The Half Dovetail Rabbet

As an alternative to more familiar case comer joints such as rabbets and lock miters, Pat Warner, a router wizard from California, developed this router-cut comer joint. Simple to make with a router, the joint comes together neatly and squarely. It is more resistant to racking than a conventional rabbet joint.

Warner prefers to work with hand-held routers, and his technique for cutting the joint reflects his preference. 1 think it's easier to do the cuts on the router table or the horizontal router table.

To make the half-dovetail cut on the case sides, Warner fits a 1 Winch outside diameter (O.D.) pilot bearing on the shank of a 1-inch dovetail bit, then clamps a fence to the work for the bearing to ride against. You can achieve much the same effect by positioning the fence so the router base rides against it.

Next, Warner cuts the dovetail rabbet on the horizontal pieces. He uses a right-angle platform, much like the one we made for routing tails, but Warner references the platform edge with an edge guide to control die cut. He secures the workpiece in a vise, then clamps the platform to it and sets the router's edge guide. The router's depth of cut should be the same as before. Then he makes the second cut.

Cutting a half-dovetail rabbet is a two-pass operation. Both use the same bit with one height and fence setting. The first pass is made with the workpiece flat on the router tablctop, as shown on top right. To make the second cut for the joint (bottom right), stand the mating work-piece on end and brace it against the fence. For both cuts, back up the work, especially if it is narrow like these pieces, to keep it square and to prevent the bit from blowing out the edge.

You'll find that you can use this to great advantage where the workpiece is clamped flat on the bench top. Hold the router horizontally, and fit it onto the work. The weight of the router will press the facing against the bottom of the work, and the facing will keep the machine level.

For cutting the sliding tail, the bit must be largely housed in one of the guides, so it makes only a shallow cut in the work. Make one pass, cutting one face of the board, then turn the router around and make a second pass to cut the other face, completing the tail. Test the tail in a slot, and adjust the guides as necessary to get the fit you prefer.

With two edge guides on it, the router can literally be hung on the edge of the work (right)- That enables you to use a hand-held router to cur dovetail pins on the edges of case parts. By adjusting the guides,you control the bit's position in relation to the work, and thus alter the thickness of the dovetail pin. Since few commercial edge guides are designed to he doubled up on the router, you probably will have to make a double edge-guide baseplate like that shown. Once you have it, you II discover other uses for it—like mortising and slotting.

With two edge guides on it, the router can literally be hung on the edge of the work (right)- That enables you to use a hand-held router to cur dovetail pins on the edges of case parts. By adjusting the guides,you control the bit's position in relation to the work, and thus alter the thickness of the dovetail pin. Since few commercial edge guides are designed to he doubled up on the router, you probably will have to make a double edge-guide baseplate like that shown. Once you have it, you II discover other uses for it—like mortising and slotting.

The half'dovetail rabbet is a "designer"joint: It looks just a little different, just a little more stylish than the rabbi-t joint you're used to. And that Z-shaped interlock enables a well-fitted one to resist some stresses a little better than the standard rabbet joint.

cut the ha^p-dovetail ra&be1 witm a meld rou'

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cut the ha^p-dovetail ra&be1 witm a meld rou'

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To adjust the fence, you should "read"your test cuts. The samples at left indicate that the setting is right on. The samples in the center indicate that you need to move the fence to expose more of the bit. The samples at right indicate that you need to house more of the bit.

As I said before, I ihink it's a lot easier to make this joint on either the regular router table or the horizontal one. When you set the fence properly, it becomes a halving process. Both halves of the joint are cut with the same setup. The difference is in the angle of attack: One piece is laid flat on the table and pushed across the bit, while the other is held upright against the fence. But the fence position is the same for both cuts. What could be more simple?

To cut this joint on Winch stock, you need at least a Winch dovetail bit. The Winch bit, which is the most common size, won't give you a satisfactory joint because it is just a little too small. The angle of the bit is irrelevant, since you use the same bit for both cuts. Use the bit you have. The bit height for this operation is up to you. It's irrelevant to the fit of the joint, so set a height that looks righr. I he fence setting is what makes it come together perfectly. Take the time to cut tests on scraps of the working stock.

Here's how to make the double edge guide:

1. Dress the hardwood for die guides, sand it smooth, and glue the pans together. After the glue has dried, screw—but don't glue—the facing to one of the guides (for some operations. you may need to remove it).

2. Cut the acrylic, rounding off the sharp corners. Sand and polish the edges if desired. Cut the slots with a Winch straight bit. This is easiest to do on the router table.

3. Using the factor)- baseplate as a template, lay out the router location, the bit hole, and the mounting-screw holes. Give some thought to the orientation of the router handles in relation to the plane of the guide. Cut the bit hole, and drill and countersink the screw holes.

4. Set the edge guides under the baseplate and mark the locations of the carriage-bolt holes. Drill and coun-terborc the holes.

5. Insert the carriage bolts into the guide and tap them home with a hammer. Insert the projecting studs through the baseplate slots, drop washers onto them, and turn plastic knobs onto them. Mount the unit on your router in place of the factor)' baseplate.

Sliding the Dovetail on the Router Table

The advantage of the router table is that you move the work over the bit. Unless the workpiece is inordinately large, this is a plus in forming tails. And in cutting a dovetail slot in the edge of a workpiece, this is a distinct plus. But if you are doing something like routing dovetail slots in bookcase sides, do it with a hand-held router. There just isn't a good way to locate the slots on the router table.

To rout a slot in an edge, set the tail height and the fence position. You'll probably want the slot centered across the edge. While that's a

The assembled drawer is clean and functional. The sliding dovetail joint is a natural for this application, since its shape mechanically resists the tendency of the front to separate from the sides. And assembly is quick—no fasteners or clamps required.

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