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Cura Fix Horrible Setting

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I've used and needed to use all 4 fix horrible options and sometimes 2 of them at once but they don't seem to do what the hover (title) text seems to say they do.

There are 16 possible combinations of checking those boxes and I've not tried all 16 yet I don't think but I've played with them a lot. Sometimes they just never do what I want no matter what I try. Usually they are very helpful. I suspect some of the 16 combinations are identical to others -- for example checking A and B at the same time may be no different from checking A only or B only but I can't find a pattern.

I would love to understand better what they do. Only daid knows.


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STL file format not only contains triangles of the surface of the part but also the "normal" which tells you which side of the triangle faces "out". Depending on at least one of those checkboxes I think steamEngine can ignore these normals. For example in sketchup you want outward faces to be white and inward to be gray and you can swap these as an option if you right click a face. Cura should be able to make it so it doesn't matter in sketchup.

If you have intersecting solids in your cad and it results in "internal" walls, cura has to be told if it should fill the "hole" or leave it empty. This is also controlled by the checkboxes.


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"Combine everything Type-B" overrides the Type-A, so checking both won't do any different then checking only Type-B.

All 4 options actually work on the 2D slices not on the 3D model. Only Combine everything Type-A does something with normals, all other code ignores normals.

In detail, CombineEverything tries to do a CSG boolean union with everything. In can do this in 2 different ways, with or without normals. If it ignores normals it will remove any internal holes you see on a layer. So a cube with a straight hole downwards in it becomes a cube. While a cube with a hole from side to side will remain the same.

"Keep open faces" happens in a step before that. What Cura does at first, is taking a knife and slicing your model into tiny slices. Each slice is a layer as you might understand. But, 3D models are never perfect, so what I end up with is a lot of small line segments in a 2D plane. The next thing I do is joining up small gaps between the line segments, and any line segment that makes a full circle is stored for later reference. Any line segment that fails to make a full circle is normally discarded. UNLESS you have this option checked, then it makes a line from one end to the other to close up the line.

Simple example would be to take a cube, remove 1 side from the cube, save it, load it in Cura. It won't generate any GCode because no slice is closed, unless you check the "keep open faces" then it will effectively fake in the removed surface again.

Results may vary, and it usually works best in combination with "Type-B combine everything".

"Extensive stitching" is something related to open surfaces, but not exactly. Imagine you have this cube where you removed the side, and then you move this open cube with the opened up side against a larger cube. From the outside this will look "solid" but in reality you have a big gaping hole and an internal surface that will cause issues. Extensive stitching fixes this, it tries to find the partial internal surfaces, and the open parts and tries to stitch them together so they form a solid outside.

(I know some pictures would really help here)


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This is great, thanks. If you *do* create drawings they should all be 2D to show the thinking and "view" of a slice and you should *not* show 3d pictures since these options only affect a slice. But I read your post twice and I think it's reasonably clear and not sure pictures would help unless you showed all kinds of examples like what you do do if two lines cross in an "X" or if two lines are on top of each other and identical, or if there are 2 possible loops to choose from and so on.

Do you ever do things like combine line segments shorter than say .05mm into one longer line?


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