Simplified Router Fence Setup

I wanna help you out with the layout on a couple of joints that I've watched people struggle with in their woodworking shops. One is a lock miter. The other is a mortis. The lock miter is a great joint once you master it. Have a look at one here. What we get is a great look on the outside 'cause the parts are mitered so we have no end grain showing on the outside of the joint. On the inside, we have a great mechanical grab thanks to the way that this thing actually kind of tongue and grooves together. There's a lot of automatic mechanical structure to this, plus significant amount of glue surface. So once this is glued together, it's really, really, really strong. That's the good news. The bad news is a lot of people struggle making a lock miter because both the height of the bit and the fence location have to be just perfect. So here's the way I'm gonna make this happen. Using this tool which has a half inch diameter pin in this end, I'm gonna put that half inch pin in the collet to my router once the routers in the table. I can open the vice on this end. And notice that as the vice slides, this nose out here is sliding as well. So then I can take the material from my project, squeeze it in here, and automatically get the fence location. That's gonna come off of this small pin up here. So thanks to the mechanics of the way that this device has been figured out, I can automatically get my fence in exactly the right spot for that particular lock miter bit. So let me show you now that you've seen the overall here how this actually works in the router table. First step, get the router in. Drop the large pin into the collet. Bring the fence forward and put my project material in the vice. Now the fence can just kiss that small pin right there. Lock that fence in place. So now at this point, we're not gonna wanna mess with that fence anymore. Thanks to this device it's perfectly faced, it's perfectly aligned for this cutter. So we can pop this out. And put the lock miter in. Now remember I said that where people struggle with the lock miter is the fact that you got to work and think in two dimensions. We have to get the lateral dimension right. That's the fence location. At the same time in order for a lock miter to cut perfectly, we have to get the vertical dimension right. That's the height of the bit. Well, thanks to the way we've set this up and with the addition of another tool here, I can make this happen pretty easily. What I'm gonna do now is take this measuring tool. It has a pin on it that's thin enough on the end to go into the slot on the lock miter bit. So what I'll do is I'll bridge the fence, allow that pin to seat into the slot in the lock miter. Now I've got the offset that I created in the fence locked into this tool. Now I can use it this way and dial in the height of my cutter. Lock the height. With that, we're set to make a lock miter in our material. Now remember when you do a lock miter, one face will feed down on the table with end grain against the fence like this. The mating piece is gonna feed end grain down on the table, face against the fence. So in this case, we can't have the guard on here because we have to be able to pass over the cutter. Let's do a cut and see what we have. Now let's see our joint here. That piece that way. This piece this way. Closing a very, very nice lock miter. Great fit between those two parts. And a lot of times it takes me a number of test cuts to get to the point where I've got everything working just right like it is on this one here. Part of the beauty of the system is when I put this in a closed position, an offset number here that's provided by the manufacturer lock miter bit by lock miter bit. Slightly different number for each bit. That gets this part of the jig correctly positioned. Makes it very, very easy to set up these lock miters. Now let me show you a little bit about mortises. For mortis layout, I've got a couple of legs here I need to cut mortises into. And in this case, what I wanna do is end up with a mortis that's centered on the leg. Now if the leg is a perfect inch and a half, it's a perfect two inches, mathematically finding the center isn't a big deal. Sometimes by the time these parts are machined, they're a little bit of a funky size. Let's say it's an inch and 7/16 instead of an inch and a half. Finding the center by math can be a little bit tough. So let me show you how I'm gonna do it. Back to my jig, I'm gonna take this lock miter offset off the jig. And close this, lock that pin back in place. So basically what happens here is that as I move the vice, I'm on a 2:1 ratio with the movement of the arm on this end. That's how I find the center of stuff so easily. So now on my plunge router which I'll use for cutting the mortises, I've got it equipped with a fence. The half inch pin goes into my router collet just like I did on the router table. My leg goes into the vice. Lock that in place. Now regardless of that leg size when I slide my fence over like that and lock it in place, I'm perfectly located here so that the distance from here to the center of the collet is exactly to the center of the leg. Now if you think about it a little bit, doing a mortis like this let's say I don't want the mortis in the center. Let's say I want it offset toward the outside. I can figure that out. If I had a 3/4-inch piece of material and I wanted an eighth-inch reveal on it, that would make it a half inch to the center of the mortis. So instead of actually using my leg, I could put a one-inch piece in here. Close the vice on that one-inch piece, and that would give me a perfect half inch to the center of my mortis. So a very, very easy way to find center on mortises.