Stringing or Oozing

Stringing, or oozing, whiskers, or “hairy” prints happen when small plastic strands are left on your 3D model. This usually occurs because the nozzle leaks plastic while the extruder moves between different points. The most effective setting to reduce stringing is retraction. When retraction is enabled, the filament is pulled back into the nozzle after printing a section, reducing the chance of excess plastic leaking. The filament is pushed back into place when the print resumes and the plastic flows again. Below, we’ll cover key retraction settings and other ways to prevent stringing, such as adjusting the extruder temperature.

Common Causes and Solutions:

Retraction Distance

The most crucial retraction setting is retraction distance, which controls how much filament is pulled back into the nozzle. The greater the retraction, the less likely plastic is to ooze while the nozzle moves. A retraction distance of 0.5-2.0mm is usually sufficient for direct-drive extruders. In contrast, Bowden extruders may require as much as 15mm due to the longer distance between the extruder and nozzle. If your print shows signs of stringing, try increasing the retraction distance by 1mm and see if the result improves.

Retraction Speed

Next, check the retraction speed, which controls how quickly the filament is pulled back into the nozzle. If it is too slow, the plastic may leak before the extruder reaches its new location. However, retracting too quickly can cause the filament to detach from the molten plastic in the nozzle, or it could even grind the filament. The ideal retraction speed typically lies between 1200-6000 mm/min (20-100 mm/s). Depending on your material, you may need to experiment with different speeds to reduce stringing.

Temperature is Too High

After reviewing the retraction settings, the next most common cause of stringing is an extruder temperature that’s too high. The plastic becomes more fluid at high temperatures, making it more likely to ooze. Conversely, the plastic may have trouble flowing smoothly if the temperature is too low. If your retraction settings are correct but stringing persists, try lowering the extruder temperature by 5-10 degrees. This adjustment can significantly improve your print quality.

Long Movements Over Open Spaces

Stringing often happens when the extruder moves across empty spaces between different areas of the model. The length of this movement plays a big role in how much oozing occurs. Shorter movements don’t give the plastic enough time to leak, while longer ones increase the chance of stringing.

Movement Speed

Lastly, increasing your printer’s movement speed can reduce stringing by limiting the nozzle's time moving between parts. The X/Y Axis Movement Speed determines how quickly the nozzle moves across the print area. If your printer can handle higher speeds, increasing this value may help reduce stringing during travel moves.