The Toyota Production System — Lean Manufacturing here in North America — will tell you that batch-building is bonkers. Lean suggests that we should limit work in progress, and build things one at a time. By building in batches, we build batches of blunders.
Maybe they’re right. As I started assembling the flat car sides and ends tonight, I found that the outermost nut-bolt-washer casting is almost beyond the edges of the side sills. I will probably have to shave all twelve of them off and reapply them. That’s twelve NBW castings that I could have saved myself.
I only got as far as assembling a single car before deciding that I need a better way. Predictably, the wood layer on the inside of the sills wicks solvent away from the bond, and makes it difficult to get a strong styrene bond. Adding more solvent yields a car that is permanently fixed to the canonical load – unless you panic quickly.
I think I will assemble the sides around the weights instead. Offsetting the hard lessons of the evening, the weights came out pretty close to bang on the measurement predicted by OnShape. Being 1/32″ lead, they’re very soft, and I had to roll them with a rolling pin (not the food one) to get them flat.