Easy splines for mitered corners (biscuit joiner method)

I’m currently working on two projects: the nightstands to match the bed I recently made, and also this desk that was commissioned for some friends.  I am not going to share the entire build process for the desk (I think they’d appreciate their desk being unique), but I wanted to share an easy little workaround I made for a spine jig.

“What is a spline?” you may be asking.  Well, when you make mitered corners for any sort of box, the corner ends up becoming two pieces of end grain that are joined together.  End grain glue ups are substantially weaker than long grain (face grain) glue ups.  How do we improve that?  Well, one way is to add a spline.

For a picture frame or small box, you can accomplish easy splines by creating a sled for your miter saw that you set the frame in which will cut a slot perpendicular to the miter.  For a big desk like this, though, it becomes a lot harder.

One solution is to use a biscuit joiner on which you create a jig that attaches to the joiner.  I really didn’t want to spend a ton of time building that.  All I needed was a perpendicular reference point; I could use the fence on my joiner to adjust the height, and use the alignment points to make sure I got the corner on center.

The solution?  Use two cutoffs to create a reference edge!

Since these are cutoffs from the stock I used to make the mitered edges, the height is exactly the same, making clamping a breeze.  And, since I used my miter sled to cut them, I know they’re accurate 45 degree angles.  I just plunge the biscuit joiner in at it’s deepest setting to cut the slot.

I ran a strip of 1/4 inch walnut through my planer until I got a snug fitting piece that would slide in the slot.  Glue liberally, let them dry.  Then, use a flush cut saw to cut off the excess, sand, and finish!

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