FBX/ OBJ import problem Geometry CAD mesh

https://www.opencascade.com/products/cad-assistant/ if you download cad assistant and import/export from there both files (fbx and obj) import fine in blender.

Wow, didn’t know that tool. Interesting technology.
So it basically resamples all polygons with more than 4 vertex into triangles. Is there way to limit that?
But more interesting is that it does do the normals right with OBJ.

At least an alternative. FBX however offers lot more than OBJ.

And I also got no vertex normals using USD… maybe Blender can’t handle that on meshes with more then 4 vertex, except FBX ?

Anyway, thanks for that tool !

CAD Assistant is very good in some cases.
I believe the stepper addon uses the same library i.e. open cascade.

Note that unfortunately there is no way to get instances into Blender via CAD Assistant. At least not that I know of, while the stepper addon imports them as linked geometry.

Unlike MOI3D it keeps the hierarchies intact, though, which is nice.

Edit: sometimes it is useful if a step import with Stepper fails. You open it in CAD Assistant, save it as Step file under a new name and try again with Stepper. If you are lucky Stepper will now be able to import the file.

The big questions in CAD import are always about triangulation or polygons and Instance vs one mesh.
You get instances with other software like Modo or C4D. Then you can bring it to Blender.
C4D only imports triangles and instances are hard to manage, as it has quite a random block as source and you can‘t unparent instances. Modo does a much better job, but the PowerTranslator plugin is quite instable and slow.
I prefer to have just a few meshes in the end and rather make proxies or keep some mesh as polygons to rework them.
Triangulated mesh is like dead meat in 3D.