How Do You Combine PLA Filaments?

Fact Checked By:Aithley Balder

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3D printing with PLA (Polylactic Acid) filament has become increasingly popular due to its biodegradable nature, ease of use, and wide range of colors and finishes. However, combining PLA filaments can open up new possibilities for creative and functional prints, allowing you to use multiple colors or materials within a single project. In this article, we will explore various techniques for combining PLA filaments, tips for success, and answers to frequently asked questions, helping you unlock new dimensions in your 3D printing endeavors. Whether you’re an experienced 3D printing enthusiast or just getting started, this comprehensive guide will help you understand the ins and outs of merging PLA filaments for impressive and eye-catching results.

How Do You Combine PLA Filaments

Combining PLA (Polylactic Acid) filaments can be achieved through several methods, but I’ll discuss three common techniques: filament welding, dual extrusion, and mixing hotends. Keep in mind that combining filaments will generally require a bit of trial and error to find the best method for your specific use case and 3D printer setup.

Filament welding:

This method involves manually fusing two pieces of PLA filament together. It is suitable for switching colors or materials during a print, but it’s not recommended for blending colors or materials. Here’s a simple way to do it:

  • Cut both ends of the filaments at a sharp angle to create a point.
  • Heat up a flat surface, like a metal plate or a glass surface. The surface should be hot enough to slightly melt the filament ends.
  • Press the pointed ends of the filaments together on the heated surface and hold them in place for a few seconds until they fuse.
  • Allow the joined filament to cool and solidify before feeding it into the 3D printer.

Dual extrusion:

Dual extrusion 3D printers have two separate extruders, which can print with two different filaments simultaneously. This technique allows you to create prints with multiple colors or materials. However, blending colors or materials is not possible with this method. To use dual extrusion:

  • Load each filament into a separate extruder.
  • In your slicing software, assign each part of the 3D model to the appropriate extruder.
  • Configure the settings in the slicer to ensure proper alignment and calibration of the extruders.
  • Begin your print, and the printer will automatically switch between the extruders as needed.

Mixing hotends:

Mixing hotends are specifically designed for blending different filaments. They usually have multiple filament inputs and a single output nozzle. The filaments are fed into the hotend, where they are mixed and extruded together. This method allows for color or material blending in a single print.

  • Load your filaments into the different inputs of the mixing hotend.
  • Configure your slicing software to support the mixing hotend, specifying the appropriate mixing ratios for your desired outcome.
  • Slice your model and begin your print. The printer will automatically blend the filaments as specified in the slicer settings.

Custom filament splicing:

A specialized device called a filament splicer or filament joiner can be used to combine PLA filaments. These machines precisely control the heat and pressure to create a seamless bond between two pieces of filament, making them ideal for multicolor printing. Some popular models are the Mosaic Palette and Prusa MMU (Multi-Material Upgrade). To use a filament splicer:

Gradient color printing:

This method is a variation of the mixing hotend technique. By adjusting the mixing ratios of two or more filaments in real-time during a print, you can create a gradient color effect. This is possible with some advanced mixing hotends and the appropriate slicer settings. Here’s how you can do gradient color printing:

  • Load your PLA filaments into the inputs of the mixing hotend.
  • In your slicing software, enable the option for gradient color printing (this may vary depending on the slicer).
  • Configure the gradient settings, such as the starting and ending mixing ratios, the transition length, and the layer heights at which to apply the gradient.
  • Slice your model and begin your print. The printer will automatically adjust the mixing ratios to create the desired gradient effect.

Note that gradient color printing requires a more sophisticated mixing hotend and may involve a steeper learning curve. Also, keep in mind that not all slicers support gradient color printing natively; you may need to find a specific plugin or use a custom post-processing script to achieve this effect.

As always, combining PLA filaments involves trial and error. It is essential to ensure compatibility between the methods, the 3D printer, and the slicer software. Make sure to calibrate and test your setup thoroughly before committing to a large print.


Here are some tips for successfully combining PLA filaments using the various methods described earlier:

  • Ensure filament compatibility:Not all PLA filaments are created equal, and some may have slightly different melting temperatures or additives. When combining filaments, choose filaments with similar melting temperatures and properties to avoid issues during printing.
  • Prepare the filament ends: When manually joining filaments or using a splicer, ensure that the filament ends are clean and cut at a sharp angle. This helps create a better bond and reduces the chance of blockages in the nozzle.
  • Keep the filament path clean and clear: When combining filaments, especially when using dual extrusion or mixing hotends, ensure that the filament path is free of debris and obstructions. This helps prevent jams and ensures smooth feeding of the filament.
  • Calibration and alignment: When using methods like dual extrusion or mixing hotends, proper calibration and alignment are critical to successful prints. Ensure that the extruders are level and aligned with the print bed, and that the slicer settings are configured correctly for your specific hardware setup.
  • Test and iterate: When attempting to combine PLA filaments, it’s essential to perform test prints and iterate on your settings. Start with small test prints to confirm your setup and settings before moving on to larger or more complex prints.
  • Manage print speed and temperature: Combining filaments may require adjustments to print speed and temperature settings. Slower print speeds can help achieve better color blending, while adjusting temperatures can help ensure optimal adhesion between different filaments.
  • Use appropriate slicer settings and software: Some slicers have specific settings or plugins for dual extrusion, mixing hotends, or gradient color printing. Make sure to use appropriate settings in your slicer, and experiment with different options to find the best results for your setup.
  • Minimize oozing and stringing: When combining PLA filaments, especially with dual extrusion or mixing hotends, oozing and stringing can be problematic. Use slicer settings like retraction, coasting, and wiping to help minimize these issues.
  • Watch for clogs and jams: Combining filaments can sometimes lead to clogs or jams in the nozzle. Keep an eye on your print and be prepared to pause the print and clear any blockages if necessary.
  • Be patient and experiment: Combining PLA filaments can be challenging, and it may take some trial and error to find the best methods and settings for your specific setup. Be patient, experiment, and learn from your mistakes to improve your results over time.

