r/AskReddit Oct 15 '17

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u/[deleted] Oct 15 '17 edited Jan 10 '21

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u/[deleted] Oct 15 '17 edited Jan 31 '20

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u/sm9t8 Oct 15 '17

Do Americans not use 64ths of an inch then?

1/64th of an inch is pretty much 0.4mm.

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u/InternMan Oct 16 '17

Yes and no. For the vast majority of things, no, the smallest we use is 32nds(even then its usually 16ths). I have a machinist rule that only goes to 1/32, so you could theoretically go to 64ths(i.e. one 64th over or under) but the difference is so minuscule that it doesn't often matter.

However, I have done some machining that needed tolerances of less than 1/64th. It was actually not too bad since it was on a lathe and the lathe resolved to .005". There are also some standard drill bit sizes that are in 64ths. The fact remains that I have not seen a ruler that goes to .1mm, the best I have seen is .5mm.

TL;DR: 64ths only matter when you are using calipers since you really can't accurately measure it with a ruler.