Splined Miter Joint Jig

by Roger on January 8, 2012

When I’m making picture frames, I like to “beef up” the mitered corners of the frame with a spline.  As you can see in the photo, using a contrasting wood provides an opportunity to highlight the joint.  Or you can make it nearly invisible by using the same type of wood.  Either way, the spline adds a lot of glue surface that really strengthens the joint.


Splined Miter Joint 300x202 Splined Miter Joint Jig

Splined Miter Joint


To cut the kerf for the spline, I use a shop-made jig that straddles the rip fence on the table saw, as shown in the drawing below.

Screwing two supports to the face of the jig at a 45° angle to the blade forms a “cradle” that holds the glued-up frame securely in place.  All you need to do to cut the kerf is set the frame in place and make a pass across the saw blade.  (I use a rip blade to cut a flat-bottomed kerf.)


Once the kerf is cut, you can glue in the spline.  After gluing and clamping the joint (see detail), remove the excess material with a handsaw and then sand the spline flush.

Splined Miter Joint Drawing 300x203 Splined Miter Joint Jig

Splined Miter Joint Drawing

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