Has the fan config changed in 1.21?



  • I have been using these two lines to configure my hotend fan and also a fan that blows on the Duet.

    M106 P1 T50:150 H1 ; thermostatically control hotend fan
    M106 P2 T150 H1 ; turn on control room fan when hotend above 150

    Previously, this was working fine, the hotend fan would come on at 50 and ramp up to full speed at 150 and the other fan just came on when the temp was above 150.

    But I noticed today that the hotend fan now just comes on above 150.

    Any suggestions as to what has changed here?


  • administrators

    There was no intentional change to the fan behaviour in 1.21.



  • Thanks for the reply.

    In the end, I twigged that the real difference was that I had changed the hotend fan and the new fan can't cope with PWM. Is that common? I have not come across a fan before that couldn't cope with PWM. This one was supplied by e3d.


  • administrators

    The heatsink fans that E3D supplies to cool the hot end heatsinks don't work with PWM.


  • Moderator

    I've had very bad luck finding 2 wire fans that cope well with PWM. I've switched to using mainly 4 wire fans meant to use PWM already. Even when only connected to 2 wire, the duet PWM works perfectly with them.


  • administrators

    I have bought several 2 wire axial fans over the last few years and all have worked with PWM except the E3D ones. Sometimes I needed to reduce the PWM frequency to 100Hz. I have had less success with centrifugal blowers.



  • Has anyone tried going really low on the PWM frequency with the E3D fan? I mean like 10 Hz. I only mention it because that's what I had to do get a really odd 30mm, 12V blower to work. Oh, and use a blip > 0.1 too. Just a thought....



  • Yes on the e3d radial blower I used a frequency of 10 or 15


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