Mixing Extruder: How do you program it so that both extruder motors move during retraction and unretraction (regardless of active tool)?
I have a zonestar z5fm2 running marlin 1.1.8 with a mixing extruder. That is, 2 extruder stepper motors feeding a 2-in 1-out hotend (similar to the E3D cyclops).
This kind of printer works best if both extruders reverse during retraction (and obviously then both unretract). If just one retracts, the filament continues dripping from the nozzle because the filament from the other extruder is still advanced into the mixing chamber.
How can I set up a profile that prints with extruder 1/2 normally but retracts with both at the same time?
For convenience I have set up:
T0 as the first extruder;
T1 as the second extruder;
T2 as a virtual extruder consisting of a 50/50 mix of extruder 1 and 2 (made by having this in the start code: M163 S0 P50 followed by M164 S2)
I was thinking of a find-and-replace script that finds the retraction (G1 E-5.5) and replaces it with T2 G1 E-11, then somehow finds the un-retraction and switches back to the original tool (T0 or T1) that was active before the retraction. But perhaps I'm getting ahead of myself and there's already a simpler way I'm not perceiving in the existing graphical settings? Or some other alternative to tame my stringy mixing extruder (like set T0 and T1 as 10%/90% mixes so both filaments get some exercise...?)