Gcode to retract/reverse filament

I like to experiment a bit by having the filament be reversed out of the extruder at the end of print to facilitate a faster filament change. Is there a way to do this? I tried telling the extruder to move by a G1 E-30 but that did nothing.

M600 ??? That is the official command to facilitate filament changes.

What exactly does a M600 command do? I won't actually be at the printer. My goal is to get a print going and then when it is finished retract the filament so it pulls out of the hotend but stays in the idler at the extruder so it doesn't cool in the hotend. Then, I can just come in the next morning and remove the old filament without the heating and waiting.

Now that I say it it seems like a crazy (lazy) idea but still I can think of a fee times where this may be useful.

If you retract until the filament leaves the hot end but stays pinched then more often than not you will have to dismantle it when you turn it back on because the pinch roller squashes the hot filament as it is cooling down resulting in no feed when you fire it back up.

You may get away with it sometimes but it will bite you eventually.

Heat it and wait. pulling the filament partially out and letting it cool is going to be/cause more trouble that it's worth. That said, it's easy to just add a retract command in your end gcode.

What is the retract code?

I would have to look it up.

looked up from my prime/wipe startup gcode (which is basically Clough42's prime/wipe code):


G90 ; absolute positioning
G92 E0 ; reset extrude
G1 E12 F200; extrude 12mm at 200mm/min
G1 E9 F200; retract 3mm at 200mm/min

when I change filament I heat it up, pull the idler over to free the grip on the filament and pull it out by hand. you don't want to retract hot filament all the way back to your extruder or bowden tube.