I am using a Prusa i3 printer, and have been for about 6 months now and it has held up very well. However, recently I got some new PLA filament and have been having some issues, I have only had it out of the box for about 3 weeks now and it seemed to be working fine. But, now every time I print, the filament seems to work fine until I have finished. Now, after leaving my print resting on the bed, I find that after 2 hours or so, the filament begins to break in the PFTE tubing. And after leaving it over night, it is completely snapped loads of times into segments of about 1cm. (I must add at this point that my previous filament worked fine). This now leaves me the job of trying to get it out of the tubing which usually presents a struggle. I have now resorted to retracting all of the filament on to the reel after printing. I was wondering if anyone had a solution to my problem as it has become very time consuming… I was wondering whether it is simply a quality issue? …or maybe something else?
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I have had exactly this issue with PLA that I got from Fry’s Electronics. It was fine for a couple weeks and then it started behaving this way. I did the same thing you did - put it back on the spool after every print. Since it was fine when it was first opened, I would have to assume that it has something to do with moisture.
I’m keeping my filament in a big plastic bag that has a valve to suck the air out with a vacuum now. I pack it with reusable moisture absorbing silica beads. Hopefully this will be the last roll I have to recycle. I’m not patient enough to mess with a problem like that.
Thanks for the idea I did think that it might have something to do with the moisture so I will check out the vacuum bags. Thank you
I had this happen with voltivo excelfil black PLA filament. The company was helpful and replaced it but even the new filament does it. Not sure what is different about their formula. Fresh filament seems flexible but once it’s been straight for a few hours it is quite brittle.
adiab
5
Alot of people think that it’s a moisture absorption problem with pla but it’s not. It’s the mechanical stress of being straight after having been curled around the reel. If it was moisture it would continue to break along the air exposed filament but you will find that only the straight part breaks. Some filament brands are worse than others but filament from Frys is especially bad. Hatchbox filament works well in my experience.
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drakkn
6
Sounds like a quality issue , contact the supplier and see what they have to say.
PLA absorbs moisture, so you need to store it somehow where it cannot absorb, or at least to minimize the amount absorbed.
When I purchased my printer, it came with a spool of PLA already opened, and the exact same issue was occurring. Once I purchased a quality filament, I have never experienced this issue since. I also store any spools not being used in sealed bags with those absorbent silica packets. So far so good.
If its a new roll, then it must be a quality control thing. I cannot state enough how important it is to purchase quality material, and pay a few extra bucks. The headaches it will save you is easily worth it.
I’m fairly new to 3D printing, but this is my take on it 
adiab
8
Moisture absorption does not cause the pla to snap off. It is the mechanical stress of being straightened. This is evident in the way that the brittle part of the filament is not the exposed part of the filament but the part that was held straight. If it was mousture absorption the entire exposed portion of filament would be brittle. I do not store my pla in air tight containers and it is still perfectly flexible when I go tp use it. I also print alot, nearly every day on multiple printers and have been for a while. Quality filament snaps less often than poor quality filament but you do not necessarily have to store it in an air tight container. Another thing is that quality filament is not always more expensive. I have been using Hatchbox in mu custom delta and it works well at only ~24$ for 2KG roll.
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From what I’ve read, PLA certainly absorbs moisture, and to combat that I store my PLA in as close to air tight environment as possible. I was simply stating my experience, and the combination of using high quality filament, and proper storage of my PLA I have never had the issue occur again. Like I said, I’m fairly new to 3D printing, but this combination has worked flawlessly for me. I’m certainly not going to take my chances when it comes to storage when it’s a fact PLA absorbs moisture. Perhaps it is not causing the snapping, but I’m sure it can be a factor when it comes to inconsistent printing results.
3DWelt
10
I’m thinking the same.
Quality is a big thing in this case…
We use our own Filament (www.3dwelt.ch) Made in Germany. The Spools are Made with 100% clean Powder PLA / ABS. So there is no impurity that make problems with printing. Sure. The Price is higher. But it is it worth. So we can offer good parts to our customers.
Hope your problem is solved.
Good print!
adiab
11
I have read that too but my experience has proven otherwise. The pla will only break where it was stretched out straight. If it was a moisture problem it would break much farther down the roll. I leave spools on my printer for days in humid environments and it only ever breaks where it was stretched straight.
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This is consistent with my experience too. I’m in a very dry environment and through various tests, it does seem to be related only to holding it straight as happens in the guide tube. That additional stress applied seems to cause it to get brittle. Even if it doesn’t snap on it’s own, sections that have been held straight are much easier to break. There may be some sort of stress/strain induced phase transition in the material: something similar to work-hardening metal by bending it repeatedly.
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RCole
13
After reading through the answers here, I have to say that both sides of this argument are right. Being straightened coming off the spool puts more stress on the filament and it is more brittle after absorbing moisture. It is both of these that causes this problem as often as not (yes, cheap, low quality filament is much more prone to this problem).
I had this problem with a roll of filament, but only after it had been used for a while. Every morning, I was cleaning all the small pieces out of the tube. I put the roll in the oven and baked the moisture out of it (and now keep it in a sealed bag with silica packets) and the problem went away. Keep your Filament dry and there will be less of this problem - dry PLA is more flexible.
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Adagio
14
Hi! Please tell me how you “baked” the filament?
Because, it’s pretty annoying to have to respool the filament every time… Much appreciated!
RCole
15
The link I have stored for this is this one.
The basics: long low heat. Bake at 185F for 2 to 3 hours (depending on how much moisture to be removed). A lot of ovens won’t go this low, so then it’s store in a sealed bag with desiccant. Luckily, I have an over that can maintain the low temperature. Low temperature is needed to keep the filament from all sticking together on the spool.
Bit of a late reply, but hopes it helps anyone out there. Simply put cheaper graded pla snaps and becomes brittle.The actual extruding process to form the uniform diameter of filament is a stressful procedure on the filament itself. Quality filament after extrusion is destressed and coiled carefully with meticulous stages. If a cheaper filament is stored in different transitions of temperature then this will impact the printing quality and often cause jamming, sometimes even higher temps required up to 250deg.(yep on pla). If you unfortunately purchase what seems to be awkward stuff the best solution would be to bin it, if that’s not an option then store the roll at a constant temp ie.Main living room in the home as this is usually the warmest and most stable temperature room. And of course use it all up as quick as you can. I have cracked it with lots of trial and error and no longer buy the sub £15 filament. Hope this helps.
I had same problem and where I live really humid and I had to dry my pla constantly, and I don’t have low temp oven so I use heated bed which is perfect size for 1kg spool and temp controlled.
Just set temperature to 85 c cover over the bed with some kind box leave it for 3 hours.
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Lol, I’m an idiot for not seeing this myself - this is such a simple solution compared to messing around with the oven. Thanks!
I’m using an old round cookie tin as the cover to hold the heat in, works perfect.
Adding my 2 cents worth here. I don’t believe it to be a quality issue as I have had this exact problem with multiple rolls of filament from multiple name brand manufacturers. There is some minor credence lent to the theory of moisture as I live in Portland Oregon but the house is pretty dry in the summertime and the AC is running. The only thing I can really add to this thread is that I have ONLY EVER had this issue with black filament! I loaded up some clear and drained the roll with zero issues. The moment I load up black from the exact same manufacturer as the clear, the problem is back. I don’t believe it to be stress because the length of filament will break in 2 or sometimes 3 spots and today’s was less than 1" from the extruder feed inside of the head. I’m resolved to loading black, using it when I need it then sealing it back up and reloading something else.
SifuGreg
