Linear advance

Updated 8 months ago ​by Tomáš Chvalina

This is an advanced calibration, recommended only to experienced users.

Linear advance is a technology which predicts the pressure build-up in the extruder when printing at higher speeds. The firmware of the printer uses that prediction to decrease the amount of filament extruded just before stopping and decelerating, which prevents blobs or artifacts at the sharp corners. 

This feature is supported in firmware 3.1.0 and later as wel las in our PrusaSlicer

To see the speed increase, you must test on larger models! PrusaSlicer limits the minimum time per layer to 15 seconds and in case the limit is crossed, print speed is lowered. This prevents insufficient cooling and ugly prints. Printing one Marvin will not be any faster than before.

Linear Advance for advanced users

If you are using other slicer than out PrusaSlicer, or if you just want to tweak and play around with different values, you can manually change the settings in gcode script. 

However, if you do not understand the concept of gcodes yet, or never played with editing it, stop reading and leave it for later :)

The K values (the parameter affecting how much Linear Advance affects the print) we measured and tested are as follows: 

  1. PLA: M900 K30
  2. ABS: M900 K30
  3. PET: M900 K45
  4. For Multi-Material upgrade version 1 (NOT the latest one): M900 K200 for all materials 

These values are preset in our PrusaSlicer. The K value is set in the custom gcode section in the Filament Settings tab, NOT under the printer specific custom gcode.

Simplify3D, Cura, ... users just need to add “M900 K??” into the starting gcode script. Keep in mind you need to manually change that for different filament materials. Only PrusaSlicer has custom gcode for each filament preset and therefore the K value is changed automatically. Set the desired speed and print something (large enough for speed to show up). If sharp corners have blobs, increase K value. If you see missing filament, decrease the K value.

Please note that different brands and colors of the same material may require a slightly different K value when printing at extreme speeds, however, our presets should be fine with all of them. 


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