PTFE tube stuck in heatbreak (prusa mini+ original)
 

PTFE tube stuck in heatbreak (prusa mini+ original)  

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johanwiner
(@johanwiner)
Active Member

Using a Prusa Mini+ with Prusament and 0.25mm nozzle. No modifications.

Long story short: I try to pull out the PTFE tube in order to clean the inside of the heatbreak since I suspect that there is something wrong there since material does not get extruded. But the tube is stuck so I need some recommendation on chemicals that could melt any PLA stuck in the  heatbreak but that does not melt the PTFE tube, so that I can pull it out.

 

My prusa mini+ (owned for 1 month) stared to give of loud bangs from time to time. Not the ticking sound from the extruder failing to grab filament and push it forward as mentioned in other threads. The sound was louder and just one short click/bang. Hard to tell but I think it came from the nozzle parts. This continues from time to time, one band every hour maybe. And in the prints bottom layer i started to notice underextrusion, lines where too little filament was extruded. I could not notice any issue beyond the bottom layer.

I calibrated the distance between the nozzle and the heatbead to let the material flow out of the nozzle more easily. It did not help.

The extrusion became worse in the next print and finally no material was extruded at all.

I tried unloading the filament but it was stuck. And after a couple of attempts the extruder had chewed up the filament. I disassembled the extruder and started to pull out the filament manually while the nozzle was hot. I could not see any issues with the filament.

After pulling the filament out the nozzle was still clogged. I removed the nozzle, it was full of plastic, expected I guess since that is how the nozzle works (it will contain a lot of melted plastic). The heatbreak was still clogged so I inserted the needle included in the Prisa Mini+ and after some time i had all the PLA removed from the heatbreak.

Now I wanted to remove the PTFE tube to see if the heatbreak has plastic in its bottom part where the PTFE tube ends. But after heating the heatbreak to 215 degrees the tube was still stuck and I could not pull it out using a pliers.

I heated the heatbreak to 280 degrees in order to melt any remaining PLA holding the PTFE tube in the heatbreak but I could still not pull the tube out.

 

Is there any way to get the tube out without trying to pull even harder, since I am afraid of damaging the tube? Is there any chemicals that can be applied to melt any remaining PLA to get the tube out if it is PLA that is holding the tube in the heatbreak?

 

 

 

 

 

Best Answer by johanwiner:

Thanks for the info, now I do not need to worry to much about damaging the tube.

I actually managed to get the tube out and it looked fine. I used multiple cold pulls and finally the tube came out with the PLA.

There was some PLA that had somehow created a blob beneath the PTFE tube in the heatbreak. Whether this was the reason to my problems of if this happened just as I was searching for the solution, I dont know. I inserted the PTFE tube again after cleaning the heatbreak etc and now the PLA flows again through the nozzle. Only issue is that it flows too well and oozes so I will have to raise another topic and search for more info.

The PLA keeps flowing out after every print for another 10 seconds. My prints also comes out super stringy and a bit more fragile (small parts break off more easily between different layers compared to before).

Never had this problem before. And the nozzle oozes (bubbles comes out) just before printing.

Posted : 16/04/2021 9:12 am
johanwiner
(@johanwiner)
Active Member

So i foundation info on dissolving PLA, is possible. Various types of chemicals react and dissolve parts or all of PLA, such as the following:

  • Methyl Ethyl Ketone (MEK)
  • Acetone
  • Ethyl Acetate
  • Tetrahydrofuran
  • Caustic soda (Sodium Hydroxide

problem is that I don’t know if the PTFE tube can withstand these.

That is my question.

Posted : 16/04/2021 10:12 am
johanwiner
(@johanwiner)
Active Member

I have tried to do cold pulls in order to get the PTFE tube out together with the PLA I put into the heatbreak  in the cold pull without any success so far.

Posted : 16/04/2021 12:33 pm
mark
 mark
(@mark-6)
Estimable Member

I ordered more PTFE tubes, considering if you have to pull it out, it is likely damaged and should be tossed. If you get other things from Prusa that cover the shipping, they are less than a dollar apiece. I was never able to remove one without damaging the top anyway. I'd suggest just throwing it away, unclogging as they describe and installing a new one as they describe.

https://help.prusa3d.com/en/article/clogged-nozzle-hotend-mini_112011

https://help.prusa3d.com/en/guide/how-to-replace-a-hotend-ptfe-tube-mini-mini_119449

Regards,

Mark

 

Posted : 16/04/2021 5:29 pm
johanwiner
(@johanwiner)
Active Member

Thanks for the info, now I do not need to worry to much about damaging the tube.

I actually managed to get the tube out and it looked fine. I used multiple cold pulls and finally the tube came out with the PLA.

There was some PLA that had somehow created a blob beneath the PTFE tube in the heatbreak. Whether this was the reason to my problems of if this happened just as I was searching for the solution, I dont know. I inserted the PTFE tube again after cleaning the heatbreak etc and now the PLA flows again through the nozzle. Only issue is that it flows too well and oozes so I will have to raise another topic and search for more info.

The PLA keeps flowing out after every print for another 10 seconds. My prints also comes out super stringy and a bit more fragile (small parts break off more easily between different layers compared to before).

Never had this problem before. And the nozzle oozes (bubbles comes out) just before printing.

This post was modified 2 months ago by johanwiner
Posted : 17/04/2021 6:07 pm
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