What is the best way for pulling out the fillament from a metal print head

[oliverca]

As far as i know retractions above 4 mm can jam due to plastic sticking to the cold half of the metal print head, I wanted to know the best way to avoid jams when swapping filaments.

 

[kyle]

This isn't a 3D printing forum, but I'll tell you what I do. I have a delta FDM printer with a Bowden tube. I let the nozzle go below 120 degrees Celsius, then I release the PTC fitting at the bottom of the tube where it connects to the head and attempt to push out filament. Since the nozzle is too cold, the filament doesn't actually come out of the nozzle. That causes the tube to retract as the filament length increases. Then I cut the filament (leaving enough to grasp) and set the nozzle to 150 Celsius, and pull up slightly on the filament while it heats up. I keep constant slight tension on the filament and once the plastic softens as it heats up, the plug of plastic releases, but it's not liquid.

Those are the temperatures for ABS. Different materials require different temperatures. You just need it to get soft but not liquid.

 

[msaeger]

I heat it up to the temp I would run whatever filament is loaded and pull it out but I have a direct drive prusa clone.