut half of the key. Then flip the workpiece and run it back through the bit to cut the other half. Testfit the piece in one of the slots. If it’s too tight, nudge the fence to take a slightly deeper cut from one side. It doesn’t matter if the key is not centered on the board because you’re going to cut it off anyway. Once you’re close, use a block plane to take a swipe or two from the bottom, fatter part of the key to make it fit a little…