Core one makes a mess when retracts filament at the end
I have my core one for a week now, and while it works perfectly (so far) yesterday i opened my first full filament roll. Boy, what a mess when printer finished! The problem is that core one retratcs quite some filament at the end of print, which results of filament being pushed back while not being rewinded on the spool. This made a total mess and i’ve had to rewind quite a few turns of my roll hoping that i didn’t tangle anything.
Does someone has this problem and how to solve it? My filament is not from prusa, btw. but i don’t think this is (should) be a problem.
should i make some kind of a buffer or what? This is unacceptable, since sooner or later i’ll destroy my whole roll… or is there a solution to cancel this filament retraction (and make it as MK4)?
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I'm not quite understanding how retraction could tangle, let alone destroy, a roll of filament.
The only way for a roll to tangle is when you are handling it and the tip is loose. The tip could then work its way under another winding and, in the worst case, cause a failed print. This happened to me a few times. But as long as the tip is in the extruder or bowden tube, this can never happen.
What can also happen is that the loose windings end up next to the spool, preventing it from futher unwinding. Also a failed print is the worst scenario. Your filament is safe.
RE: Core one makes a mess when retracts filament at the end
It only retracts around 2 inches or so - and then it will pull it back in when next printing (if you haven't change the spool of course). It never retracts more then this, so Im not sure what you are doing in order to have to rewind the spool several turns?..........
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Well, it makes this on the picture (and it did it several times). So, if it's not retraction then....only thing i can imagine is too agressive pull, which causes spool to unwind too much. It's original spool holder, which i don't like it at all anyway, so i'll have to make something else, i guess... It never happened on MK4S... not once... in fact, this whole filament loading, unloading... is the only thing i really "kinda" hate on this machine... (for now). MK4's way was much better in this regard.
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That is normal. Filament wants to be straight. So if it just gets a bit pushed back, the last few windings will expand and fall off the spool. This only happens with a full spool. Just put it back on and roll back the spool with your hand until all filament is back inboard and tightly wound. Like I said, there is no chance of tangling the filament this way.
RE: Core one makes a mess when retracts filament at the end
Yeah, but the fact remains that this never happened on my MK4. I've had filament holder on two rollers (with bearings), and it was on top. I don't think that position matters, which only remains filament holder to be the culprit. I'm thinking of making something similar to THIS , although a bit different...
RE: Core one makes a mess when retracts filament at the end
Yeah, that’s a common issue—just add a filament buffer or rewinder, or tweak the end G-code to stop it from pulling too much at the end.
RE: Core one makes a mess when retracts filament at the end
That is certainly not normal - the spool should not rewind that much with the 2 inch retraction.
That is normal. Filament wants to be straight. So if it just gets a bit pushed back, the last few windings will expand and fall off the spool. This only happens with a full spool. Just put it back on and roll back the spool with your hand until all filament is back inboard and tightly wound. Like I said, there is no chance of tangling the filament this way.
RE: Core one makes a mess when retracts filament at the end
I think your below theory is more probable, although Ive never seen it myself (but I do not use the side spool holder in the first instance)......
Well, it makes this on the picture (and it did it several times). So, if it's not retraction then....only thing i can imagine is too agressive pull, which causes spool to unwind too much. It's original spool holder, which i don't like it at all anyway, so i'll have to make something else, i guess... It never happened on MK4S... not once... in fact, this whole filament loading, unloading... is the only thing i really "kinda" hate on this machine... (for now). MK4's way was much better in this regard.
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I'm thinking that it can be because spool "hangs" on holder it doesn't roll evenly - instead it "leans" forward and when tension is over limit it "jumps" (unrolls) and it does it too much. I think that's why some guys created a holder with teflone tubes for smoother rolling...
iftibashir: what holder do you use?
RE: Core one makes a mess when retracts filament at the end
https://www.printables.com/model/68781-simple-spoolholder-with-skateboard-bearings
RE: Core one makes a mess when retracts filament at the end
Aha...you have the roll simply on the desk beside printer? Smart move... I might just try that before i print anything (i still have my old holder from MK4, similar to this), to be sure that holder is really the culprit.
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It never happened on MK4S... not once
Did you feed your filament into your printhead through a bowden tube? If not, then that is the reason why it never happened on your MK4S. The bowden tube in the Core ONE restricts the sideways movement of the filament and when the extruder pushes it back by 5 cm, it comes out by 5 cm on the other end. That is how bowden tubes work.
I have my filaments in overhead dryboxes with bowden tubes feeding in a straight line directly into the printhead. The bowden tube is not fixed to the printhead, so when the filament is being pushed back it doesn't push back the filament through the tube. When something like your situation happens, I have to open the drybox to fix it, which is a hassle. This is how it that looks:
But that is not an option for you, since the Core ONE has the tube fixed to the printhead.
I might just try that before i print anything to be sure that holder is really the culprit.
I can already tell you that this will not help. It's simple 'filament mechanics': you can not push it back onto the roll. It will unwind and fall off in the same manner. That's why there is a filament buffer and all kinds of auto rewind spool designs for use with the MMU3.
If I were you, I would take the pragmatic approach: just put the filament back on the spool and don't worry about it. Like I imagine every one of the thousands of Core ONE owners do. I have not heard anyone complain about this.
RE: Core one makes a mess when retracts filament at the end
The unwinding of 1-3 loops happens to me too from time to time with a full roll, but apart from being a little extra step, I don't really care.
Having the filament retracted from the nozzle means there's no oozing when heating up and I can swap the nozzle before a print without having to unload the filament and waiting for the hotend to cool down again. Prusa implemented it for multiple reasons, with the only downside being the tangling on full rolls.
Just take off the little string on the nozzle after each print and check the spool.
RE: Core one makes a mess when retracts filament at the end
I have my filament sealed in cereal containers, on a shelf above the printer, with a longer PTFE that feeds directly in.....that way I can just leave the filament in place and loaded without worrying about humidity...
I'm thinking that it can be because spool "hangs" on holder it doesn't roll evenly - instead it "leans" forward and when tension is over limit it "jumps" (unrolls) and it does it too much. I think that's why some guys created a holder with teflone tubes for smoother rolling...
iftibashir: what holder do you use?
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just put the filament back on the spool and don't worry about it.
Yeah... i guess you're right... at least until all it does is tangle at the end of print. If things will start to go wrong during print then it'll be worrying. And, correct, MK4 doesn't have long tube, so air between spool and intake acts like a buffer.
That's why there is a filament buffer and all kinds of auto rewind spool designs for use with the MMU3.
So if i wanted to be "picky" i could make one of that mmu3 buffers... on the other side, MMU3 just came out for core one, and it's tempting...