Servo to control a part cooling air valve

  • Currently hovering over the buy now button on a Duet WiFi.
    I'm currently using a dual extruder setup with a remote air feed used for both extruder cooling and part cooling for compactness and flow, currently the air flow is regulated by hand controlled valves and the printer controlled the basic stock board but I've long been wanting to control air flow via board controlled servos.

    Do you reckon the duet WiFi would be able to do this? I know it can control servos but can this be linked to a fan control input from a slicer such as cura? Sorry for the potentially basic question but I'm trying to justify the need for the upgrade!


  • administrators

    Currently there is no facility in RepRapFirmware to turn a M106 fan command generated by a slicer into a servo command. Is that what you mean? OTOH some slicers allow you to configure the fan commands, so you may be able to set up your slicer to generate M280 commands instead of M106.

  • Actually, this is something that is on my to-do list. The way I would approach it would be to post process the gcode file to replace the M106 commands with the servo commands. It might be doable with a simple search and replace using a text editor like notepad++. If not, then a Python script.
    Not sure what the OP has in mind but I'm thinking along the lines of something like a berd air but using a quieter pump like a pond air pump. I'd control the air flow by having a bleed valve fitted to a tee piece. So the pump would run full speed but the airflow would be regulated by varying the bleed valve.

  • It is (was?) common to use solenoids with pwm to control the bypass air in some fuel injected engines and I control the bypass air for my supercharger with one. You would need to do some voltage shifting but a simple mosfet circuit would do. Google "pwm boost control solenoid"

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