Hi Gaaldornik
>>> Still don't get it why rebuilded curves and solids extruded from them causing these problems.

As "Phiro" mentioned your "G. Grid A" curves are too dense in control points.
Also, you have some tangled points here, that I think, should be the problem. (See attached)
I've unraveled some control points to show it better.
Redraw your curves with fewer points and check again.

Hi gaaldornik, it's the self-intersection areas that MO illustrates above that are the problem. Spots like that where a curve (or surface constructed from such a curve) kind of backtracks and squiggles over top of itself will make surface intersection and volume analysis algorithms not work correctly.

Data in PDF can often have this kind of messy geometry that needs to be rebuilt before being used for 3D construction. When the curves are only being used for 2D imaging it's not as sensitive to the messy areas as 3D solids boolean calculations are.

- Michael

Thanks a lot for all your answers! Appreciate it)
I'll keep that info in mind.

One more question about rebuilding curves - Is it better to always rebuild them to get 'cleaner' geo without extra edges
or it's not necessary?

Hi gaaldornik,

re:
> One more question about rebuilding curves - Is it better to always rebuild them to get 'cleaner' geo
> without extra edges or it's not necessary?

It kind of depends on the particular situation. If you are getting a tremendous number of extra edges it could be that the curves are actually a whole lot of little line segments instead of smooth curves and you would want to rebuild that.

But if it has separate segments in logical areas like where the shape should be a single line, it can be good to keep those separate.

- Michael