Keller aluminum dovetail templates have been around since 1976, and now I know why. They’re practically bulletproof and are wonderfully straightforward to use. I was sent the Model 1601 template kit, which routs 7°, 7/16" dovetails, spaced 1-1⁄8" on-center, with a pair of Keller piloted dovetail and straight bits. Two hefty 1/2"-thick templates get that job done — one for pins and one for tails — on any width stock.
Getting the system up and running is quick: you mount each template to a block of wood that becomes a workpiece clamping surface. Only the pin template requires initial adjustment, and that happens by sliding it back and forth on two slotted screw holes, making a few test cuts and fastening it permanently with heavy screws.
I followed the manual’s recommendations for initial template setback on the blocks. To my surprise, the pin size was spot on: my first test joint was a pleasing slip fit, ready for glue and clamps.
The process for making a joint involves routing the tail board first on either your router table or with a handheld machine. Then you use the tail board as a pattern to knife a single tail location onto the pin board. No calculations or difficulty to it. Clamp the pin template to these lines, and rout the pins. Careful knife lines will ensure dead-even board edges when you’re done.
Keller Pro templates come in three sizes. While they’re meant for fixed-space joints, you can vary the pattern by shifting the template during routing. A $269 (2009) price tag may seem high for a jig that only cuts through dovetails. (A lower-priced “Journeyman” series is also available.) Still, these Pro templates carry 20-year warranties and should take a lifetime of hard use.