Hi Supagoat, thanks for posting the problem file. One thing that you can try with boolean union if it goes wrong is to do the union on just 2 adjacent pieces at a time, which in this case does help out.

From what I've seen in the past, the geometry library that MoI uses can be sensitive to cases like this when the first 2 pieces that it tries to union together are the ones that don't touch each other. When you grab only 2 adjacent ones at a time, it then avoids that particular case.

The same thing can also occasionally be a problem with union between solids as well. For solids it tries to sort a batch of selected objects by initially starting with the largest object so that if you're doing a union of a lot of little things hanging off one one big block that will avoid trying to process the little non-intersecting pieces with each other first. But if you have a kind of chained sequence of objects like you have here that can benefit from "2 at a time" unioning instead.

Hopefully at some point in the future I'll be able to dig into it and try to improve these cases, it's a quite complex area to investigate though and so there is a lot of time involved with doing that.

By the way I've just figured out a fix for the "straight sections" loft problem that you reported previously in another thread, that one will be fixed for the next v3 beta.

Thanks,
- Michael