Retraction

What retraction does

Molten plastic in the hotend is under pressure. When the head travels without printing, that pressure pushes plastic out of the nozzle and leaves strings or blobs. Bambu Lab's retraction guide explains the fix: pull some filament back before the travel to relieve the pressure, then push it back in at the end of the travel so printing resumes normally. If strings are what you see, start with Stringing and Oozing.

Where the settings are called what

What it controls	PrusaSlicer	OrcaSlicer	Bambu Studio	Cura
How far to pull back	Length	Length	Length	Retraction Distance
How fast	Retraction Speed	Retraction speed, Deretraction speed	Retraction speed, Deretraction speed	Retraction Speed
Shortest travel that retracts	Minimum travel after retraction	Travel distance threshold	Travel distance threshold	Retraction Minimum Travel
Lift the nozzle on travel	Lift Z	Not confirmed	Z hop when retracting, Z hop type	Z Hop When Retracted
Retract at each layer	Retract on layer change	Retract on layer change	Retract on layer change	Retract at Layer Change
Wipe the nozzle while retracting	Wipe while retracting	Wipe while retracting	Wipe while retracting	Not confirmed

Not confirmed means we did not find the name in that slicer's documentation; the feature may still exist. PrusaSlicer keeps these under Printer settings, Extruder 1; Bambu Studio under Printer settings, Extruder, with per-filament overrides in Filament settings, Settings Overrides. OrcaSlicer also lets each filament override the printer's retraction.

Length

Which way it pushes: more length relieves more pressure and oozes less. UltiMaker says longer retractions reduce oozing but stress the material and take more time.

What it costs: OrcaSlicer warns that too long can lead to clogs or under-extrusion, and Bambu Lab that too much or too often under-extrudes, leaves layer gaps and can clog the extruder.

It depends on the printer. Prusa's own profiles show it: the MINI presets use a longer default length than the limit Prusa gives for its MK3 family, which Prusa puts down to the MINI's Bowden extruder (see Direct Drive versus Bowden). That is why MESH gives no universal number. Measure it Start from your printer maker's profile and find the right length with a retraction test.

Flexible filament: the makers disagree, because flexibles behave differently on different extruders. Prusa says flexible filaments need longer retractions; Bambu Lab warns retraction can stretch and shrink elastic filament such as TPU and cause clogs. Follow the filament and printer makers' profile for TPU before experimenting.

Speed

Faster retraction relieves pressure sooner. Prusa says faster helps with stringing, but too fast can make the extruder motor skip steps; UltiMaker says too fast can grind the filament, and too slow oozes more. Deretraction speed, the speed of pushing back, defaults to the retraction speed in OrcaSlicer and Bambu Studio when set to 0.

When it retracts

• Minimum travel. Short travels skip retraction. Prusa says a higher minimum shortens print time but increases oozing and stringing; UltiMaker says raising it reduces grinding, but too high causes strings and blobs. Bambu Lab shows strings across small gaps fixed by lowering it.
• Retract on layer change. Prusa recommends leaving it on.
• Maximum retraction count (Cura) caps how many retractions can happen within a set length of filament. UltiMaker notes too low a value on models with many holes can cause stringing.
• Inside infill. Bambu Studio's Reduce infill retraction skips retractions for travels inside infill, where strings are hidden.

Z hop

Z hop (Lift Z in PrusaSlicer) raises the nozzle during travel so it does not drag across the print. Prusa notes a lower value helps stringing, but disabling it can let the nozzle hit the printed part. UltiMaker says many hops add print time. Bambu Studio offers several hop types, including slope and spiral, which it says reduce oozing and stringing.

Wipe and travel routing

• Wipe while retracting moves the nozzle back along the last line as it retracts, cleaning off leaked plastic. Prusa recommends leaving it on. Bambu Lab notes that not retracting before the wipe gives a better outer wall seam with the default wall order.
• Avoiding walls. PrusaSlicer's Avoid crossing perimeters and OrcaSlicer's Avoid crossing walls route travel around walls instead of over them. OrcaSlicer calls it highly recommended for detailed prints with stringy materials like PETG or TPU, at a small cost in time. Cura's Combing Mode keeps travel inside the part, with fewer retractions but longer travel.

What to change first

1. Dry the filament. Bambu Lab says damp filament strings more and usually cannot be fixed by retraction settings alone (see Wet Filament Symptoms).
2. Lower the nozzle temperature a little within the maker's range. Prusa suggests 5 to 10 °C steps Starting point.
3. Run a retraction test and change length first, in small steps, keeping speed fixed.
4. Then speed, then minimum travel, wipe and travel routing.
5. If strings persist on good settings, clean the nozzle and try another spool.