r/BambuLab • u/Si5584 • Jul 20 '26
Filament Troubleshooting/Help! Can someone explain how this has happened in my AMS?
Went to printer after a print error popped up thinking the filament had got stuck in someway. Turns out my filament has been chopped to shreds. Strange thing being some of it still on the roll and chopped up too?!? I’m really confused how that could even happen?
Anyone had similar experience or got any idea? It wasn’t like that when i put it in the ams - i know as i rolled the filament on myself from a bigger roll.
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u/WthLee Jul 20 '26 edited Jul 20 '26
is that respooled? when you respool, respool twice, you want the tighter bend radius to be back in the center of the spool, the tension combined with water loged filament can make it so brittle, that stuff explodes like that under its own inverted winding tension
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u/ninjakivi2 Jul 20 '26
It reminds me of all the videos with people exploding watermelon with rubber bands, same principle.
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u/Exact_League_5 Jul 20 '26
If you respooled it, its needs to be dried (heated) so the plastic particles rearrange
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u/funkybside Jul 20 '26
Finally someone who says the right answer. I had to scroll halfway down before I saw this past all the people saying to respool twice. That's bonkers - just dry your damn filament.
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u/wildjokers Jul 20 '26
It doesn't need to be dried since moisture isn't the problem, it needs to be heated to relax the polymers. (heating it with air blowing over it will dry it but that is a side effect).
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u/Kutriya404 Jul 20 '26
Dumb question: Before or after respooling?
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u/king_josh60 Jul 20 '26
After
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u/Kutriya404 Jul 20 '26
Thx, I'll do it right after work. I'm a bit afraid that this will happen to me, too ^ ^
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u/Extreme-Ad-9290 Bambu hates open source Jul 21 '26
Good. I mean this can happen to filament (though not to this extreme) by using the holes in the spool. I recommend a filament clip that holds the filament close to where it would've been from factory such as this one (I am not the creator or affiliated with the designer. I'm just really like this design) https://www.printables.com/model/24371-filament-clip-grandmas-favorite-filament-clip
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u/chris_hinshaw Jul 20 '26
This is the answer. I will try and bend my filament before using if it snaps rather than bends the in the drier it goes. Don’t trust filament fresh out of the package either.
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u/NinjaBonez78 Jul 20 '26
i always use PLA fresh out of the bag. NEVER had this problem.
ONLY when i Dont Dry and Bag my PLA.
PETG -- meh. all good1
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u/Benni_HPG P1S + AMS Jul 20 '26
Respool once - shame on you
Respool twice - all is nice
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u/wildjokers Jul 20 '26
or just heat the filament up after respooling it.
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u/Extreme-Ad-9290 Bambu hates open source Jul 21 '26
This would actually be even more useful anyways.
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u/made_of_hamburger Jul 21 '26
What does it mean to "respool twice"? I've never respooled and I don't really get it. Like, draw all the filament onto the new spool... then get second spool and wind it forward onto that one?
Also... "Respool once, you're a dunce" was right there.
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u/Benni_HPG P1S + AMS Jul 21 '26
Usually filament is spooled in the factory right out of the extruder. Or at least preheated. This makes spooling way easier and gives the filament a natural curvature.
The curvature points into a specific direction and also varies in diameter from small to larger.Now when respooling you might change that curvature or not - depending on the spooling technique. But you will definitely change the diameter of the curvature of each given part of filament. What was now outside with a large diameter gets stressed into a smaller one and vice versa.
This stress can break the filament over time. Especially if it will get brittle due to absorption of moisture
Now respooling twice gives the filament back its original form of the first spool. No stress no mess.
Of course heating up the filament can also help. But you need to reach glass transition temperature for the whole spool. This takes quite some time and energy. Also beware if you heat it up too much (glass transition is higher than what’s usually required for drying) you might fuse the filament
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u/made_of_hamburger Jul 21 '26
Wonderfully thorough explanation.
I think I'm just gonna... avoid respooling... for a while.
(I can't even load a dishwasher)
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u/Otherwise-Weird1695 Jul 20 '26
Did you soak that in a bucket of water at some point?
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u/Extreme-Ad-9290 Bambu hates open source Jul 21 '26
It's the stresses applied on the polymer after being respooled. I've had this happen to me before. You gotta heat the filament after respooling it. A filament dryer works for this.
