3D Printing

4538 readers

36 users here now

For everyhting 3D printing related.

Please be excellent to each other :)

Icon by Freepik, Banner photo by Thiago Medeiros Araujo

founded 4 years ago

MODERATORS

[email protected]

Does PLA go bad? (lemmy.sdf.org)

submitted 1 month ago by [email protected] to c/[email protected]

11 comments fedilink hide all child comments

And more strangely, does it suddenly go bad?

I printed this pair of glasses with a roll of ugly bright green PLA I use to print prototypes or silly things with - because, well, it's ugly - at the last minute to go to a party where the idea is to not look too serious.

But it took me three tries: the nose bridge readily broke off the first print without even trying very hard, and one hinge split in the middle before I could even drive a pin through it. I was really careful with this third print and I managed to complete the assembly and leave to go to the venue.

But it's really weird: this roll of PLA had been in the printer's room for at least 2 years, I and others have printed a million things with it without any problems as recently as last week - including multiple iterations of these glasses - and today the prints feel "dry", or less "waxy" that other PLA parts when I file them smooth, and they're really brittle.

Also, it's winter and here up north, it gets really dry in the winter - like 15% humidity - so I'm pretty sure the material is quite dry.

What gives? Any idea?

top 11 comments

sorted by: hot top controversial new old

[–] [email protected] 11 points 1 month ago (1 children)

Just because the room is currently dry doesn't mean the filament is dry. But that said filament doesn't suddenly go bad, it takes time for it to absorb humidity and start having it's problems.

If something suddenly went bad I'd be looking at your printer. As the other person said check your nozzle for clogs, double check the nozzle itself didn't get damaged (or maybe just replace it anyways) And generally check it's calibration.

[–] [email protected] 0 points 1 month ago (1 children)

It's been below freezing and super-dry since October here. So I'm pretty sure the filament had time to dry "naturally" - if that's even a thing.

As for the printer, I printed a bunch of stuff in PLA and PETG before using the green filament, no problems. But yeah, maybe something went out of whack just as I switched filament. I'll check tomorrow. Thanks!

[–] [email protected] 6 points 1 month ago

Nah, it’s regularly 5% humidity here in Colorado and even a single slightly humid day (20%) is enough to wreck the filament. I’ve resorted to actually drying my filament and storing it enclosed and my print quality went up dramatically.

[–] [email protected] 7 points 1 month ago

Not so much go bad but kinda like others have mentioned, moisture in the air will always eventually get soaked into it. It’s worse with other filaments - Nylon, PETG, and ABS are particularly bad for it - but PLA definitely shares the same issues. Moisture from the air also doesn’t just suddenly leave - you need to manually and purposefully dry the filament out with a filament dryer or food dryer. Moist PLA can print just fine, but the moisture can also cause the filament to be super brittle, and/or cause little bubbles or breaks in the filament after it comes out of the nozzle.

Not sure why it would appear to have happened suddenly after a number of years, but I have a suspicion that it probably didn’t happen quite as suddenly as you think it did. Could also be the shape of the roll itself - maybe it’s got little “windows” towards the center of the roll that allowed in more moisture than the closed-off portions and you only just now used the roll up to that point?

[–] [email protected] 5 points 1 month ago

Could be that specific roll is just low quality, or the brand is kinda low quality

As for a reason to "suddenly" go bad, maybe it's due to the winter and some of the layers were too thinly melted together?

[–] RememberTheApollo_ 5 points 1 month ago

Just because it ran through the hotend doesn’t mean the moisture magically vanished. It’s not droplets of water in the plastic evaporating, it’s molecular water vapor. It’s still there, just probably less of it after being heated. Also, some plastics have volatiles that help with flexibility that disappear over time. Dunno if PLA or cheaper PLA has that issue, but it’s a possibility. I’ve found the same issues you have with PLA cracking when old after printing. Not sure what the cause is.

[–] [email protected] 4 points 1 month ago (1 children)

Partially clogged nozzle?

[–] [email protected] 2 points 1 month ago (1 children)

I don't think so. I printed other things in different rolls of PLA before the glasses and they came out fine. Also, I purged several times to switch to green and the flow of molten PLA looked normal.

[–] [email protected] 3 points 1 month ago (1 children)

Hmm, how much did you print with the spool? Is it possible it got moisture in it, but sitting for so long dried out the outer layers of the spool but not the inner layers?

[–] [email protected] 1 points 1 month ago (1 children)

It's a one-kilogram spool and I'd say half of it is gone. It's never been problematic in any way. It even got a real workout recently as my coworders used it quite a bit to print Christmas tree decorations. Again, nobody had any problem. And in fact, it printed my eyeglass frames just fine - three times. It's just that they were really brittle for some reason.

Before leaving yesterday, I started an 8-hour print with a spool of flat black PLA. I'll see how it turns out today. If it's good, I'll reload the green filament and reprint the glasses to see if they come out as fragile as yesterday. It's a 10-minute print so it's a quick test.

[–] [email protected] 2 points 1 month ago

Yea, super weird. Curious how the black turns out, maybe you just got a bad spool with a manufacturing defect.