3D Printer Stringing (6 Easy Fixes to Prevent It)

Updated

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Two 3D prints side by side. The one on the left has stringing issues while the one on the right doesn't

You’ve just finished a 3D print, and there it is, the dreaded web of plastic strings marring the surface of your print. Stringing can be a real headache, but it’s easy to fix with proper slicer settings.

You can say goodbye to those unwanted strands and hello to clean, crisp prints with a few tweaks.

How to Fix 3D Printer Stringing

A 3d printed pikachu with print imperfections like stringing, zits, and blobs caused by wet filament

3D printer stringing occurs when your nozzle deposits filament while traveling over open space. Stringing creates a cobweb-like appearance to your 3D prints that can be detrimental to display or cosplay items.

1. Enable Retraction Settings

A 3D printed stringing test print with retraction turned off
Retraction turned off
A 3D printed stringing test print with retraction turned on
Retraction enabled

Your slicer’s retraction settings are your first line of defense against stringing. Retraction works by pulling the filament back during travel moves to prevent extrusion over open spaces.

Two key retraction settings you’ll encounter are distance and speed. Retraction distance controls how much filament is withdrawn, while retraction speed dictates how fast the retraction occurs.

Here are the ideal retraction settings based on my experience working with over 30 3D printers :

  • For Bowden tube 3D Printers
    • Retraction Distance: 6 mm
    • Retraction Speed: 50 mm/s
  • For Direct Drive 3D Printers
    • Retraction Distance: 0.8 mm
    • Retraction Speed: 50 mm/s

Bowden setups require higher retraction distances due to the larger gap between the extruder and nozzle. Direct drive extruders have better control of the filament feeding and don’t require a high retraction distance.

In our experience, enabling retraction settings in your slicing program helps to eliminate 90% of 3D printer stringing issues.

If you’re still struggling with print quality after enabling retraction, consider adjusting the other print settings below.

2. Lower Printing Temperature

Temperature tower printed on an Ender 3 S1 with grey filament
This temperature tower helps you calibrate the perfect print temperature for your filament (Source: Schmuuu via Thingiverse)

High temperatures increase the viscosity of molten filament in the print head, making it too runny. The runny filament leads to oozing and stringing. Lowering the print temperature decreases the filament’s viscosity and prevents strings in your 3D prints.

Decrease the print temperature by 5°C increments until stringing is minimized, but avoid dropping below the manufacturer’s advised temperature. For instance, if you notice stringing with PLA at 220°C, try printing at 215°C next and carefully observe the results.

Alternatively, you can print a temperature tower from Thingiverse or use the Calibration Shapes plug-in in Cura to help fine-tune your nozzle temperature.

As a general guideline, here are ordinary printing temperatures for various filament materials:

  • PLA: 180-220 °C
  • ABS: 210-250 °C
  • PETG: 215-235 °C
  • Nylon: 240-260 °C
  • TPU: 225-250 °C

Editor’s Note

Print this temperature tower from Thingiverse to find the best print temperature easily.

3. Increase the Travel Speed

Increasing your printer’s travel speed reduces the nozzle’s time over open spaces. A faster travel move gives less time for the filament to leak out of the nozzle during non-printing movements.

You’ll need to find a balance, as too fast a travel speed might cause the printer to miss steps or lead to other quality issues. An excellent range to experiment with is 150-200mm/s, depending on your machine’s capabilities and the complexity of the print.

4. Clean Your Nozzle

A clean nozzle is crucial for avoiding stringing. Accumulated residue creates partial blockages, leading to uneven extrusion and unwanted strings. Dust, debris, and filament residue can accumulate within your nozzle. After using your printer for a long time, the accumulated residues can create surface defects such as strings.

There are several ways to clean your 3D printer nozzle:

  • Cold Pull: Our favorite technique for cleaning partial nozzle clogs is cold-pulling filament. It involves inserting a filament into a heated nozzle and allowing it to cool before pulling it out, removing any residual material stuck inside.
  • Wipe the nozzle head: Use a small wire brush to gently scrub the nozzle’s exterior to remove external debris and burnt-on filament.
  • Cleaning filament: Cleaning filament is a special kind of filament designed to clean the inside of the print head. Simply load the cleaning filament and heat the print head to the normal printing temperature, and it works to capture and remove debris and filament residue as it extrudes.
  • Using a Needle or Pin: For finer clogs, a thin needle or pin can be inserted into the nozzle tip when heated to dislodge any blockage.
  • Acetone: If you’re really struggling to clean the nozzle, an acetone bath can remove tricky contaminants.

5. Dry Your Filament

Wet filament can spell disaster for your prints. Moisture in the filament turns to steam in the hotend. The steam looks for a way to escape the nozzle, disrupting the extrusion process and increasing the risk of stringing.

Wet filament is easy to identify. Wet filament is the culprit if you hear popping or hissing sounds from your extruder head.

Our Pick
SUNLU Filament Dryer Box
Amazon
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You can prevent moisture absorption by storing your filament in a dry, airtight container with desiccant packs. If your filament has absorbed moisture, you can dry wet filament in a filament dryer.

6. Enable Coasting

Diagram explaining how coasting works on a 3D printer
(Source: support.ultimaker.com)

Coasting is a lesser-known feature that can help curb stringing. When enabled, this slicer setting stops extruding plastic a short distance before the print head completes a segment.

Coasting reduces pressure within the print head before it travels over an open area, preventing filament from oozing while traveling.

How to Remove Strings From 3D Prints

Dealing with stringing in your 3D prints isn’t fun.

You can remove most of the stringing by hand with a printed object with visible strings. But there will always be stubborn bumps on the surface.

The best way to remove the residual strings is with a heat gun or small torch for a smooth surface finish.

Ensure you don’t keep the lighter in the same spot for long because the plastic may get soft, melt, or even burn. 

Editor’s Note

Only use a heat gun, torch, or lighter in a well-ventilated outdoor space. Ensure you wear personal protective equipment, flame-resistant gloves, and a P100 respirator. Heated plastic can be toxic.

Mario De Lio
Mario De Lio

Mario is a Mechanical Engineer with experience working at one of the largest industrial printing companies in the country. He previously owned a rapid prototyping company specializing in designing mechanical parts for 3D printing applications.

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