The Metric System
Back in the 80s somebody at our place decided we would go to the metric system. They made all the new part drawings in metric. Seemed like a good idea at the time. However all the NC mills, lathes, CMMs & other stuff was all programmed in inches. Had to convert every dimension. Then had to convert all the measurements back to metric to see if they matched the drawings when they were done. What a goat rope.
Thought we would fix some of that. Bought ovens that displayed temperature in C rather than F. Somebody set an oven to 160 C rather than 160 F ( some number of times). Quite a bit hotter. That was the end of those parts.
We finally gave up and went back to inches rather than recapitalize The whole plant.
Never have had a fondness for the metric system since that.