I have noticed that when the AMS detects the end of a spool and switching to another spool, it immediately purges everything in the tube until the extruder. This seems a complete waste of filament and time. It takes several minutes to purge all this filament. The printer still has control of the filament since it is able to feed it to purge it. Why doesn’t the printer continue to use what is in the tubes until it reaches the sensor in the extruder? Doing so would save time and filament.
I’m not sure if this is the same behaviour if not switching as I have never been present when this happens.
The problem is that once the AMS runout switch is hit, there is no way to retract the filament, so it must purge. At the time it sees the AMS runout, it doesn’t know if all the filament in the tube will be used. If it isn’t, that blocks new filament from entering the hub.
The problem I did see when I tried this was that it purged a LOT in one go, bunching up in the poop chute. I put in a suggestion that it wipe more often in this operation (I am told it does occasionally wipe, but I didn’t see it do that.)
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After the AMS runout switch is triggered, there is no need to back the filament out. You keep printing until the extrusion runout is triggered. If there is a color change or the print finishes before the extrusion runout is triggered, then you purge the rest like it currently does.
I had a print end right as the filament ran out. It purged all the filament in the pipeline taking several minutes, and then loaded the next spool to print a couple passes on the top layer. No more than 100mm. All that purge was a waste when it could have been used to finish the model instead of filling the poop chute.
Basically, purge it into the model, not the poop chute.
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