There are five. DNA and RNA each have four but not the same four. RNA uses uracil instead of thymine. The basic five can be modified after the nucleic acid is formed, methylctosine being the most common.

There are also a bunch of other nucleotide bases that aren't normally incorporated in DNA or RNA, some of which have been found in space, and artificial ones we've engineered to fluoresce or kill cancer.

I've done my first test of buying a whole pallet of filament straight from a Chinese manufacturer. It's a risk - it could be all junk - but if it's usable, the price advantage is insane. Like $3/kg for PETG at the factory gate (like $5/kg after sea freight and our 24% VAT). Versus local stores which sell for like $30/kg.

I'd love to see someone try to 3d print with a filament that melts at 162K. Where do you even buy xenon filament? ;)

Yeah, if you had injected moulded PLA, it would have been just as terrible

Early on, I was overdoing chamber heating, and later discovered that was part of my problem. A blanket and a duvet can get a P1S's chamber over 70C. But if you do that, in my experience, like half an hour or so into the print you'll get heat creep problems and the filament will split & the extruder will just dance around in the air as though it were clogged (though maybe my filament was just garbage... it certainly was *wound* terribly). I ended up using a meat thermometer stuck in through one of the holes to measure temperatures, and then I'dadjust the positioning of one small blanket over the chamber to try to keep it in the mid to upper 50s, and was able to finish big prints that way.

But yeah, whatever means you use, you need some sort of raft and very strong reinforcements.

As was mentioned earlier, this isn't talking about a turbine blade, it's talking about an air intake. Also, "millimeter level"? This isn't the early 2000s. I usually print with a layer thickness of 100 microns, and the printer's control of the Z axis is well finer than that.

The problem is that they made an insane choice of a material for the intake. It was supposed to be ABS-CF, but instead it was apparently PLA. Corn plastic. The stuff people make Warhammer figures and the like out of.

I mean, the fact that PLA's chain is vulnerable to scission by water is in a way nice - not just from a compostability perspective, but from a health perspective too. I don't mind sanding PLA, for example, because PLA microplastics aren't going to build up in your body the way that, say, PETG or ABS might. At 60C, PLA microparticles decompose fully in just 10h. It's significantly slower at lower temperatures, but still, they don't persist. Also, a lot of people like that it's made out of corn rather than petroleum (personally, I don't care).

But yeah, it's pretty insane to use a PLA part on a plane.

It's pretty counterintuitive for those used to working with macroscopic fibre composites. For example, glass fibre fill adds more strength than CF fibre fill (CF fibre fill adds more stiffness). Because it's not so much about the strength of the fibres themselves, but rather how well the polymer matrix grips the fibres.

an aquantance made one from PLA ... ... WHY?

There's literally no reason you shouldn't at least use PETG. PETG is even *easier* to print, and *cheaper* than PLA. Was this long ago, when PLA still had a stranglehold on the market?

Aviation has a lot of rules, but it's not for pointless reasons. When things go wrong in aviation, they tend to go very wrong, and you sent some big heavy mass carrying hundreds of people travelling at many hundreds of kph crashing into a building.

Jesus. PLA has *no business whatsoever* being *anywhere* on a plane. Even in the cabin. It can melt in a hot car on a sunny day. It's hard but brittle. It's not entirely water-stable. It's fine to make a *model* of a plane, but making actual plane parts out of it? That's insane.

For any non-printers in here: PLA is "corn plastic". You know those compostable grocery bags? Those are mainly PLA , plus some PBAT (another biodegradable polymer, added to make it flexible). Imagine a rigid version of those bags - that's what PLA is like. They made a part out of that and stuck it on a plane.

The fumes thing is overrated - typical measured levels in a room printing ABS are in the ppb range, whereas the PELs are in the ppm range. That said, don't sit right next to your printer for a long time while it's printing if you don't want to breathe a lot of styrene.

Main annoying thing is that ABS is hard to print. I mean, it's far from the hardest, that'd be something like polypropylene or whatnot - but vs. say PLA and PETG, there's a learning curve. Big thick ABS cantilevers and the like can accumulate some really significant thermal stresses. It takes practice learning how to control them (using a raft and an appropriate plate coating for the base, going way-overkill with really frequent, very sturdy supports on cantilevers, etc).

You can do PPS at 300C and it has nearly as high of a working temperature. From a factory in China I've bought filament from before, you can order it (with a minimum order of like 60kg, mind you) for like $15/kg.

PPS is a fun one. Maximum service temperature of 220-240C, yet melts at 280C and you can print it at 300C (doesn't require a super-high-temperature printer). You can literally cast some pewter alloys directly in it in a hot oven. :) Also does not dissolve in any known substance below 200C.

ED: Sorry, didn't read enough into your post. But the TL/DR is: know what stresses and temperatures your part will be exposed to, and make sure the part can actually withstand them. And if you can't do it directly with plastic, then either use something like Virtual Foundry Filamet + sintering, or print a mould and cast it.