Bed-heated chamber PID temperature control
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I have an enclosed chamber with a large bed. There is a filtered vent on the back and I'd like to modulate the speed of the extraction fan to hold a target temperature (e.g., 50c) in the chamber. On a previous printer I made a microcontroller, display and rotary encoder to set it by hand. With a Duet 2 Wifi I'd expect to be able to set this up via gcode.
Reading the GCode page I don't see an affordance for it, but I'm new to RRF. How do people configure this kind of behavior? -
@krohelm
Keep in mind you can also setup chamber heaters like regular tools as well. Then the paired fan will engage to keep it cool if needed. In general though, I’d be surprised if you needed a fan. Tuning the heater and the natural thermal losses should get you pretty close.Not sure if the chamber command actually has a fan capacity in it as well though. Might.
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Just saw that your bed heater is your chamber heater... might be difficult to setup in that configuration.
Maybe setup a non-functional tool, and set the thermostatic fan mode to that channel? (M106: Fan On) Might throw an error if it’s trying to increase the temperature and the bed isn’t on. Might work even after the heater fault though...
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@TLAS Thanks for the ideas! I'm not sure this will do what I'm after - for now I will just use 20% pwm while printing and hope temperatures stay relatively steady then amp up to 100% for a few minutes after printing to evacuate fumes through the charcoal. Might be a neat new gcode, I'll keep it in mind in case I get the urge to contribute to rrf.
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If you have a spare heater output (or you use RRF3, which allows you to configure a fan pin as a heater output), you can connect the fan to it. Then use the M307 I parameter for that heater to invert the sense of operation, i.e. the PWM will increase as the temperature rises. Is that what you need?
