I’m running an A1 with AMS Lite, the AMS is in an enclosure to control humidity. I also have a y-splitter at the AMS hub/toolhead for an external spool. When I want to load filament from the external spool I have to remove the enclosure cover, back out the filament past the splitter and push the external filament in–this procedure lets humid air into the enclosure.
In searching the web for possible solutions I came across this code:
"To implement retraction at the end of a print, you can use the following G-Code snippet:
M83 ; Set to relative mode
G1 E-4 F900 ; Retract 4mm at 15mm/sec
G92 E0 ; Reset extruder position
My thoughts are that I change the 4mm to 40 (which will clear the Y) but I don’t know where to put this code snippet.
The command G1 is working with the extruder motor. The extruder motor is mounted on the toolhead. You can tell it -100 but it still has a physical reality problem where it cannot push the filament back any further than the position of its own gears. Once it crosses that line, No bite, no force, just some gears spinning.
That being said, it probably still will help your scenario to have it retracted more than normal. But it can’t pull it back to a neutral position in the ptfe line like the ams feed motor can. Ams is holding on way further down the line and has tens of cm of "slack’ to pull up on. I’m not sure you can issue commands directly to the ams, there is probably custom Bambu gcode macros to do that that might need more analysis. Whatever it’s doing during a “unload” is the kind of thing you want.
Another wrinkle is that the ams lite spool holders have only a short spring rewind mechanism. If the retract is now much longer than this rewind can accommodate, filament might get messy/escape the spools side, so there’s probably a sweet spot to target. I think your goal of a few cm is ok.
