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Filament getting stuck in hotend.  

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Gbutton
(@gbutton)
Active Member
Filament getting stuck in hotend.

Ok, this is for PLA:

  1. I start a print and get 2 to 10 layers
  2. The extrusion gets thinner and thinner and eventually stops
  3. The extruder begins to click and grinds down the filament

Things I've tried

  1. Heat the nozzle and use a needle to clear away PLA.
  2. Cold pull
  3. Completely replace the nozzle

When I pull the filament out, the last 5mm or so, the part that was in the nozzle, is about as wide as the bowden tube and I really have to yank it to get it out because it's so tight. 

I guess my next step is to take apart the hot end, but I'm very new to all this so I'm a little nervous to. Are there any troubleshooting steps I'm missing, or is it possible it's not a hotend issue? Just not sure what to do next.

Posted : 30/07/2021 11:58 pm
BogdanH
(@bogdanh)
Reputable Member

Partially depends on how many printing hours printer has and if you also printed mixed types of filaments (i.e. PLA & PETG). But as I can see, you already assume the answer...

Clogs, which block filament flow, rarely happen inside the nozzle (except if switching from high temp filament to lower temp filament). There's bigger chance for that to happen inside heatbreak. Because of high temperatures (at least for original heatbreak), PTFE tube inside heatbreak shrinks over the time. Not by much.. but even 1mm can be enough to cause a jam. So, take hotend apart, clean heatbreak, check PTFE tube length and replace PTFE tube if necessary.

Usual precautions: be careful not to damage hotend wires (heater & thermistor) and don't over-tighten three small screws that hold heatbreak. That is, if you're not sure how to do it, I recommend reading Prusa assembly manual again.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 31/07/2021 12:43 pm
Gbutton liked
Gbutton
(@gbutton)
Active Member
Topic starter answered:
Just thinking through it.

Ok, just thinking through this:

  • I probably have 100 print hours at this point.
  • I've only ever used esun pla+.
  • I've never changed the PTFE tubes.

So next steps are PTFE replacement and heat break cleaning.

Posted : 31/07/2021 1:38 pm
bobstro
(@bobstro)
Illustrious Member
Heat or airflow issues?

Just to eliminate the obvious: Are you printing in an enclosure or space where temps can approach 40C/104F? This is "heat creep season" in many parts of the world.

I've collected my accumulated notes from 3 years of troubleshooting posts here. There might be something useful there.

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 : 31/07/2021 2:50 pm
BogdanH
(@bogdanh)
Reputable Member

 

Posted by: @gbutton

...So next steps are PTFE replacement and heat break cleaning.

Just something to think about... Some have reported good experience by using Capricorn tube inside heatbreak (instead of normal PTFE tube). Reason being, Capricorn has quite higher temperature resistance against shrinking, and so there are less chances for that to happen soon again.
Capricorn can be kinda expensive, though. So, for just a little more, you can already upgrade to better heatbreak (~17€) -which is overall better solution in my eyes.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 31/07/2021 4:45 pm
Gbutton liked
Gbutton
(@gbutton)
Active Member
Topic starter answered:
I don't think there are airflow issues

I'm in a relatively big office that's air conditioned. It's the summer in the american south, so things get hot and muggy, but AC keeps things cool and dry.

Posted : 31/07/2021 7:07 pm
Gbutton
(@gbutton)
Active Member
Topic starter answered:
Thanks

I just ordered some capricorn tubing. I also pulled the hotend ptfe out and it's about a mm shorter than is should be at 42.5. I'll post if the ptfe replacement fixes is.

Posted : 31/07/2021 7:34 pm
Gbutton
(@gbutton)
Active Member
Topic starter answered:
PTFE Replacement worked

I'm glad I changed out everything else, as my printer is now running like new, but it was the PTFE tube that fixed it in the end.

Posted : 02/08/2021 1:20 pm
BogdanH
(@bogdanh)
Reputable Member

Glad you managed to repair -thank you for reporting.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 02/08/2021 1:33 pm
cwbullet
(@cwbullet)
Illustrious Member
Good news

 

Posted by: @gbutton

I'm glad I changed out everything else, as my printer is now running like new, but it was the PTFE tube that fixed it in the end.

Happy printing!

--------------------
Chuck H
3D Printer Review Blog...
Posted : 02/08/2021 4:25 pm
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