[4.1] Slicing with 100% infill

[rgov]

I'm trying to use CuraEngine to generate an efficient path that fills in a 2D polygon, like a pen plotter shading in a shape, or a Roomba trying to vacuum an entire room.

To start with I am attempting to slice a 3D file with 100% infill and no supports or plate adhesion. I'm testing with the Utah teapot.

When I set the settings as desired in Cura and enter Preview mode, I can take slices and it does look like it is solid:

Here is my JSON file configuring these settings:

{
  "version": 2,
  "name": "Generic Printer",
  "inherits": "fdmprinter",
  "overrides": {
    "adhesion_type": {
      "default_value": "none"
    },
    "machine_start_gcode": {
      "default_value": ""
    },
    "machine_end_gcode": {
      "default_value": ""
    },
    "infill_pattern": {
      "default_value": "lines"
    },
    "infill_sparse_density": {
      "default_value": 100
    },
    "support_enable": {
      "default_value": false
    }
  }
}

I run CuraEngine with CuraEngine slice -j "printer.def.json" -l ~/Downloads/Utah_teapot_\(solid\).stl > /tmp/out.gcode and then view the GCode file with this online viewer.

At the widest layer of the teapot, the GCode viewer suggests that the printer would only make 5 stripes to fill it in:

Am I failing to set this up correctly?

Here is my Gcode file.

[rgov]

Other questions:

• What setting dictates the spacing of the infill lines? I would guess it's related to the thickness of the filament. I.e., in the pen plotter scenario, I want the fill lines spaced by the width of the pen; in the Roomba scenario, I would want the lines spaced with diameter of a Roomba.

• Can I disable the inner/outer walls and only generate a fill that goes right up to the boundary of the shape?

• How do I use the SVG debug functionality to view the paths without using a GCode visualizer?

[rgov]

When I export GCode from Cura itself, the resulting file is 1.8 MB, and the online viewer shows a much denser fill. But also, if I reduce my infill percentage to 50%, the file gets smaller, so my infill setting is having an effect.

[rgov]

A solution seems to be:

    "bottom_layers": { "default_value": 999999 },
    "top_layers": { "default_value": 0 },

These are conditionally set in fdmprinter.def.json when infill_sparse_density == 100, but this doesn't seem to get evaluated.

[rgov]

I'm satisfied with how this turned out now.

[Ghostkeeper]

Am I failing to set this up correctly?

CuraEngine actually only reads the leaf-settings, not the parent settings such as infill_sparse_density. CuraEngine only reads infill_line_distance. Cura's front-end sets the line distance such that the desired density is achieved, given the infill line width and pattern.

What setting dictates the spacing of the infill lines?

infill_line_distance.

Can I disable the inner/outer walls and only generate a fill that goes right up to the boundary of the shape?

Yes, set wall_line_count to 0.

How do I use the SVG debug functionality to view the paths without using a GCode visualizer?

The SVG debug functionality is meant for programmers who are able to compile CuraEngine. If you can compile CuraEngine, you can output the Polygons instance to a file by calling:

SVG svgfile("file.svg", aabb);
svgfile.writePolygons(polys);

When I export GCode from Cura itself, the resulting file is 1.8 MB, and the online viewer shows a much denser fill. But also, if I reduce my infill percentage to 50%, the file gets smaller, so my infill setting is having an effect.

Yeah, that's because the front-end will adjust the Infill Line Distance setting automatically for you.

A solution seems to be:

Typically, setting the skin thickness to be infinite results in a better print quality than actually increasing the infill density.

These are conditionally set in fdmprinter.def.json when infill_sparse_density == 100, but this doesn't seem to get evaluated.

Only the front-end can evaluate these expressions. They are Python expressions after all.