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Comment by Centigonal | Hacker News Reader

The spec is fiberglass, which has better thermal resistance.

But not that much better compared the better filaments out there. Fair chance it was printed out of PLA, ABS or PETG, by the shade of the part it looks like it was CF loaded filament.

A better choice would have been PEEK. But even then, I would have done a lot of on-the-ground testing before trusting my life to a part from the printer.

100% -- the original design for the Cozy is from the early 90s, before 3D printing became popular, and this part seems like a good candidate for 3D printing. It just seems like the maker chose the wrong materials and didn't test it adequately.

It's a candidate, but it is definitely not a run race, temps under the engine covers of a plane can get surprisingly high (surprising because you'd think you have plenty of airflow half a meter behind a pocket hurricane). I'm not sure if high temp filaments would be the solution here, but they'd be better candidates. It would need some very thorough testing before trusting your life (or in this case: someone else's) to that kind of solution.

There’s a massive difference between the thermal properties of the materials you listed.

Yes, that's why I listed them. And even then: none of those first three are (safely) usable for this application. PEEK or ULTEM or something better than that.

I absolutely agree. At the same time, I’m just flabbergasted that someone really thought they’d pass off PLA crap for such a purpose, it literally loses shape in sunlight. PETG isn’t going to cut it and I wouldn’t want to be on a plane with PETG in a heat-sensitive part, but that would still have been less ridiculous given that a) it’s significantly better than PLA in this regard, and b) unlike PEI and PEEK, it can be printed with ease on just about any FDM.

Whoever sold that part deserves to be sued. I'm not from the 'sue happy' department but this was extremely irresponsible and unless the swap for PLA was accidental (which can easily be proven, they must have sold more than just one of these). At a minimum they should recall each and every one of these they have made and on top of that they should review all of the other parts that person has made for similar issues.

My guess, given the sheen that looks like CF would be PA-CF, which is the most appropriate and common filament with CF.

And PA-CF is usually pretty good with temps, I have used it for parts on engines before with good results, but not in safety critical scenarios.

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