PID Tuning: Hotend and Bed Temperature Control

Logan F.

Stable Temperature = Consistent Extrusion

PID (Proportional-Integral-Derivative) control is the algorithm your printer's firmware uses to maintain steady temperatures at the hotend and heated bed. A well tuned PID controller maintains your target temperature within ±1°C, adjusting heater power continuously to counteract thermal disturbances. A poorly tuned PID oscillates temperatures, swinging ±5–15°C around the target, causing visible variation in extrusion rate, line width consistency, and surface quality. Temperature stability is one of the most foundational factors in print quality, yet PID tuning is rarely discussed in beginner guides.

Many printers ship from the factory with generic PID values tuned for their specific hotend and bed hardware. These values are often adequate, but any hardware change, replacing the thermistor, changing the hotend, installing a new heater cartridge, or even adding an enclosure, changes the thermal characteristics enough to warrant retuning. If your temperature graph shows oscillation, or if you've made any hardware changes, run a PID autotune.

Running PID Autotune

PID autotune works by deliberately oscillating the heater several times and measuring the characteristic response: how fast it heats, how much it overshoots, and how quickly it stabilises. The firmware calculates optimal P, I, and D values from this measured response. In Klipper: PID_CALIBRATE HEATER=extruder TARGET=200 (replace 200 with your most commonly used print temperature). In Marlin: M303 E0 S200 C8 (8 cycles more cycles give more accurate results). Run the autotune at the temperature you actually print at; a hotend tuned at 200°C will perform differently at 250°C because the thermal dynamics change at different power levels.

The autotune takes 5–10 minutes. When complete, it outputs PID values (Kp, Ki, Kd). In Klipper, these are automatically applied and need to be saved with SAVE_CONFIG. In Marlin, apply them with M301 (hotend) or M304 (bed) and save with M500. In some cases, multiple autotune runs at slightly different temperatures and averaging the results yields more stable final values.

Bed PID Tuning

Heated beds can also benefit from PID control, many printers default to simple bang-bang (on/off) bed temperature control, which is adequate but produces slow oscillation around the target temperature. Enabling PID control for the bed (in Marlin: enable PID_BED in Configuration.h; in Klipper: use the heater_bed section with a control: pid line) and running autotune (M303 E-1 for bed in Marlin; PID_CALIBRATE HEATER=heater_bed in Klipper) stabilises bed temperature during long prints. This matters most for temperature sensitive materials like ABS and PETG, where even 5°C of bed temperature variation can affect first layer adhesion. Combine stable PID control with the temperature calibration process for the most consistent print quality possible.