Calibration: Flow, Temperature & Pressure Advance

Calibration has a natural order — each step builds on the last. Do them once per printer (and re-do flow/temperature per new filament):

1. First layer / Z-offset
2. Extruder steps (E-steps / rotation distance)
3. Temperature
4. Flow rate (extrusion multiplier)
5. Pressure advance / linear advance
6. Retraction

Most modern slicers (OrcaSlicer especially) include built-in tests for each of these.

E-steps ensure the extruder pushes exactly the filament it's told to. Mark 120 mm of filament, command a 100 mm extrude, and measure what's left — adjust until 100 commanded equals 100 extruded.

Flow rate (extrusion multiplier) then fine-tunes how much plastic is laid down. Print a calibration cube or single-wall object, measure the wall thickness with calipers, and adjust flow so the measured wall matches the slicer's line width. Too much flow gives bulging, rough tops; too little leaves gaps between lines.

Every filament — even two spools of the same brand — has a sweet spot. A temperature tower prints the same shape at descending temperatures so you can compare.

Look for the band with the best layer adhesion, cleanest overhangs, and least stringing. Hotter improves strength and bonding but worsens stringing and overhangs; cooler does the reverse. Pick the lowest temperature that still bonds well.

Pressure advance (Klipper) / linear advance (Marlin) compensates for the springiness of molten plastic so corners stay sharp and seams don't blob. Print the test pattern and choose the value with the crispest corners — typically ~0.02–0.06 for direct drive, higher for Bowden.

Finally, tune retraction (distance and speed) to kill stringing without causing clogs: increase distance until strings disappear, then stop. Direct-drive extruders need far less retraction (0.5–2 mm) than Bowden (3–6 mm).