I usually unload filament using the extruder motor, with the nozzle around 30 °C below the filament's print temperature. Despite this, often a significant amount of filament is left in the nozzle, and the filament comes out with a long stringy tip.
- Does this suggest that the procedure might be leaving deposits of melted filament outside of the melt zone (potentially leading to blockages)? and if so,
- What sequence of temperature/movement controls would be most likely to remove or mitigate the risk of deposits?
I am familiar with the “cold pull” technique, but I am looking for the best strategy for a solution using the printer's controls.
I usually extrude a quantity of cleaning filament when changing filaments, though I'm not sure whether this would also clean any deposits outside the melt zone.
I have seen a procedure called “cooling moves” in the Prusa Slicer code. I understand this is intended to produce a cleaner filament tip upon unloading in a multi-material scenario, and I wonder whether a similar strategy should be employed for regular unloading, although I am unable to tell from the code what exactly is happening.
I am using a genuine E3D V6 hotend and a Bondtech BMG Extruder.