AMS randomly retracts filament

I will be printing a single color print with the AMS on my P1S. Everything will be going fine then the printer will stop printing, head head will go to the home position over the wiper. The filament will retract. It will then load it again It will purge the filament and then resume printing. This will randomly happen several times during a long print.

This seems to happen on almost every print I do. It is really odd and really annoying. Unless I fundamentally misunderstand how the AMS works there isnt any reason the filament should be retracted during a print unless it’s changing colors right? Am I missing something? Any help would be appreciated!

I have seen my AMS retract the filament mid print if it’s having a hard time pulling filament off the spool. I have some spools that seem to be wound too tight and would have a problem when it gets down to about ¼ remaining. I ended up re-spooling the filament and it worked fine after that. Sometimes it will give an error and complain about a motor working too hard or something and sometimes it will not give any error.

Yes, this is exactly what is happening to me. I often get the error. But what is really odd is many times there is no error.It just stops printing completely retracts the filament then loads it again and continues.I will try respooling thanks.

Check the spool rotation is not obstructed by the lid, or that it’s not some terrible cardboard roll that can’t be rolled smoothly. But say you are respooling, and yes, that should fix all the problems, but there might be a quicker way.

I have tried every other way. I just tried respooling a spool that was giving constant errors and I am 2 hours intto a print wiht zero erros so looks like the Bambu spools are magic.

Humans have been winding cables for centuries. Why are some filament companines just unable to wind a spool without tangling it?

I wanted to report back that all my issues are gone now after I stopped using third party spools. I printed this spool Bambu Reusable Hex Spool with Label Remixed by chsi76 - MakerWorld

which is awesome and have re-spooled all my filament and no more issues.

Just wanted to pop in to say that I just picked up a P1S and I’m having this same problem. Been printing on an X1C with the same spools with zero issues. Really strange that it seems to be having trouble with this AMS. I wonder if the new AMS v2 motor isn’t as strong or something. Also wonder if the PTFE tubing just needs to get worn in a little first. Thanks for the tips here in the thread.

I just started to have the issue described and I am using spooled original Bambu Lab Filament. I have checked for kinks, worn tubing, etc. and just can’t find anything that could be causing the filament to retract, reload, print for awhile, then go through the process of retracting, reloading, etc. again. It keeps repeating. My print is a 15 hour print, and it has eight hours remaining.
I’m researching on how I might be able to get the spool moved over to another slot on the AMS 2 Pro to see if that might work as I’m thinking it might have something to do with the mechanicals for the current slot (#2).

I have the same issue here. It retracts more or less after each layer. In my opinion the spool rolls pretty smooth and i can’t see any overlapping filament. after each layer there is a error message. after unpause the print it continues printing but after one layer the same error occures. i didn’t try respooling yet because it a new spool from sunlu (PLA glow). i tried to change the spool to another slot, but apparently this is not possible mid print.

Sometime you can unwind a few coils of filament and rewind it, just in case it’s stuck but doesn’t look like it.