How do I set Fill Density in CuraEngine

[dougconran 1]

I'm using CuraEngine v3.1.0 on Ubuntu 18.04 to slice an stl file and using the ultimaker.def.json definitions file.  That file suggests that there is an infill setting called 'infill_sparse_density' with a default value of 20%.  When I first ran CuraEngine it generated a huge number of settings which I captured and then modified and used for subsequent slicing.  However, whatever 'infill_sparse_density' value I use the end result is always sliced with 50% infill.

 

How can I change the infill density?

 

Any suggestions would be gratefully received - thanks.

[tinkergnome 927]

A have not the slightest clue how the CuraEngine works, but...

a search for "infill_sparse_density" in CuraEngine results in zero hits. It's obviously not used at all.

It seems like "infill_line_distance" is a better bet... 🤷‍♂️

[dougconran 1]

Brilliant! That's it.  Thanks, also, for the pointer to the GitHub repository.

[ahoeben 1,986]

As a general rule, only settings that don't have children in fdmprinter.def.json are actually used by CuraEngine. All the other settings are used in formulas to feed into those "final"/leaf settings. For example the infill_line_distance gets calculated from the infill_sparse_density and the infill_pattern by Cura (from a python expression) and fed to CuraEngine

"value": "0 if infill_sparse_density == 0 else (infill_line_width * 100) / infill_sparse_density * (2 if infill_pattern == 'grid' else (3 if infill_pattern == 'triangles' or infill_pattern == 'trihexagon' or infill_pattern == 'cubic' or infill_pattern == 'cubicsubdiv' else (2 if infill_pattern == 'tetrahedral' or infill_pattern == 'quarter_cubic' else (1 if infill_pattern == 'cross' or infill_pattern == 'cross_3d' else 1))))",

 

 

[ahoeben 1,986]

And the unreadable mess above translates to:

  

if infill_sparse_density == 0
    return 0
else
    if infill_pattern == 'grid':
        factor = 2
    elif infill_pattern in ['triangles', 'trihexagon', 'cubic', 'cubicsubdiv']:
        factor = 3
    elif infill_pattern in ['tetrahedral', 'quarter_cubic']:
        factor = 2
    elif infill_pattern in ['cross', 'cross_3d']:
        factor = 1
    else:
        factor = 1

    return (infill_line_width * 100) / infill_sparse_density * factor