Sunday, December 7, 2008

The dovetail jig

I've always wanted to get a dovetail jig because I love the way dovetail joints look on drawers and boxes. I finally had a reason to buy one yesterday, and Rockler just happened to have a Christmas sale on theirs for $99.
Warning: This post is really more for my benefit than yours. The instructions for the jig were sort of cryptic, and it took a while to figure out what I was doing. This is my attempt at creating something I can refer to later. =)
I decided to use through dovetail joints because the front of the drawer box will be covered by a framed face. Otherwise, a half-blind dovetail joint would be preferable to hide the ends of the tails. Illustrations can be found on Wikipedia.

The first step was to create a "clamping shim." This is basically a piece of material about 1/4" thicker than the stock you're cutting, and its purpose is to raise the template high enough so your router bit doesn't cut into the metal jig. The manual greatly overexplained this step and caused a lot of confusion.

Next, center your stock in the template, ensuring that the outer tails (i.e. the top- and bottom-most tails on the drawer side) are far enough from the edge of the stock to allow room for the pins. Adjust the side stop to mark this position for the other sides.

Now hold a piece of the front/back stock perpendicular to your drawer side, up against the template, and make a scribe line on the piece to be cut. Set the router on the template and adjust the depth so that you will remove the scribe line. I used the 8ยบ bit and brass guide bushing included with the jig.

Cut all the drawer sides first. The manual stated that the outside of the drawer sides should be facing the jig, but I couldn't figure out how this would make any difference.

The only thing being cut in this photo is the vertical piece.

The tails cut into a drawer side.

When all the sides have been cut, switch to the straight router bit and replace the tail template with the pin template. Mount your stock vertically in exactly the same position as the drawer sides -- do not adjust the side stop.

Adjust the template to position "F" for the first cut. This will almost certainly create a fit that is too tight, and you will need to adjust the template backwards, one mark at a time, until the fit is perfect. Then you can make all other cuts without further adjustment.

Cut the fronts and backs with the inside of the drawer facing the jig. Unlike the sides, this cut is not symmetrical, so the position is critical if you have routed a channel for the drawer bottom.

Here's a shot of the assembled joint, prior to any gluing or sanding:

We didn't want the drawer bottom channel to be visible from the sides of the drawer, so we routed a channel in all the drawer pieces prior to cutting the dovetails. Using the router allowed us to stop the channel about 1/4" short of the ends of the drawer pieces.

Here's a shot showing the router set up in the plunge base with a 3/8" straight bit and fence adjusted to put the channel about 1/2" from the bottom of the drawer sides.

When assembled, the channel on all drawer pieces aligns and is ready to accept the 3/8" bottom piece.

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