Thanks for this info Rick.
On an older thread I pointed out why electric sharpeners led to uneven (curved) cutting angles and advised using a file with a gauge attached, same number of strokes on each cutter from the same angle of 'attack' (i.e. half from one side of the bar that cut one way, half from the other).
Was unaware of the hard chrome factor and will go from the soft side in future. Makes real sense which side to file from.
Razor blades were subject to a patent years ago on the same principal (soft side corroded / wore away and were self sharpening but the big players apparently bought the rights and that's why throwaway stuff is not cheap.
Snow ski edges is something else similar I recall.
DL



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