Are you seriously telling me that American ballscrews never wear out and need replacing, and that a switch to SI would be difficult?
(Very conveniently and accurately enough, Diesel and steam engine indicators usually had springs that were calibrated to 1kg/mm, which was also 360lb/inch. Obviously you can’t do that with a ballscrew, but a conversion in the ratio 2.5:2.54 has little effect on manual setup. 2.5mm/rev with suitable readout isn’t very difficult. In fact, I have seen old machines in the UK which still retain Imperial screws but have simply been fitted with motors, shaft encoders and conversion software to provide simple CNC control and drive displays.)
