Had a leak. Cleaned hotend, can't reassemble. Help?  

Active Member

I'm going to go through the whole saga because I'm hoping I can find all the places I've screwed up and never do it again.

I'm a totally novice at this. The MK3S is my first 3d Printer and I've had it less then 2 weeks.

This all started when I thought I'd try a different nozzle to see if I could print some objects that didn't need detail a bit faster. I tried following the instructions in the Prusa video ( ). Once it's heated up the video says to slightly rotate the heatblock. I did that and when I went to unscrew the nozzle, it wasn't budging so I turned the heatblock back and figured I'd try again at a later date. 

Then I started getting blobs, and failed prints. I finally diagnosed this as a leak. The filament was oozing up over the heat block. Okay. Now I need to clean it. I follow the guide about how to replace the pieces of the hotend in order to get it apart so I can do this. ( https://manual.prusa3d.com/Guide/How+to+change+a+heatbreak-heatsink-heaterblock+-+MK3S-MK2.5S-MMU2S/1451 ). 

All that went fine. It's clean. Now to reassemble. I put some new thermal past on the heatblock and go to screw it into the heatsink but it won't go all the way, a few threads are visible.  I realize it's probably the PTFE. I make sure to push the the collet down and try to pull out the PTFE. It's not moving. After fussing a bit I push it down and that works. I'm able to get it out. Without that in, the heatblock has no problem screwing flush. I look at the PTFE. I see the problem. I don't know what to do. That's not like the PTFE in ANY video, manual image, part image, or anything I've seen online. Anyone have any insight? I'll try to get on chat with Prusa tomorrow but I can't find when they are available. 

PTFE and Heatsink

Posted : 10/04/2020 2:52 am
Active Member

I did discover I have another PTFE tube that came in the spares! So I'm able to move forward. I also realized that something likely caused this. I just don't know what. 

Posted : 10/04/2020 3:36 am

Here are diagrams showing how to trim new PTFE tubes from bulk tube



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 : 10/04/2020 11:25 am
Active Member


Thank you. I had seen that. Seeing the tube like that took me by surprise until I saw an image where someone else had one like it because of compression and clogging. I was so happy I realized there were spares! 

Posted : 10/04/2020 12:41 pm

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