MMU2 sometime doesn't release filament (video)
Occasionally (like maybe 1 in 10 times) the MMU2 does not rotate the tumbler to release the filament after loading. In the video, it unloads the purple then loads the black. If you look carefully, you will notice that the bearing is not rotated away from the pulley after loading and the extruder is dragging the MMU2 pulleys along with it. Most of the time this doesn't happen and the filament is released properly but it happens often enough to be a problem. This is resulting in an occasional print error because sometimes the MMU grinds the filament and then cannot retract when time comes to change. Luckily it is a recoverable error - the printer detects it and waits for me to fix the problem but I have already had to fix it about a dozen times on this 29 hour print. I am on the latest firmware for both the i3 and MMU2S.
RE: MMU2 sometime doesn't release filament (video)
Check/tighten the screws for the tumbler. Maybe the shaft just slips if the motor gets hot from time to time.
PETG is not perfect material for the tumbler. Some people reprint it in PC because of this issue.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: MMU2 sometime doesn't release filament (video)
Good advice - but I had already done that. It is tight - I am unable to wiggle it at all with my thumbs. I'm going to dig into the firmware and see if I can find how this can happen. One thing I did recently was trim about 8mm off the PTFE leading to the extruder and did not recalibrate the MMU length. Wondering if maybe the filament is reaching the IR sensor early causing it to skip the final step on the tumbler.
RE: MMU2 sometime doesn't release filament (video)
Well... Cross my fingers but I just completed a print with no failed filament changes. What changed? I re-calibrated the PTFE length. Not sure how removing 8mm would cause the tumbler to sometimes not rotate but the issue did not arise this last print. This was a shorter print (only 8 hours and the other with the problems was 29 hours) so I'll keep watching. Cautiously optimistic.
RE: MMU2 sometime doesn't release filament (video)
This was an issue with firmware 1.0.5.... https://github.com/prusa3d/MM-control-01/issues/135
I built from the current commits and it did resolve this issue.
Anything can be made better
https://www.myminifactory.com/users/Joe%20Prints
RE: MMU2 sometime doesn't release filament (video)
Thanks! I will go grab the latest.
RE: MMU2 sometime doesn't release filament (video)
This was an issue with firmware 1.0.5.... https://github.com/prusa3d/MM-control-01/issues/135
I built from the current commits and it did resolve this issue.
Do you still have the newly built firmware? If so, can you upload it so we can benefit from your efforts? 🙂
RE: MMU2 sometime doesn't release filament (video)
MM-control-01_1.0.5c
Here ya go, it's been doing better than it was before.
I did also flash the printer FW with a version to enable the cutter on the selector, but that still needs work.
Anything can be made better
https://www.myminifactory.com/users/Joe%20Prints
RE: MMU2 sometime doesn't release filament (video)
MM-control-01_1.0.5c
Here ya go, it's been doing better than it was before.
I did also flash the printer FW with a version to enable the cutter on the selector, but that still needs work.
Thanks!!
I printed a new selector head with better cutter holder, mostly for the better filament route and ability to clean the area around the metal ball (and use a magnet) without having to disassemble it.
RE: MMU2 sometime doesn't release filament (video)
just printed that same head, testing it tonight
fix
I had exactly the same issue, Prusa support spent 2 months with me to try to find the issue. I found it myself. The 2 screws at the left of the tumbler were loose, so the motor didn't rotate it. So dumb and basic, but fixed and perfect functionning since.