Procedure for PID Tuning Gigabot 4 and Terabot 4 Dual Extruder Hot Ends

re:3D’s Gigabot 4 and Terabot 4 printers come standard with dual extruders having hot ends heated by 65W cartridge heaters.  Temperatures are monitored by thermocouples, and this provides closed-loop feedback to maintain the extruder temperatures using PID control.  The PID parameters are tuned at the factory and can maintain temperatures within ± 0.2°C during steady-state operation under certain conditions.  If the PID parameters are off, then reaching a stable extruder temperature can take longer as shown in the plot below, increasing your overall print time - especially if you have a lot of tool changes (e.g., dual-extruder prints.)

If you install new hot ends, your extruders take  too long to heat and stabilize (more than two minutes), or if you are experiencing excessive temperature fluctuations during printing, you may wish to retune the PID control parameters yourself.  The following steps and conditions are used for factory tuning.  You may choose to tune to a different setpoint temperature and/or tune without the part cooling fan active depending on the printing profile for your specific filament material and part geometry.  

The following procedure is for a re:3D Gigabot 4, dual-extruder printer with standard hot ends, 65W cartridge heaters and tube style thermocouples.  The same procedure may be used (assuming the printer is running Klipper) for the Terabot 4 and for other hot ends, but the resulting PID parameters may vary significantly from those shown.

1) Extruders to be tuned should have filament loaded.
2) Turn off extruder heaters and the bed heater and wait for everything to cool to near room temperature (< 30°C).
3) Home all axes using the “Toolhead” widget or issue G28 from the console line.
4) Move the extruder to near the center of the print bed using the “Toolhead” widget.
5) Turn on the print cooling fan to 100% using the “Miscellaneous” widget or by issuing M106 S255 from the console line.
6) Calibrate the left extruder (Extruder0):

     a) Issue PID_CALIBRATE HEATER=extruder TARGET=250 from the console line.
     b) Extruder0 will begin heating and cycle around the temperature setpoint (250°C) six times before the tuning routine completes.  This should take less than 10 minutes.
     c) Typical display in the “Temperatures” widget after the PID tuning completes:

     d) When the tuning routine completes, the tuned PID parameters will be displayed in the “Console” widget:

     e) NOTE: Using the SAVE_CONFIG command will not work to update the parameters using re:3D’s current image of Klipper (as of June 2023).  You may manually enter the tuned values into the standalone.cfg file.

          i) Click on the “Wrench” icon on the left-hand side of the interface to bring up the list of configuration files.
          ii) Double-click on standalone.cfg
          iii) Make the following entry, replacing the “x”s with the appropriate numbers returned from the PID tuning routine:

               Sample:
                    #EXTRUDER 0 HEATER
                    [extruder]
                    control: pid
                    pid_Kp: 22.700
                    pid_Ki: 1.200
                    pid_Kd: 110.000
          iv) Click “Save and Close” in the upper right corner of the edit window.
     f) If the PID tuning routine fails:
          i) Ensure your tuning conditions match the factory tuning conditions
               1) Z-axis is homed and centered on the bed (0.3mm gap)
               2) Part cooling fans are on 100%
               3) Temperature setpoint = 250°C
          ii) Verify the part cooling fans are properly seated on the hot ends
          iii) Verify you have standard hot ends installed on you machine
          iv) With the machine power off, check for loose/frayed heater and thermocouple wire connections
          v) Contact re:3D Customer Support
7) Let the left extruder cool to below 30°C, then repeat the tuning process for the right extruder (Extruder1).
     a) Issue PID_CALIBRATE HEATER=extruder1 TARGET=250 from the console line.
     b) Repeat the above steps to edit the standalone.cfg file, but replace “#EXTRUDER 0 HEATER” with “#EXTRUDER 1 HEATER” and “[extruder]” with “[extruder1]”.
     Sample:
          #EXTRUDER 1 HEATER
          [extruder1]
          control: pid
          pid_Kp: 22.700
          pid_Ki: 1.200
          pid_Kd: 110.000
8) Restart the printer and firmware to update the PID parameter changes. 

Your control software now has the updated PID parameters and the hot ends are properly tuned.  Happy Printing!

Questions or concerns? Reach out to our team at [e-mail] or open a support ticket.