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Filament clogging the upper part of PTFE tube, MK3S  

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kimdrummel
(@kimdrummel)
Active Member
Filament clogging the upper part of PTFE tube, MK3S

Hello!

I've been using my printer now for the better part of the last half year and i recently upgraded my Mk3 to Mk3S. Lately though i have been having problems with filament going soft on the top of the PTFE tube mid print, causing it to collapse and clog the upper part of the tube. It is easily fixed by using a pair of pliers and simply pulling the filament out of the tube through where the idler door is, although by then, my print is already ruined. And this happens every single print now. I never had this problem with the regular MK3. My theory is that the extruder motor becomes hot, and the heat is spreading to the gears, which in turn heats up the filament, causing it to collapse and block the upper part of the PFTE tube. I see no other cause to this.

I'm using Prusament Galaxy black PLA filament.

Is there a nifty way to cool the gears? As i recall, the regular MK3 had peeping holes on both sides of the extruder body, whereas the Mk3s only has it on the idler side. I think this is a contributing factor to my problem.

Posted : 28/06/2019 10:19 pm
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(@)
Illustrious Member
RE: Filament clogging the upper part of PTFE tube, MK3S

While a hot motor is possible, it is just as likely the heat sink and cooling fan have been building up dust and debris and need to be thoroughly cleaned. 

 

I own a MK3, and I've never had the gear melting plastic issue, but noticed early on my E motor hitting 55c so I added a passive heat sink and it dropped my motor temp about 8c.  But there are fan designs for the extruder motor on Thingyverse that look like they will seriously help with hot motors.  Or a person could add four heat sinks like I am using and probably gain 15 to 20c. 

Posted : 29/06/2019 12:23 am
kimdrummel
(@kimdrummel)
Active Member
Topic starter answered:
RE: Filament clogging the upper part of PTFE tube, MK3S

There's no dust. I recently took the whole extruder assembly apart to inspect for faults regarding this problem. Still happens. Every print.
I'll have a look at thingyverse to see if i can find something useful.

Posted : 29/06/2019 7:47 am
Peter M
(@peter-m)
Noble Member
RE: Filament clogging the upper part of PTFE tube, MK3S

https://www.thingiverse.com/thing:2975582

I have the mk3 (no s), and installed this on the extruder, to cool it down.(check if it fits on the mk3s), and blow to the top.

i have a enclosure, so in the summer it gets hot,and i made also a extra fan to blow in the enclosure, only for pla printing, and door open.

I had also clogging, rebuild the tube/nozzle/heatbrake, changed the heatbrake to standard e3d heatbrake(prusa has a different one), if you need to change the heatbrake i do not know, possible not needed.

Be 100% certain that you did a good rebuild nozzle/tube /heatbrake, check prusa manual, and youtube.

Posted : 29/06/2019 11:32 am
kimdrummel
(@kimdrummel)
Active Member
Topic starter answered:
RE: Filament clogging the upper part of PTFE tube, MK3S

Maybe i should also have mentioned that i also have an enclosure. Tried some more prints today with the doors open and no clogging. I'll see about getting some active cooling for the extruder as it kept around 45-49 degrees celcius on the motor. With the doors closed it was almost 60 degrees.

Posted : 29/06/2019 5:44 pm
bobstro
(@bobstro)
Illustrious Member
RE: Filament clogging the upper part of PTFE tube, MK3S

The E3D V6 hotend is air cooled and is rated to work at ambient temperatures up to 40C. Go above that and you're very likely to have a hard time with PLA softening in the extruder. Providing the hotend adequate cool air to do its job is essential. Opening the enclosure doors may be all you need. At 60C, you're getting up to the glass transition temp for PLA. If you still have problems with the doors open, a fan or repositioning to improve airflow so the hotend fan has some cool air to work with should help.

Summer is a great time to learn how to print with PETG!

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 29/06/2019 8:07 pm
Antimix
(@antimix)
Estimable Member
RE: Filament clogging the upper part of PTFE tube, MK3S

Hello, I did not understand all the terms of your issue, but I have a very similar issue that I explained in another post.

Have a look at the attached document I wrote to better explain my current issue, and see it this issue apply also to you.

Regards

Attachment removed
Posted : 29/06/2019 11:06 pm
kimdrummel
(@kimdrummel)
Active Member
Topic starter answered:
RE: Filament clogging the upper part of PTFE tube, MK3S

Thanks for the tip. But that's not the same issue i'm having. In my case, the filament collapses and clogs the upper part of the PTFE Tube due to high temperature of the extruder gears, which in turn is caused by a hot extruder motor and too high ambient temperature with the doors closed on my enclosure. Probably also because it's summer. It only happens with PLA. I printed with some Addnorth Amphora last night, which is a type of PET, with the doors closed and extruder motor surface temp at around 60 degrees celsius. I had no issues then.

I will add a cooling fan to my extruder motor anyway. The part i printed with Amphora was the fan shroud so i just need a fan and decide on a way to connect it to the Rambo.

Posted : 30/06/2019 8:08 am
frukto
(@frukto)
New Member
RE: Filament clogging the upper part of PTFE tube, MK3S

Hello @kim-g5

I have exaclty the same issue and same theory about the cause. How did you end up here? Did you add another fan or cooling? If so can you share a picture of it?

Posted : 29/05/2020 12:04 pm
Piet
 Piet
(@piet)
New Member
RE: Filament clogging the upper part of PTFE tube, MK3S

Hello together,

how did you fix this issue? I am also struggling with PLA and stock MK3s.

Posted : 21/06/2020 6:40 am
frukto
(@frukto)
New Member
RE: Filament clogging the upper part of PTFE tube, MK3S

As a workaround I leave the door of the enclosement open while printing. Since then I had no issues. But I still plan to install some ventialtion. And by the way I do not have these issues with PETG.

Posted : 21/06/2020 9:24 am
kimdrummel
(@kimdrummel)
Active Member
Topic starter answered:
RE: Filament clogging the upper part of PTFE tube, MK3S

I also leave my enclosure open. No issues then. The reason it's doing this is that the Stepper motor for the extruder gets very hot, and that heat transfers to the extruder gears, which in turn, makes the PLA soft to the point that it clogs the PTFE tube. I plan on mounting a fan on the extruder stepper, but i have yet to decide where to hook up the power to it.

Posted : 24/06/2020 6:50 pm
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