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BeardedRyan
(@beardedryan)
New Member
Nozzle Clogs repeatedly after filament reel got stuck

I have a Prusa Mini+ and have been printing for a few months.  I changed the nozzle from 0.4mm to 0.6mm, first layer cal was good, test print was good, and regular print was good.

I started doing a large print, came back after an hour to find the filament spool tangled so the extruder was pulling on it very hard. Some of the filament seemed burned (it was blue filament that had turned a brownish white color).

Now it seems that it doesn't feed the nozzle enough to keep a solid flow and then it jams (filament stops coming out and clicking noises occur).

I can unload and load filament with no issues, so it seems the extruder is fine. For extra measure I took out the PFTE tube, checked for blocks, and cleaned it out with compressed air. Didn't help.

I can clear the clog with a cold pull ( https://help.prusa3d.com/en/article/cold-pull-mini_126399), thought if its less than 140C the filament breaks. During the cold pull when its hot, i can get a consistent flow out of the nozzle by shoving in filament.  I did a cold pull 2-3 times.  Didn't help.

Afterward the cold pulls, I load filament, it works. I purge, it works. I run a first layer cal, filament flow starts to lessen as it goes through the cal. I try to print something next and 0 filament comes out; it's already jammed and the extruder is making clicking sounds, again

Using this ( https://help.prusa3d.com/en/article/clogged-nozzle-hotend-mini_112011/) i inspected the PTFE tube and it was mostly clean. There was no filament until you get all the way down to the nozzle head.

I can clear the clog without a cold pull or unloading. I can take the nozzle to 270C, it starts to ooze out and after 30-45 seconds its clear, but then always jams again as described above.

I remove the 0.6mm nozzle, i can see through the hole.  I reamed it with the needle while hot, didn't seem to help.

I'm not sure what next steps should be. What should I do next to diagnose?  What is broken?

Best Answer by BeardedRyan:

I just got back up and running today.  I took apart the extruder and it was fine; minimal filament stuck in there but no show stoppers.

I ended up taking apart the hot end; remove the heat block from the heatsink, remove the thermistor and heating element from the heat block (to get the heating element out after removing the screw I had to pry it open with a Philips head).  The heat block was clearly clogged.  I put it in a toaster oven at 450F hoping the filament would ooze out.  It didn't, but it was hot enough to remove the heat pipe from the heater block.  At that point I just took a lighter and burned the PLA out of the pipe.  Worked pretty well, pretty blue flames.

I cleaned it up with IPA, heated it up, connected the heater block to the heat pipe.  I had to buy thermal compound (something with a functional temperature to 300C), then I reversed the process and put everything back together.

What I didn't realize is that I couldn't get the hot end assembly to sit like it had previously, so I messed up the alignment between the PINDA sensor as the nozzle, so I had to re-adjust.  I had to recal the z-axis a few times, but now I'm 5 hours into a successful print.  

Burning out the filament was ham-fisted, but I was tired of messing around with this issue.

Posted : 13/05/2021 1:41 am
cwbullet
(@cwbullet)
Illustrious Member
RE: Nozzle Clogs repeatedly after filament reel got stuck
Posted by: @beardedryan

I have a Prusa Mini+ and have been printing for a few months.  I changed the nozzle from 0.4mm to 0.6mm, first layer cal was good, test print was good, and regular print was good.

I started doing a large print, came back after an hour to find the filament spool tangled so the extruder was pulling on it very hard. Some of the filament seemed burned (it was blue filament that had turned a brownish white color).

Now it seems that it doesn't feed the nozzle enough to keep a solid flow and then it jams (filament stops coming out and clicking noises occur).

I can unload and load filament with no issues, so it seems the extruder is fine. For extra measure I took out the PFTE tube, checked for blocks, and cleaned it out with compressed air. Didn't help.

I can clear the clog with a cold pull ( https://help.prusa3d.com/en/article/cold-pull-mini_126399), thought if its less than 140C the filament breaks. During the cold pull when its hot, i can get a consistent flow out of the nozzle by shoving in filament.  I did a cold pull 2-3 times.  Didn't help.

Afterward the cold pulls, I load filament, it works. I purge, it works. I run a first layer cal, filament flow starts to lessen as it goes through the cal. I try to print something next and 0 filament comes out; it's already jammed and the extruder is making clicking sounds, again

Using this ( https://help.prusa3d.com/en/article/clogged-nozzle-hotend-mini_112011/) i inspected the PTFE tube and it was mostly clean. There was no filament until you get all the way down to the nozzle head.

I can clear the clog without a cold pull or unloading. I can take the nozzle to 270C, it starts to ooze out and after 30-45 seconds its clear, but then always jams again as described above.

I remove the 0.6mm nozzle, i can see through the hole.  I reamed it with the needle while hot, didn't seem to help.

I'm not sure what next steps should be. What should I do next to diagnose?  What is broken?

I would recommend a complete disassembly and reassembly of the hotend.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 13/05/2021 10:52 am
jackyjoy123
(@jackyjoy123-2)
New Member
RE: Nozzle Clogs repeatedly after filament reel got stuck

thanks my issue has been fixed.

Posted : 18/05/2021 1:39 pm
hatch
(@hatch)
Active Member
RE: Nozzle Clogs repeatedly after filament reel got stuck

@jackyjoy123-2

Hi, would you mind describing how you fixed the problem? This sounds exactly like my issue - purging works fine, but first layer instantly clogs. I made a post about it here: https://forum.prusaprinters.org/forum/hardware-firmware-and-software-help/at-my-wits-end-with-extrusion-problems-pla-first-layer-petg-works-better/

I have cleared any clogs in the nozzle/hotend with cold pulls and refitted the ptfe tube, but still the same issue.

Posted : 28/05/2021 11:57 am
BeardedRyan
(@beardedryan)
New Member
Topic starter answered:
RE: Nozzle Clogs repeatedly after filament reel got stuck

I just got back up and running today.  I took apart the extruder and it was fine; minimal filament stuck in there but no show stoppers.

I ended up taking apart the hot end; remove the heat block from the heatsink, remove the thermistor and heating element from the heat block (to get the heating element out after removing the screw I had to pry it open with a Philips head).  The heat block was clearly clogged.  I put it in a toaster oven at 450F hoping the filament would ooze out.  It didn't, but it was hot enough to remove the heat pipe from the heater block.  At that point I just took a lighter and burned the PLA out of the pipe.  Worked pretty well, pretty blue flames.

I cleaned it up with IPA, heated it up, connected the heater block to the heat pipe.  I had to buy thermal compound (something with a functional temperature to 300C), then I reversed the process and put everything back together.

What I didn't realize is that I couldn't get the hot end assembly to sit like it had previously, so I messed up the alignment between the PINDA sensor as the nozzle, so I had to re-adjust.  I had to recal the z-axis a few times, but now I'm 5 hours into a successful print.  

Burning out the filament was ham-fisted, but I was tired of messing around with this issue.

Posted : 07/06/2021 1:52 am
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