Troubleshooting Stringing Issues with PLA and PETG Filament

Stop the Strings! Troubleshooting Stringing Issues with PLA and PETG Filament

That dreaded spiderweb of thin plastic strands connecting different parts of your 3D print – it’s a common frustration known as stringing. While it might seem like a minor annoyance, excessive stringing can significantly impact the aesthetic appeal and even the functionality of your creations.

At 3D Fusion, we want your prints to be as clean and precise as possible. That’s why we’ve put together this comprehensive guide to help you identify the causes of stringing when using our high-quality PLA and PETG filaments and, more importantly, how to resolve them. Let’s cut those strings and achieve flawless prints!

Understanding Stringing: The Oozing Culprit

Stringing occurs when molten filament oozes out of the printer nozzle during travel moves (when the print head moves from one part of the print to another without actively extruding). This happens because the filament inside the hot end remains liquid and pressure can force it out.

The Main Culprits: Retraction, Temperature, and Filament Quality

While several factors can contribute to stringing, the most common culprits are:

Incorrect Retraction Settings: Retraction is the process of pulling the filament back into the nozzle when the printer isn’t actively extruding. The goal is to relieve pressure in the nozzle and prevent oozing during travel moves.
Too High Nozzle Temperature: If your nozzle is too hot, the filament becomes more liquid and flows more easily, increasing the likelihood of oozing.
Poor Filament Quality (Especially Moisture): The quality and condition of your filament play a crucial role. Moisture absorption, particularly in PETG, can lead to stringing and other print defects.

Let’s delve deeper into each of these and explore how to address them.

1. Retraction Settings: Pulling Back the Ooze

Retraction is your first line of defense against stringing. Here’s what you need to know:

What is Retraction? When your printer needs to move the nozzle to a new location without printing, the retraction setting tells the extruder motor to pull a certain amount of filament back towards the cold end. This reduces the pressure in the nozzle and minimizes the amount of molten plastic that can ooze out.
Retraction Distance: This setting determines how much filament is pulled back. The optimal distance varies depending on your printer’s extruder type:
- Bowden Extruders (e.g., Creality Ender 3 V2): These setups have the extruder motor mounted away from the hotend, and the filament travels through a PTFE tube. Bowden systems generally require a longer retraction distance (typically between 4-7mm for PLA and 5-8mm for PETG) to compensate for the tube length.
- Direct Drive Extruders (e.g., Creality Ender-3 V3 SE): In direct drive systems, the motor is mounted directly above the hotend. This shorter filament path means you’ll need a much shorter retraction distance (typically between 0.5-2mm for PLA and 1-3mm for PETG).
Finding the Right Distance: Start with the recommended ranges above and incrementally adjust by 0.5mm. Running a retraction test print (a series of small pillars or shapes with gaps between them) is the best way to visually determine the optimal distance. You want the shortest distance that eliminates or significantly reduces stringing.
Retraction Speed: This setting dictates how quickly the filament is pulled back. The ideal speed also depends on your printer and filament.
- PLA: Generally works well with retraction speeds between 30-60 mm/s.
- PETG: Often benefits from slightly slower retraction speeds, typically between 25-45 mm/s. Faster speeds with PETG can sometimes cause the filament to snap or grind.
Testing Retraction Speed: Similar to retraction distance, you can test different speeds using the same stringing test print. Adjust in increments of 5-10 mm/s.
Retraction Prime Speed (or Retract Speed): This setting controls the speed at which the filament is pushed back into the nozzle after a retraction. It’s usually best to keep this setting similar to your retraction speed.

2. Temperature Control: Finding the Sweet Spot

Your nozzle temperature plays a critical role in filament flow. If it’s too high, the filament will be excessively liquid and prone to oozing.

Nozzle Temperature’s Role: The hotter your nozzle, the lower the viscosity of the molten filament. While a certain temperature is necessary for proper extrusion and layer adhesion, going too high makes the filament too runny and more likely to leak out during travel moves.
Recommended Temperature Ranges for 3D Fusion Filaments:
- PLA: Our 3D Fusion PLA typically prints best between 200-215°C. Start with 205°C and adjust in 5°C increments.
- PETG: Our 3D Fusion PETG usually requires a higher temperature, around 230-245°C. Start with 235°C and adjust accordingly.
Temperature Towers: Printing a temperature tower is an excellent way to visually identify the optimal nozzle temperature for a specific roll of filament. This test print consists of sections printed at different temperatures, allowing you to observe which temperature produces the least amount of stringing and the best overall print quality.

