Many automation systems, from drones to cruise control to home heating systems, make use of PID controllers to regulate their output. PID stands for proportional–integral–derivative, and the PID controller is a closed-loop means of regulating the output of a system.
They work by measuring the system output with a sensor, then running that value through the controller where it is modified according to the PID algorithm to run at a specified state.
They are used extensively on 3D printers to regulate the temperature of the hotend and heater bed, and to minimize fluctuations about the steady state.
In this article, we’ll take a look at how to PID tune using the Klipper firmware.
In case your printer is running on Marlin firmware, we’ve also written a guide how to PID tune in Marlin.
Importance of PID Tuning in Klipper
Properly tuning the PID controller in Klipper is necessary if you want to maintain the quality of your printed parts.
If the PID controller is not properly tuned, the temperature of the hotend and bed can oscillate, leading to poorly printed parts, warping, and even poor bed adhesion.
In addition, the PID controller can also impact the print speed, as the controller may be slower to respond to temperature changes if it is not properly tuned.
To tune the PID controller in Klipper, you will need to adjust the three main PID parameters: the proportional gain, integral gain, and derivative gain.
These parameters determine how the controller responds to changes in temperature and how aggressively it attempts to correct any deviations from the target temperature.
Adjusting these parameters can be a trial-and-error process, as the optimal values will depend on the specific characteristics of your printer and the materials you are using.
Luckily, the tuning process in Klipper is fairly well automated, so you just have to tell Klipper to perform the tuning, sit back, and wait for the process to complete.
Let’s take a look at how to do exactly that.
How To PID Tune in Klipper
Once Klipper is connected to your web interface, then follow the steps below to PID tune your hotend or heatbed.
Before you start, ensure that your hotend and heatbed are at room temperature. We recommend starting from a cold start, but you can use the TURN_OFF_HEATERS command also.
The procedures for PID tuning the bed and the hot end are more or less the same, but with the heater element names changed according to what is found in the config file.
Below is a list of commands and their corresponding G-code that will help with your PID tuning. Note that Klipper uses Extended G-code commands for many functions, and so you will not need to use the standard G-code command (M303) for auto-tuning the PID.
|–||G28||Home all axes|
|–||G28 [X] [Y]||Home to specific axes|
|–||M106 [S<speed>]||Turn on fan at speed 0-255|
|–||M107||Turn off fan|
PID Tuning the Hot End
Assuming your hot end and heat bed are cooled to room temperature, follow the steps below.
- Make sure your silicone sock is on the hot end. This will keep it insulated and will give better results. It will also negate any effects of the cooling fan on the hot end.
- Set the printer to the home position with the G28 command.
- Switch the part cooling fan on to full speed using M106 S255, if you plan on using it during your average printing session. If you don’t ever plan to use it, then you can skip this step.
- Begin the PID calibration routine for the hot end.
In your interface, type the following command:
PID_CALIBRATE HEATER=<extruder> TARGET=<“X”>
Replace the “X” in target with the target temperature for your specific hotend. These figures will vary depending on your hardware, and what the maximum temperature needed for your highest temperature filament will be. Personally, I use Nylon a lot, so my hotend temp is calibrated to 250 °C.
When done, run the SAVE_CONFIG command and the new PID settings will be saved to the printer config file.
This is basically the same as PID tuning for the hotend, but you are sending the command to the element designated as the bed. In the config file, this will normally be designated as heater_bed.
If you plan to use a plate, or other surface such as a PEI sticker on your bed, be sure to apply it to the bed before tuning. You are tuning the PID for printing, so make sure your bed is configured as it would be during a normal print job!
- Set the printer to the home position with the G28 command. You can raise the hotend a little if you want.
- If you plan to use the part cooling fans often, then switch them on for tuning using the M106 S255 G-code command.
- Begin the PID calibration routine for the hot end.
In your interface, type the following:
PID_CALIBRATE HEATER=<heater_bed> TARGET=<“Y”>
Replace the “Y” in target with the target temperature for your specific heater bed. For your average stock heater bed, this will be 60 °C, so replace “Y” with “60”.
Personally, I tune it to 65 °C, but I print with Nylon a lot.
When complete, you should again run the SAVE_CONFIG command to save the settings to the config file.
Common Issues of PID Tuning With Klipper
Sometimes things don’t go as planned. Don’t worry, here are a few common errors and how to resolve them.
And don’t forget, Reddit, Google, and YouTube are also your friends.
Don’t be afraid to ask the 3D printing community for help. They are usually quite friendly and have more than likely had the same problems that you are experiencing.
No PID Tuning Results
So you have completed your PID tuning routine and your interface doesn’t show the results of the PID tuning. This is no problem, as you can find them in the klippy log file at /tmp/klippy.log. Open the log file in notepad or text editor of your choice, locate the results, and enter them into the config file.
Command Not Working
To troubleshoot why the PID tuning command is not working on your printer, try accessing the printer’s firmware configuration files and searching for “class PIDCalibrate“.
The code beneath that class should enable the PID_CALIBRATE command to function.
PID Calibration Interrupted
There can be a number of causes for receiving this message in your terminal. Most of them are associated with some fault with the sensor. If this happens, check that your thermistor is the correct type, and that it fits properly.
Ensure that your thermistor is the correct type in the config file. Check that the cables are not loose.
PID Values Not Updating
If your recently gleaned PID values are not being sent to your printer, then you can simply open up the config file in Octoprint or Mainsail, look for the line marked as “pid_kp“, and update them with the values.
So there it is, that, in a nutshell, is how to use the PID autotuning function on Klipper to tune your heat bed and hotend.
Both procedures are the same in principle, you just need to make sure you point the command to the correct heater element.