Multi retract and prime pillar

[Kulitorum]

I'm building a new printer with a experimental triple-filament-in-one-nozzle hotend.

I have printed two prints with it, one with a single color and one tri-color. My problem is that I cannot use retraction, because if I retract the filament from the active (currently printing) extruder, the molten plastic flows back up into the inactive extruders, so the two inactive extruders has to remain un-retracted, leading to stringing.

So I was hoping for an option to always retract and un-attract all extruders at once for all retracting operations, to see if that may allow me to get nice non-stringing prints.

I would also like an option to change the size of the prime structure, so I can adjust the amount of priming needed.

https://www.youtube.com/watch?v=kMnbMV2gg2I
https://www.youtube.com/edit?o=U&video_id=oLBPVm56kKI

[lonesock]

Nice! Could you give an example of the G-code you would use to do the retract / prime? I'm not sure I understand exactly how it should work.

thanks,
Jonathan

[Kulitorum]

Well, I made a firmware hack that retracts all three extruders when reciving the G10 command (Ultimaker 2 gcode) and back at G11.
This works pretty well, except that the G10 and G11 are send for *every* move command, even just changing between the perimeters.

So please make some way to determine when to send G10 and G11 - like it can be defined for z-lift moves.

Like Minimum move distance for G10/G11 or simular