I served a machine shop apprenticeship in England back in the 70's. At that time we were 50-50 metric and imperial.
We were taught to use measuring equipment (micrometers, verniers rules etc.) to match the drawing irrespective of the scales on the machine tool. Just convert 25.4mm to the inch (or 0.0254 mm to the thou) when setting the dials / scales etc on your machinery and measure in the units on your drawing. This has worked for me for the last 40 years (and is why I possess 4 imperial micrometers and 4 metric). HTH.
John
Amateur Audiophile and Backstreet Boffin.
Original Foreplay with C4S + Sweet Whispers
ParaSEX amps with MQ nickel-cored outputs
Factory-built Lowther Acousta 115s with silver-coiled DX3s, wired in DNM solid-core
KEF active sub (help for the last couple of octaves).
Bottlehead DAC on batteries.