Make the "always on" fan pins also "pwm" and "codable"

  • Hi,
    would be great to have at least -1 of the always on fan connections in future hardware with +1 on the "smart" ones.

    That is because like in my current case: I convert an old anycubic i3 mega, with a bmg-direct-drive-mosquito-hotend. So I need fan0 for part-cooling, fan1 for heat-sink mosquito, fan2 for the direct-drive-hotend-stepper-motor because this gets quite hot, and another fan (chamber) on top of the wooden box, the machine sits in (for thermal stability).

    So all in all 4 fans even with only 1 extruder, and in my opinion all of them should be connected to "different" sensors or heater(s) in separate control loops, and all of them should be "pwm-able".

    Thermistors are cheap, and fans also. So it would just require very little money and some minor work to have a thermistor-controlled fan for each stepper-motor, heatbreak, chamber, mainboard, etc....

    I am fully aware that this is not a real scenario on the entry-level hardware like the maestro, but maybe more and more the "bigger/better" the boards get...


  • @LB said in Make the "always on" fan pins also "pwm" and "codable":

    fan1 for heat-sink mosquito, fan2 for the direct-drive-hotend-stepper-motor because this gets quite hot,

    if they are the same fan, just splice them onto the same connector an run them in parallel.

    But why does your bmg stepper motor get hot? with its 3:1 ratio a pancake motor at its normal current should be enough.

  • administrators

    The Maestro has been phased out in favour of the forthcoming Duet 3 Mini, which has four controllable fan outputs.

    If you are only using one extruder, then you should have a spare heater output. Recent firmware versions allow you to connect fans to heater outputs.

  • @dc42

    Thanks so much - cannot wait to get my hands on it, meanwhile only using the duet2-ethernet to get somehow started with RRF3.x but as soon as it is out the company I work for, for sure like the "new" maestro/duet3-mini then because of price, because on the longrun there are quite a few anycubic here, with dying original mainboards (I think the board is called "gorilla" or something like this) over time...


    Yeah - half a year ago I couldn´t have imagined it, but recently my boss started playing around with Poly-Carbonat material and the printer sits in a chamber with heatplate reaching 120°C and extruder around 300°C... the chamber heats on long prints up (without any chamber-heater just because of heatplate and extruder) to around 60°C. You can build a printer with all motors outside, but as long as you have a direct-extruder this motor gets quite hot then -> One possiblity to extend its lifetime and avoid the the filament gets too soft too early in the extruder is an additional fan on the motor, that is driven via an additional thermistor attached to it that measures the quasi-chamber-temperature a few millimeters over the extruder motor...

    On the other side when you print PLA at considerably lower temperatures for heatplate and extruder you do not need at all the fan for the directdrive-motor to run.

    I hope this also explains why I do not want to wire it together with the heatbreak-fan. Also they are quite diffrent in size and power and first test have shown that they need completely different pwm-values if I want to use pwm. The only way to have them work realiable if driven via one single fan-port/-pin, is to make it 0/1...

    a cheap chinese thermistor + fan is around 3-5 euro which is the same as a beer in the next "biergarten"(beer-garden), so it is mainly something to play around.

    Hope that explains it well

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