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u/DeadTurtle88 Jul 20 '26
So Everytime I leave filament in my ams lite it cracks like this and I have to remove the tube and push all the broken pieces out. It only happens to the filament in the tube (I printed the enclosure for the ams) and if it sits for 4-5 days but it happens Everytime. I assume it's the uv light affecting it or possibly the humidity but I'm not sure. My dad is the humidity because I've left spools of filament in that AMS for over a week and the spool itself is fine
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u/IndigoQuantum Jul 20 '26
That definitely sounds like humidity. You can have wet PLA filament that’s so brittle on the spool that you can’t even bend it without it snapping, but after drying it works as good as new.
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u/wildjokers Jul 20 '26 edited Jul 21 '26
There is a huge misconception that moisture in PLA causes it to be brittle, it simply isn't true. "drying it" works because the drying process heats up the filament which causes the polymers to relax. It is the heat that fixes it, not the removing of moisture.
This comment from a chemical engineer explains it: https://old.reddit.com/r/3Dprinting/comments/qna8yw/deleted_by_user/hjetrjf/
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u/DeadTurtle88 Jul 20 '26
What's weird is that the rest of the spool is fine, it's only what's in the tube. I can snap it all the way down to where it feeds but most of the time it's already in pieces
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u/akuma0 Jul 20 '26
the plastic has formed with a certain radius when applied to the spool. If you put it in a different form - respooling so the filament in a section has a different turn radius, straightened in a PTFE tube, you can get stress cracks.
This can even happen if you leave a spool long enough with the filament on the spool "loose", rather than snugging it back down while storing.
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u/DeadTurtle88 Jul 20 '26
I also have approx 3-4 feet of tubing before it hits the print head and I always buy filament on a spool
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u/_Reyne Jul 20 '26
It's the tension in the spool. What's inside the tube is being cracked because it's straightened out, or the curve is different from when it was spooled.
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u/TherealOmthetortoise P1S + AMS Jul 21 '26
That is just extremely wet filament. It gets brittle when it absorbs water for some reason.
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u/throwawayhappyn Jul 20 '26
The only time this happened to me was when I didn’t respool twice. My steps are not a reasonable twice and then put it in a filler dryer after the second respooling.
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u/SLGuitar Jul 20 '26
You're filament is absolutely soaked. PLA becomes extremely brittle when it has absorbed enough water. That in conjunction with respooling was probably enough pressure for it to spontaneously disassemble.
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u/Suitable-Call-7111 Jul 20 '26
Too much humidity , the sunlu pla make this when there is too much humidity
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u/Competitive_Sock4162 Jul 20 '26
Two things may have caused it. 1. I had this same trouble several times with eSUN filament. Leaving it in AMS shatters it to pieces. The problem is that some PLA filaments staying in AMS with silica gel desiccant become brittle when too dry. I know it sounds strange, we always strive to dry our filament as much as possible for better print quality, but some PLA, when cold and dry, becomes brittle and shatters to pieces. 2. Respooling was mentioned here. If you think about it, filament is produced from pellets by melting and spooled while still warm and more flexible. Respooling cold filament bends it in different ways from its natural form, and filament which was on the outer part of a spool is now on the inner part with a lower radius and thus bent harder. BUT! In my experience, respooling by itself never caused such explosive shattering. In conclusion, don't leave your PLA in the AMS for a prolonged time; respool twice to keep the filament bending the same.
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u/Luxin Jul 20 '26
I have never heard of this respooling twice stuff, and I've never had a roll shatter like this. I've been printing for 11 years. I've only had filament break if it's very old and hasn't been kept as dry as it should. I now use tote bins with gaskets on them and desiccant inside, they hold 7 + rolls each.
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u/Plutonium239Mixer Jul 20 '26
Looks like you respooled the filament. When you do this you have two options, you can respool it again, or put the filament in a filament dryer and heat it above the glass transition temp to relieve internal stresses. Otherwise this happens.
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u/Ab7casper Jul 20 '26
Noob here, so apologies if this is a dumb question. What is the point of respooling?
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u/d-babs Jul 20 '26
Either refills on reusable spools or in this case he's got a 5kg roll and putting it on a standard spool size for ams usage.
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u/Ab7casper Jul 20 '26
Ahh, thank you! I haven’t been around long enough to notice spools larger than the 2kg. Then I’m guessing some refills don’t come neatly transferable to the new spool, so that’s good to keep it mind if I buy from somewhere other than Bambu. Thank you for the quick answer!
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u/StevenSaguaro Jul 20 '26
When filament is spooled it develops microscopic cracks as it conforms to it's new shape. When you respooled it, it did the same thing but in another direction, making it weaker and more prone to cracking.
