How to Make a Spline Jig for Picture Frames and Boxes

How to Make a Spline Jig for Picture Frames and Boxes

November 30, 2019 100 By Peter Engel


Want an easy way to strengthen up mitered corners on picture frames and boxes? Check it! This is the second video in a multi-part series on picture frame making. You can find the other videos in the links down below. This here is a real simple and easy to make jig that rides along your table saw fence and allows you to cut splines in picture frames. Just using glue on mitered corners may seem good enough but over time as the width of the wood expands and contracts with the seasons the joints will eventually break. And that’s why you need splines. Unlike a lot of spline jigs this rides along the fence and not in the miter slot which means you can place the spline anywhere you want and even cut wider splines by moving the fence and making multiple passes. Setting the blade height is easy since the corner sits just a hair above the table and the two guides easily clear the blade. Let’s get started! I’ll measure the height of my fence and cut two pieces of baltic birch plywood to that measurement. Then I’ll measure the width of the two pieces and the fence and cut the top on the tablesaw. I’ll attach the top piece by lightly clamping the two side pieces to the fence and then glue and screw it together. Making sure it slides nicely along the fence I then attach the support board to the assembly. You’ll also want to make sure it’s square to the table before gluing it up. You can use any material you like but here I’m using MDF that will be used to hold the the picture frame in place. Although this step is not necessary I’m cutting 45° miters on the ends as you’ll see why shortly. I’ll then clamp down a drafting triangle to the support board and use a speed square to make sure it’s at 45°. The drafting triangle is then used as a
guide for the two MDF pieces The 45° angles we cut earlier align with the edges of the board. Again not necessary. After the MDF is clamped down I can then remove my drafting triangle and once everything dries we’re all set to cut some splines. Setting the blade height is just a matter of setting the picture frame in the jig and raising the blade to the desired height. I then slide the fence over and visually align the blade to the center of the frame. I suggest clamping the frame to the jig as you run it over the blade. I like to shut the saw off between every cut just to be safe as I don’t like handling material over a spinning blade. Over on the bandsaw I’ll then cut out the spines and glue them in place. A nice fit and doesn’t need to be too snug. No clamps necessary. And when they dry I just sand them down flush. You can also use this gig to cut spline keys for boxes using the same steps. I suggest using a full kerf blade with a flat grind. A thin kerf blade will work just fine and if your blade doesn’t leave a flat bottom cut, don’t worry about it too much. The tiny little gap that it may leave may not even be noticeable and it could always be filled in with sawdust and glue. Well thanks for watching! This is a multi-part series in picture frame making and I encourage you to check out these other links. Well that’s it! Be safe, stay passionate and make something!