I believe it may be part of the ams start routine of a preloaded ams , especially when reading tags,
if youve noticed to load/read spool one it always pre rotates spool two before going on and reading spool one , then it does the same for two and three , three and four, its like a pre check scenario and thats when it is happening most, if not all the time , pre load or reload /swap filaments , ive not had an instance of it happening while in use
The weight of the spool being pulled may help mitigate the lock up / jam
Could well be, but as i stated earlier on in the thread , all my ams slots were locked up and i was using them all saturday and sunday and i will assume starting the process would of unlocked them all,as the spools are fullish and one is card
It happens when the printer retracts the filament. If you look at the filament between the spool and the prefeeder, the locked front roller will be the spool where the filament is under tension (That tension is what does not allow the retraction gear to disengage). One approach to the issue is to add PTFE tubing from the prefeeder up to 3/4 of the height of the spool.
I just started a new print of an Item I need printed for my repair business. I came back to the bar flashing red and it telling me to loosen the filament on the AMS Spool. I did and it just did it again.
Then it told me to pull the filament all the way out. I did and it was very stringy at the end. This causes the filament to get caught and not make it to the extruder. Why isn’t the filament being cut before unloading?
Fck, just failed again. This H2S is getting just like my K2 Plus, where I have to kiss its ■■■ to start printing!
Its never been that much of an issue , ive used the same spool and slot over the past few weeks with multicolour prints (white 70-100gs spool) it only got stuck a couple of times ,after swapping filament, youve got rolling the spool backwards (for when you leave spools in the ams) or reseating (whilst printing) or read on startup )
Best practice, remove the spools when the jobs finished and start with the loading process every job , then its cause becomes irrelevant ,
Do you think it could be due expansion and shrinkage in the filament when its switched off ?
Not really, but who knows. This front roller being stuck clears itself a lot. I was standing in front of the printer and the spool starting jumping up and down, just crazy, and then it cleared the stuck roller. That is where I got the idea to add additional rollers…
Mine started tapping the lid , i dont have any score marks from feeding (ams 1 gen ?) but i have noticed its more of an issue for some rather than others, even after swapping feeders adding little bits ptf tubes or even weight , i havent gone as far as to strip it or add mods , i may go and check the wiki a little later on and have a good read about it though
When I opened a trouble ticket with Bambu on this issue, I sent them the video of it occurring. They recommended that the mods, including a long PTFE tube leading to the feeder, should be removed and might be causing the issue. They were incorrect, but I did determine that the tube thing didn’t really help much in the end. At least on the roller/gear/motor sticking issue.
I haven’t had time yet to try to see if some well placed watch gear oil might help the sticking yet. But that sounds like a good possibility. I’ll post here when I get the time to try that.
I heard a gcode rumour on sm after they had tried the above with the ptf and feeder fix (new cs ) but i took it with a pinch of salt (possibility of) DL , power supply issue also, mine are currently linked (dc)
Had this occur to me last night. I got a notice that the AMS feeder was stuck, failed to retract. Went out to the unit and it would not roll forward. I jiggled it a bit and it let me roll backwards to get the filament out. By the time I got it out, I noticed it would roll forward again. Could it be a gear alignment/tolerance issue? It didn’t feel like I was fighting a motor, more like a jam in the gears.
I believe the concensus of opinion is weight and power , as spools get lighter they dont have the weight to move the roll bar, so it pulls the spool up instead, because there is to much resistance from the roll bar , which would explain why it does across the ams slots , and its not just limited to one slot,
I don’t get into that “public opinion” of the issue. The rollers should not have resistance, and normally do not. Why do they get resistance after a while? Of course the spools jump up as they get lighter. But they shouldn’t jump up to begin with. What is causing the rollers to resist?
When the spool is retracting there is a gear which moves up to allow the pre feeder motor to retract. You can see this gear, just look. Normally the gear falls back down and releases the front roller, again when it is stuck you can see the gear. Rolling the spool backwards, lets the gear disengage.
Theory on why weight helps? Maybe the mass causes a jerk when the mass suddenly stops. The jerk aids in helping the gear drop down…
Same with how jumping spools will often clear the issue. Or my fix ???
I’m having the exact same issue with my AMS 2. It’s happened since it was new, I got it around Christmas. I researched this a few months ago, and it didn’t seem like there were any solutions, so I just decided to search again… and still no fix
I have a YouTube video, but can’t link to it for some reason.
I just started having this issue with a new spool. The constant checking in is driving me crazy. I am running all the current firmware. I get the notification that there is too much spool tension and when I come to fix the spool does not rotate freely until I lift it out and reinsert. Then it works for awhile.
Yup, same here, but not all the time. This happens especially with a new “heavy” spool.
My Creality K2 Plus would do something similar so I would leave the lid open and it cured it. I am not sure it helped with the AMS2. I think it did sometimes allowing the spool to hop, releasing itself.
So much for keeping a spool dry in the AMS. Maybe Snapmaker has the right idea on the U1, not bothering with an enclosed AMS. Filament mainly absorbs moisture through the cut end and not so much the outer walls.
