Marlin K-factor script: what is "Nozzle Line Ratio"  

RE: Marlin K-factor script: what is "Nozzle Line Ratio"

Posted by: @gauthier

[...] The description of "Nozzle Line Ratio" for the Marlin script says: "Ratio between extruded line width and nozzle diameter. Should be between 1.05 and 1.2"

The ratio is a multiplier applied to the nozzle size to derive a suitable extrusion width. I think they've done it this way to simplify working with different nozzle sizes. The default of 1.2 works well IME.

[...] Another related question: Extrusion width has several values in PrusaSlicer. I went for the one in Default. It's the same everywhere but in "First Layer" and in "Top solid infill". Correct?

A good general guideline is to use extrusion widths between 100 and 120% of your nozzle size. I usually leave them set to 0 in PrusaSlicer, which will use values derived from the nozzle size. This lets me use one Print Settings preset with any nozzle size.

You can definitely experiment with these, and if you stick to quality nozzles (E3D, P3-D, TriangleLab), you can go up to roughly 200% of nozzle size and still get good quality, provided you don't mind the more rounded corners it produces. If I'm printing something that consists primarily of perimeters, I'll often crank up the perimeter and external perimeter widths higher. I've even gone with wide 200% single perimeter prints giving "pseudo vase mode" speeds but still very strong walls. If I'm doing a large print with lots of infill and I'm only using infill to support top surfaces, I'll specify a narrower width for infill.