u/Cautious_Spite_2735

i want now my level

Hi everyone,

I have a problem with my BMCU 370 (Hall sensor version). When the printer triggers a filament change, the BMCU only retracts the old filament about 1 centimeter and stops. Then it immediately tries to load the new filament, but since the old one is still sitting in the path, the new filament has nowhere to go and crashes into it.

What I've tried so far:

• BMCU firmware version: 10.5
• Printer: Bambu Lab (AMS emulation)
• Bambu Lab firmware: latest version
• Flashed firmware using bmcuflasher (Auto online mode)
• In the firmware settings, I manually set retract length to 9.5 cm (also tried 10 cm and 20 cm)
• The settings seem to have no effect at all - the actual retract is always ~1 cm

Hardware:

• BMCU 370 (Hall)
• Connected to Bambu Lab printer (AMS emulation)
• Firmware flashed via bmcuflasher

What I need:
Why is the firmware ignoring my custom retract length settings? Is this a bug, a calibration issue, or am I missing something obvious?

Video attached shows:

1. Filament change starts
2. BMCU retracts ~1 cm and stops
3. New filament tries to load into the old one → jam

Any help would be greatly appreciated. Thanks!