Thank you for the explanation, Pascal!
I used that setting for a very refined result and it worked on any model (even complex polysurfaces made of hundreds of joined surfaces) except this simple pipe.
Can you tell me which of the parameters in the Polygon mesh detailed options will override the others? It seems like Rhino regularly ignores some of them. For example, recently I had one occasion where I was unable to force Rhino create an analysis mesh of a 3 mm diameter circle (not flat; part of a trimmed double-curvature Sweep 2 rail surface) with more than 8 sides, even though I set “Maximum edge length” at 0,1 mm and “Minimum initial grid quads” to 10 000.
Also, I find it strange that Rhino will always render spheres with way too many polygons, despite using the “Jagged and faster” render mesh quality setting. For example, a sphere with 2 mm diameter uses a whooping 18752 triangle polygons. It’s a bit unnecessary to use that much geometry for such a tiny object. Considering the size, number of polygons should be no more than 600-800. It would be nice to set more strict maximum amount of polygons when using the default rough mesh setting. Here are some interesting results when using the “Polygon count” tool:
0,1 mm sphere = 528 triangle polygons
1 mm sphere = 3968 triangle polygons
2 mm sphere = 18752 triangle polygons
3 mm sphere = 18752 triangle polygons
5 mm sphere = 18752 triangle polygons
10 mm sphere = 18752 triangle polygons
20 mm sphere = 18752 triangle polygons
50 mm sphere = 18080 triangle polygons (fewer polygons than the 2 mm sphere, despite the bigger size)
100 mm sphere = 14136 triangle polygons (more than 4500 fewer polygons compared to the 2 mm sphere!)
1000 mm sphere = 18752 triangle polygons