Travel and Retraction

Travel and retraction settings govern how the printhead moves between extrusion points and manages filament pressure to minimize defects like stringing, oozing, and collisions. Proper configuration balances speed, precision, and material behavior for clean, efficient prints.

Retraction Parameters and Calibration

Retraction Distance

• Direct Drive: 0.5–1mm (e.g., 0.8mm for Hemera).

• Bowden: 4–6mm due to filament slack in the tube.

• Material Variations:

  • PLA: Lower distances (0.5–1mm direct; 4–5mm Bowden).

  • PETG: Higher distances (1–1.5mm direct; 5–6mm Bowden) to combat stringing.

Left no retraction, right with retraction on

Calibration Method:

1. Print a retraction test model (e.g., stringing tower).

2. Start with 0mm retraction to establish a baseline.

3. Incrementally increase distance (e.g., +0.2mm steps) until stringing resolves.

Retraction Speed

• Optimal Range: 25–45mm/s for retraction; 30–80mm/s for prime.

• Bowden Systems: Higher speeds (40–45mm/s) reduce oozing during long travels.

Minimum Travel Threshold

• Function: Retracts only when travel distance exceeds this value (e.g., 1–2mm).

• Adjustments: Lower thresholds (e.g., 0.5mm) reduce stringing on small features but increase retraction frequency.

Travel Optimization Strategies

Combing Modes

• All: Limits travel moves to within the model, reducing stringing and collisions.

• Not in Skin: Avoids top/bottom layers, balancing speed and surface quality.

• Off: Forces direct travel paths; use with Z-hop to prevent nozzle drag.

Avoidance Settings

• Avoid Printed Parts/Supports: Diverts nozzle around existing structures, critical for tall or fragile prints.

• Trade-offs: Increases print time and potential oozing but prevents part dislodgement.

Z-hop Configuration

• Purpose: Lifts the nozzle during non-extrusion moves to avoid collisions.

• Recommended Height: 0.2–0.4mm (match layer height for consistency).

• Drawbacks: Can introduce blobs or stringing if retraction is insufficient. Older printers without well made parts can cause print issues (eg. printer Z-hops upward 0.2mm but goes back down 0.21mm).

Advanced Settings for Specific Scenarios

High-Speed Printing

• Travel Speed: 200–500mm/s (ensure frame stability to avoid layer shifts).

• Acceleration Control: Lower values (500–1000mm/s²) reduce ghosting on detailed models. Not needed on new printers with vibration compensation or input shaper.

Material-Specific Adjustments

• TPU/Flexibles: Disable retraction or use ≤1mm distance to prevent jams.

• ABS/ASA: Moderate retraction (1–2mm direct; 3–4mm Bowden) with minimal cooling.

Nozzle and Layer Height Considerations

• Large Nozzles (≥0.6mm): Increase Z-hop to 0.4–0.6mm to clear wider extrusion paths.

• Thick Layers (≥0.3mm): Disable combing to prevent collisions with dense infill.

Troubleshooting Common Issues

Excessive Stringing

• Causes: Insufficient retraction distance/speed, high nozzle temperature.

• Solutions:

  • Increase retraction distance by 0.2–0.5mm.

  • Lower nozzle temperature by 5–10°C.

Nozzle Collisions

• Causes: Disabled Z-hop, low travel avoidance settings.

• Solutions:

  • Enable Z-hop at 0.2mm.

  • Activate Avoid Printed Parts and Avoid Supports.

Under-Extrusion Post-Retraction

• Causes: Excessive retraction distance, low prime speed.

• Solutions:

  • Reduce retraction distance by 0.1–0.3mm.

  • Increase prime speed to 80mm/s.

Workflow for Optimal Configuration

1. Baseline Calibration:

   • Print retraction towers at varying distances/speeds.

   • Use line-type preview in slicers to validate travel paths.

2. Fine-Tuning:

   • Adjust minimum travel and combing based on part geometry.

   • Test Z-hop and avoidance settings on tall, multi-part prints.

3. Material Validation:

   • Recalibrate retraction for each filament type (e.g., PETG vs. PLA).

   • Adjust cooling and temperatures to complement retraction settings.