Original CNC-Cut 3-way Interlocking Mitered Corner Joint.

This joinery sample was inspired by several 3-way miter joint solutions posted on YouTube.  A common one you can find is a solution with three unique parts that slide together using normally hand cut tenons into machine or hand cut mortises  Side one tenoning into the second, with the third part using two tenons to lock into the previous two. All the clever cutting hides inside the mitered facades. Optionally a tenon end or two can peek through the outside faces.

My goal was to come up with one unique part I could make three times using the same file on a CNC router.  They have a single tenon protruding inside their miter-cut shell. The core of the joint is a floating cube of wood with three mortises through it. Each of the mitered parts slide into one face of the cube.   The mortises in the cube are cut using the same single tool path file, with the cube rotated to a different face for each of the three cuts.

When assembled no end grain is showing. There is no external clue of what goes on inside this joint. When clamped together all parts bottom out against the cube making it easy to pull together tightly with no slipping of the mitered edges.

The tool path files for this joint can be scaled to any size within range of the router bits available.    This single corner example was done in 6/4 oak with a 1/4" diameter end mill to pocket around tenons and a 1/4" diameter ball nose bit  for the mitered edges.   I've made a 1/4 scale model of an 18" parsons table using this joint.  A 5/16" long 1/16" diameter end mill was all I needed for all the tiny tool paths required.

4D