Retraction settings for PETG: avoiding stringing
PETG is a popular material, but its viscosity and tendency to create fine "strings" can be frustrating. Proper retraction (pulling the filament back) is the key to clean parts.
Basic parameters (for direct‑drive and Bowden)
- Retraction distance: for Bowden – 4–6 mm, for direct – 1–2 mm. Start with the lowest value and increase in 0.5 mm steps until strings disappear.
- Retraction speed: 25–40 mm/s. Too fast may deform the filament, too slow gives little effect.
- Extra restart distance: leave at 0 mm or a small negative value (–0.1 to –0.2 mm) to avoid over‑extrusion at the start of a new layer.
Temperature and cooling
PETG prints at 230–250 °C. Higher temperatures make the plastic more fluid and harder to control stringing. Try lowering the temperature by 5–10 °C (but stay above 220 °C to keep good layer adhesion). Use part cooling fan at 30–50 % – too much cooling makes layers brittle.
Extra tricks
- Coasting – stops extrusion a few millimetres before the end of a line. For PETG, 0.2–0.4 mm works well.
- Wipe – moves the nozzle over an already printed area after retraction. Enable it in your slicer (e.g. "Wipe Nozzle" in Cura).
- Always use dry filament – moist PETG produces more strings.
Practical tip: print a retraction tower test (available in Cura or on Thingiverse) and vary distance and speed. Note the winning combinations for each brand of PETG you use.