Filament bunched up around the print head - can't free it
How to best describe this mess... The prints would not sprint. I used 3Dlac and still the prints wouldn't stick. I finally got a print to work and figured all was okay. I started a print that was going to run overnight but lo and behold the print didn't stick which caused the filament to bunch up around the head the collision detection needs work because it didn't detect it until this mess around the print head was created. Now, I can't figure out how to free the print head from the filament. I can't heat the nozzle (which might not work anyway) because it causes a "thermal anomaly". Any thoughts on how to fix this mess?
Thank you.
You have a first class blob of doom. Search for blob of doom to see how others have dealt with them.
Before doing anything, look at pictures of a clean extruder and note the position of the rather delicate wires that are currently hidden, if you damage them you will have to buy replacement parts as broken wires can't be rejoined.
You may have damaged your fan shroud, in which case you will need a replacement. It may still be just good enough to print its replacment...
To remove it:
Raise the nozzle temperature to the printing temperature for the filament in question and allow it to heat for several minutes.
If you are lucky you will be able to prise the blob open - more likely you will need to add heat from outside with a heat gun to aid the softening, sometimes it's worth using a soldering iron to carve chunks off the mass.
Use needle nosed pliers to prise this away; remove it in parts if it won't release the wires.
Once you have the worst removed you decide whether you need to disassemble the extruder to get at all the blob or perhaps you can clean up in situ.
After the cleanup there will be overcooked filament inside the nozzle so at least a purge and probably a cold-pull will be necessary.
Cheerio,
RE: Filament bunched up around the print head - can't free it
Unfortunately if the OP is using firmware 3.12 then the new thermal protection model is going to shut down the heating, making the traditional advice to heat up the extruder to soften it up no longer viable. I doubt PRUSA considered that scenario when they developed it unfortunately. I suspect they will end up taking it apart to get the extruder with blob out and heating it up with a different heat source, away from the rest of the printed parts.
The advice to search for previous blob of doom threads is good though.
For future reference this is caused by poor part adhesion, it’s why all the regulars here are so insistent on getting your bed cleaned and the live z dialled in properly.
That side effect hadn't occurred to me. It's so long since I had a BOD that I just trotted out the standard advice without thinking.
So: use a soldering iron for the first dissection and a heat gun for the bulk, with PLA a hairdyer might just manage it.
Perhaps we should suggest a de-blobbing override setting for thermal protection ... thoughts?
Cheerio,
RE: Filament bunched up around the print head - can't free it
The new thermal protection model should have shut down the printer before the blob was so big. It failed.
To fix, the new thermal protection has to be disabled: "The thermal model protection can be disabled by connecting the printer to your computer (Octoprint, PuTTY...), and sending M310 S0." https://help.prusa3d.com/article/thermal-model-calibration_382488
Useful but annoying for those unused to raw terminal comms. Perhaps it's time for experiments.
Cheerio,
RE: Filament bunched up around the print head - can't free it
Thank you everyone who helped with this. After using my heat gun on it a few times I got it to the point where I could heat the head and pull the rest of the blob off. I didn't have to take it apart as in the video but I have to reprint part of the head assembly because it melted when using the heat gun.
RE: Filament bunched up around the print head - can't free it
Taking it apart is done so that you don't melt the printed parts with the heatgun. Those are pretty indiscriminate.