Dual Layer Fan Help

  • Hi, I think this is a fairly simple question and based on research online I think I know the answer but was hoping someone could provide a definitive answer.

    I have a custom made Kossel type printer that I have been building as an upgrade for my DIY Rostock. I want to have 2 layer fans on it both run with PWM. While the Duet Wifi has several PWM pins from what I have found the slicers (in my case simplfy3d) dont support 2 PWM fans. Is there a way around this so i can have the layer fans driven in the slicing. My 2 thoughts were if there is a firmware trick to make one PWM Pin always match the other, or to wire 2 fans together and plug them both into the Fan 0 PWM pins.

    Has anyone else come up with a solution to this? Will running both fans on the same set of PWM Pins lower the speed, performance or life span of the fans?

    Thanks for all of the help!

  • Both fans on the same set of pins is no problem.

  • I run two 24vdc 5015 blowers with printed nozzles off my Duet085 off the single Fan0 connection. No problems other than they do cool down the E3DV6 by about 8C when running. I'm planning on insulating it.

  • Perfect, Thank you both. That is what I was leaning towards and thought would be easier but wanted to make sure it wouldn't mess up the fans or even worse the board. I assumed the current they are using wouldn't be anywhere near enough to mess up the board or the fans.

    @StephenRC I got the new e3d socks for my chimera hot end which should help insulation quite a bit I am hoping. Just have to figure out if I can get them both on as it seems like it is a tight squeeze. I can get one on and will probably only be using the one side anyway while I calibrate so that will be a fight for another day.

    Thanks for the help!

  • administrators

    As others have said, running two "normal" fans from the same PWM fan channel is fine.

    The FET user is the PMV40UN2R is rated to ~4A, however that should be derated significantly to take into account the PWM switching losses and to reduce the max temp the FET gets to so 1A should be safe. Given that most fans that would be used for this are <0.2A your configuration should be fine.

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