There are numerous jigs for cutting dovetails with a router. My go-to is the Keller pro series model 1601. It’s simple to use, though unlike jigs that cut pins and tails in one fell swoop, it takes two operations (and two different cutters) — one for tails, another for pins. The resulting joint is so attractive, with wide tails reminiscent of hand-cut joints, that I think it’s worth the extra time.
The following is a basic guide to cutting dovetails with a Keller jig. Although I’ll be referring to drawers, the same basic principles apply whether you’re dovetailing a trunk, a jewelry box, or a dresser.
1. On your marks.
As with any drawer making technique, it’s critical to keep your parts in order; one misaligned piece can result in a dogleg instead of a rectangle. So be sure you mark each piece of every drawer with its location (e.g., “4 R” for drawer number 4, right side) and mark the face and edge with whatever symbol you use. I use the traditional English face mark, seen here. (It’s just how I was taught.)
2. Get set.
Start with the tails. For these, you’ll need the straight-fingered template and the dovetail cutter fitted with a bearing, which you can buy with the jig from Keller. I cut so many dovetails for built-ins that I keep a dedicated router set up for pins and tails.
Cut the tails first. Be sure you keep the face edge on the same side of the template for every cut. The cutter should protrude by the thickness of your stock (in this case, 1/2″) + 1/2″ for the thickness of the template + about 1/32″ waste for cleaning up the pins and tails. To allow for this waste at each end of each part (fronts, backs, and sides), I add 1/16″ to the overall length.
Plan the layout of the tails with the groove for the drawer bottom in mind. In this case I was using Blum Tandem drawer slides, which require a 1/2″ cavity below the drawer bottom, so the drawer groove starts 1/2″ from the bottom edge of the drawer and extends up by the thickness of the drawer bottom — in this case, 1/4″.
Another consideration to bear in mind when planning your layout is the location of the tail or pin at the top edge of the drawer. You don’t want to have a thin sliver of material that can break off. It’s best to plan for about half the thickness of a pin or tail, depending on the height of your parts; if my layout ends up too close to the edge of a pin or tail, I’ll usually rip a bit more off the width of the drawer parts (i.e. the “height” of the drawer once it has been assembled and installed in the case). If you always use the same slide hardware (I do not; the hardware varies, depending on the requirements of each job), you can standardize your drawer sizes based on the dovetail template spacing.
Once I have determined where the bottom edge of the drawer side will fall relative to the template, I make a mark on the template that I can use to align each part.
Once you have the position worked out, clamp the template onto the end of your workpiece. Be sure the template is sitting squarely on the end and is firmly in contact with the piece all the way along its width; if the template is cocked up at one end, you’ll produce tails that are too shallow at that end. (In other words, the joint won’t fit.) For wide pieces, I use a clamp on each side.
Set the router squarely on the template and turn it on. Move smoothly in and out of the spaces between the “fingers” until you reach the end of the cut. Leave the router resting on the template while you turn it off, then wait until it has stopped completely before lifting it off; otherwise, you run the risk of cutting into your template. (Don’t ask how I know this.)
As with hand-cut dovetails, the pins are laid out based on the tails, as you can see in the illustration above. (Yes, I cut tails first. This post is not about that controversy.) When all the tails are cut, set up the pin cutter in your router. It should protrude by the same amount as the tail cutter did.