Step 14.18 — Read the pattern and save the value¶
Step 18 of 36 with a helper · Chapter 14 — Calibration and tuning
(no image — see text)
Parts:
- good light · tool
- loupe, optional · tool
Do:
- Find the sharpest corner with the fewest artefacts: no gaps, no bulges, no divots.
- Re-run at 0.001–0.002 intervals around it to refine.
- Put the value in the PrusaSlicer filament custom G-code for ASA:
SET_PRESSURE_ADVANCE ADVANCE=<your value>
Check
One corner is visibly the sharpest, and the value you saved is in the 0.01–0.08 band, most often 0.02–0.05.
Helper Once the pattern has cooled off the plate, counts lines from its start to the sharpest corner with the loupe.
What you're looking at
You are hunting for the one corner in the sweep that is sharp with no gap and no bulge. The value belongs to the filament, not the machine, so it is saved in the filament profile rather than in printer.cfg.
Or set [extruder] pressure_advance: if you only ever print ASA on this machine.
Where the 0.01–0.08 band comes from
The LDO config's own commented starting point is #pressure_advance: 0.05, and
Klipper documents typical values as "between 0.050 and 1.000 (the high end usually
only with bowden extruders)". For a direct-drive Clockwork 2 with a Revo HF and a
0.4 nozzle in ASA, expect the bottom of that band. No vendor publishes a
Revo-HF-specific number; treat 0.04 as the place to start looking and let the
pattern decide. Most land between 0.02 and 0.05; the wider 0.01–0.08 gate only
flags a reading worth a second look.
Pressure advance — the value the pattern picked — the calculator needs JavaScript; the limits are in the table on this page.
Tip
there is rarely a perfect value. Ellis leans higher: if the sharpest corner has a tiny bit of gapping, still take it. Direct drive is that sensitive.
Caution
If you cannot get a clean corner at any value, or you see gapping and bulging simultaneously, stop tuning — Ellis: "you likely have extruder issues." Check the CW2 for backlash: with the toolhead cold, reverse the extruder gear direction by hand and feel for a dead zone.
Good stopping point · ~20 min since the last one
the PA pattern is printed, read and the chosen value saved into the ASA filament profile. One calibration item closed; extrusion multiplier is the next.
Source: Ellis' Print Tuning Guide — saving the pressure-advance value · Klipper docs § Pressure advance · Klipper docs § SET_PRESSURE_ADVANCE