UM3 Firmware feature request: Extrude when changing print cores

[KickahaOta 12]

I've had my UM3 for less than a month, and I'm loving the swappable print cores -- I've already added an AA0.8 to the mix and I've got an AA0.2 on the way.

 

One thing I've found to be inconvenient: When I swap print cores, there's nearly always remnants of some other filament color in the new core (or I have to assume there is, since I can never remember). That means that after completing the PrintCore X -> Change process, I have to go to Material X -> Move and extrude material until the old filament is flushed out and the new stuff is running smoothly. So I wish there were at least an option to have the end of the PrintCore X -> Change process be "I'm going to automatically extrude material until you press Confirm", like the automatic extrusion at the end of Material X -> Load and Material X -> Change. 

[robinmdh 34]

I'll add it to the board, since we can actually see if the previous material was different than the current material we could do this automatically when needed.

 

The question then becomes should we only do this for a material type change or for a color change as well (keeping in mind that if you don't use use material identified by RFID this won't work)?

OR just add a flush material option to the print-core or material menu to allow the user to do so manually after changing cores?

[KickahaOta 12]

I hadn't considered adding a Flush option, but now that I think about it, that would be extremely useful and possibly the best solution to the problem. I currently use Material -> Move for this, but that option really seems intended for a certain amount of precision that isn't required here; and having to crank the dial umpteen turns clockwise is a pain. Being able to say "Look, just flush this" would be useful in a variety of circumstances, actually.