Festool PN574332, DF 500, PI574332, PI574432, PN574432 user manual Making Three-Way Lock Miter Joints

Making Three-Way Lock Miter Joints

Three-way miter joints have been around for ages as a way of creating a corner joint without having any endgrain visible. Using the Domino Tenon Joiner, you can create easy to construct, locking, three-way miters.

The key to these joints is that they require floating tenons at 45 degrees to the main body of the wood. Unlike non-locking joints, no single piece can be removed from the joint without separating all three pieces. The joint must be assembled or disassembled all at once.

The first step in creating the joint is creating the frame stock. Each piece of the frame must be square in profile. In this example, the frame stock is 2 inches by 2 inches. Smaller stock can be used, but you may have to trim the corners of the tenons where they intersect (the transparent image in the middle-right shows the Domino tenons just barely touching).

The square frame stock then needs to be mitered. Each piece is mitered at 45 degrees from two different faces, creating a pointed, double miter.

With the frame stock cut and mitered, set up the Domino joiner. The following settings are based on using 8x40mm tenons in 2-inch by 2-inch frame stock:

1.Set the fence height between 8mm and 10mm.

2.Set the plunge depth to 20mm.

3.Set the mortise width to the minimum setting.

4.Using a sharp pencil, mark each mortise location at 45mm (1 ¾ inch) from the point of the miter (see image below).

5.Plunge a mortise slot at the pencil line of each piece.

6.Assemble all three frame members simultaneously.

18 Domino DF 500 Tenon Joiner