Im trying to cut holes in the surface using Solid difference and this wierd thing happend and i dont know why- looks like it randomly cut some of the holes and didnt get to all the surfaces.
i would like to know why it happend and second if there is a better solution to make holes on surfaces with curves.
it looks like you have forgoten to internalize data.
I think it will be easier if you produce one of the 8 triangles first and then mirror and array it.
Here is an example that only uses two lines as input.
(also, I don’t know if you want the holes in the diagonals)
in the definition I sent you, I assumed the center of the umbrella was at the beginning of the xy axes.
You obviously created the ‘triangle’ a little bit off, so you can either redefine it centered (simpler) or align the symmetry plane to its tip.
when you apply mirror to a geometry, it needs a plane to act as the symmetry plane.
by default, mirror component, uses the yz plane. (defined by the green and blue lines in your viewport)
Your geometry is a little to the left. if you center the original surfaces it will work perfectly