Passively heated build chamber on Duet Maestro

MacNite

Hey guys,

I want to built a passively heated build chamber using a thermostatically controlled fan for my Voron V2.1.2 and found this information about it:

Passively heated build chamber

But I have a small problem on the firmware-configuration side. I killed one of my fan outputs so I use my 2nd heater output as a fan output.

I planed to setting it up something like this:

M141 H3 ; heater 3 is the chamber heater
M305 P3 R4700 T100000 B3950 ; heater 3 is monitored by a 100K thermistor with B=3950 and a 4.7K series resistor

M106 P2 L255 B60 H3 T55

But where do I connect the thermistor for heater 3 on my Duet Maestro? Or can I just use the Thermistor input of Heater 2?

Greets,
Max

dc42

Configuring it as a chamber heater won't work because that requires a heating element for the PID controller to operate. But you can set up a virtual heater (e.g. heater 103) and use it to control the fan, increasing its speed as the temperature gets higher (is that what you want it to do?). The Maestro has a 4th thermistor input, so you can use that:

M305 H103 T100000 B3950 X3

The X3 says that thermistor 3 input is used. Then configure the fan:

M307 H2 A-1 C-1 D-1 ; disable heater 2, we want to use its output for fan 2
M106 P2 A2 H103 T45:65 ; fan 2 uses logical pin 2, controlled by heater 103, minimum sped at 45C, maximum speed at 65C

If instead you want to increase the fan speed to increase temperature, then you could pretend the fan is a heating element, but you will probably trigger the heater fault subsystem - especially if you try to turn it on before the bed is hot.

MacNite

@dc42 said in Passively heated build chamber on Duet Maestro:

M307 H2 A-1 C-1 D-1 ; disable heater 2, we want to use its output for fan 2
M106 P2 A2 H103 T45:65 ; fan 2 uses logical pin 2, controlled by heater 103, minimum sped at 45C, maximum speed at 65C

Wow. That solution is way to simple. Thanks for your help!

MacNite

@macnite said in Passively heated build chamber on Duet Maestro:

That solution is way to simple. Thanks for your help!

I tried that but I have a "problem":

The virtual heater does not show up in DWC. Or is the "virtual" monitor only "virtually monitored" to turn on / off the fan? I won't think so. I have no thermistor connected to the thermistor C input on my Duet Meastro yet (so the return value would be 2000C) and my fan does not spin up.
If I remove the thermostatical control and turn the fan on manually it works fine.

dc42

If you give the virtual heater a name using the A parameter in the M305 command, then it will show up in the Extra tab of DWC (next to Tools) and you can choose to include it in the temperature graph.

MacNite

@dc42 said in Passively heated build chamber on Duet Maestro:

M305

Typo - I'd assume you mean S-parameter.
Will test that ! Thank you vor your help

dc42

Yes I did mean S. I was thinking of the new M308 command in RRF3.

MacNite

@dc42 said in Passively heated build chamber on Duet Maestro:

M307 H2 A-1 C-1 D-1 ; disable heater 2, we want to use its output for fan 2
M106 P2 A2 H103 T45:65 ; fa

I found the mistake - it P103, not H103 - now it works fine!

M305 P103 T100000 B3950 X3 S"Chamber" ; virtual heater 103 uses 100k NTC at Thermistor Input 3 (C)

Thanks.

NitroFreak

By passively heated chamber, do you mean more like just a monitored temperature probe?

MacNite

Yes. And the fan for the chamber is only turned on when the temperature reachers a certain threshold.