Machinery depends on metal-working to a fine-enough precision. Steam can escape through very fine gaps and greatly reduce the effectiveness of the engine. Apar

Machinery depends on metal-working to a fine-enough precision. Steam can escape through very fine gaps and greatly reduce the effectiveness of the engine. Apart from that being a dangerous place to be in for humans. Even 60 years ago, your new car needed to be 'run-in' for a couple of thousand miles because tolerances in the cylinders weren't able to be made fine enough yet. When was the the last time you had to 'run-in' a new car?