Fan Config Change - Toolhead

The Monolith toolhead uses the ducts as heatsinks, so to prevent heatcreep and increment the efficiency of the coldside it can be useful to have the part cooling fan always running at least at the minimum speed when the heater is on. This greatly helps with heatcreep prone materials, and it lets you print in hotter chambers without any fears.

I've edited the [heater_fan] definition in Kalico to accept SET_FAN_SPEED commands to let you use that for the part cooling. A pull request is currently pending, if you want the functionality now you can manually swap the /klippy/extras/heater_fan.py file with the one uploaded here, and change the printer.cfg accordingly.

The new behavior is this:

• While the heater is active and enforcing an enabled_fan_speed, manual commands that request a lower speed will not lower the actual fan immediately - the heater's enforced speed remains in effect.
• Once the heater become inactive, the fan speed will be lowered to the manual value (if lower).
• Manual commands that request a higher speed than the enabled_fan_speed will override the fan speed upwards immediately, but downward overrides only take effect when the heater no longer requires a higher fan speed.

heater_fan.py

# Support fans that are enabled when a heater is on
#
# Copyright (C) 2016-2020  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
from . import fan

PIN_MIN_TIME = 0.100


class PrinterHeaterFan:
   cmd_SET_FAN_SPEED_help = "Sets the speed of a fan"

   def __init__(self, config):
       self.printer = config.get_printer()
       self.printer.load_object(config, "heaters")
       self.printer.register_event_handler("klippy:ready", self.handle_ready)
       self.heater_names = config.getlist("heater", ("extruder",))
       self.heater_temp = config.getfloat("heater_temp", 50.0)
       self.heaters = []
       self.fan = fan.Fan(config, default_shutdown_speed=1.0)
       self.enabled_fan_speed = config.getfloat(
           "fan_speed", 1.0, minval=0.0, maxval=1.0
       )
       self.last_speed = 0.0
       self.last_gcode_speed = 0.0

       # register SET_FAN_SPEED mux command so users can override this fan
       self.fan_name = config.get_name().split()[-1]
       gcode = self.printer.lookup_object("gcode")
       gcode.register_mux_command(
           "SET_FAN_SPEED",
           "FAN",
           self.fan_name,
           self.cmd_SET_FAN_SPEED,
           desc=self.cmd_SET_FAN_SPEED_help,
       )


   def handle_ready(self):
       pheaters = self.printer.lookup_object("heaters")
       self.heaters = [pheaters.lookup_heater(n) for n in self.heater_names]
       reactor = self.printer.get_reactor()
       reactor.register_timer(
           self.callback, reactor.monotonic() + PIN_MIN_TIME
       )

   def get_status(self, eventtime):
       return self.fan.get_status(eventtime)

   def callback(self, eventtime):
       speed = self.last_gcode_speed
       for heater in self.heaters:
           current_temp, target_temp = heater.get_temp(eventtime)
           if (target_temp or current_temp > self.heater_temp) and self.enabled_fan_speed > speed:
               speed = self.enabled_fan_speed
       if speed != self.last_speed:
           self.last_speed = speed
           curtime = self.printer.get_reactor().monotonic()
           print_time = self.fan.get_mcu().estimated_print_time(curtime)
           self.fan.set_speed(print_time + PIN_MIN_TIME, speed)
       return eventtime + 1.0

   # SET_FAN_SPEED can only override this fan speed to a speed higher than the minimum one set by the heater
   def cmd_SET_FAN_SPEED(self, gcmd):
       self.last_gcode_speed = gcmd.get_float("SPEED", 0.0)
       speed = max(self.last_speed, self.last_gcode_speed)
       self.fan.set_speed_from_command(speed)


def load_config_prefix(config):
   return PrinterHeaterFan(config)

Fan config

[heater_fan part_cooling]
##  Print Cooling Fan
# Add here all the normal config options previously in the [fan] section
#
heater: extruder
#   Name of the config section defining the heater that this fan is
#   associated with. If a comma separated list of heater names is
#   provided here, then the fan will be enabled when any of the given
#   heaters are enabled. The default is "extruder".
heater_temp: 50.0
#   A temperature (in Celsius) that the heater must drop below before
#   the fan is disabled.
fan_speed: 0.1
#   The fan speed (expressed as a value from 0.0 to 1.0) that the fan
#   will be set to when its associated heater is enabled.

[gcode_macro M106]
#rename_existing: M106.1
gcode:
    {% set speed = (params.S|float / 255 if params.S is defined else 1.0) %}
    SET_FAN_SPEED FAN=part_cooling SPEED={speed}

[gcode_macro M107]
#rename_existing: M107.1
gcode:
    SET_FAN_SPEED FAN=part_cooling SPEED=0