Using a Biscuit Joiner: Reinforcing a Miter

When you're working on a project that has miters in it, like this one does, it's best to reinforce that miter to make sure it stays together, because of the end grain to end grain nature of that glue joint. So what I want to do is cut a biscuit slot there, so that I can have that in there as a spline to help hold this thing together. So here's one way we could do this. Get the material in a vice. And then with my biscuit joiner, what I really need to do for perfect registration here, is I have to wrap around that corner.

So what I have to be able to do with my biscuit joiner is loosen the fence, and change it from 90 degrees to 135 degrees, which is really crazy hot. But anyway, angle not temperature. Anyway, I gotta be able to do this, so that I can capture that angle like that. That's okay. But a couple of things, one is it's one more setup I have to do with my biscuit joiner, two, not every biscuit joiner out there is capable of going 135 degrees in that direction.

So here's an alternative. Let's put our fence back to 90, and then this is where we're gonna change the setup. Instead of a single board deal, I'm gonna make this a two board deal, making sure that the knife edge of my miters up here is nice and flush, even all the way across. Now, what's cool about this is because I'm 45 and 45, the resulting angle is 90. On my biscuit joiner, then, I can leave my fence at 90 degrees, let the fence rest on the 45 degree angle that's on the other side, and cut my slot.

And as long as both boards are in there, you might as well cut them both at one time. So it gives you a little twofer on the cutting operation. That, I find, is a much easier way to get these 45 degree splines cut in, and allows us to take advantage of the strength that a biscuit's is gonna offer to that join. So next time you're reinforcing a miter, like I did here, check this out, try doing it back to back, so you get a two for one deal out of it. You're gonna find it works really great.