Clock Script for Reduced Friction (4 gears, 2 shafts) (Q45486)

This is an alternate configuration for the printable clock, using four gears instead of eight, as well as some suggestions from rustedrobot and barrychuck (thanks guys!) to further reduce friction in the gear train, like only using concentric shafts to support the hands. It's also much faster to print, of course! :-) Because there are fewer gears, the 60:1 reduction is accomplished as 8x7.5 and the 12:1 reduction is accomplished as 4x3. This places some severe constrainst on the size of the gear hubs, but I think I managed to make everything fit. The downside in this trade-off is the size of the gear teeth, which is much smaller than in the 8-gear version. We'll have to see if it was worth it. This script relies on both the MCAD involute_gear library and on my own clockwork library. Current repository for the latest version of the clockwork library: http://www.thingiverse.com/thing:8155