Really strange failure mode. What/Why?
This is in regards to the: MK2.5S/MMU2S. I am on the latest firmware (4/1/2019) for both the printer and the MMU2S.
After leaving a print to run over night I will wake up to find that there was an unloading issue. No biggie, seems to happen fairly often. The printer's display indicates that the MMU2S needs attention. The temps have dropped, etc. I'm able to fix the MMU2S jam, and get it to flash the red+green light, indicating it's ready to proceed. At this point, I press the right-most button on the MMU2S to let it resume. And this is where it starts getting weird.
When the printer goes into "MMU2S needs attention" mode, the extruder is docked to the back left and raised up about 60mm from the print. Resuming the print causes the extruder to move over to the purge block (but not down), and it starts doing its purging material dance (in mid air). There's no filament in the tube, so it's not spitting anything out of the extruder. It then lowers down to the right height.
At this point the MMU2S feeds in filament, but there's another problem. The extruder temperature is never brought back up to print temps. It's just stuck at room temperature. So the filament feed never succeeds. It will load and unload the filament a couple of times. And then it will proceed printing the model, even though the feed never succeeded and the extruder isn't up to temp.
This only started happening with the latest firmware. It's really bizarre. I'm wondering if anyone else has seen this, or knows how to fix it?
RE: Really strange failure mode. What/Why?
Unfortunately, I am not able to offer you a fix, but I can confirm that I have had very similar issues. On several prints, I have had load/unload failures with the MMU2 where the printer says "fix the problem and resume". However, upon resuming, the extruder either neither warms up... or it warms up to temp but then seems to freeze and never continue. My primary issue with the MMU2 is that when these types of failures occur, they are more often than not unrecoverable, even with manual intervention.
RE: Really strange failure mode. What/Why?
I have seen similar failures and had to intervene several times to complete a print. I also get the impression that fixing these MMU2 issues has been shelved due to the SL1 and Slic3rPE recoding for the SL1. Not sure if the MMU2 is going to be fixed for a while if ever. I'm on the point of ordering a Palette2, or just giving up on multi material printing as something that is just not usable at present.