Retraction on mixing extruder just do not work as expected, and this is the key of stringing problems.
Basically when one side/filament is retracted, it suck from the other side/filament rather than from the nozzle , that's why the retraction just does not have any effect...
Here are some more informations
I found a solution that mitigate the problem when printing with one PLA filament I just use a higher temperature filament in the second extruder (ABS for example)
Here is Marlin 2 Configuration_adv.h settings you have to change to enable extruders synchronized retraction and completely remove stringing problems
Code: Select all
#define FWRETRACT #if ENABLED(FWRETRACT) #define FWRETRACT_AUTORETRACT // Override slicer retractions #if ENABLED(FWRETRACT_AUTORETRACT) #define MIN_AUTORETRACT 0.1 // (mm) Don't convert E moves under this length #define MAX_AUTORETRACT 15.0 // (mm) Don't convert E moves over this length #endif #define RETRACT_LENGTH 5 // (mm) Default retract length (positive value) #define RETRACT_LENGTH_SWAP 13 // (mm) Default swap retract length (positive value) #define RETRACT_FEEDRATE 45 // (mm/s) Default feedrate for retracting #define RETRACT_ZRAISE 0 // (mm) Default retract Z-raise #define RETRACT_RECOVER_LENGTH 0 // (mm) Default additional recover length (added to retract length on recover) #define RETRACT_RECOVER_LENGTH_SWAP 0 // (mm) Default additional swap recover length (added to retract length on recover from toolchange) #define RETRACT_RECOVER_FEEDRATE 8 // (mm/s) Default feedrate for recovering from retraction #define RETRACT_RECOVER_FEEDRATE_SWAP 8 // (mm/s) Default feedrate for recovering from swap retraction #if ENABLED(MIXING_EXTRUDER) #define RETRACT_SYNC_MIXING // Retract and restore all mixing steppers simultaneously #endif #endif
Hope it helps !!!
@admin : maybe this post should be stick as I have not seen around a lot of right answers (exept commons : lower your temp, increase your retract etc...) for stringing problems on mix extruder printer