Dovetail Bits

Page 1

For centuries, the hand-cut dovetail joint has stood as a testament to the quality of the case, box, or drawer that beheld it. These days, thanks to routers and dovetail bits, even a beginning woodworker can incorporate this joint to enhance the simplest projects.

Dovetail bits come in an array of cutting angles, usually 7-140, and heights (see photo, above), on both 1/2" and 1/4" shanks. Generally speaking, the greater the cutting angle, the stronger the joint. But beware: The acute angles on the tails make them more fragile as the cutting angle increases, and they can break more easily along the grain.

Because of its opposing-wedge action, a properly fitted dovetail joint self-tightens. This means you can use it to eliminate fasteners, such as screws or nails. You should still glue the joint, but you won't need clamps.

 

You'll see the three basic parts of every dovetail joint in the Parts of a Dovetail Joint drawing above. The pin is the part that fits into the socket, which is formed by two tails. Pins and tails are often confused, but there's an easy way to remember which is which. If you look at the face of the workpiece and see birdtail-shaped protrusions, those are tails; if you see rectangles, you're looking at pins.

The tails bear the brunt of the joint's stress, so when planning your project, point the tails in the direction of the stress. For example, opening and closing a drawer creates front-to-rear stress on the drawer. Therefore, point the tails front and rear, which means cutting the sockets in the drawer sides.

Here in the WOOD. magazine shop, we like to cut the sockets first, about 1/32" deeper than the thickness of the pins, using a dovetail bit in our router table. Then, using a straight bit, we form the pins, leaving them just a hair wider than the sockets. This lets us gradually remove more stock from the pins until we get a good fit. Once the joint is complete, we sand the tails flush with the pins.

Making well-fitting dovetail joints in boxes or drawers requires a high degree of precision. That's why you'll find a covey of commercial jigs on the market today, each designed to simplify cutting the pins and sockets with bearing-guided bits. Less-expensive jigs make only half-blind joints, where the dovetails are visible only from one side of the joint. With pricier models, you can cut through-dovetails, where both sides show (see Common Corner Joints drawing, above left).