MMU2 Load and Unload failing some of the time
I've just upgraded my mk3 to a mk3s with mmu2 and the load or unload process is failing some of the time mid print. The MMU is the source of the problem I think (rather than the sensor on the extruder chimney.) Any suggestions for things to check/adjust?
RE: MMU2 Load and Unload failing some of the time
Why are you ruling out the IR sensor as a possible source?
If the IR sensor is indeed not giving you issues, then look at reducing friction in the filament path from the spools to the MMU as much as possible.
Additionally try setting the "Unload speed at start" to 120mm/s as that seems to help with shaping the tip and reducing stringing.
RE: MMU2 Load and Unload failing some of the time
Thanks for the reply Gnat. What sort of things have people found works for reducing friction in the filament path? Is it simply making sure that the gears are properly aligned or are there some tweaks that can be made to the tubes?
RE: MMU2 Load and Unload failing some of the time
In my case I do not have the physical space for the buffer and suggested spool layout.
Initially I printed an auto-rewind spool and used bearings from the Prusa spool holders, but I found that the bearings did not spin freely enough. So I removed the seals and soaked them in 99% IPA to clean out their lubrication and find that the spin much more freely now.
Additionally I also initially continued to use the long (buffer -> MMU) PTFE tube between the spool holders and MMU, but due to the close proximity (6" from the rear of the printer) to the printer I found that it created some rather tight curves that made just feeding the filament to the MMU difficult. So I swapped out for the shorter (spool -> buffer) PTFE tubes in the back of the MMU. I suspect there is nothing inherently wrong with spool to MMU PTFE tubes, you just need to have them sized right so the filament flows as easily (e.g. directly) as possible. I just didn't want to cut the factory tubes at the time
Since then the only time I have had issues is when I had the tension on the auto-rewind spring set too high and when I apparently let a roll of filament get tangled while moving it back and forth between the spool holder and dry box.
Issues with my idler door not properly tripping my IR sensor was definitely my biggest headache though.