Fan0 and Fan1 not working together.

  • Running into a strange problem that I cant see to figure out for the life of me. I have my part cooling blower on F0 and my hot end fan on F1. On the web interface I wanted to be able to see both and control both. I have tried to do the M106 P0 H-1 S500 and same for the P1. It would seem that I can only get P0 to come on with the slider or the command when they are both plugged in. I have checked the fans each solo and the voltages for them show 24v on the cables. I can swap the blower and the hot end fan in on F0 and they both work and solo on F1 they both work. When they are both plugged in 1 of the will drop to 12V while the other is running. Any ideas ?

  • @melfesto I guess the first question has to be "why do you want to manually control the hot end fan"? This is the fan that blows air over the heat sink to keep the filament below the glass transition temperature before it enters the melt chamber. So by default, it would either be on all the time, or controlled thermostatically so that it runs when the hot end reaches a certain temperature. I can't off hand think of any usage case where you might want to override this behaviour so please enlighten me.

    The fan sliders on DWC are used to control part cooling fans. These are the fans that can be controlled by gcode commands - either manually or via commands that are generated by a slicer. If you want to use Fan1 like this, then you need to map it to a tool using M563. So for example M563 P0 F0:1 will map fans 0 and 1 to tool 0. Or something like M563 P0 F0 and M563 P1 F1 would map fan 0 to tool 0 and fan 1 to tool 1. Then you would be able to use the sliders to control the fans. But of course, you won't have any automatic cooling of the hot end so you'll likely end up with molten filament solidifying in the heat sink.

    Edit. Unless of course you use water cooling or some other method to cool the heat sink and simply want to re-purpose fan1 (but you didn't make that clear).

  • Hi @deckingman thanks for the response. To answer the first one I like to try to optimize everything to get the most out of it for efficiency. If I could drop the fan speed down to say 50% on warm up then ramp it up as it neared max temp I wanted I could potentially shave a few seconds off the start time. Plus I am a stickler for seeing everything in nice panels where I can verify everything is working before a print. I thought about water cooling but was afraid it might add a little to much weight to print head but still might be interesting to try I have a bunch of old computer water blocks that might fit. I had been trying to enable the fans using the commands but I don't remember off hand if I tried the M563 ones I will have to give that a shot but still lost as to why the voltage of the fan would drop to 12v on one fan when F0 and F1 are plugged in even during printing. I will try setting them as tools when I get home later and let you know if this fixes it.

  • @melfesto The hot end cooling fan really needs to be on when the hot is heated, both before and after a print, and not just during a print. If you map that fan to a tool, then the slicer will be turning it on and off during a print so you'll end up with big problems.

    However, you can indeed drop the fan speed when it's warm and ramp it up to full speed as the temperature increases without resorting to manual control. Here is how I do it.

    M106 P1 S255 I0 F259 L125 H1 T60:140.

    The L parameter sets the minimum non-zero fan speed to 50%. This is to prevent the fan from running at very slow values which I found to be annoying but which you can omit. The H1 parameter sets it to run in thermostatic mode. The T parameter defines the temperature range. So below 60 deg C the fan is off. At 60 deg C the fan will come on at 50% (as defined by the "L" parameter) then it will ramp up to full full speed between 60 and 140 deg C and remain at 100% for any temperature above 140 deg C.

    You can if course play around with those L and T values to suit.

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