Warning: Excessive retraction can cause clogs, especially with direct drive extruders. If you're above 2mm on direct drive or 8mm on bowden and still have stringing, look at temperature and other factors first.
Retraction Calibration
Find optimal retraction settings to eliminate stringing and oozing.
What is Retraction?
Retraction pulls filament back from the nozzle during travel moves to prevent oozing and stringing. Two key parameters:
- Retraction Length: How far to pull back (mm)
- Retraction Speed: How fast to pull back (mm/s)
Starting Values
| Extruder Type | Length (mm) | Speed (mm/s) |
|---|---|---|
| Direct Drive | 0.5 - 2.0 | 30 - 50 |
| Bambu Lab | 0.5 - 1.0 | 30 - 40 |
| Short Bowden (<30cm) | 2.0 - 4.0 | 35 - 50 |
| Long Bowden (>30cm) | 4.0 - 8.0 | 40 - 60 |
Running the Test
- Go to Calibration > Retraction Test
- Set the retraction length range to test
- Print the retraction tower
- Examine each section for stringing
- Note the length with least stringing
- Optionally run a second test to fine-tune speed
Evaluating Results
Look at the strings between the towers at each level:
| Appearance | Status | Action |
|---|---|---|
| Heavy stringing, thick strings | Under-retraction | Increase length |
| Thin wisps, minimal strings | Close to optimal | Fine-tune |
| No stringing | Optimal or over-retraction | Use this value |
| Gaps/holes at restart points | Over-retraction | Decrease length |
Other Factors Affecting Stringing
If you still have stringing after calibration, check:
- Temperature: Lower temps reduce oozing
- Travel speed: Faster travel = less time to ooze
- Z-hop: Can sometimes increase stringing
- Wet filament: Moisture causes stringing - dry your filament
- Coasting: Stops extrusion early before travel
- Wipe: Moves nozzle while retracting
Material-Specific Tips
| Material | Notes |
|---|---|
| PLA | Standard settings work well |
| PETG | Very stringy - try higher temp + faster travel |
| TPU | Little to no retraction (0.2-0.5mm max) |
| ABS | Similar to PLA but at higher temps |
| Nylon | Very stringy - increase retraction, lower temp |
Advanced: Fine-Tuning
After finding basic retraction length:
- Test speed: Try 25, 35, 45, 55 mm/s at your optimal length
- Test temperature: Lower temp often helps more than more retraction
- Enable wipe: 0.5-1.0mm wipe can help with blobs
- Pressure Advance: Good PA reduces need for high retraction