Pressure Advance and Linear Advance Tuning
The problem they solve
When the extruder is pushing filament fast, pressure builds up in the melt zone. When motion slows for a corner, the slicer commands less extrusion, but the residual pressure keeps pushing filament out, causing a bulge. Pressure / linear advance pre-emptively reduces extruder pressure ahead of slowdowns so the actual extrusion matches the commanded flow.
How to tune in Klipper
- Run a pressure advance test pattern (single-line or grid)
- OrcaSlicer's Calibration > Pressure Advance handles the slicing
- Print the pattern
- Inspect for the cleanest corners
- Set PRESSURE_ADVANCE=
in your printer.cfg
How to tune in Marlin
- Enable LIN_ADVANCE in Configuration_adv.h and reflash
- Or use M900 K
commands at the top of test G-code - Print a calibration pattern (Marlin LA generator on the Marlin docs site)
- Pick the cleanest K value
- Save with M900 K
; M500
Typical values
- Direct drive PLA: 0.02 to 0.06
- Direct drive PETG: 0.04 to 0.08
- Bowden PLA: 0.4 to 0.8
- Bowden PETG: 0.5 to 0.9
When to retune
- New filament material (PLA → PETG)
- Brand or batch change (different pressure characteristics)
- Hotend swap (different melt-zone geometry)
- Speed regime change (calibrate for the speed you actually print at)
Browse the range
All filament. Consistent diameter filament makes pressure advance more effective.