Greetings to all; I am attaching scans of a tool that I once made my version of, for setting the table saw blade square to the table. It’s electric running on batteries with a led to indicate. You set it with a steel square on a flat surface; when both pointed probes are touching the blade, the light lights up. They work great and I’m making one after I finished my ersatz Biesmeyer fence. You can get the little battery holders at Radio Shack or simiar.
Check out the drawings and let me know if you have any questions about it; it’s really pretty straight forward though.
-- “Computers have enabled people to make more mistakes faster than almost any invention in history, with the possible exception of tequila and hand guns.” — Mitch Ratcliffe