[BP-Revo]

Looks like someone beat me to the response with the flat spot - and yes, this is possible. However, in my mind I feel much more secure with a physical pin through a hole than a simple loctite'd set screw. I understand that certain loctites are like cement, but even so, in the end its a screw, and screws eventually work their way loose.

As for the space, I just left it as is. If I turn the pinion around (set screw toward the motor with the gear toward end of shaft) it lines up without a problem. Its a 4mm shaft so I'm not worried much strength wise. 5mm shafts will be even better.