Achieving high-quality 3D prints involves tuning several firmware parameters, and one of the most crucial in Klipper is Pressure Advance. This feature controls how filament pressure is compensated during acceleration and deceleration, improving sharp corners, retractions, and overall print quality. In this guide, we’ll walk through exactly how to perfectly calibrate Pressure Advance on Klipper, step by step. Whether you’re using a Bowden or direct-drive extruder, this tutorial is tailored for beginners and advanced users alike.
What Is Pressure Advance in Klipper?
Pressure Advance (PA) is Klipper’s implementation of linear advance, a concept that anticipates the delay in extrusion caused by pressure build-up in the hotend. When the print head accelerates or decelerates, the extrusion amount needs to adjust accordingly. If not compensated, corners can become blobby, and lines may show inconsistencies.
Think of it as helping your printer “think ahead” about extrusion, ensuring that filament flow matches nozzle movement precisely.
Why It’s Important
- Reduces corner blobbing
- Prevents under-extrusion during fast moves
- Improves dimensional accuracy
- Minimizes stringing and oozing
Prerequisites Before You Begin
Before calibrating Pressure Advance, make sure of the following:
- Your printer is mechanically sound (no loose belts or pulleys).
- Extruder steps/mm are calibrated.
- You’re using the latest stable Klipper firmware.
- Input Shaper is already tuned.
Step-by-Step: How to Calibrate Pressure Advance
Step 1: Prepare a Test Model
Klipper provides a built-in command to generate a Pressure Advance test line:
gcodeCopyEditTUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0.000 STEP=0.005 FACTOR=50
This command creates a tower where Pressure Advance increases along the Y-axis. You’ll visually inspect this to choose the ideal value.
Tips:
- Use a simple rectangular model, about 100mm in length.
- Set a consistent print speed (40–60mm/s).
- Disable retraction for this test.
Step 2: Slice Your Test G-code
In your slicer:
- Set 0.2mm layer height
- Disable retraction
- Set wall speed to 40–60mm/s
- Enable z-hop if needed
Insert the TUNING_TOWER command into the “Before layer change” G-code in your slicer.
Step 3: Run the Test Print
Start the print and observe the extrusion at corners along the Y-axis. The ideal Pressure Advance value is where:
- Corner bulging disappears
- Extrusion is even at starts and stops
- There’s no under-extrusion at sharp changes
Mark the area where the print looks the cleanest, and note the corresponding Pressure Advance value based on the Y-axis height.
Example:
- Tower height: 100mm
- Start: 0.000
- Step: 0.005
- Ideal section is at 60mm → 0.005 × 12 = 0.060
Step 4: Set the Ideal Pressure Advance
Once you’ve chosen the best value, update your printer.cfg:
iniCopyEdit[extruder]
pressure_advance = 0.060
Then run:
gcodeCopyEditRESTART
to apply the changes.
Troubleshooting Common Issues
| Issue | Cause | Solution |
|---|---|---|
| Corners still have blobs | PA too low | Increase Pressure Advance |
| Under-extrusion at corners | PA too high | Decrease Pressure Advance |
| Inconsistent test print | Retraction or speed changes | Disable retraction & keep speed constant |
| Poor layer bonding | Other slicer settings interfering | Check extrusion multiplier, temperature |
Advanced Tips for Pressure Advance
- Different materials need different PA values: PLA, PETG, and TPU behave differently. Run tests for each.
- Use macros to quickly test and adjust Pressure Advance without restarting.
- Bowden setups usually need higher PA (0.1–0.2), while direct drive systems require lower (0.02–0.08).
Best Practices
- Always run PA calibration after changing extruder, hotend, or filament.
- Maintain consistent print temperature during the test.
- Keep your slicer G-code clean—disable retraction temporarily.
FAQs
Q1: Can I use the same PA value for all filaments?
No. Different materials respond differently to pressure. Always calibrate PA per material for best results.
Q2: How often should I recalibrate PA?
Only when you change:
- The extruder type or gear ratio
- The filament type or brand
- The hotend or nozzle
Q3: Does Pressure Advance replace retraction?
No. While PA helps reduce oozing, retraction is still needed to prevent stringing between moves.
Q4: Can I set different PA values per toolhead or extruder?
Yes. Klipper supports different values for each defined [extruder] section in your printer.cfg.
Conclusion
Perfectly calibrating Pressure Advance in Klipper is one of the most effective ways to improve your 3D print quality. With just one test print and careful observation, you can dramatically reduce print imperfections, leading to cleaner, more accurate parts.
Take your time with calibration, document your results, and enjoy the improvements in your prints. Precision starts with pressure control—and Klipper makes it easier than ever.