I made some experiments where the nozzle is swapped upside down so that gravity cannot pull out a string.

My theory is, that with retracting, some air gets inside the hotend which is caught by surrounding, sealing melt and warmed up then, pressurizing the melt again. Therefore my strategy would be a fast, short retract of about 1mm to remove printing pressure, followed by a very slow retract (for about 15-30sec with about 0.5mm/min and step-wise descending speed) after swapping to the experimental idle position, which should compensate expansion of trapped air or outgassing moisture/other fumes.

I already did some tests with a macro and it reduced the length of the emerging string significantly (about 3mm instead of >10mm) but still not 100% and therefore, I will do some further testing in the next few days.

Hi folks,

i am currently trying out new ways to reduce oozing of inactive tools and came up with the idea of slowly retracting inactive tools (while printing with another tool) to counteract slowly emerging strings on the inactive nozzle. They are not caused by gravity and not preventable by bigger initial retracts.

Is there an easy way for doing such movements (important: WHILE printing with another tool) since in RepRap g-code, it seems like only the active extruder can be commanded?

I am using a Duet 3 6HC board with 3HC expansion and 3 tools with individual hotends and extruders.

Best,
mad_engineer