Rough-cut two
circles 1/4" larger in diameter than the disc you want. Drill a 1/16" hole
through the center of one disc, which will serve as a model for the hole-free
disc. Clamp a block to the sliding bar so it will stop the bar's nail at a
distance from the sanding surface equal to the desired radius of your circle.
Slip the model disc's hole over the nail in the bar, and sand it to size by
rotating and feeding it into the sanding disc until the stopblock contacts the
jig's base. Attach the second roughed disc to the top of the model with
cloth-backed carpet tape, and sand the second disc the same way you sanded the
model.
