Mastering Linear Advance on Your 3D Printer

Linear advance is an advanced technique used in 3D printing to improve the quality of printed parts by ensuring precise filament extrusion. It compensates for the lag between the extruder’s movements and the actual deposition of the filament. This guide will walk you through the process of setting up and fine-tuning linear advance on your 3D printer.

Understanding Linear Advance

Linear advance adjusts the extrusion rate based on the speed of the print head. Without linear advance, the filament flow can lag when the print head accelerates and decelerates, leading to issues like blobbing, stringing, or inconsistent extrusion lines. By adjusting the extrusion rate dynamically, linear advance helps in achieving more accurate and higher-quality prints.

Prerequisites

Before you begin, ensure you have the following:

• A 3D printer with a compatible firmware (Marlin is commonly used).
• Basic knowledge of G-code and printer settings.
• A reliable method to measure and adjust extrusion settings (e.g., a digital caliper).

Step-by-Step Guide to Setting Up Linear Advance

1. Update Your Firmware

Ensure your 3D printer’s firmware supports linear advance. Marlin firmware, for instance, includes this feature. If you need to update your firmware:

• Download the latest version of Marlin firmware from the Marlin GitHub repository.
• Configure the firmware for your specific printer model, enabling linear advance by setting #define LIN_ADVANCE in the Configuration_adv.h file.
• Compile and upload the updated firmware to your printer.

2. Determine the K-Factor

The K-factor is a key parameter for linear advance that determines how much the extrusion is adjusted based on print speed. To find the optimal K-factor for your printer and filament, follow these steps:

1. Prepare a Test Print:
   • Create or download a linear advance calibration pattern. Many such patterns are available on platforms like Thingiverse.
   • Alternatively, use a simple G-code script to generate a series of lines with varying print speeds.
2. Print the Calibration Pattern:
   • Load the calibration pattern into your slicing software (e.g., Cura, PrusaSlicer).
   • Use a consistent filament and printing environment to ensure accurate results.
   • Start with an initial K-factor (e.g., 0.00) and gradually increase it (e.g., in steps of 0.05).
3. Analyze the Print:
   • Examine the printed lines for consistency and quality.
   • The goal is to find a K-factor where the lines are even, without blobs or gaps at the start and end of each segment.
4. Fine-Tune:
   • Once you identify a rough range where the K-factor works well, perform more prints within this range for fine-tuning.

3. Update Printer Settings

After determining the optimal K-factor:

1. Modify Firmware or G-code:
   • If using Marlin, set the K-factor in the firmware: #define DEFAULT_Kp your_k_factor.
   • Alternatively, you can set it directly in your G-code by adding M900 Kyour_k_factor at the start of your print file.
2. Save and Test:
   • Save the updated firmware settings or G-code.
   • Perform a test print to ensure that the linear advance is working correctly.

Tips for Successful Linear Advance

• Consistent Testing: Use the same filament type and print settings (temperature, speed, etc.) during testing.
• Environmental Control: Ensure a stable printing environment to avoid fluctuations that could affect results.
• Firmware Documentation: Refer to your firmware’s documentation for specific commands and detailed instructions.
• Community Resources: Engage with online communities and forums for additional tips and shared experiences.

Conclusion

Mastering linear advance can significantly enhance the quality of your 3D prints by providing smoother and more consistent extrusion. While it requires some initial setup and calibration, the benefits in terms of print quality are well worth the effort. By following this guide, you’ll be able to implement and fine-tune linear advance on your 3D printer, resulting in better and more reliable prints.

An excellent how to guide can be found at Ellis3dp.com:

https://ellis3dp.com/Print-Tuning-Guide/articles/pressure_linear_advance/pattern_method.html