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Comment by wolfram74 | Hacker News Reader

Being a spherical cow loving physicist, I still get caught off guard by what counts as "precise" in engineering contexts. Even when I'm making stuff in meat space I don't think I've ever bothered to intentionally get better than 1% relative precision.

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For a framer, 1/8” is precise enough. For a finish carpenter, 1/32” is precise enough. For a 3D printer, 0.004” is precise enough. For a machinist, 0.0005” is precise enough.

0.004" is read as "four thou", and 0.0005" as "five tenths", as in five tenths of a thou, FWIW.

I only picked up imperial thanks to binging This Old Tony videos.

If you enjoy https://www.youtube.com/c/ThisOldTony, you might also enjoy https://www.youtube.com/c/Clough42 https://www.youtube.com/c/Blondihacks and https://www.youtube.com/user/JohnGrimsmo

Unless it's PCB, in which case its "4 mil", as in milliinches, among the great bastardized units

It really depends on what you are doing and what 1% means. For example, a tiny ridge on a sliding surface will result in a noticeable catching of the slider down to even visually imperceptible heights.

Being a structural engineer, I usually think the same way. But then I started tinkering with 3D printers, built a MPCNC, and have since busted my share of endmills due to accuracy and repeatability issues. Being off by a fraction of a mm is enough to bust your tool or mess up the workpiece.

Hello! I have seen your question about the the pf3cmp file of the perform-3D .Have you solved the problem? Cause i have the same question right now.Thank you very much.

It's worth reading the various recent articles about the construction of ASML's machines that make next-gen chips. LIGO, and diffraction gratings are two other nice examples.

It's basically the culmination of thousands of years of humans getting better at precision. Things didn't take off until the 1700s, really got amazing around WWII, and has undergone amazing results since then.

There's a long way to go still. Nothing in your house is made to LIGO precision, not even your own body, the spiders, and the bacteria in the toilet, which are all a lot more precise than next-gen chips.

you're misusing the term precision to apply to size. Precision doesn't mean anything in bacteria.

I meant precision, not size. Bacteria build their proteins with ribosomes, which assemble the proteins with atomic precision (about 100 femtometers). LIGO is built with several orders of magnitude tighter tolerance than that, but none of the parts of your computer are even that precise.

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