I have a somewhat interesting issue.

Recently I’ve installed the BTT SFS v2 filament sensor, which detects both if filament is present and if there is a jam or not. The jam detection works with an encoder that spins whenever filament is running through it.

Pressure advance however works by slowing down and speeding up extrusion based on motion of the nozzle to prevent bulging and oozing.

This however triggers false positives in the jam detection. Without pressure advance it works fine.

Does anyone have experience with this? Below is example code of my Klipper config related to the jam sensor. Raising the detection length from 2.88 to 10 did not solve it and I don’t want to put excessive numbers there.

[filament_motion_sensor encoder_sensor]
switch_pin: i forgot lol
detection_length: 10
extruder: extruder
pause_on_runout: False
runout_gcode:
  PAUSE # [pause_resume] is required in printer.cfg
  M117 Filament encoder runout
#insert_gcode:
  #M117 Filament encoder inserted
  • roofuskit@lemmy.worldEnglish
    4·
    15 days ago

    PA isn’t the issue. Klipper compares the rotation of the sensor to that of the extruder. It’s when one is moving and the other isn’t that’s the issue. You probably need to tweak a setting. I had to bump the filament distance up on mine.

      • ExcessShiv@lemmy.dbzer0.comEnglish
        11·
        15 days ago

        Ah OK makes more sense then.

        As for detection length, default is 7mm for encoder-type sensing according to klipper documentation. So 10mm is far from excessive and you should be able to bump it even more just to check.

        Is your extruder direct drive or bowden?

          • ExcessShiv@lemmy.dbzer0.comEnglish
            11·
            15 days ago

            What did you set your event and pause delays to?

            Edit: NVM, looking in to the docs shows they have no relevance in this case.

            what accelerations, speeds and PA values are you running with?

            • Rolivers@discuss.tchncs.deOPEnglish
              3·
              15 days ago

              Ah, I see the problem. I messed up the calculation, instead of .072 PA I used 0.72. The part that got printed looked quite bad as well so that explains a lot. I’ve entered more normal values and now it looks much better.

              Thanks!