At the request of oscorner, I’ve posted some pics of the jig that I use to cut box joints on the table saw.
The box joint jig that I use is a shop made jig from ¾” Birch ply. I recall getting the plans from a Mark Duginske book (“Mastering Woodworking Machines” – I think). I remember that he called a “Universal Table Saw Jig” that you adapt for making box joints. So, it basically improves upon the stock miter gauge and if you make up a bunch of fences you can use them for various box joint sizes.
It’s about 4” high (or wide) and 20-some-odd” long.
Here are some photos…starting with the basic backer that mounts to the gauge and has holes to accept the various fences:
The front of the fences receive a ¾” groove, 3/8” deep or so (I made these a while back, so I’m sort of winging it with the description) and then a ¼” groove all the way through cut on the router table:
Here’s the back of the fence:
This is the “slider,” cut to fit the groove to allow for adjustment of the fence:
Slider with ¼-20 machine screws, washers and wing nuts (WOW!):
Front view all mounted up (happens to be the 3/8” box joint fence):
Rear view all mounted up:
An assortment of fences for various sizes:
-- Dorje (pronounced "door-jay"), Seattle, WA