Rustedrobot reports that there are alignment problems with the gears from the clockwork library. Some of that can be fixed by making the gears thicker, and tightening the tolerances between the gears and the shafts they sit on... but he points out that herringbone gears might really help.

I implemented herringbone gears in the clockwork library, made sure they meshed, and while I was at it, beefed up the pinions and introduced a little (parametric) space between the two gears of a wheel... because with herringbone gears, the gears MUST line up.

To use the herringbone option, call the pinion modules normally (pinionWheel, pinionDrum or pinionEscapementWheel) and pass the argument twist_factor.

It adds herringbone to the gears by exactly twist_factor times the size of the teeth of the pinion, e.g. twist_factor=1 means the pinion has 45 degree herringbone.

The default value if you don't pass the argument is zero, which corresponds to normal gears.