These are common frames artists to strech their canvas on. It is a floating hardwood angled tongue and groove joint. It's a little more complicated than that. They use "keys" to tighten the canvas, in time the canvas tends to loosen and sag. They interlock with no glue or fasteners.
-Joe
Maitland, FL
Our Expert
This joint is essentially a mitered spline joint which can easily be cut with an Amana Prestige saw blade and a tenon jig on the tablesaw. The groove for the adjoinin
g spline is cut with the stock on end and supported by the jig. As you can see in the drawing the jig rides along the fence and the fence keeps
the jig and workpiece on a linear path.
The miter is cut on the tablesaw with the blade height adjusted to create the shoulder of the spline.