Pressure Advance tuning
Pressure Advance (PA) is a Klipper feature that compensates for the pressure lag in the melt zone — the delay between when the motor commands more flow and when molten material actually reaches the nozzle. In FGF (pellet) printing, the melt volume is much larger than in filament printing, so PA behavior is different.
What the machine actually starts with
Section titled “What the machine actually starts with”Two things set Pressure Advance, in this order.
The printer profile sends PRESSURE_ADVANCE=0.2 and
PRESSURE_ADVANCE_SMOOTH_TIME=0.5 at the start of every print. That pair is the
same on all five nozzles — Pressure Advance is not a per-nozzle setting.
The material profile then overrides the first number with its own, and every shipped profile but one does exactly that. So 0.2 is what you get only if the material you picked leaves Pressure Advance switched off.
Smooth time stays at 0.5 throughout.
When PA helps
Section titled “When PA helps”- Blobs or over-extrusion at corners and direction changes
- Oozing during travel moves
- Inconsistent line width at the start and end of each pass
When PA does NOT help (or causes problems)
Section titled “When PA does NOT help (or causes problems)”- Under-extrusion overall → adjust Rotation Volume first, not PA
- Layer shifting → belt/mechanical issue, not PA
- Very high PA values can fail at the purge line — a value around 0.75 in vase mode has thrown an error immediately after the purge. Note that the shipped 20% filled PETG profile sits at 0.7, so the problem is not the number alone but the number combined with vase mode. If it happens, come down in steps rather than dropping to a default.
Tuning procedure
Section titled “Tuning procedure”Method 1 — Klipper PA calibration print
Section titled “Method 1 — Klipper PA calibration print”- In the Mainsail Console, set a PA test value and print:
SET_PRESSURE_ADVANCE ADVANCE=0.2 SMOOTH_TIME=0.5- Print a calibration pattern (corner test or tower)
- Examine corners: look for the value where corners are sharpest without under-extrusion
- Adjust and repeat
Method 2 — Live adjustment from display
Section titled “Method 2 — Live adjustment from display”During a test print, adjust PA from the KlipperScreen display:
- Navigate to the Pressure Advance setting in the tune menu
- Increase in steps of 0.05 and observe corner quality
Saving the value
Section titled “Saving the value”Once you find a good value, save it to printer.cfg:
[extruder]pressure_advance: 0.2pressure_advance_smooth_time: 0.5Or use SAVE_CONFIG after setting via console.
What the shipped material profiles use
Section titled “What the shipped material profiles use”| Material profile | Pressure Advance |
|---|---|
| Every PLA and rPLA profile | 0.3 |
| Plain PETG | 0.25–0.3 |
| PETG 10% filled | 0.5 |
| PETG 20% filled | 0.6–0.7 |
| PP | 0.2 |
The pattern is the useful part: the more filler in the grade, the more Pressure Advance it wants, and it climbs steeply — a 20% filled PETG runs at more than twice the value of the unfilled one. Unfilled grades sit in a narrow band around 0.3 and rarely need touching.
Start from the profile for the grade in your hopper. Tune from there, not from these rows — they are what Ginger ships, and the grade decides.
Vase mode (spiralize)
Section titled “Vase mode (spiralize)”Vase mode (spiralize outer contour): set Pressure Advance to 0 when using vase mode. Any PA value creates visible artifacts on the continuous spiral wall — the compensation pulses appear as a repeating texture on the outer surface. PA = 0 produces the smoothest result for vase mode prints.
- PA tuning is nozzle-size dependent — retune when changing nozzle diameter
- At very high MVS values (> 300 mm³/s), PA becomes less effective; prioritize Rotation Volume calibration first