STEP export problems (bad surfaces after re-import)

Rhino Rhino for Windows
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1

I export a closed polysurface from Rhino 8 to step file. No bad surfaces detected. Perfectly solid. No naked edges. I imported that step file to Rhino again to check if everything is okay. I used the same accuracy settings as before. STEP imported as a block object with errors. I exploded the block and fixed a few disjointed surfaces (I trimmed them again). All looks fine again. No naked edges. No errors. I export that to a new STEP file. I import that new STEP file to Rhino and that situation repeat again :slight_smile: New surfaces are exploded as bad and I have to fix them again (those I fixed are ok but different ones are marked as bad ones). It looks like it won’t ever stop and I`m in some wired loop :slight_smile:

Questions:

  • Why this happen?
  • How to prevent it?
  • What is a real situation it looks like some software error.
2

On those imported STEPs which were exported and imported in the same Rhino 8 I have also invisible surfaces which have only visible edges :slight_smile:

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image654×1047 72.5 KB

So I see holes in objects which are described as a closed polysurface and have no naked edges :slight_smile:

Transparent surfaces are not pointed as bad.

I have also bas surfaces on the same model after a reimport.

The model is symmetric and the same surfaces on one side are interpreted as good and the mirrored side surfaces are interpreted as bad after reimport (4 surfaces from 3000)

What`s the hell !!

I can`t show it here (NDA). This is a symmetrical closed polysurface with 3000 surfaces.

3

Maybe you can create a partial model? Like a solid intersection of a box and the surfaces that appear to be problematic.

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