Flat cars teach a Lean lesson

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.

Flat car not going to plan

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.

Flat car weights

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