You're welcome Marc!

Re: union issue - one thing you can do if union is getting confused at the overlapping pieces is to delete the side pieces for your segment so that your segment is just a surface (or possibly a set of joined surfaces) instead of a solid.

Then replicate your segment, and you will have a set of surfaces that touch each other precisely edge-to-edge.

In that kind of situation you can then use Edit/Join to glue the surface pieces together into a solid.

Join can be more reliable in situations like that because it does not try to find any intersections between the pieces, it only tries to glue edges together and not remove material or create new edges by surface/surface intersection.

Trying to get clean intersections between pieces that overlap tends to be a difficult area of calculation.

You do need to have the pieces have a pretty precise alignment with one another for the join method to work though.

- Michael