[vivek16]

1. obtain makeshift compass (some thin plastic or metal with holes drilled slightly farther apart than the radius of your sprocket).

2. use makeshift compass on suitable material( we used some 1/16 polycarbonate but any plastic thin enough to cut easily and still not fail will work)

3. cut out with jigsaw, bandsaw, scissors, dremel, hacksaw, etc.

4. cut a smaller hole in the disc you now have, glue or screw it into your sprocket so that there is an even ledge around your sprocket.

-Vivek

p.s. works like a charm, we used button head 6-32 bolts.