Miter joints are some of the weakest in woodworking because of poor end-grain to end-grain gluing. That’s why I always reinforce my miter joints with a decorative spline.

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Miter joints are some of the weakest in woodworking because of poor end-grain to end-grain gluing. That's why I always reinforce my miter joints with a decorative spline. I used to cut the spline slots with a V-groove jig on my tablesaw, but that gets awkward with a large frame.


I now use my biscuit joiner to simplify this process. By adding hardboard plates to the jointer's fence, where shown, the slot is automatically centered on the joint. I cut two triangles and screwed them to the fence with the inside corners touching.

One caveat: Remember that you could accidentally cut into the added plates with the joiner's blade if you don't properly adjust the depth.
—Jack Williams, Elephant Butte, N.M.