Just to share a small experience and if any one else had similar issue, or is it the process .
Found da Vinci XYZ PLA unopened couple of boxes from my da Vinci days , my guess is that is at least 2 years old , but sealed
Re-wined on a suitable Roll for Bambu AMS
And After my traditional procedure drying it for 18H at 50C and put it in a dry Box with silica ready to be used. For my Surprise today i looked in the box for some other filament to find out that the filament was broken on many places by it self and really Brittle
I had problem in the past with old da Vinci PLA but was open for a long time and just through away the rest
I am using this process for PETG, ASA, ABS, TPU, Nylon and others mainly from eSUN and Bambu and no issues. Also used eSUN PLA the same process have not seen the same problem but have not done too many rolls with PLA and do not think that was in the drier for more than 5h-6H
I had the same problem with new filament. I think it gets wound when hot and takes a set into that shape. When rewinding, the outside is wound in a tighter curve than before. I rewound at night and the next morning I had a pile of 6" long pieces of filament. That was when I decided to stop buying master spools.
Thanks, i did re-winded it cold and then in the drier , could be similar due to the temperature variations
and it was all the way Brittle - and broken in hundreds of places up to around around the middle
and even after the middle was breaking like pretzels . I have one more box and will try after collect some more info
I had the same thing happen with 3yr old PLA that I thoroughly dried. It was really brittle and impossible to print as it kept snapping off. I think there must be some shelf life for PLA filament.
I did finally do a new test , opened the second Box of daVinci PLA ( at least 2 year old ) never opneded
dried it for around 36 hours on the minimum setting cooled it down in a dry box with silica and then re-winded . And now no breaking
Then put it back in a drier directly connected to the Prusa and printed ok ( did not want to risk it in the AMS for the X1C), there is small part from the drier to the Prusa which is not in PTFE tube and next day this part broke by it self . I think it is still quite brittle but usable , And will not risk to use it for a bigger print or use it with AMS too brittle especially after drying procedure
I think will go into the bin anyway ,
Thanks every one here is bullet points from your advises and tests:
PLA needs to be re-winded dry and cold - probably the same for other types
Old PLA gets more brittle no matter what you do , and even if it has been unopened - at least for this brand
I watched a very thorough video that did a test of PLA and what caused it to be brittle. Even after 24 hour submersion in water it did not make it brittle. However, the real conclusion was that PLA takes a “set” and does not like to be kept in a different position. He unrolled some filament from a spool and into a PTFE tube which was being held straight. The next morning it was broken and cracked.
Originally the filament is wound onto a spool during manufacture. It cools with the curve in it. My disaster was when I rewound a spool, making the curve for the original outside being more curved on the inside of the new spool. The next morning I had a pile of pieces. I quit rewinding.
I think I may have identified the source of this issue. Each time the AMS unloads a spool it pulls on it slightly after feed gears are engaged. This causes a kink in the filament at the port. This repeated bending back and forth will cause the filament to break. That is why you will find multiple sections of filament on the spool. It would be good for Bambu Lab to update AMS software to decrease the “tightening”. Don’t allow the spool rollers to continue after feed gears are stopped at the end of a retract.
From my experience, all transparent filaments do this (not necessarily the ‘natural’ ones but any of the ones that look clear or are based around clear filament (such as some sparkle, glitter, or color shift filaments that use particles for color with limited filament coloration.)
All of them seem to become fragle with humdity. hatchbox is notorious for this problem with their transparents. I don’t run older transparent filament through the ams because I can’t imagine having to clean that out. To use brittle transparents I would dry them, use them for no more than a few hours and dry them before further use.
. I have one more box and will try after collect some more info