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Comment by cinntaile | Hacker News Reader

Do you know how accurate it is?

I milled a test block in wood to check the accuracy, and it was sub-millimeter accurate. I can't measure further than that as my tools doesn't allow it. But I doubt that it's super accurate due to the 3d-printed parts, aluminium instead of steel etc.

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.

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.

That would depend on many things including the material and feed rate.

For plastic/wood you can get pretty decent precession on these machines within 200-300 microns or so since it should be rigid enough to not deflect much with these materials.

For smaller parts any issues of gantry squareness would also not translate to the milled part as much.

You can also cut aluminum as long as you are going slow to avoid deflection but don’t expect excellent surface finish and sub 500* micron tolerances.

*High end industrial machines can do tolerances within 10 microns when they are operated by an experienced machinist. 100 microns off spec not to mention 500 microns would result in parts being binned normally at least for critical tolerances.

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