Mitered joint jig

[mklotz]

While building my trefoil...

Cubic trefoil

and infinity cube...

Infinity cube

models I quickly realized that I needed some way to glue small, mitered lengths of wood into accurate orthogonal shapes.

The mitered surfaces in contact are small so, for a strong joint, I prefer to use wood glue. The wood pieces need to rest on a flat surface and be held at a 90° angle while the glue dries. Although I try to use a thin layer of glue, squeeze out can occur so the pieces need to be held in such a way that they can't glue themselves to the flat surface.

All of these conditions led to this design for a jig...



Two guide strips were glued to a scrap of thin 5 mm plywood. A machinist square kept these strips orthogonal as the glue dried. The area of the plywood where the miter joint will lie (regardless of the size of the mitered wood) was cut away. This guarantees that any joint squeeze out won't contact the plywood.

A picture of the jig in use will make things clearer...



As this picture shows, the resulting joint is very nicely orthogonal...



Now, I realize that most people will not have use for a jig for making mitered joints in 6 mm square sticks. What's important is the form of the tool, which can be scaled up to almost any size. A metal version could be used to solder/braze mitered joints in metals.