Yet another cooling question (Cooling of Duet WiFi board)

  • Hey Duet3D forum!
    This is a question regardning my DIY printer here:

    On the Duet Wiki it is written that:
    “If you mount the board horizontally then a cooling fan is recommended, especially if there are other heat-generating components in the vicinity such as power supplies, SSRs or stepper motors. Position the fan to blow air underneath the board (optionally along the top as well), especially along the row of stepper driver chips and between the power input and bed heater terminal blocks.”

    In another thread in this forum it was stated that if there were good convection cooling then up to 2A could be used without cooling.
    My printer has a closed cabinet under the bed. Between the bed and the cabinet is:
    Bed -> 3 mm of cork -> 4mm of aluminum -> 1 mm of cork
    The cabinet has two 60 mm fans pushing and two 60 mm fans pulling air. My cabinet has a number of heat sources as shown on the image below.

    The heat generated from the motors are a guess from my side. I honestly have no clue. In addition to these is the heat leaked from the build chamber above. I also have no clue what this is but I hope it is less than a 6th of my envisioned 600W mains heater thus being 100W.

    My fans can move 9 CFM each. So I guess I will be moving around 18 CFM of air through the cabinet. A simple heat analysis shows that I will have a temperature difference on inlet air and outlet air of 15 degrees (6 degrees if I ignore the leak heat from the chamber) if inlet air is 25 degrees. That analysis is done on the heat loads shown on the image above. Theses should be absolutely maximum and will most likely be significantly less at normal use. In addition to this my printer has a 4 mm aluminum plate in the bottom as well serving as a heat sink.

    I made this design to be able to use the super quiet Noctua 60 mm fans. Thus I would hope that I do not need yet another fan on the duet itself. Though I now see that it is stupid not to have direct flow over the duet itself.

    My motors are currently running at 1.1-1.4A.

    Can anyone tell me if I would be safe in this application or if I will need a fan blowing directly at the Duet?
    I also considered to direct all the air from one of the pushing 60 mm fans to the board via a duct like this:

    This will take a lot of space though and trap the air around my X-tower motor.

  • administrators

    You probably won't need a fan. You can keep track of the MCU temperature in the web interface once you have calibrated it.

  • Okei good to know, i will get the MCU calibrated then.
    What is a okei temperature range for the MCU?

  • administrators

    If it gets above 50C when it is calibrated, then i suggest you made a fan.

  • administrators

    If it gets above 50C when it is calibrated, then i suggest you add a fan.

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