Box joints, also known as finger joints, are a popular option when joining two pieces of wood at right angles due to their strength, visual appear, and relative ease to make when you have the right tools. Whether they are for boxes, drawers, storage containers, or decorative furniture components, box joints are an essential skill for any woodworker to master at some point in their journey. These box joint jig plans can guide you the creation of your own jig, taking you one step closer to creating box joints.

These box joint jig plans are designed to make 1/2″ wide fingers, which I find suit most of my needs. When using the jig, you want to set the depth of the dado stack to the thickness of the work pieces so the finger are appropriate length. You can also use a piece of sacrificial hardboard in front of the rear fence to reduce tearout when cutting fingers that are shorter than the slot in the rear fence face.

Materials Needed

• 1 – 3/4″ plywood at 8″ x 18″ (base plate)
• 1 – 1″ hardwood maple at 2 1/2″ x 18″ (rear fence)
• 1 – 3/4″ hardwood maple at 3 1/2″ x 18″ (rear fence face)
• 1 – 3/4″ hardwood maple at 2″ x 10″ (front fence)
• 1 – 1/2″ x 3/8″ x 3″ hardwood maple (key)
• 2 – hardwood runners – 3/8″ x 3/4″ x 10″
• 2 – 1/4″ x 1 1/2″ carriage bolts, washers and nuts
• 2″ wood screws
• 3/4″ wood screws
• wood glue

Tools Needed

• Table saw
• 1/2″ dado stack
• Double-sided tape is helpful
• Tape measure
• 2 (or more) Quick clamps
• Square
• Drill / Driver with a countersink bit
• 1/4″ drill bit
• 3/4″ forstner bit
• Brad nailer
• Socket wrench set

Step 1: Cut the base, fences, and runners

We’re going to start this box joint jig by cutting our 3/4″ plywood base (8″ x 18″), and adding the rear fence only. I recommend making all of the fences out of hard maple. For the rear fence, I recommend making this at least 2 1/2″ high, and using at least a 1″ thick piece of maple. Use wood glue and and 2″ wood screws to secure the rear fence in place along the back edge of base.

Now we’re going to add the hardwood runners to the base. You need to take your time attaching the runners as they will help ensure the back fence stays 100% square to the table saw black. We’re going to use two runners so they ride in both miter joint slots on the table saw. Note, the runners are 2″ longer than the base because I like to have my runners extend 2″ past the front of the jig.

Start attaching the runners by screwing in the back end of one of the runners, countersinking a 3/4″ wood screw, so that the jig is close to centered on the table saw with that runner sitting in the miter saw slot. Then use your square against the rear fence and the table saw blade to ensure they are perfectly aligned. Even a small discrepancy will result in gaps in your box joints. Once you are 100% confident in the alignment, pop two brad nails down through the base into the runner to hold it in place. Flip the jig, and countersink a 3/4″ wood screw into the front end. Put the jig back in the miter slot and double check it is still 100% square. If it is, add a third screw for extra stability. Once you have the first runner in place, put the second runner in the miter slot with a piece of double sided tape on top. Place your box joint jig back on the table saw, press down firmly, then flip it over and add three counter-sunk screws to the second runner.

For the front fence, this can be a bit shorter, but I’d still go at least 2″ high. It does not have to extend the entire length of the jig. This fence does not need to be perfectly square to the blade, as we are not using it as a guide for our work pieces. Use wood glue and 2″ wood screws (counter sunk) to attach it to the base.

Now, using a 1/2″ dado stack, set to 1 1/4″ high, cut a slot through the entire jig.

Step 2: Cut and attach the rear fence face and key

For the rear fence face, this is made from a 3/4″ wide piece of hard maple. I prefer this to be about 3 1/2″ high so it provides a higher surface for holding the work pieces when using the box joint jig. Start by cutting a 1/2″ wide x 3/8″ high notch in the rear fence face about 1″ off-center using the same dado stack as above. Now cut a 1/2″ wide x 3/8″ piece of hardwood maple, about 4″ long, to be your key. Ensure this piece is snug in the notch you just cut, cut 1″ from the length of the key, then glue the 3″ piece in place in the notch. Use the 1″ cut-off a spacer between the slot in the base and the key in the rear fence face. Then clamp the rear fence face in place.

With the rear fence face clamped in place, drill two 1/4″ holes all the way through both the rear fence and the rear fence face. Remove the clamps and use the forstner bit to create a 3/8″ deep recesses in the rear fence face, using the 1/4″ holes as centers. Put the rear fence face back into position and lock it in place using the carriage bolts, washers, and nuts. Using scrap wood, do a trial run to check positioning of the key. If needed, loosen the hex nuts slightly, tap the fence left/right as needed, then re-tighten and test again. Repeat the trial test and adjustments until your box joints are perfect.

I hope you enjoy these plans and find them useful. Please check out our other jig and workshop plans. If you have any questions, leave us a comment below. And don’t forget to submit your build if you use these or any of our plans to build something of your own.

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