WoodsmithPlans Sandpaper Sharpening Plan‏‏

This jig is adjustable for different size circles and it’s held to the table with simple turnbuckles. You can cut circles on a band saw by simply driving a nail into a piece of plywood clamped to the table, using the nail as a pivot point for your workpiece. But if you plan to cut circles more than once, a better way is this shop-built adjustable circle jig. A sliding tongue easily adjusts the pivot point for different size circles.