Adaptive Linear Advance

This is not another of those test models meant to help you calibrate the Linear Advance for your specific hardware. Rather, it is a bit of simplified G-code which takes standard 0.4mm-nozzle K-factor values and adapts them based on your actual nozzle size and extruder type.

Explanation

The provided code is meant to go in the custom G-code of your filament profiles. Rather than specifying several K-factor values in a long series of conditions as in the G-code of Josef Průša's filament profiles, you specify just one standard K-factor and an appropriate value is calculated for your nozzle size and extruder type. This is because I've found that suitable K-factors can be calculated based on the following formulas:

k_factor = standard_k_factor / (nozzle_diameter / 0.4)

bowden_k_factor = direct_k_factor * 4

You'll still need to determine the appropriate K-factor value for each material type, which you may base on Mr Průša's recommendations for a 0.4mm nozzle or on the results of your own experiments.

Instructions

My suggested Start G-code for the filament profile of a typical PLA filament, as used in the attached project, is as follows:

; Filament gcode
M900 K{0.05/(nozzle_diameter[current_extruder]/0.4)*(printer_notes=~/.*PRINTER_(MODEL_MINI|HAS_BOWDEN).*/?4:1)} ; Linear Advance v1.5

In the example above, 0.05 is the standard K-factor for PLA, the value used for direct extrusion through a 0.4mm nozzle. For printing with other materials, this is the only value that you need to change.