bobj3 - Thanks for the quick reply. Maybe I should have been a bit clearer. I know there is a woodworker's formula that involves the diameters of the bushing and bit. So, I have a piece of wood that's been made from several pieces which have been biscuited and glued together. The finished size is 12" in diameter. I would like to cut a circular jig out of some 1/2" thick ply I have. I'll clamp the circular jig on top of the 12" round finished piece I have and I want to route around the jig using a 5/8" bushing and 1/2" straight cutter. I'd like to calculate the diameter of the jig before cutting it out. My intent is to leave a 1/8 to 1/4" wide lip around the entire top of the finished round board. I used to know how to calculate the diameter of the jig I need to cut out with a jigsaw - but my memory is on vacation. Thanks again! |