Rat Pack Rear Exhaust

Panel mount rear exhaust fan duct modification for the RatRig Rat Pack large filter.  

When printing PLA or PETG, I wanted to exhaust any chamber heat to the outside of the enclosure through a HEPA and carbon filter, rather than just opening the door / top.  This has a benefit for noise and air quality.  

In the printer.cfg define a temperature fan as “exhaust”.  For the stock Octopus Pro v1.1 board there should be a pair of two free fan connectors at Fan0 and Fan1 if you're already using the Fan5 and Fan4 slots for the standard filter control.

 “Control: watermark”

Use your material presets to also change the target exhaust fan temperature, otherwise you can end up manually preheating the chamber, but also turning on the exhaust fan.  There is probably a way around this with delayed G-code, just haven't done it yet.    

[temperature_fan exhaust]
enable_pin: PE5
pin: !PA8
max_power: 1.0
shutdown_speed: 0.0
off_below: 0.25
sensor_type: Generic 3950
sensor_pin: PF4
min_temp: 0
max_temp: 90
target_temp: 25.0
control: watermark
[include exhaust_fan.cfg]

Add into the printer config or call this as a macro.

[gcode_macro EXHAUST_FAN]
description: Control exhaust fan based on chamber temperature

# This macro controls the exhaust fan based on the chamber temperature sensor.
# Fan will increase speed if the chamber temperature goes above 25°C which is set as the target temp.

gcode:
 {% set Exhaust_temp = params.Exhaust_temp|default(0)|float %}
   
 {% if Chamber_temp == 0 and chamber_heater_enable == false %}
     SET_TEMPERATURE_FAN_TARGET TEMPERATURE_FAN="Exhaust" target={Exhaust_temp}
 {% else %}
     SET_TEMPERATURE_FAN_TARGET TEMPERATURE_FAN="Exhaust" target={Chamber_temp +10}
 {% endif %}