I've used 1/2" lexan & other bits of thin plastic, cardboard and
paper. Cut out a 2-inch dia. circle with a hole saw on the drill press
and then bore out the centre hole to 5/8" (or whatever your arbour
diameter is).

I had not thought of those materials. I have some 1/4 (I think) phenolic
plate that never because a router table for over a decade ago. That might
work well. Glued paper might just be the thing for final adjustment.


Note that a 1/2" spacer won't give you a 1/2" tenon as the carbide saw
teeth project further than the sides of the blade. Hence the need to
add thinner plastic or cardboard shims.

Yup. That's why I had planned to possibly use dado shims.

Thanks for the ideas.

-Steve