Introduction: Locking Rabbet Miter Joint
Want to up your woodworking game? Give this crazy joint a try, which requires NO measuring! Miters are a classic joint, and for good reason, because they look awesome! But they aren’t very strong. So instead of cutting a traditional miter, try to use a locking rabbet miter joint. It fits together sort of like a puzzle, but once you add glue, you’ll have a rock-solid joint that will have people baffled as to how you made it.
The joint is made entirely on the table saw. Here are the tools that I used:
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Prep Your Materials
I’m making a walnut box that’s approximately 10” x 10”. To cut this joint, you’ll want to prep your material by cutting your boards to your desired length and width. My boards are approximately 5/8” thick. However, you can use just about any thickness board. Just note that the thinner your boards, the more difficult it may be to make this joint.
I labeled my boards 1, 1, 2, 2. Two of the boards will have one part of the joint, and the other two boards will have the complementary part of the joint. I’m also going to put a ripping blade in my table saw. A rip blade has a flat bottom tooth. It makes for a nice, flat groove when you use it.
Step 2: Cut a Center Groove in Board 1
To start the joint, you’ll have to cut a groove in the end of your number 1 boards. Set your saw blade so that it is the same height as the thickness of your workpieces. Stand your workpiece on end and push it through the blade, so that the blade cuts just off center of the board. To do this safely, you will need to have a tall table saw fence or a make a jig to hold your boards. You can simply clamp a piece of plywood to your fence. I’m using a jig that rides on my saw fence. It’s also a good idea to have a sacrificial board behind your workpiece. This give your board more stability, making the cut safer, and it also helps to reduce any potential tear out of the grain when the saw blade exits the board.
Step 3: Mark Your Layout Lines
With your groove cut, it’s time to mark lines for the rest of your cuts. Butt boards 1 and 2 together to form your corner. Mark a line on the inside face of the groove that you cut in board 1. Using a square, draw those lines all the way across board 2.
Mark a 45 degree angle starting at the corner of your boards, using a combination square. Your #1 boards should have a 45 mark running from the outside edge to the notch that you cut. Your #2 boards should have two lines with a 45 degree mark across them.
Step 4: Cut Your Outside Rabbets
Set the height of your blade so that the tip of the tooth just touches where the diagonal mark intersects the outside layout line. Set a miter gauge in your saw and attach a sacrificial board. Push your #2 workpiece through the blade, nibbling away from the end of the board, inward, until you approach your line. Use your #1 board to test the fit. When one side of the notch fits perfectly in your rabbet then you are good.
A good tip is to use your table saw fence as a guide. Once you are happy with your rabbet, set your table saw fence so that you can’t push the workpiece any further to the right. Now, it’s a stop block that will allow you to cut the rabbets on the rest of your #2 board ends so that all of your cuts are the same.
Step 5: Cut the Inside Dado
You’ve cut the rabbet for the outside part of the notch, so now it’s time to cut a dado for the inside part. To do this, leave the blade at the same height, but move your table saw fence so that it is the same distance as the thickness of your material.
Using the same technique as in Step 4, use the miter gauge to push the #2 board through the blade. Slowly nibble away at your board, moving towards your layout line. You can use your #1 board a guide, randomly checking to ensure it fits. Once you have a snug fit that not too hard to put together then you are ready to move on to the next step.
Step 6: Cut the Miters on the #2 Boards
Set your saw blade so that it’s at a 45 degree angle. Set the blade height so that the tip of the blade just kisses the edge of your board. You do not want the blade to stick up higher than the board.
Using a miter gauge, cut the miter in your board along your diagonal layout line. You only need to trim away a tiny amount. Starting with the very outside edge, make multiple passes until your miter is right in the nook of your rabbet.
Pro Tip: If you are cutting miters and need to be precise, raise your workpiece off the table using a piece of flat stock or MDF. Use a stop block on your miter fence to butt your piece against while you cut your miter. After one side is cut, flip the board around to cut the other side. Elevating the workpiece prevents the tiny edge of the miter from slipping underneath your stop block.
Step 7: Cut the Miters on the #1 Boards
Set your saw blade so that it’s high enough to cut all the way through one of the sides of the notch in your #1 board. Using a miter gauge, cut your miter. Don’t cut too much off your board. Start by barely cutting your board and work your way inward. You only need to cut it until you get a sharp outside miter edge.
When you’ve finished your miters, assemble your joint. You should see that there’s a slight gap. That’s okay! We will close it in the next step.
Step 8: Trim the End of Your Notch
The last cut that we need to make is to trim the end off of the inside notch of your #1 board. Set the table saw blade to 90 degrees and the height of the blade so that it’s tall enough to cut through the bottom half of your notch. Using the miter gauge, trim the end of the board. You will like make multiple, small passes. Periodically test fit your joint. Once it seats together tightly, you’re done!
I hope that this Instructable was helpful. This is a fun joint to make, and it is sure to make other woodworkers gasp at the complexity of your joinery. If you like this sort of content, you can find my work at the following links: