Pressure Advance Tuning on the Kobra 3
kobra3pressure advancecalibrationklipper
Pressure Advance (PA) — sometimes called Linear Advance in Marlin — compensates for the elasticity in your filament path. Tuning it eliminates bulging corners and improves sharp detail.
What It Does
When the printhead slows at a corner, uncompensated pressure in the filament path keeps pushing material out slightly too long. PA pre-emptively reduces extruder pressure before deceleration.
Too low PA: Bulging corners, overextrusion on direction changes Too high PA: Gaps at corners, underextrusion after direction changes
Running the PA Tower in Orca Slicer
- Open Orca Slicer
- Calibration → Pressure Advance → PA Line
- Set PA range: 0 to 0.1 for direct drive, 0 to 0.8 for Bowden
- Slice and print
- Look at the printed lines — find where the corners are sharpest with least bulge
- Read the PA value at that height from the scale
Starting Values by Material
| Material | PA Start |
|---|---|
| PLA | 0.02–0.05 |
| PLA+ | 0.03–0.06 |
| PETG | 0.04–0.08 |
| TPU | 0.00 |
| ABS | 0.03–0.06 |
Applying in Orca Slicer
- Printer profile → Machine G-code → Start G-code
- Add:
SET_PRESSURE_ADVANCE ADVANCE=0.045 - Or set per-filament in Filament settings → Pressure advance
Tuning Tips
- Print at your actual print speed — PA is speed-dependent
- Tune with a single-wall vase mode cube for easiest reading
- Re-tune if you change: nozzle, filament brand, print speed significantly
- Direct drive (Kobra 3) values are much lower than Bowden setups