Filament twists during print
Hello,
after an hour or so into a print I recognize that the filament is twisted by one revolution. This just started happening yesterday after a few days without that issue.
When I take off the spool from the holder during the print I have to turn it one time (360°) counter clockwise in order to untwist it.
I am using the filament guide provided in the kit.
As far as I can tell the idler wheels can move freely ( https://help.prusa3d.com/guide/5-nextruder-assembly_434014#434412)
The printer runs on the 4.6.4 firmware. After assembly during initialization I was asked to loosen the screws of the extruder in order to align the planetery gears. I got no error messages whatsoever. I then tightened the screws of the extruder again according to the instruction on the display.
How can I fix this issue?
TE
RE: Filament twists during print
ok. Whooo. I thought I was the only one.
ive not iced this since day one. I’m on alpha firmware now and still there.
I was going to contact support but I want to get some video and photo done and I’m lazy
RE: Filament twists during print
Thank you very much for your reply! So now I learned I'm not the only one (just as you did 😀)
Prusa support couldn't help me. I was told not to worry and that the Nextruder will continue pulling the filament no matter if it was twisted or not.
Still – when the filament gets twisted too much it will break eventually. I tested this with a piece of filament and twisting it between my hands. So in order to don't have my prints fail I will monitor it and twist in back as soon as needed. I also thought of pre-twisting it in the opposite direction before longer prints so it can untwist in the process before twisting again. With this method you'd gain about 6 hours before it looks critical.
I still wonder what could cause that issue. The only cause I can think of is the machining of the gears of the nextruder but that's nothing I could do about anything.
RE: Filament twists during print
Just out of interest - is this on an assembled or a kit MK4?
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I see this issue on mine as well. And it is a big issue that we should worry about. Why? I use dual-colour filament. The one that makes the print one colour on one side and another colour on the other side. I've printed the cali dragon, so a small print, and half of the dragon is in wrong colour, meaning the filament twisted itself during printing. My MK3S+ never did anything like that. The prints with this filament look bad on a MK4 because of that. I love this printer and the quality and silence, but will Prusa pay me for the expensive dual-colour spools I bought and can't use now? 😛
To be clear, my filament doesn't twist nearly as much as yours. I just notice it because dual-colour filament shows the twisting instantly.
It's a kit.
RE: Filament twists during print
I can no longer edit the post, but just got an idea. Would appreciate if a mod merged the posts.
Could the tension screws being tightened unevenly cause the bearings to be slightly shifted to one side? And cause twisting due to uneven pressure? Or is it impossible? I'm not familiar with 2-screw design, so I have no clue.
RE: Filament twists during print
Mine is an MK4 fully assembled.
I will be contacting them tomorrow. This is having and effect on my printer and prints.
I’ve had a couple of times it get twisted to the point where it hits hard on the mount for the filament holder. The printer even if at the start of the print while it checks axis’s, if the filament twist hits the mount it will stop and start over.
RE: Filament twists during print
@iftibashir Mine is a kit
@shushuda I started playing around with the screws. When it twisted, they were perfectly at the same length (as instructed) but I recognized that the idler lever wasn't perfectly parallel to the Nextruder, so I fastened one of them about 1–2 mm more than the other. Since I didn't print anything for longer than 1.5 hrs without a change of filament so at this point of time I can't tell if this makes a difference. I'm just wondering why PRUSA didn't recognize this on their machines – I guess their prints should take longer because they fill the whole beds with parts.
RE: Filament twists during print
Hmm, maybe. I'm not sure if my idler is twisted, but I unloaded the filament for the night, reloaded it today and so far I see no twisting. Maybe I've inserted it wrong before? Strange.
@iftibashir Mine is a kit
@shushuda I started playing around with the screws. When it twisted, they were perfectly at the same length (as instructed) but I recognized that the idler lever wasn't perfectly parallel to the Nextruder, so I fastened one of them about 1–2 mm more than the other. Since I didn't print anything for longer than 1.5 hrs without a change of filament so at this point of time I can't tell if this makes a difference. I'm just wondering why PRUSA didn't recognize this on their machines – I guess their prints should take longer because they fill the whole beds with parts.
RE: Filament twists during print
Any joy with a fix for this - I’m starting to see some signs of this also…..
RE: Filament twists during print
More discussion here - https://forum.prusa3d.com/forum/english-forum-original-prusa-i3-mk4-assembly-and-first-prints-troubleshooting/nextruder-twists-the-filament-as-it-feeds/
Adjusting the screws worked pretty well for me, but since the screws are now uneven I plan to replace the extruder plastic parts with ones I've printed which are higher quality than what Prusa supplied.
RE: Filament twists during print
As I mentioned above I have the idler wheel screws now fastened unevenly just by eyeballing getting the wheel straight – that seems to kind of work. It's hard to fine tune because it's trial and error with the result only after hours of printing time.
I still get a slight twist though but not as much as before.
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Like my predecessor, I had problems with filament twisting. Tightening and loosening the bolts did not have an effect. Finally, I printed parts idler-lever-A-R2.stl, idler-lever-B-R2.stl, idler-nut-R2.stl and 2x idler-swivel-R2.stl. Print settings: layer 0.15QUALITY, 20% infill. After replacing these new parts, the filament stopped twisting. Do not forget to calibrate the gearbox after assembling new parts!
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@miroslav-h4
Glad that you could solve your issue. What material did you use for the parts?
RE: Filament twists during print
Black PETG.
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The idler-nut-R2 and 2x idler-swivel-R2 parts together with the 5.5 mm spacer must not be assembled too loosely. This assembly not only pulls the pulleys to the gear, but also holds the idler assembly so that it cannot move sideways. If the idler assembly is adjacent to the gear a little obliquely, I think this is one of the causes of filament twisting. The fact that the 5.5 mm spacer will not rotate completely freely does not matter so much, in my opinion. After all, this work is not manipulated so often.