Dovetail Keys
Perhaps no other joint has more strength or better looks than a corner joined by through dovetails. But here's a much simpler joinery process that comespretty close. With just a router table and a bare-bones homemade jig, you can crank out terrific-looking box corners like the one at right.
1. The jig below mounts to a miter gauge that slides in the miter slot of a router table. Built to the length shown, on most router tables it will handle boxes with sides up to about 24" wide. You can tailor the length to better suit your router table and to accommodate smaller or larger boxes. The miter slot-to-router bit spacing on your table may affect the exact placement of the screws. Be sure to put them where the router bit will not cut into them. (Before you build this jig, please read the next step and note.)
2. Mount a dovetail bit in your table-mounted router. We used an 11⁄16 "-diameter bit with an 80 cutter angle and a 1⁄2 " shank for the dovetails shown in the 3⁄4 ";-thick stock of the corner. Most dovetail bits will work, and you may want to consider using smaller bits for thinner stock. Raise the bit so it will cut to the correct approximate depth through your workpiece sitting in the jig. Mark the location where the shank of the dovetail bit will pass through the jig in the following steps. You need to remove the stock in this area of the jig so the bit can pass through it. We did so with a dado set as shown below. Make this cut through only the "V" portion of the jig do not cut through the vertical piece that mounts to the miter gauge. You also could make this cut by sawing a series of kerfs with a handsaw and chiseling out the waste.
Note: If your table has a plunge router, it may be impossible to raise the bit high enough to make a full-depth cut. Also, the shorter shanks on smaller bits may prevent the bit from cutting high enough. In that case, you may have to make the jig from 1⁄2 " plywood.
3. Pass the jig through the spinning dovetail bit as shown. The bit's shank should prevent the bit from passing through the back side of the jig.
4. Assemble a mitered corner from scrap stock of the same thickness as the wood used in your box. Use this test piece to fine-tune the height of the router bit. Then, on the inside of the "V", mark the center of the dovetail cut as shown.
5. On a piece of paper that's as long as your box corners, lay out the position of the dovetails. You can space the dovetails evenly or unevenly, but it usually looks best to have a symmetrical arrangement. For our box, we put one dovetail in the exact center, with equal spacing between the dovetails. The space between the end dovetails and the ends of the corner equal half of the space between the dovetails. Mark the dovetail centers. Position your layout on the inside of the jig's "V" as shown, with the center of the right-most dovetail aligned with the center mark on the jig. Position and clamp the block at the end of the paper layout.
6. Place your box in the jig, butt it against the stop, turn on the router, and pass the V portion of the jig through the bit as shown. After making the cut, lift the workpiece off the jig and pull the jig back through the bit. Do not leave the box in the jig when you pull the jig back doing so may enlarge the dovetail cut. Make this cut on each of the box corners (four total cuts).
7. Rotate the box 1800 so its bottom faces in the opposite direction it faced in the previous step. Butt the box against the stop, and again cut each of the four corners. Rotating the box in this fashion ensures symmetrical spacing. Move the clamped stopblock as necessary to make the remaining cuts.
8. Measure the depth of the dovetail cuts as shown. Your dovetail key stock should be 1⁄16 " thicker than the depth of the dovetail cut. Rip this stock so it's 1⁄16 "; wider than the widest part of the dovetail cut.
9. Using the same dovetail bit as before, adjust it 1⁄16 "; higher than the thickness of your dovetail-key stock. Adjust the fence on your router table so the bit just barely cuts into the key stock at table height as shown. Pass the stock through the bit. At the end of the cut you will get a small amount of snipe you'll cut this off later.
10. Rotate the key stock end for end, keeping the same face down. Cut the other edge.
Test the fit of this stock in the dovetail cuts. (Slide the unsniped portion of the stock into the dovetail cut.) The stock should be slightly too wide. Adjust the fence forward just a hair and recut the stock. Do this until the stock fits tightly in the dovetail cuts. Cut off the sniped ends.
11. Cut the key stock into lengths about 1⁄4 " longer than the dovetail cuts. Apply glue to the dovetail cuts and slide the keys into them, leaving about 1⁄8 " extra key length at both ends of the dovetail cuts.
After the glue sets, saw off the excess key stock. A special flush-cutting handsaw works well, or you can use a typical handsaw if you protect the box with a sheet of card stock as shown.
