Cura uses lines instead of concentric infill I'm printing a ring that's a replacement for the non-slip base of a mixing bowl. The ring is about 130mm in diameter, with a rectangular cross section, like this: ![rubber ring]( I'm using Cura as the slicer, and I've set the infill to 100% and `concentric`, but after slicing it looks like Cura used `lines` instead; the ring is filled with parallel straight lines: ![lines infill]( Is this a problem with Cura? Is there something I can do to encourage it to use concentric infill? I don't really care what the infill pattern is, but I think `concentric` would print a lot faster since the head wouldn't have to switch directions all the time.

This is a known issue. Cura's profile variable logic sets the number of bottom layers to 999999 if infill is set to 100%, overriding infill by replacing it with additional bottom layers. If you go find the setting for number of bottom layers and set it back to the number you actually want, overriding this, infill should work as expected.

Alternatively, setting top/bottom pattern to concentric should also fix it, and you probably want that anyway so that you don't have distinct bottom layers that are printed as lines.