How to Use a One-Piece Tongue and Groove Bit

Let me show you how you can set up, a one piece tongue and groove bit in your router table. Now, let's backup a little bit, and talk about another option. Sometimes, you'll see that, with tongue and groove sets, they come with two bits. One of the bits, is designed to cut the end grain cut, leaving the tongue behind. The other one, is designed to do the long grain cut, that leaves the groove behind, but like I said, you can do the whole thing with one cutter.

Let me show you that. I've got a bit in the router table, that's designed to do both the tongue and the groove cuts. The way that's going to work is that, at it's current elevation, I'll be able to run across the end grain of a piece, in order to make the tongue. Then, what I'm going to do is, lower the bits, so that I'm using only the top cutter, and that lets me make the groove. So, my elevation is right, I need to get the fence located.

I'm going to do that, by bringing the fence forward, until the face of the fence, is even with the ball bearing on the bit. Then I'm going to spin that my hand, and make sure I'm clear, of course, doing all of this, with the router unplugged. Now I'm ready for that end grain cut. When you do this, make sure that you're supporting the material, with a piece of waste, because as we exit through, if you don't have a piece back here, you're really going to chip that exit side, it's going to look ugly. So, that gave me the tongue on this piece.

Now, we'd do that, of course, to all the parts involved in the project. Now, for the next setup, we're going to unplug my router, move the fence out of the way. Now, I'll show you the easiest way to make sure you get the elevation right, on probably the first try. The way to do it, is to take one of the tongues that you cut, and use the tongue to set the height of the bit, for cut number two. So, I'm going to bring this over here, think of it as, I've got a tongue sticking out, this bit has to make a slot, a groove for it.

So, I'm going to set my height, until the top of that carbide, is even with the top of the tongue. Right about there, feels pretty good. This is a case where, boy, do I appreciate the router lift I have on the table, because it makes it real easy to dial this in, but even without a router lift, you'd be doing the setup, exactly the same way, with the height control, on the router itself. That looks good. Now we need to do a test cut, but we need to have the fence back in place.

I'll set up the fence the same way, get right on the face of the ball bearing. Now, we can do a long grain cut on a piece, in order to check our work here. Now, your test is, put the parts together, and see if the faces are in alignment. So, remember, I had this face down on this cut, this face down on this cut, so those are my reference faces, so, when I put those together, I want to make sure I've got the same faces down, as I'm testing. If the faces are aligned, and these actually feel pretty good here, then your height is ready to go, and you can make all your cuts.

If there's a discrepancy here, then you can raise, or lower the groove cutter, until you have it just right. So, with that bit, we can do both the tongue, and the groove, all with one cutter.