Hi Micha,

> (6) mesh #4
> The Rhino mesher create big kinks at this cylindrical surfaces.
> It is an old test object, but if I remember me right, it was
> from a project STEP file.

No big kinks in MoI, right? So that is good! :)

Is your concern about getting only quads on this? If you do you'll probably need to simplify the edge structure of the shape, if you select the edges you can see that the boundary of those cylinder parts is split up into some additional edge segments rather than it having only a simple edge structure.

I've attached a tuned up version which will now generate all quads.

I did the tuneup by selecting the object, running "ShrinkTrimmedSrf" on it (which you have to set up with a keyboard shortcut to use in MoI, there is not currently a button for it), then Edit/Separate, then Select all edges, then Delete to untrim, then joined again.

The same comment applies as from that previous example - if the shape is set up to be overly complex like in this case with trim curves split up into more pieces than necessary, then that can often have some kind of impact on meshing as well.

If you have clean and simple geometry and topology it will help to generate clean and simple mesh results as well.

Complex geometry and topology will tend to make the mesh somewhat more complex as well.

- Michael