Linear Heater Control

This config allows you to linearly control the heating or cooling of a heater in Klipper.

The most common use case would be to control the temperature of the heated bed during cooling to prevent warping in materials such as ABS/ASA/etc. The bed temperature can be slowly/linearly cooled over time allowing the material to release internal stresses and cool uniformly.

Without Linear Heater Control	With Linear Heater Control (1°C/min)
36°C Temperature Drop in 10 Minutes	10°C Temperature Drop in 10 Minutes

How To Set-Up

I believe the easiest method to manually copy the config file onto your Klipper host using your front-end:

• Download Linear_Heater_Control.cfg from this GitHub repository.
• Open your Klipper Front-End (ie. Fluidd or Mainsail) and navigate to your configuration section.
• Paste/Upload/Drag-Drop the downloaded file Linear_Heater_Control.cfg into your config folder.
• Place the following somehwere in an included Klipper cfg file (ie. printer.cfg):
  [include Linear_Heater_Control.cfg]
• Done! You can now call the macro using LINEAR_HEATER_CONTROL

Macro Information

Macro Name:

LINEAR_HEATER_CONTROL

Macro Arguments:

Argument	Unit	Type	Default	Description
HEATER	n/a	string	heater_bed	The name of the heater you would like to control (ie. heater_bed or extruder).
TARGET	°C	float	0	The desired final temperature. This is what the heater will be set to when the macro ends control.
TRANSITION_RATE	°C/min	float	1.3	The desired rate of temperature change of the heater (if achievable).
COOLING_ABORT_DELTA	°C	float	1.5	The control will terminate early if TRANSITION_RATE exceeds the natural cooling rate (measured temp - control temp > COOLING_ABORT_DELTA). Only during cooling.
REFRESH_TIME	sec.	float	5	Duration of time between control actions (ie. 5s --> 12Hz update freq.)

Examples:

Calling the macro with default parameters:

LINEAR_HEATER_CONTROL

Calling the macro with a custom transition rate:

LINEAR_HEATER_CONTROL TRANSITION_RATE=1.0

Calling the macro with a custom heater name and transition rate:

LINEAR_HEATER_CONTROL HEATER="extruder2" TRANSITION_RATE=1.0

Using the macro in your END_GCODE (example):

...
SET_HEATER_TEMPERATURE HEATER=extruder TARGET=0     ;Turn off the extruder heater
LINEAR_HEATER_CONTROL                               ; Controlled Cooldown Bed
M107                                                ; turn off fan
G90                                                 ; absolute positioning
G0 X5 F3600                                         ; park nozzle
M84                                                 ; Turn off steppers
...

Pending Updates:

• Improved detection/alert for invalid input arguements (ie invalid heater names)
• Improved Installation instructions using SSH + automatic updates with moonraker

Disclaimer

Warning

Use this macro responsibly.

YOU are responsible for ensuring the safety of your printer and the commanded temperatures.

Do not operate your printer un-attended.