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    BL Touch doesn't deploy when bed heater is on

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    Duet Hardware and wiring
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    • JonasBaleineundefined
      JonasBaleine
      last edited by

      Hi,

      I have a Duet Mini 5+ board and use Duet Web Control 3.4.5 and RepRapFirmware for Duet 3 Mini 5+ 3.4.5.
      My bed is powered through a mosfet by OUT3, connected to V_OUTLC1+ and out3-, on the duet board.
      My BL Touch (and CR Touch, tested both) is connected on IO_1 using the 5V_EXT.
      As long as my bed is on standby or off, the probe works perfectly.
      As soon as I turn on the bed heater, the probe won't deploy or retract, whether through homing or simply sending the deploy/retract gcodes.

      If I use the 3.3V_EXT to power the probe, I don't have this issue, although the probe is not 100% reliable (sometimes it deploys, sometimes it doesn't, or it won't retract on some occasions).

      The behavior was the same when I powered the bed directly from OUT0.

      Do you have an idea of what could be causing this behavior?
      Thanks!

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      • Phaedruxundefined
        Phaedrux Moderator
        last edited by

        The bed can create a strong magnet field which can interfere with the BLtouch. Or perhaps your 5v or 3v rail is drooping.

        Either way, you can probably work around it with the M558 B1 parameter which turns off the bed heater during the probing move.

        https://docs.duet3d.com/User_manual/Reference/Gcodes#m558-set-z-probe-type

        Z-Bot CoreXY Build | Thingiverse Profile

        JonasBaleineundefined 1 Reply Last reply Reply Quote 0
        • JonasBaleineundefined
          JonasBaleine @Phaedrux
          last edited by

          @Phaedrux Thanks, it seems to solve my issue!

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          • Phaedruxundefined Phaedrux marked this topic as a question
          • Phaedruxundefined Phaedrux has marked this topic as solved
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