Router Table Box Joints Wheeling WV
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Mount Pleasant, OH
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Router Table Box Joints
Router Table Box Joints
The perfect fit comes easily with a shop-made jig.
by Tom Caspar
Box joints are a cinch to make on a router table. All you need are a sharp bit and a basic plywood jig.
The biggest problem in making box joints has always been getting a precise fit, because the line between success and failure is only a few thousandths of an inch thick. Fortunately, the solution simply requires that your jig be easy to adjust, not difficult to make. I’ve added a micro-adjust system to my jig that is incredibly precise but takes only a minute to put together.
This jig is specifically designed for the jewelry box on page 64. You can certainly use it for other projects, but there are some limitations. It’s dedicated to only one size of router bit. To make wider or narrower box joints, you must build another jig. For box joints wider than 1/2 in., you’re better off using a tablesaw and a different kind of jig. If your project requires box joints that are more than 5 in. wide, widen the jig accordingly.
Setting up this jig does require some test cuts. Plan ahead by milling some extra parts from the same wood or wood of equal hardness. In addition, make all the pieces extra wide by 1/4 in. or so. It’s much better to rip your pieces to final width after all the box joints are cut. Then the last finger or notch will be exactly the same size as all the others.
Photo 1: Rout a groove down the length of a piece of plywood to begin making the jig’s base (Fig. A, below). Make the base the same length as your router table.
Use the same size bit that you’ll use for the box joints. Here, it’s 3/8 in. A spiral bit makes the cleanest joints (see Source, below), but a straight bit works fine.
Photo 2: Fasten a runner to the jig’s sled section (Fig. B, below). The runner’s fit in the base is crucial, so begin slightly oversize. Rip the runner on the tablesaw so it barely slides in the base’s groove. Then sand one edge with a block until it slides smoothly.
Photo 3: Clamp both ends of the base to the router table so the bit is approximately centered in the hole. The base’s groove goes in front of the router bit as you face the router table. Raise the bit so it’s exactly as high as your workpiece is thick (see inset).
Photo 4: Position the base so the runner is exactly 3/8 in. away from the bit. Use a drill bit as a measuring device. To adjust the base, withdraw the drill bit, loosen one of the clamps and gently tap the base’s edge with a hammer. Recheck the spacing with the drill bit and tighten both clamps.
Photo 5: Rout the first notch in test piece A. Mark one edge as the bottom. Butt the workpiece up to the runner, and slide the sled back and forth 1/2 in. or so to cut the notch all the way through. Press down on the sled so it doesn’t tip forward.
Photo 6: Continue routing notches all ...