Frequently Asked Questions (FAQ’s)

Here are some common questions and answers related to combining PLA filaments:

Q: Can I mix PLA with other materials, like ABS or PETG?

A: Mixing PLA with other materials can be challenging due to differences in melting temperatures and properties. While it is possible in some cases, it often requires a specialized setup and careful calibration. Mixing PLA with other materials is generally not recommended for beginners.

Q: Can I create custom colors by mixing PLA filaments?

A: Yes, using a mixing hotend or a specialized filament splicer, you can create custom colors by combining different PLA filaments. However, the resulting color may be different than expected, and the blending may not be perfectly uniform. It is important to experiment and test different mixing ratios to achieve the desired color.

Q: Will the combined filament be as strong as a single filament?

A: The strength of the combined filament will depend on the quality of the bond between the two filaments and their compatibility. In general, if the filaments are compatible and joined properly, the strength should be comparable to a single filament.

Q: Can I use a regular single extruder printer to combine PLA filaments?

A: While a single extruder printer is not designed to combine filaments directly, you can use techniques like filament welding or custom filament splicing to create a combined filament that can be used with a single extruder printer. Note that this method will not allow for color blending or real-time material changes during printing.

Q: Are there any special precautions I need to take when printing with combined PLA filaments?

A: As with any 3D printing, it’s essential to ensure that your printer is calibrated and properly maintained. Additionally, you should monitor the print closely to ensure that the bond between the filaments remains intact and that there are no jams or blockages in the nozzle.

Q: How do I prevent color contamination when using dual extrusion or mixing hotends?

A: To minimize color contamination, you can use slicer settings like retraction, wiping, and coasting. Additionally, you can perform a “purge tower” or “ooze shield” during printing, where the extruder purges a small amount of material onto a separate structure to ensure a clean transition between colors or materials.

Q: What are the methods for combining PLA filaments?

A: There are a few methods you can use to combine PLA filaments:
·       Splicing or Joining: This method involves melting the ends of two PLA filament pieces together to create a secure connection. It can be done using a soldering iron, heat gun, or a 3D printing pen. By heating the filament ends and pressing them together, they fuse and form a strong bond.
·       Filament Welding: Some 3D printing pens or handheld heat tools are designed for filament welding. These tools heat the filament ends and press them together to create a fused connection. They can be useful for combining PLA filaments without the need for additional equipment.
·       Filament Connectors or Couplers: There are filament connectors or couplers available that can be used to join two PLA filament pieces together. These connectors typically have a threaded design, allowing you to screw the filaments together securely.
·       Knotting: In some cases, you can tie a tight knot with the ends of the PLA filaments to create a temporary or less permanent connection. However, this method may create a slight bump in the filament and is not as strong as the other methods.

Q: What are the best practices for combining PLA filaments?

A: To ensure successful and reliable results when combining PLA filaments, consider the following best practices:
·       Trim the filament ends to create clean and flat surfaces before joining them.
·       Clean the filament ends to remove any dust or debris that may interfere with the fusion process.
·       Use the recommended temperature and heat source for the specific filament type you are using.
·       Allow the filament joint to cool and solidify completely before using it in a 3D printer or other applications.
·       Test the strength of the filament joint by gently tugging on the connected filaments. If the joint feels weak or separates easily, consider using a different joining method or adjusting the parameters.
·       Practice on scrap or test pieces before attempting to combine PLA filaments for your main project.
·       Take note of the filament colors and properties to ensure consistency and compatibility when joining different PLA filaments.

Q: Can I combine PLA filaments of different colors or types?

A: Yes, you can combine PLA filaments of different colors or even different types. The process of combining them remains the same as long as the filaments are made from PLA material. Keep in mind that the resulting combination will have a blended color or properties, depending on the specific filaments used. It’s important to consider the compatibility of different PLA filaments in terms of melting points and other characteristics to ensure a successful fusion.

Q: Are there any limitations or considerations when combining PLA filaments?

A: When combining PLA filaments, it’s important to consider a few limitations and factors:
·       Different PLA filaments may have slight variations in color, texture, or properties, which can affect the appearance and performance of the final combined filament.
·       Avoid excessive heating or over-fusion, as it can lead to degraded or weakened filament joints.
·       Ensure that the combined filament diameter is consistent and compatible with your 3D printer’s specifications.
·       If the combined filament has significantly different melting points, it may affect the printing temperature and require adjustments to prevent issues like clogging or under-extrusion.


In conclusion, combining PLA filaments presents a world of opportunities for 3D printing enthusiasts, offering a variety of techniques to create multicolored or multi-material prints. From simple filament welding to advanced dual extrusion and mixing hotends, these methods cater to different skill levels and printer setups. With the right tools, proper calibration, and a little experimentation, you can achieve impressive results that elevate your 3D printing projects to new heights. As you explore these techniques, don’t forget to implement the tips and best practices discussed in this article to ensure success in your endeavors. Always remember that patience and a willingness to learn are essential in this process, as combining PLA filaments may require trial and error. By embracing the challenges and opportunities that come with merging PLA filaments, you’ll be well on your way to creating stunning and unique 3D prints that truly stand out.

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Aithley Balder

Hello there, my name is Aithley Balder from Texas. I am a cookware, sewing, toilet, technology enthusiast and I have been sharing my passion with my friends and likeminded folks for close to 4 years now. Don’t hesitate to get in touch with me via the contact page.

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