Slow Motion Control Coming Together

The black squares on the spur gear axis are an attempt to stabilize the axis' position relative to the pillow blocks.  The screws are not locking the axis solidly enough.  I think stainless steel screws on stainless steel shafts are not getting enough bite.  Perhaps 6-32 set screws instead of machine screws?

As soon as I solve this, I will machine a flat on the end of the spur gear axis so that a handwheel can lock it down securely to allow rotation.   Perhaps I should machine a flat to allow the machine screw to lock down as well?