Some thoughts on what the buffer/hub spring position hall sensor might mean - might be useful when for example trying to manually feed TPU into a multi colour AMS print.
Background info here - Introduction to AMS | Bambu Lab Wiki
My guess is that it is important for the buffer to be held in a fixed position .
plus the other end of the output ptfe to be held in a fixed position, but with a bend in the tube to allow the spring to still move without the print head movement affecting spring tension,
The hall sensor I suspect needs to report the following 4 spring positions
- Spring Fully extended - no tension in filament - ok during initial feed or during last part of filament running out - but possible error depending on readings of print head and AMS hub filament sensors
- Spring Almost fully extended - max normal slack in filament - ideal position - AMS drive motor can stop feeding
- Spring almost fully pressed in - little slack left in filament - normal state - AMS needs to drive out more filament until position 2 above reached.
- Spring fully pressed in - filament over tensioned - possible error - filament might be stuck at AMS/spool.
Between 2 and 3 - slack in filament - ideal position - no action required