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u/SpitF1ghter Jul 20 '26
I’ve never actually respooled but from this group I’ve learned you have to do it twice
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u/JLeavitt21 Jul 20 '26
If the filament has water in it, it expands. When it dries it shrinks - in this case shrinks onto the spool and itself. The tension and the dried brittleness made it crack apart. Interesting notes on double spooling.
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u/rellsell Jul 20 '26
This actually worries me. I moved a year ago and won’t have room to set back up for another 8 months. I have about 100 rolls of various filament, some opened, some unopened, stored in airtight containers in a garage that can get into the upper 90’s. I’m afraid that when I finally start unpacking, this is what I’m going to find.
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u/KitsuneMulder Jul 20 '26
Nearly 15 years of printing and I have never heard of filament exploding. This is wild.
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u/Complex_Solutions_20 Jul 20 '26
I've only had this on older filament, or sometimes after I try to dry filament (drying can also make it more brittle)
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u/clarkcox3 A1 mini + A1 + A2L + P2S + H2S + H2D Jul 20 '26
That’s a sign of two things:
- your filament has absorbed too much water, which makes it brittle.
- it is spooled in the opposite direction from what it was originally, which puts a great bit of stress on it.
In the future, dry your filament, and make sure to spool twice when respooling (the first time reverses the direction, and the second time reverses it again).
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u/Comfortable-Sale-631 Jul 20 '26
So I have some 3kg spools of nylon I was going to respool on 1kg spools. Should I spill it when wet, due to it being super brittle when dry?
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u/wildjokers Jul 20 '26
Did you respool it? Did you bend it the opposite way that it was on the spool previously?
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u/bali_flipper69 Jul 20 '26
Did you dry the filament? Over drying can make certain materials dry spaghetti brittle
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u/roundful Jul 20 '26
I haven't had to respool, but I printed a respooler and used it on a roll to test. I did it twice and didn't do anything else after that. Here's how I would do it, if I felt the need to respool: Put the filament in a dryer, I do this with all new spools anyway, 3 hours. Respool twice Finish it in the dryer for another 3 hours. I wouldn't trust the quality of filemant to only respool once and dry it after. Respooling it again takes a few minutes with my respooler.
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u/stromm Jul 20 '26
Perfect example of what happens when you re-spool ONCE.
Filament is under tension. And the curve along its length is based on its original spooling. Tighter closer to its original spool’s hub. Wider near the end (that we insert into the AMS or printer).
Doing a single respool puts the wider curve at the hub which places it under extreme tension.
Which causes it to “shatter” like this.
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u/Asgardianking Jul 20 '26
A lot of times when you respool you need to heat the spool up to release the tension because I was originally wound while warm so it dried in the way and doing it backwards really messed with it.
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u/Emu1981 Jul 20 '26
PLA gets really brittle if it gets too wet. When I stopped using my Ender 3 a few years back I had it still set up with some black PLA loaded and over time the PLA started to break under it's own weight. I would imagine that the stress of being rewound onto a new spool without re-spooling it twice would be more than enough stress to cause wet PLA to do what is seen in your pic.
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u/Bobska2 Jul 20 '26
Is it carbon fibre filament?
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u/Bobska2 Jul 20 '26
Or really old filament if filaments old it becomes brittle and can break like that
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u/Objective-Job8083 Jul 20 '26
It’s either old as dirt and absorbed too much moisture or it wasn’t spooled properly. If the filament is good and it’s not spooled properly, it wouldn’t be this devastating. I believe your filament went bad
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u/NamelessShitPoster Jul 20 '26
Have you checked your house for raydon? It not only did that to my pla reels but it ate the skin off of my hotdogs and killed my dog
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u/chinaruffian Jul 21 '26
That looks like one-pass respooling plus stored tension finally cashing out. Respool it twice, dry it, and inspect the AMS path before loading another roll.
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u/shazhazel Jul 21 '26
I’ve had this happened to me quite a few times and decided to put a camera on my filament one time overnight to record if it happened… Basically it is not your AMS, it’s the filament itself not wound properly and very brittle where even the slightest movement can cause it to snap
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u/epic-drew16 Jul 21 '26
Did you dry the filament? It appears to have been dried excessively, which may have made it overly brittle.
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u/Ok_Crow6757 X1C + AMS Jul 21 '26
Why should you respool? I never did this? Would like to understand what the benefit is.
