[martin417]

Not easy to do, but first you have to press off the gear that came on it (be very careful, the magnets inside are fragile!) then you have a 1/8" diameter shaft you can use as you see fit. (the shaft is knurled for the gear press, but you can run he motor and press a small file against the shaft to get rid of the knurl). You can use 1/8" bore sprockets with setscrews.