Pulling filament backward into the nozzle before a non-print travel move to prevent oozing and stringing.
Retraction is controlled by distance (mm pulled back) and speed. Direct-drive extruders sit close to the nozzle and need only 0.5-2 mm; Bowden systems with long PTFE tubes require 4-7 mm. Retraction creates negative pressure in the melt zone, reducing ooze during travel. A prime distance partially reverses retraction before the next print move.
Start with slicer defaults for the extruder type. Run a stringing tower test to find minimum effective retraction distance. Increase retraction speed (50-60 mm/s) before increasing distance. For PETG and flexible filaments reduce distance. Enable Pressure Advance (Klipper) or Linear Advance (Marlin) for dynamic compensation.
Too-high retraction on direct-drive causes filament grinding and jams. Retracting below 180 C snaps brittle filaments. Frequent retractions on the same section cause cumulative grinding. PTFE-lined hotends degrade above 240 C; switch to all-metal for high-temperature filaments.
Related terms: Stringing, Print Speed, Filament Drying
| Field | 3D printing |
|---|---|
| Source | EDi Brain: tech/fdm |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert