Now that distance is fixed, speed is the one remaining variable. Too fast shears the filament in the drive gear and creates the jam it was meant to prevent.
Phase 4 — Motionabout 30 minper filament
How to do it
Hold the distance you just chose fixed. That number is now settled.
The setting sits next to the distance one, usually called Retraction Speed or Retract Speed, in mm/s.
Sensible range: roughly 25–45 mm/s for most machines. Faster is not better — past the point where it works, the drive gear starts chewing the filament instead of pulling it.
Print the same test across a speed range, changing only the speed.
LISTEN as well as look. A click or grinding noise at the extruder during travel moves means it is too fast, even if the print looks fine.
Pick the fastest speed with no stringing and no grinding sound.
How to read the result
Clean travel moves with no filament grinding audible at the extruder.
Your slicer may do this for you
OrcaSlicer's retraction test varies distance rather than speed, so this one is usually done by hand — same print, same distance, one speed change at a time.