Belt drives?

[Wolftone]

Just a thought. What if you put a hole for a grub screw in the center of the part of the pulley that the belt sits on. eg in the groove.

[blimp]

Mmmm , how about - remove bosses, sleeve the bores and then key them together with pins , bolts , glue etc ? only the final drive one really needs to be fixed to the shaft . Then the gearbox in Danl's illustration would be very doable no ? I just posted the last link as an example , there are sure to be others out there * another linky , SDP's range http://www.sdp-si.com/eStore/CoverPg/Dr ... onents.htm" onclick="window.open(this.href);return false;