Pressure Advance: What It Is and How to Tune It

Pressure advance is retraction's more precise cousin: instead of just pulling filament back for travel moves, it continuously compensates for melt pressure changes as the printer speeds up, slows down or changes direction — which is what actually causes blobbing at corners and gaps at the start of a line, not retraction settings.

What it actually fixes

Molten plastic under pressure in the nozzle keeps extruding for a moment after the extruder motor stops pushing, and takes a moment to start again after it resumes — like a garden hose with some give in it. Pressure advance predicts that lag and adjusts extrusion timing ahead of it, so corners don't blob and line starts don't leave a gap. It is a per-filament calibration, not a one-time machine setting: different filaments (and different colors of the same filament, sometimes) have different melt viscosity and need different pressure-advance values.

Typical values across our vendor data

Vendors that expose pressure advance in their OrcaSlicer-family profiles show real, material-dependent variation:

TPU consistently needs the highest pressure advance of any common material (up to 0.3 in Creality's own profile) because its soft, elastic feed characteristics need more compensation than a rigid filament like PLA. Bambu Studio doesn't expose a raw pressure_advance value in its filament profiles the way Klipper-based printers do — it uses its own Flow Dynamics (K-value) calibration to the same end.

Klipper's tuning method

Klipper's own documentation gives an exact procedure: run TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.005 (direct drive) or FACTOR=.020 (Bowden) on a printed test tower, then read the height at which corners stop blobbing. Typical tuned values across all filaments fall between 0.05 and 1.0 — Klipper's docs note that if no improvement shows up by 1.0, pressure advance probably isn't the fix for whatever's being chased.

When a high value is a warning sign

Our own diagnosis engine flags pressure advance above 0.15 (or above 0.3 specifically for TPU) as suspiciously high — a value that far outside the normal range on a non-TPU filament usually means an upstream problem (partial clog, under-extrusion, wrong filament diameter) rather than a filament that genuinely needs that much compensation. Klipper's own docs back this up from the other direction: above roughly 0.2, high acceleration combined with high pressure advance can make the extruder skip because the motor doesn't have the torque to push the required filament fast enough — a reason to lower acceleration rather than push pressure advance even higher.