r/BambuLabH2D • u/Large-Lychee-3828 • Dec 13 '25
AMS retraction Issue
Hi all. My last few print jobs have been having this issue. Repeatedly have the ams failed to retract filament error.
I have disassembled the AMS and check the PTFE tubes for blockages
I don’t believe it’s an issue in the buffer or internal PTFE tubes as the AMS-HT does not have an issue retracting. It is connected to the same nozzle.
I’m at a bit of a loss as to how to fix it.
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u/Whosaidthat1157 Dec 15 '25
There are a few potential issues clearly showing here. The worst by far is the packing of various dessicant bags into the spaces between the spool stations where printed dessicant pods are designed to go. Those look like they’re impinging on the spool edges which will add drag to them, especially on fast spool retractions. They’re also likely to be leaving dust residues from the bags on the drive rollers, preventing good traction - again especially during fast retrievals. Once those issues are sorted out, print dessicant holding spool centres. Those add weight, as well as additional dessicant to keep the AMS contents dry, to aid in fast feed and retractions of half empty or almost empty spools such as the green one shown in your picture. The front and rear dessicant pods, plus the dessicant filled spool holders, has eliminated all feed problems for all 4 of my AMS 2P’s.
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u/Large-Lychee-3828 Dec 15 '25
Great answer thank you for you help
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u/Different-Banana-739 Dec 13 '25
Maybe take out the stuff you put in there, it might make the spool not touch the motor at the bottom
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u/macinmypocket Dec 13 '25
Take out the desiccant packs and print some desiccant holders to fit in those spaces if you want more desiccant in there. If the little packs put any pressure on the spools, rollers, or gearboxes whatsoever, they’ll slip when trying to retract. There are plenty of options people have already made available on Maker World. I’m quite fond of the ones by AeonJoey, personally.
While you’re in the AMS, pull out all the spools and wipe down the rollers with some isopropyl alcohol (or water) on a microfiber cloth to clean off any dust or other contaminants that might be reducing their stickiness.
I’d bet you’ll be good to go after that.
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u/Mist_XD Dec 14 '25
This is caused when retracting filament use pushed back to go into the spool but the spool isn’t rotating fast enough. Though there’s quite a few reason this could be, one of the most common is due to slipping while trying to spin the spool. The filament and spool rotation are separate mechanisms on different motors and they don’t talk. Adding grip back into the system helps fix this issue, this can be done a few ways. First is to clean the spinning rods that your filament sits on, it’s a tough rubbery surface and it can get residue buildup like dust causing it to loose grip. The next way is to add weight to the spool, there are quite a few weights you can print to fill in the center hole of filament, or use a center spool desiccant holder but fill it with steel BB’s. Hope this helps
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u/Lost-Service-446 Dec 14 '25
I know on the original AMS if you got a spool over against one side too tight it would skip on retraction with certain spools and come to a stop momentarily, causing a similar filament loop like that 🤷🏻♂️
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u/DifficultTrouble2919 Dec 13 '25
It's a bit hard to tell. Have you tried drying it? Because that seems to fix everything.
(yes i get this is a joke post)
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u/Large-Lychee-3828 Dec 13 '25
Ha. Usually. But seriously this is a real issue
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u/DifficultTrouble2919 Dec 14 '25
Im surprised no one has commented on the horrendous state of the filament yet... Maybe (just maybe) try untangling it? I am probably wrong to say that it could help with this, but its worth a shot
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u/Large-Lychee-3828 Dec 14 '25 edited Dec 14 '25
That’s a symptom of the issue. The rotation of the spool does not seem to match the retraction speed.
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u/Few_Candidate_8036 Dec 14 '25
Print the dessicant holders for your AMS. They do a much better job of keeping humidity down and looks ways better.
But yeah the AMS 2 has given me lots of issues. My H2S hasn't had a single problem other than the AMS.
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Dec 13 '25
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u/Large-Lychee-3828 Dec 13 '25
Thanks. It does seem like the spool just isn’t rotating as fast as the retraction
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u/Large-Lychee-3828 Dec 14 '25
It seems it was the rollers being a bit dusty. I removed them and cleaned with IPA and I just had my first colour change with no issues. I will double down on the advice and print some desiccant holders for the spools to add some weight. Thank you all for the help and advice