Actively cooling a passively heated chamber

iporty

I was wondering if it was possible to setup a fan so that it cools a passively heated chamber when it goes above the target temperatures. I've enclosed my printer both to help with noise and to increase the chamber temperature for some filaments. However, it's too hot for printing PLA. I was wondering if there is a way to setup a fan control to cool the chamber. Inverse of a heater control.

I'm using a Duet Wifi + Duex 5

Alex.cr

@iporty
This is absolutely possible. Just set it up as a thermostatically controlled fan, similar to a hotend fan.

Below is my code for a thermostatically controlled fan that comes on when the MCU temp sensor reaches certain temps.

;Electronic cooling fan
M950 F2 C"0.out7" Q100                              ; create fan 2 on pin out7 and set its frequency
M106 P2 L0.25 X1 H7 T25:32 C"MCU fans"                                   ; set fan 2 value. Thermostatic control is turned on

Which firmware version are you using? Do you have a thermistor to measure chamber temp set up?

OwenD

Just put thermistor in your chamber and set up a thermostatically controlled fan.
https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans#Section_Thermostatically_controlled_fans

Something like this in config.g
Just change the pins and names as required.

; chamber temp monitor & fan
M950 F2 C"!fan2+^exp.e3_stop" Q25000                                        ; create fan 2 on pin fan2 and set its frequency
M308 S5 P"e1temp" Y"thermistor" A"Chamber temp" T10000 B3950  					; Configure Water temp sensor
M106 P2 C"Chamber Fan" H5 L0.3 X1 B1.2  T30:50    	; set fan value, turn on at 30% if the chamber temperature reaches 50C, and increase to full speed gradually as the temperature rises to 50C

I would suggest that in your filaments config.g, you set the temps depending on the filament type.
So in PLA you'd set something like as above,
but in say ABS you'd change to something like this so that the fan either doesn't come on, or does so at higher temp.

M106 P2 C"Chamber Fan" H5 L0.3 X1 B1.2  T50:90

iporty

@owend @Alex-cr Thanks both for the instructions. Just what I was looking for. I already have a thermistor in the chamber and I'm runing 3.3.

I've been uprgrading my railcore and I was suprised how well it holds heat. 45c chamber with 75c bed temperature.