Mounting & Cooling



  • I'm going to be getting a Duet Ethernet and Duex5, and I wanted to mount them with enough cooling to push the limits of the 2.4A stepper current, with 2.8A Nema 23 steppers.

    I want to mount them horizontally like this, with a fairly large 75x75x30mm blower fan on the side.

    The hex spacers are 10mm tall nylon, and the center panel is 2mm aluminum.

    I was also thinking of getting some 10x10x10mm heatsinks, and putting them on the back side of the stepper drivers - they're self-adhesive, and would be directly in the path of the blower output.

    Any thoughts?



  • It should work. For info, I mount my duet and duex5 one above the other but not back to back. Each board has an 80mm fan blowing on the back and I've stuck thermistors on a couple of the stepper driver chips so that the fans are controlled thermostatically with the turn on temperature set to 45 deg C. With that arrangement, I've never seen the temperature any higher than 46 degC but I'm running my XY motors at 1.8 amps. I'd expect the temperature to be higher if you are running 2.4 amps but but I'd have thought it would still be well within safe operating limits. The Duex5 only runs the extruder steppers which I run at 400mA and I've never seen the fan come on because the chip temperature never gets to 45 deg C.


  • administrators

    The general arrangement looks good to me, but I don't advise using stick-on heatsinks. There would be a risk of shorting something out. Blowing air across the line of driver chips - especially on the back of the PCB - is enough.



  • Out of curiosity, what type of machine are you building that requires Nema 23 steppers running at 2.4 Amps? How much mass will you have to move?



  • Here's what I'm building:

    http://openbuilds.org/builds/corexy-cube.4856/

    And it's actually 2.8A 0.9 degree steppers running at the 2.4A limit, on 24V power.

    The Z gantry is going to weigh 20-25 pounds, lifted by 4 steppers.



  • @GiulianoM:

    Here's what I'm building:

    http://openbuilds.org/builds/corexy-cube.4856/

    And it's actually 2.8A 0.9 degree steppers running at the 2.4A limit, on 24V power.

    The Z gantry is going to weigh 20-25 pounds, lifted by 4 steppers.

    You don't need anything like those size stepper IMO. My CoreXY is 600 x 600 x 1000 with a massively heavy Diamond hot end and extruders. I regularly print at 90mm/s with non print moves at 350mm/sec. This is all achieved with 1.8 degree Nema 17s rated at 2.0 Amps but running at 1800mA. My bed is 10mm aluminium and weighs is at around 9Kg. It is lifted by three 1mm pitch lead screws with a continuous belt and a single Nema 17 running the same current (1800 mA). Oh and the stepper drivers never get above 46deg C with a small amount of air being blown onto the back of the board. Here are some videos of the printer in action https://www.youtube.com/watch?v=U733PMTou7M, https://www.youtube.com/watch?v=ZLwHOcH_UFk, https://www.youtube.com/watch?v=vG1WqijJ634


  • administrators

    Hey Giuliano, you can probably get away with using a couple of super quiet fans rather than that blower (unless that's a really quiet blower). People find with the 256 interpolation on the TMCs the loudest part of the printer is the fans!



  • @T3P3Tony:

    Hey Giuliano, you can probably get away with using a couple of super quiet fans rather than that blower (unless that's a really quiet blower). People find with the 256 interpolation on the TMCs the loudest part of the printer is the fans!

    Agreed Tony - even quieter if you run the stick thermistors on the chips and run the fan(s) in thermostatic mode like this https://somei3deas.wordpress.com/2017/04/18/stepper-motor-and-electronics-cooling/. Then use a mains bed heater so that you can have a fanless PSU and at idle, you can hear a pin drop.



  • The lead screws I'm using are 4 start 2mm lead, so 8mm per revolution.

    The good thing is that the mounting plates are usable with either Nema 17 or Nema 23, so I could easily start with 17s.

    As for the fans, would something as small as a 40mm / 50mm / 60mm typical axial fan do?



  • @GiulianoM:

    The lead screws I'm using are 4 start 2mm lead, so 8mm per revolution.

    The good thing is that the mounting plates are usable with either Nema 17 or Nema 23, so I could easily start with 17s.

    As for the fans, would something as small as a 40mm / 50mm / 60mm typical axial fan do?

    I take it you mean the lead screws are 4 start, 2mm pitch so the lead is 8mm which give 8mm per revolution. Don't get pitch and lead muddled up because they mean different things. They happen to be the same on a single start screw but it's a bad habit to use the terms interchangeably.

    These are typical for lead screws that are designed for rapid linear motion and in my opinion, not at all desirable for the Z axis due to the poor positional accuracy you will get (although using 0.9 degree steppers will help). The other problem you might run into is that with your heavy bed weighing in at 25 lbs or so, and with the very steep angle of the helix on those 8mm pitch screws, when power is disconnected from the steppers, the bed might fall under it's own weight. I did a bit of a write up on Z axis screws on my blog which you might find useful https://somei3deas.wordpress.com/2017/01/31/z-axis-lead-screws/ . These are just my own personal thoughts you understand…...

    As for fans, I'd have thought a typical axial fan would be sufficient. I use quiet 80mm PC fans but smaller ones would probably still shift enough air.
    HTH
    Ian



  • If I may "hijack" this thread, bc it relevant for my topic. I do drive a big Delta with NEMA23 motors and set the drivers to 1500mA. I do blow along the board (above and beneath) with a big 80mm fan on one side, and a "pulling" 80mm fan on the other. This alone leads to thermal shutdown of one or more drivers after several hours of printing. I did put some small self-glueing heatsinks on the underside and now it doesn't overheat anymore.
    Now I am wondering, if I do something wrong via config? Because everything I read about the cooling states, that I should be good with minimal airflow.


 

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