[KensRedZed]

It's impossible to cut brass tubing straight unless you have a lathe. Inexpensive roller bearings are sensitive to slightly uneven ends. Unsquare or uneven axle spacers can push on one part of the race, and wear the bearing out in no time flat. I used to make my own axle spacers. But since I sold my lathe, it's much easier and faster to use Sloting Plus spacers.

Axle bushings are not nearly as sensitive to uneven axle spacers.

Chris Walker taught me that the motor shaft creates a lot of drag to the crown gear. So, I cut the motor shaft down and let the gears run free. I Then need to use Sloting plus or NSR (both are good) axle spacers on both sides of the crown gear to have the perfect gear mesh. It's just a matter of measuring and installing the bushings. No fussing around. It's easy math.

   

Making sure the ends of the axle spacers are true, is critical.