My circle jig uses my router table, which is set into my saw extension table. I made it to zero out the axes so that the y axis is a constant 0 and the x axis is zero when the saw fence is set to 42". This makes precise sizing possible. Just subtract the radius of the circle and the radius of the router bit from 42, set the fence to that number and start cutting. I can cut about a 20" diameter circle from a square. Much larger ones if I rough round off the edges first. I made it originally so I could cut circles for my dust collection contraptions.
Losing fingers since 1969