[Dick Linn]

I would not depend on banging in keystock and having the gears stay put and in proper alignment. We initially hacksawed spacers just a wee bit long, after using a magic marker and the jaws of a vernier caliper to scribe a line at exactly the right length. The trick is sawing part way through, all the way around, right next to your scribe line. Otherwise you don't get a straight cut. With practise, I could get within a few hundredths, but it's a bit of work. Then the trick was to file the ends parallel and make each pair the same length. Still, we managed to get a number of them to within, I'm guessing, .010 of what they should be. Later we got a cheap $4 tubing cutter, which makes it a whole lot easier to cut the tube straight, although you still have filing to do. I used a short piece of 5/8 inch wooden dowel clamped vertically in a vise and let the spacer protrude just a bit above when filing.

I measured the gearbox and the tubes are nominally .750 for the short ones and 1.1875 for the long ones. This is without any spring preload washers. I still do not know how much shorter to make the spacer tubes in order to properly preload things using the spring washers that came in the kit. (These are the slightly cone-shaped steel washers.) They are too large in diameter for the small gear but can butt up against the large gear. If the spacer tubes are too long, these axle assembly will push too hard against the bearings and create a lot of friction. For now, we're trying to use only the tubes, make each pair on a shaft exactly the same length and end up with little or no slop.

If you do get spacers of equal length but get them a wee bit short, you may be able to find extremely thin shimming washers to add to each end to take up any slop.