PETG Filament tangles
I have an MK3S+ which is generally very reliable. The one persistent problem is the filament tangling on the reel when printing PETG. The tangle jams, makes a mess of the print, and eventually the filament breaks. I have a partial roll of Prusa PETG that is unusable because of this problem. Is there some modification to the filament reel holder that will prevent this problem?
RE: PETG Filament tangles
It's almost imposible for a new roll of filament to include a tangle - the manufacturer would have to remove a part filled spool from the spooler, invert a loop and then finish to fill ...
Keep control of the end, never let it fly loose or, if you do, unreel a few turns until you are sure there are no crossings and then rewind.
Cheerio,
RE: PETG Filament tangles
In hundreds of spools I've seen one jam, and it was right at the beginning, so I think when they tried to fix the end to the spool, they must have let go of it and twisted it. As @diem said, much more likely you let go of the end at one point or let it jump off the spool. I'd rewind it onto an empty spool. There are autowind spool holders on printables that keep pressure on the spool but I don't think they're worth the hassle unless you have an MMU.
RE: PETG Filament tangles
Thanks for you replies. It's not that the filament was somehow tangled when the reel was filled, or that somehow the end got passed through a loop due to mishandling. It's more like the kind of tangle that can occur on a fishing real - part of an "inner" layer ends up wrapped on top of an "outer" layer. This seems to occur because, in operation, there is very little tension on the real and the actual pulling action of the print head is inherently jerky. I have actually watched the tangle develop - usually near the side of the real a loop crosses over the the filament that is being pulled off and slowly tightened. Usually it slips out, but sometimes not. If I'm standing there I can intervene and loosen the loop, but that is not a practical solution. I think perhaps PETG is particularly vulnerable to this problem because it is fairly stiff.
RE: PETG Filament tangles
What spool holder do you use to feed the filament, and what is the filament path? Maybe a photo of your setup? I've printed hundreds of spools and have not seen what you're describing (although I can picture it). Actually, I have but that was when I transferred filamenbt samples to a sample spool and didn't pull it tight. But if it's a persistent problem for you, you may in fact want to consider one of those auto-rewind spool holders. But it really shouldn't be.
RE: PETG Filament tangles
It's the standard out-of-the-box MK3S+ setup. I've attached a photo. I've also attached a close-up of the spool showing an about to happen tangle jam.
Try wrapping some tape around the spool holder to change the friction.
Cheerio,
RE: PETG Filament tangles
I implemented a similar solution last night and it seems to have worked. I put a piece of bicycle inner tube rubber over the spool holder and zip-tied it in place. This seems to provide just enough friction that, when the head moves to one of the X-axis extremes and thus pulls on the filament, the reel just rocks forward rather than actually turning on the holder. When the head moves back to toward the center, the reel just rocks back and tension is maintained. I did a seven hour print with no tangles.