MK3S + MMU2 without Filament Sensor?  

New Member
I had a MK3/MMU2 combo that was working pretty well ahead of the MK3S/MMU2S upgrade. I upgraded my MK3 to a MK3S to get the more reliable filament sensor, but would prefer to not upgrade the MMU2 to MMU2S because I don’t want to move the filament sensor above the extruder body to trigger off the gears. 
I tried running my MMU2 (non-S firmware) which is supposed to ignore the filament sensor altogether with my MK3S, but filament load does not work because the MMU2 never lets go of the filament. It pushes it correctly to the gears at the calibrated filament length, but when the gears grab it to feed it further, the MMU2 won’t let go and allow the extruder to do the rest and it just clicks.
I then tried ugrading the MMU2 to MMU2S firmware, and now the MMU2 stops pushing as soon as the filament sensor is triggered, stopping short of the gears because it expected it to be triggered by the Bondtech door opening. Since I’ve yet to mount my filament sensor above the extruder body, this doesn’t work for me. I disabled the filament sensor manually, and the behavior remains the same.
Is there any way, either with MMU2 or MMU2S firmware, that I can use my MK3S with the MMU without relocating the filament sensor above the extruder and triggering off of the Bondtech doors? Thanks.
Posted : 03/11/2019 11:02 pm
Noble Member

No, it’s not possible with original Prusa firmware. If you want to make some kind of hybrid, you have to adjust the firmware accordingly yourself.

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Posted : 04/11/2019 1:21 am

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