extra loading distance
i usually just go with the defaults as long as nothing looks weird but the extra loading distance on the mk4 is -52. is there a reason for that? it barely pushes anything out while in the wipe tower. i've been using it as is and haven't had any issues until i was doing a black and white print and the white is coming out in shades of grey which is weird too because i haven't had black bleed into anything else even on prints with white, just in this black and white print
RE: extra loading distance
extra loading distance influences the additional push of the MMU once the filament sensor of the nextruder has triggered. It has nothing to do with the purge tower of filament change procedure.
RE: extra loading distance
that's not accurate. when the nextruder sensor triggers the mmu disengages. the extra loading distance is +/- where the filament is returned to based on the parking position by the extruder. it is a core function in the filament change procedure. the issue is when it is at -52mm that means starts purging when it is -52mm from the tip of the nozzle and it isn't really purging the correct amount. now because the ramming on the mk4 is so effective the purge volume can be tiny and missing half of your purge volume isn't a big deal for most combinations. maybe this is just as a waste reduction aide or something but it seems weird to me.
RE: extra loading distance
OK - got it wrong. I was refering to the "extra loading distance" in the custom G-code section of the printer:
; setup MMU
M708 A0x0b X25 ; extra load distance
RE: extra loading distance
The extra loading distance of -52 on the MK4 might be set to minimize filament waste, but it can lead to under-extrusion during transitions, especially in dual-color prints. This could explain the gray shades in your black-and-white print, as insufficient loading of white filament may mix residual black filament from previous transitions. Try increasing the extra loading distance incrementally and observe the results in a small test print. Adjusting the wipe tower settings to allow for better purging of the previous color can also help eliminate contamination issues.
RE: extra loading distance
I usually increase the purge volume with "custom project-specific settings". Especially the switch from black to a brighter color (white, yellow..) needs a lot of purge volume whereas in the opposite direction you can leave the default values.