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Bent Derailleur
(@bent-derailleur)
Eminent Member
Filament tangling problems

Having serious problems with filament tangling on my printer in enclosure. First I thought it was a certain brand but it seems to happen on every roll/brand I have. Even though I use clip to secure the end.

Today I started a 3.5 hour print, it came like 5% and then just continued, because printer thought filament was flowing nice, but it was actually filed down by the gears, see below pic. And, it was so much PLA powder in the gears so I had to open up and clean it to get it working again 🙁 really tiresome this. I can't leave the printer alone, have to watch over it and un-tangle when I hear the filament shriek.

Anyone have some good tips to tackle this?

Posted : 08/03/2023 7:18 pm
Diem
 Diem
(@diem)
Illustrious Member

It's actually quite hard to tangle filament on the spool; what spool holder(s) are you using?

Cherio,

Posted : 08/03/2023 7:32 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

I'm using the one provided for Prusa enclosure. The original "pin" but with another bracket.

Posted : 08/03/2023 7:44 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

Oh, and Prusa, please add a filament "flow" sensor on MK4. It printed 3 hours without filament now. Some kind of "flow" sensor that senses filament coming instead of just something being there, would have been fantastic 😉

Posted : 08/03/2023 7:53 pm
Diem
 Diem
(@diem)
Illustrious Member

Is it *very* free spinning?  Does a small tug cause the spool to overrun?

Cheerio,

Posted : 08/03/2023 7:59 pm
fuchsr
(@fuchsr)
Famed Member
RE: Filament tangling problems

This picture is… quite something. I can't even fathom a scenario to make that happen.

Maybe if the filament jumps off the spool not once but several times.

So if you're sure it wasn't a case of you letting go off the end (which it doesn't sound like) I'd definitely try a different spool holder. I'm partial to roller style spool holders such as https://www.printables.com/model/1804 which run super smoothly and load/unload easily. 

 

Posted : 08/03/2023 8:22 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

It spins good, I mean, I use the original rod ("pin", "shaft"). One difference from printer without enclosure is that the filament must go in the center of the roll. It has a very steep angle when the filament runs from the sides of the roll. That is something that could make this worse perhaps.

It doesn't free spin when printing though, that would be bad. But I have thought of adding something that makes more friction to the roll. Contradictionary to the USSR roll 😉 I think somewhat more friction would be better here.

Posted : 08/03/2023 9:04 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Filament tangling problems

 I Agree,    Historically, the Mk3 had a laser sensor which was supposed to check filament movement, but it was quickly superseded by the Mk3S Infra red sensor, which does not check for movement. it was unfortunate that the laser sensor struggled with transparent / translucent and I believe green filaments...  and dust was also a problem.

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 09/03/2023 1:07 am
Robin
(@robin)
Prominent Member
RE: Filament tangling problems

As fuchsr said, this is very unlikely to happen during print... How do you store your filament? Do you keep the end clipped/fixed during all times?

If at first you don't succeed, skydiving is not for you.

Posted : 09/03/2023 12:31 pm
Diem
 Diem
(@diem)
Illustrious Member

Just a light brake, perhaps a strip of felt, might be enough.

Cheerio,

Posted : 09/03/2023 2:59 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

@robin: well, you guys are welcome on a study at my place, it happens often 🙂

yes I use clip on the filament. I store them in plastic bags with small anti-moisture bags in them.

But I have an idea, the filament is quite loose in between when I put it on the roll. Maybe I don't give that too much attention, it could be important to keep it stretched all the time so it doesn't get loose. Like on pic I posted last, the red filament. It is quite loose. That is maybe in between of how it gets sometimes.

I just tried a new print rolling out a metre, and roll it back, keep it stretched, load the filament and make sure it's not hanging loose. Will keep my ears open and see what happens.

@diem, yes, just a little would be enough, will try.

Thanks all

Posted : 09/03/2023 7:16 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE:

I did some revolutionary discovery. Saw a video...

The PTFE tube in the Prusa enclosure actually looks like that bad example with horisontaly curved tube that they say will twist the filament and cause issues! This sounds like the thing going on with my problem. What do you think?

This post was modified 11 months ago by Bent Derailleur
Posted : 17/03/2023 10:25 pm
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE:

funny, my video was deleted!? here comes a link again, starting at 5:35 where the phenomenon is:

/edit: Timecodes not working, paste link instead perhaps:

 https://youtu.be/03iUbhrU8xw?t=336 

 

This post was modified 11 months ago by Bent Derailleur
Posted : 18/03/2023 7:00 am
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

Ok, I think I have solved it.

The problem seem to be that the routing inside enclosure is very bad, according to the video above. Filament goes straight sideways after spool, then loops into extruder. This makes the filament twist, and after a while, tangle up. Almost EVERY print. You can hear something is wrong, the filament is sqeaking, like there is some forces need to be taken out somewhere. No wonder it tangles. It makes perfect sense now.

 

Look at the routing here. The filament goes into the plastic part which guides the PTFE tube like 100 mm sideways.

 

I noticed when I should raise Z-axis to clean nozzle that the filament on spool jumped sideways. These forces I was talking about came loose and made the filament crazy.

 

 

So now I have reverted to original position above printer. The filament goes just down to the extruder. This has worked very well ever since I reverted it.

 

So... how to tackle this!? Conclusion is that the routing made for the enclosure does not work. I need to figure out something else. I see three options:

1) Alterate the spool holder so it swings out and points the spool towards extruder. Rotation axis needs to be the hole in plastic part where the filament enters. This is doable. Could be the nicest solution.

2) Make use of that (covered) hole on top enclosure cover. Just in the middle. The hole is perfectly aligned right above extruder! You could put spool on top on a such spool roller, and for the hole you need some sort of "flange" which guides the filament and don't let it scratch to the edge. Problem is that I don't have space for this really.

3) Make a new top cover for the enclosure with either a bump for the spool or something else.

I think I go for option 1, since I also use the enclosure top for working table 🙂 would like to have that space available. Just need to solve the design 🙂

Posted : 19/03/2023 12:06 am
Bent Derailleur
(@bent-derailleur)
Eminent Member
Topic starter answered:
RE: Filament tangling problems

Problem solved: I made enclosure top roller that makes filament come on either front or center hole in enclosure. Have used it a while now without problems:

https://www.printables.com/model/467665-enclosure-top-roller-front

https://www.printables.com/model/467704-enclosure-top-roller-mid

Posted : 01/05/2023 4:07 pm
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