Pro Tip: PA values can vary by filament. Calibrate for each material type and store the value in your filament profiles for automatic application.
Pressure Advance Calibration
Improve corner quality and extrusion consistency with pressure advance.
What is Pressure Advance?
Pressure Advance (PA) compensates for the pressure buildup in the nozzle/hotend during extrusion. Without it:
- Corners are rounded due to oozing after direction changes
- Line starts may have under-extrusion
- Line ends may have over-extrusion (blobs)
PA anticipates these effects by adjusting extrusion rate based on speed changes.
Firmware Support
| Firmware | Feature Name | G-code |
|---|---|---|
| Klipper | Pressure Advance | SET_PRESSURE_ADVANCE |
| Marlin | Linear Advance | M900 |
| RepRapFirmware | Pressure Advance | M572 |
Running the Test
- Go to Calibration > Pressure Advance
- Select your firmware type
- Set the PA range (usually 0.0 - 0.1 for direct drive, 0.0 - 1.5 for bowden)
- Print the calibration pattern
- Examine the results
Evaluating Results
The calibration print shows lines at different PA values. Look for:
| PA Value | Appearance | Status |
|---|---|---|
| Too Low | Rounded corners, bulging at line ends | Under-compensated |
| Too High | Gaps at corners, thin lines at starts | Over-compensated |
| Optimal | Sharp corners, consistent line width | Correct |
Typical Values
| Setup | Klipper PA | Marlin LA (K) |
|---|---|---|
| Direct Drive (standard) | 0.02 - 0.06 | 0.02 - 0.06 |
| Direct Drive (high flow) | 0.01 - 0.04 | 0.01 - 0.04 |
| Short Bowden | 0.2 - 0.5 | 0.2 - 0.5 |
| Long Bowden | 0.5 - 1.2 | 0.5 - 1.2 |
Applying Results
You can apply the PA value in several ways:
Option 1: Filament Profile
Add the PA value in your filament's "Filament Pressure Advance" setting.
Option 2: Filament Start G-code
; Klipper
SET_PRESSURE_ADVANCE ADVANCE=0.04
; Marlin
M900 K0.04Option 3: Printer Firmware Config
Set as default in your Klipper printer.cfg or Marlin Configuration.h
Smooth Time (Klipper)
Klipper also has a "smooth_time" parameter that controls how gradually PA changes are applied. Default is 0.040 seconds. Lower values give sharper corners but may cause artifacts.