pulley for cheap skywatcher electric focuser on a dobson with 1/10 crayford

To make it function, you will need 2xM3 screw for fixing the gear motor on your Dobson, 1xM3 screw with a nut to fix the pulley on the motor shaft and a B100MXL belt (old ultimaker motor belt) to drive the fine tuning of the crayford.
This system is reversible, with the other focusesr it's impossible to adjust manualy the crayford when the focuser is mounted. With mine you just have to take off the belt..and put it again when you need it....etc.
you will increase the precision ratio of your cr