For $99 as of 2009, Prazi’s ChestMate jig will enable you to cut through dovetail joints on stock of any width, in any spacing you choose. That’s because this jig employs a pair of interchangeable inserts — one for pins and another for tails — that follow a scrap template pattern you create on the table saw. A tab under each insert fits into a series of shallow saw kerfs you cut in the template to create your own joint layout. It’s an ingenious approach that guarantees the pins and tails will register properly while giving you plenty of creative control.
ChestMate clamps over the workpiece, and you provide a 3/4" dovetailing bit, 5/8" guide collar and a straight bit to carry out the milling steps with your handheld router. The system is very easy to warm up to. After making one adjustment to the pin insert to alter my pin thickness, I was cutting glue-up-ready through dovetails on the second try. Bit depth doesn’t impact the joint fit, just the amount you want the pins and tails to stand proud for final sanding. So, that reduces the possible variables that affect how the joint fits to just one: pin thickness. It’s a huge timesaver.
Downsides to the ChestMate? There aren’t many. It’s designed to cut 3/4", 7° or 14° dovetails. If you want other dovetail sizes, you’ll need to experiment with it. The jig also won’t do half-blinds. But, Prazi recently added several more inserts as standard items, so you can now use the same jig for cutting box joints, hybrid box/dovetail joints, mortises and even dowel joints. If variable-spaced dovetails are what you’re after, ChestMate’s versatility, sturdy construction and ease of use make it an excellent value.