Hi alexito, one other note:

> I Tried to select all and join all parts and olso booleen fonction "Union"

Boolean union betweeen all curves is meant to work only on curves that are all in the same plane.

For example it can take curves like this:



And then produce this result:



So that's why it did not do anything in your case here, you don't have curves all on the same plane there.

- Michael