3. Filament Quality: The Foundation of Clean Prints

The quality and condition of your filament can significantly impact stringing.

Moisture Absorption: Both PLA and PETG are hygroscopic, meaning they absorb moisture from the air. However, PETG is particularly prone to moisture absorption. Wet filament can lead to various printing issues, including increased stringing, popping or hissing sounds during printing, and a weakened final product.
- Signs of Wet Filament: You might hear a faint hissing or popping sound as the moisture in the filament boils in the hotend. The filament might also appear more brittle or produce inconsistent extrusion.
- Solutions: Store your filament in a dry, airtight container with desiccant packs. If you suspect your filament is wet, you can dry it using a dedicated filament dryer or even a conventional oven (at a low temperature, specific to the filament type – research recommended drying temperatures).
Filament Diameter Consistency: Inconsistent filament diameter can lead to uneven extrusion and potentially contribute to stringing. At 3D Fusion, we maintain strict quality control to ensure consistent filament diameter throughout the spool. However, if you’re using lower-quality filament, this could be a contributing factor.

Other Contributing Factors to Consider:

Travel Speed: If your travel speed (the speed at which the nozzle moves between printed areas) is too slow, it gives more time for molten filament to ooze out. Increasing your travel speed in your slicer settings can sometimes help reduce stringing.
Wipe and Coasting (Advanced Settings): These are more advanced slicer settings that can further refine your prints.
- Wipe: After printing a section, the nozzle moves slightly to wipe away any remaining filament.
- Coasting: Just before the end of a segment, the extruder stops extruding, relying on the remaining pressure in the nozzle to finish the line. Experimenting with these settings might help in specific cases.
Nozzle Condition: A worn, damaged, or dirty nozzle can also contribute to stringing. Ensure your nozzle is in good condition and free from any debris.

Troubleshooting Guide for PLA Stringing:

Start with Retraction: Increase retraction distance in small increments (0.5mm).
Adjust Retraction Speed: Try increasing or decreasing retraction speed within the recommended range.
Lower Nozzle Temperature: Decrease the nozzle temperature in 5°C increments, ensuring you don’t go too low and compromise layer adhesion.
Increase Travel Speed: Try increasing your travel speed slightly.
Check Filament: Ensure your PLA is stored properly and hasn’t absorbed excessive moisture.

Troubleshooting Guide for PETG Stringing:

PETG can be a bit more challenging to dial in for stringing.

Start with Retraction: Increase retraction distance in small increments (0.5mm).
Adjust Retraction Speed: Try slightly slower retraction speeds.
Lower Nozzle Temperature: Decrease the nozzle temperature in 5°C increments. Be careful not to go too low, as PETG needs a higher temperature for good layer adhesion.
Increase Travel Speed: Try increasing your travel speed.
Check Filament: PETG is very sensitive to moisture. Ensure your filament is dry. Drying PETG is often necessary to eliminate stringing.
Experiment with Wipe and Coasting: These advanced settings can be particularly helpful for PETG.

Step-by-Step Troubleshooting Process:

Start with Retraction Distance: Adjust this first, as it’s often the primary culprit.
Fine-tune Retraction Speed: Once you have a good retraction distance, adjust the speed.
Optimize Nozzle Temperature: Use a temperature tower to find the ideal temperature for your filament.
Ensure Filament is Dry: If you suspect moisture, dry your filament.
Consider Travel Speed and Advanced Settings: If stringing persists, experiment with travel speed, wipe, and coasting.

Conclusion: Victory Over Strings!

Stringing can be a frustrating issue, but by systematically addressing the key factors of retraction, temperature, and filament quality, you can significantly reduce or eliminate those pesky plastic strands. Remember to make small, incremental adjustments and test your settings thoroughly. With the right approach and our high-quality 3D Fusion PLA and PETG filaments, you’ll be well on your way to achieving clean, professional-looking 3D prints. Happy printing!