Skip to main content

How to Make a Keyed Miter Joint in Woodworking

Learn how to make keyed miter joints from Makeville Studio in this Howcast woodworking video.


Miter joints are a very common way to join two pieces of wood that come together in a corner. Whether they're faces of wood, as in a cabinet, or a picture frame like these pieces of wood would come together.

And, the basic idea behind a miter joint is very simple. You're just cutting the wood at 45 degrees. The same with its mating piece. And they come together at 90 degrees.

Now, by itself, the miter joint is not a very strong joint. And, that is, because we're cutting through end grain where the pieces come together. And so, typically, you need to reinforce this joint with a couple, one of a few methods.

You know, some people use dowels. If you have the room for that. You can use biscuits. Another way to do it is to reinforce it on the outside using splines. And, that also adds a decorative element to the miter.

So, in our demo we're going to be looking at how to add splines to your miter. Because it's a very nice way to touch up a picture frame or decorative box or even a cabinet.

What we're going to look at right now is just how do you create these swines and how do you get them aligned in your workpiece.

Alright. So, to do this work, we're going to have to use a special jig that's designed to hold our workpiece at 45 degrees. And, the idea of this jig is that it runs along the root fence to keep it straight.

And, with the workpiece held in at 45 degrees it passes over the saw blade. The saw blade slices through the workpiece and creates the slot.

So, we're creating a slot that's exactly the size of the curve of the blade. It also requires you to make a bunch of keys. And, that's a separate procedure. And there's a lot of different ways to do that.

Some people slice these keys off a triangular piece of stock on the band saw. You can also slice them off on the table saw.

The idea here is, we're going to set this in here. The keys are going to only be cut to the height that they need to be. And so, we're going to have to set the saw blade height first.

So, let's do that. Now, I've precut a slot in here where I want my keys to show up. That's up to you. You have to measure out where you want these and actually cut the slot in your jig.

Now, to set the saw blade height, you want to be at the maximum point of the blade. So, try and find that. Just by moving your jig around a little bit you should be able to figure out where your blade is at its highest point. There we go.

And then, you want to put the key in the jig behind it. Now I can see how high I need to go in order to cover the amount of key that I'm going to insert. So, I'll just raise the blade up.

Now I'm at the top of the key. If I cut there, I'm going to make a slot so that this piece is flush with my frame. With the edge of it. Now, that's actually what I don't want. I actually want this piece to stick out, very slightly.

So that then I can come back and sand that or plane it down later. Make it flush. So, I'm lowering it down now to the right height.

Now, one benefit of having a slot cut in your jig like this is you can do one side of your piece and then just flip it around. Do the other side. And you know they'll be spaced symmetrically in your workpiece. You don't have to make two slots in your jig to do a two slot design like this.

Okay. Let's see what it looks like. So that's one set of corners done. Now, we can flip it around and do the other side. The idea is, then, after we're done is you slip these little keys in here. Glue them in and just sand them out.

Popular Categories