Simple Spline Cutting Jig for Mitered Frame

Let me explain this simple jig to you. How's that for a bad joke, this jig is going to let you use a handheld router and a slot cutter to cut splines into mitered frames. So let's talk through a couple of things here. First, the router and the router bit. In the router, I've got a quarter inch slot cutter, and you could use any size of cutter you want, doesn't have to be quarter inch.

I'm working with three quarter inch stock, so a quarter inch proportionally works well for that. It's a ball bearing bit with a ball bearing is going to ride on our jig, and just a little bit that takes care of that. Now, the jig itself, why would we do this? One of the best ways to reinforce the miter is to put a spline, in this direction. So this is going to let us cut that in.

Not only are we going to get reinforcement, but, you can also add a really nice detail. Imagine a contrast in color, a little piece of padauk or maple, or cherry or walnut, in this cherry. Anything that would be a different color than the cherry is going to look really neat, up against that material. So big picture, what happens? We've got a 90 degree nest.

This gets slipped into that, clamped in place, and then by running the router here, we can cut our spline slots. So let's get to that point. Because I tighten the clamp, I making sure I'm closed here outside corner to the inside corner. I've already set the depth on the router, so that that slot will be in approximately the center of the thickness of my material. Now you can tell this jig is actually being used for the very first time because, there are enemy slots cut in the jig.

Once it's on, I'll bring it over let the bearing make contact with the jig, go in that direction until I'm past the frame, that's all we need to do. Alright, show you what I got. There's the slide for our spline. Now you can custom cut that spline on the table so I can plan in it on the miters or on the planar or a surface sander, until it's a perfect fit. Next thing I want to do, it's a simple jig but let me walk you through making one of these so that you have one for your shot.

Assembly, is real simple. Let's talk about the parts first, for the base of my jig, I'm using half inch Baltic, Birch plywood 10 inches wide, 24 inches long. You can mess with those numbers wherever you want. The parts that the routers going gonna ride on are made out of three quarter inch MDF. Now though, do those do need to be as thick or slightly thicker than the frame piece that's going to go in here.

It's okay if your frame piece is even with, or slightly below this surface, but your frame piece can't be above it. So pay attention to that thickness. Two inches wide, long enough to span the jig like this. Then I've got two other little guide blocks, that are also two inches wide. They're going to act as filler strips here.

For assembly, here's what we're going to do in the approximate center, of your jig, make a Mark. And then ,from that point, draw a line at 45 degrees. And that's where your first cleat is gonna go. And the way I'm going to make this happen is by just clamping everything down to the table, like this Double-check my pencil line, that looks good. Then, with my framing square I'm going to take off my gauge blocks, stair gauges got myself in a little bit of trouble with my clamp, but I can fix that.

And what I want to do with this one is from this outside point, there, at flushes city, draw a line And then it's just second verse same as the first. Alright, then last step these just have to be in place so that the router base has something to sit on. And this, we can just use a rubbed joint and rubbed joint is glue, spread that around into a thin film, and then it's just what it sounds like put it in place and rub it back and forth a little bit, locate it, done. Don't even need a clamp on this. And then, if it's not intuitive the ends of all these parts are cut at 45 degrees rub, stop touching it.

There you go. Now, technically what you should do let's say you're going to use a quarter inch slot cutter for one project and an eighth inch slot cutter for another, it's best to take the time to make a jig for each of those slot cutters. What you want to do each time you use the jig. Now that we've got that slot established, use that to locate your depth so that every time the slot cutter comes across it's in that same spot, because what's going to happen with the jig is, what the jig is doing for you is it's providing support on the outfield side so you don't get chipping. So we want that slot cutter the same size and in the soil, same location, every time we use it.

So you're going to have to bid build jigs as needed as you change those parameters but they're so simple to make. It's not going to be a problem. Great way to add splines to a miter joint and worth try. And in your shot.