filament wound around gear  

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h.waibel
(@h-waibel)
Trusted Member

Hi all,

anybody any clever ideas how to get this mess of flex-filament out without destroying anything apart from disassembling the whole carriage?

I'm also open to suggestions as to how this could have happened. The filament is a TPU made by Kiwi3D and I tried to print it at the upper range of their temp recommendation.

 

Thanks in advance

Hansjoerg

Best Answer by h.waibel:

Thank you very much everybody!

After an extensive operation I managed to get all the filament out. It was wound around the gear about 4 times and I ended up partially disassembling the extruder as described in the change teflon tube how-to.

Maybe I should have been a wee bit less ambitious and got some experience with more user friendly materials first before jumping to TPU.

P.S. how do I label this thread as "solved"?

Posted : 11/12/2019 11:11 pm
joan.t
(@joantabb)
Veteran Member Moderator

Good morning Hansjoerg,

as you know, TPU is a flexible material and this makes it more difficult to print with. 

so first issue...    getting it out of the extruder...     
I heat the extruder to a reasonable temperature (say 240C) , whilst it is heating I loosen the Bondtech trap door tension screw and open the door,  then whilst pulling on the filament from above, I select the remove filament option on the LCD menu, and... usually the filament comes out, occasionally you have to do this two or three times. 

when re fitting the tension screw for the bondtech trap door, make sure that you have the absolute MINIMUM tension on the screw / spring.

if the  tension is too high, the TPU tends to wrap around the Bondtech gears instead of following through the extruder channels.

I also find that TPU prints better if you set the retractions to 0mm.  

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 : 12/12/2019 10:42 am
mdaneman
(@mdaneman)
Estimable Member

Alos, when loading TPU don’t use the auto-load feature, turn it off. It tries to load way too fast which can lead to what you’re seeing. I had the same (though somewhat less severe) issue when I first tried auto-loading TPU. I was able to untangle it by a combination of snipping, pulling with needle nose tweezers, and slowly turning the extruder motor. 

Posted : 12/12/2019 4:02 pm
Robert-mm200
(@robert-rmm200)
Noble Member

Matches my first experience with flex filament.

That stuff is not stiff enough to force itself down the PTFE tube.

My first print was fine but a little stringy, so I dropped the temp by 5 degrees to 205. Big mistake...

The entire object "printed" inside the extruder. Wrapped around, balled, you have it.

I was sure it would be a full disassembly. Working on that, I moved the printer to the kitchen table for good visibility.

Cut the filament a bit above the extruder. Used a set of dental picks to catch the filament above the gear.

With a lot of struggle, got the filament below the gear. Fortunately - flex is incredibly tough - and stretchy.

I never did break the filament by pulling on it. Once I just had a balled up mess between the Bondtech and the motor, 

I got in with fine needle nose pliers and just started teasing it. Eventually the filament unthreaded itself.

No problem getting it out of the PTFE tube. Then I replaced all the extruder screws I did not need to remove in the first place... 

Posted : 12/12/2019 4:06 pm
h.waibel
(@h-waibel)
Trusted Member

Thank you very much everybody!

After an extensive operation I managed to get all the filament out. It was wound around the gear about 4 times and I ended up partially disassembling the extruder as described in the change teflon tube how-to.

Maybe I should have been a wee bit less ambitious and got some experience with more user friendly materials first before jumping to TPU.

P.S. how do I label this thread as "solved"?

Posted : 12/12/2019 7:15 pm
Robert-mm200
(@robert-rmm200)
Noble Member

Oh - as Joan said set the retraction to zero. Flex (TPU) does not like retraction... I set up a profile specific to flex for this reason.

Posted : 12/12/2019 9:42 pm
mdaneman
(@mdaneman)
Estimable Member

Also, I’ll refer you to a post I made on my experience printing TPU. 

My Experience Printing TPU

Posted : 14/12/2019 5:32 pm
Robert-mm200
(@robert-rmm200)
Noble Member
Posted by: @mdaneman

Also, I’ll refer you to a post I made on my experience printing TPU. 

My Experience Printing TPU

Should be required reading. Thanks!

Posted : 14/12/2019 5:42 pm
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