I have a request that should fix a problem. Its happened to be twice now and I have heard of it happening to others. I assume this would be worse or better depending on the type of filament used.
Problem: When printing with multiple filaments, if one of the filaments isn’t used for a prolonged time period it will break in the feed tube between the AMS and the hotend from flexing back and forth constantly until it fatigues.
Scenario: I had a print that was 2 colors. The filament in the RIGHT nozzle was only used for the first 5 layers. After that the rest of the print was only using the filament in the LEFT nozzle. The remainder of the print was just under 4 hours long. So the filament in the RIGHT nozzle was bending back and forth in the feed tube for 4 hours until it fatigued and failed. This was with PLA.
Solution: If a single filament isn’t used for X amount of time (what ever time you decide) it will be unloaded for the remainder of the print or until it is used again. We wouldn’t want this number to be too low but if its not used for 1 or 2 hours I don’t think the one additional filament unload procedure would harm the total print time much. I would rather deal with an additional unload/load than clear out broken filament.