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    Box Joint Jig Handles Drawer Joinery with Ease

    Learn how to build and use a clever tablesaw jig for perfect box joints.

    The humble box joint (sometimes called a finger joint) is strong, attractive, and easy to cut using a sled or miter gauge on a tablesaw, outfitted with this simple jig. By cutting a series of fingers that interlock, you create a large amount of surface area for glue to adhere to, making for a super strong joint. The key to executing the joint successfully, depends upon the precision with which your set your jig up. If the joint is loose when you dryfit it after cutting, chances are it will fail sometime in the near future, so be sure to take your time time when creating, and setting up the jig.

    Building the Jig

    The jig is essentially a sub-fence that gets attached (either with screws or clamps) to a simple crosscut sled or a miter gauge outfitted with a nice beefy auxiliary fence screwed to it. In order to be able to adjust your cut to perfection, I'd actually veer away from screwing the sub-fence to your sled or miter gauge, and opt for clamps instead. This will allow you to move the sub-fence in minute amounts as you dial in for the perfect cut.

    To build the jig, mount a dado set or box joint blade set (this drawing refers to 1/2-in. increments - thus a 1/2-in. dado or box joint set) into your tablesaw and set the blade height to the thickness of your drawer or box stock, plus 1/16-in. now make the first cut in a small piece (in this case about 7-in. x 14-in.) of scrap plywood. Next, glue a key into that slot. The key is just a small piece of hardwood cut to fit the slot exactly. It's mounted so that it protrudes about a 1/2-in. from the front of the sub-fence, and is flush with the back of the sub-fence.

    The second cut used in the sub-fence assembly requires a bit of precision. Align the sub-fence to your sled or miter gauge's auxiliary fence, with the key just right of the blade. You want the edge of the key to be positioned exactly 1/2-in. from the side of your saw blade's teeth. Now clamp the sub-fence into place and make the second cut. That's it. You've now got yourself a functioning box joint jig.

    Test Your Work

    Follow the instructions below, under "Using the Jig," and produce a test joint. If the fit is too loose or too tight, it means you've got to adjust the position of the sub-fence, spacing the hardwood key either just a tad closer or further away from the tablesaw's blade. That's why it's best to clamp the fence into place, as opposed to screwing it in. Less permanence means more adjustability. Once you've dialed in your sub-fence positioning, you can go ahead and produce your final drawer box, or any other box for that matter.

    Using the Jig

    Click any of the photos for an enlarged view.

    The ends of each piece are identical. For the first cut, butt the top edge of the workpiece against the key.
    Make the second cut. To cut the second notch, just place the first notch on the key. The final notch on this drawer will be partial.
    Locating the mating side. Flip the first side, put its first notch on the key, and clamp it into place.
    Cutting the mating side. Cut the first notch on the mating side. The dado blade should just clear the first side. Then continue until you've notched the rest of the side.