Shopsmith has tips for making a jig for making finger or box joints on the table saw using a dado blade. This link covers many types of joints ... scroll down for Finger Joints.
http://www.shopsmith.com/academy/tblsaw ... /index.htm
Attached is a rough sketch of how I would modify the jig shown for 90 degree angle corners to be able to make 60 degree angle corners.
- 60 degree box joint jig.jpg (200.52 KiB) Viewed 1151 times