Gluing miter joints can be a problem. They tend to slide around when you clamp them. And a miterj o int isn't really that strong because ifs an end grain to end grain joint
So to make a miterj oint easier to assemble and stronger, I often add a spline, see inset photo. Usually 111 cut the grooves (kerfs) for the spline with a table saw. But in some situations (when working with thin stock or when the splines are exposed), narrow or flat-bottomed grooves would be better.
Thaf s the advantage I saw in this jig designed by Gregg Eaton, of Fort Collins, Colorado. It uses a router table and a slot cutter to cut the spline grooves. Slot cutters cut a flat-bottom groove, and the groove can be as narrow as Vi6 11.
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