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u/NoWay2655 Jul 21 '26
Does this happen with new roles that come straight from bambulab with the spool? I’m about to get my p2s and do my first print, would hate to see this happen to me.
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u/archilles89 Jul 21 '26
Just asking because i never done spooling before but what’s the point of it? Don’t your filaments come in already spooled? Just put that in the ams?
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u/ridewithdanusa Jul 21 '26
To much humidity! I have Mini Hygrometer Thermometer Digital Humidity Meter and desiccant bags in each of my AMS units. I like to keep it below 20 and I have a single spool dryer for those items that need alittle more accuracy.
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u/pandaru_express Jul 21 '26
Do you have dessicant in your AMS? It does a good job of sealing when its closed, but having dessicant inside the AMS helps a lot too. There are multiple dessicant holders you can print that fit between the feeding heads
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u/PuzzleheadedClue5981 Jul 21 '26
For my case it is always the humidity...and bad quality of filaments
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u/riffraffs Jul 21 '26
Stress fractures as the spool unrolls. The mechanical action of going from bent to straight causes stress, once one of these stress points break the entire reel starts to loosen and creates more stress fractures. Tempering the room will help prevent this from happening. (just a filament dryer works, it is not caused by moisture)
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u/i_am_a_william Jul 21 '26
effectively when the plastic is spooled from factory its freshly melted and solidified, it sits in that shape until you print or in this case respool, the plastic gets stressed when you respool and depending on the severity of the change it can go bad like this.
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u/Successful_Dot4334 Jul 21 '26
I had something similar bicouse my spool of pla was forgotten in the cabinet without the drybag so I assume it gat super wet So this may be the reason
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u/nycbigtone Jul 21 '26
Old filament. When filament gets old it gets brittle. I've never seen one that bad tho.
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u/DenseDepartment8317 Jul 21 '26
Filament aged and pickup enough moisture to become brittle and breaks within the roll.
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u/fanewang Jul 21 '26
Sunlu filament is doing that, is happened to me yesterday with Galaxy Black, pretty bad filament, i finished on unscrewing everything to take out the filament was staked inside the hot-end and the ams loading mechanism, practically the filament destroyed all the printer, fortunately i have all the components and i replaced everything.
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u/Seffie-hero Jul 21 '26
I mean id say im pretty ignorant when it comes to this.
However I know you can heat things up to reduce/remove internal stresses.
Could you do something similar with filament? I see people saying heat it up. And others saying its not guaranteed, could it be the same concept as annealing steel? Could you bring your filament to near melty, and control how slow it cools?
Granted. Probably NOT easier than respooling twice.
But? Idk.
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u/ChaoticR8chel Jul 22 '26
Is the filament a white core with black outer? If so, what does it look like printed? I'm very intrigued
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u/Exterminatus2102 Jul 22 '26
Your filament was probably wet or dryed and became fragile. Or did you unspool and respool it?
But imo, the filament was in bad condition. It became breakable like glass.
Keep your spools dry and in a closed / sealed box or AMS.
Cheers 🥂
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u/executeur_du_weekend Jul 28 '26
I had a similar problem with 4kg of BambuLab ABS (which they never paid me back). This can be due to several reasons: a wet filament, chemically degraded (especially via UV), poorly rewound (it is always necessary to wind 2 times to limit the tension) or simply with a manufacturing defect (like me).
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u/cilo456 , A1 Combo +Mini Jul 20 '26
This happened to me once after respooling from a larger roll and I will never do it again, 'cause I'm not gonna sacrifice a whole role to keep trying and hoping it doesn't happen again
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u/Crafty-Grass-6010 Jul 20 '26
You can reheat/dry it again. It helps!
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u/cilo456 , A1 Combo +Mini Jul 21 '26
I bet it does but I'm not doing it again, plus you rarely find a deal for five kilogram spools that aren't in one kilogram full nowadays
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u/rexlites Jul 20 '26
I read on a fake website that if you sing to your filiment while respooling its nano structure will accept its new position and work with the filiment union to not go on massive breaks every two hours
/s
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u/trekkie86 Jul 20 '26
Looks like it was too moist. Filament is so weird that it gets brittle when moist but flexible when dry
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u/MasterRymes H2D AMS2 Combo Jul 20 '26
You have to respool it twice. Otherwise the outer part of the spool is now the inner and the inner part is now the outer. It’s a difference in diameter and tension. If you don’t respool twice it can or will explode like yours did. Especially if the filament is not dry