In accordance with an example embodiment, a wrist includes a frame, ring gearrotatable about aring axis, and motor assembly with a pinion subassembly and motor with anoutput shaft. Thepinion subassembly includes an internal spline and pinion connected toopposite sides of aninternal shaft and rotatable about a pinion axis, and motor and frame boltpatterns. The motor isfastenable to the pinion subassembly at a plurality of motor-pinion indicesvia the motor boltpattern. The pinion subassembly is fastenable to the frame mount at aplurality of pinion-frameindices via the frame bolt pattern so as to mesh the pinion with the ring gearand allow the outputshaft to drive the ring gear via the internal spline, internal shaft, andpinion. The distancebetween the ring axis and the pinion axis varies for the plurality of pinion-frame indices.
