working with unions. Unioned part with holes in the sides falls through object supporting it?

I made a Union from a ball and 2 negative block parts at an angle so that only a certain angled amount of the beginning sphere remained, it looked like a section from a pie chart at this point, then grabbed another smaller sphere negated it, and unioned it to the part, making the shape sort of like a hammock, then i got a cylinder part and extended it to each side of the unioned part, negated it, and made 2 holes of equal size on each side. After, i took a smaller cylinder and extended it so that it was through the openings on each side. The smaller cylinder is anchored, the union part is CanCollide true and non-anchored. The problem is that when i load the game, the union falls through the cylinder that is supposed to be holding it up, and lands on the ground. How can i make it so that the unioned part stays and is free to spin on the cylinder, sort of like a hammock or swing? as far as i know there is no website called buildinghelpers so im putting some faith in this site that there are other builders here as well.