Hi Martin, you mean that those surfaces are not meeting up?

How are you creating them, by something like a sweep? If you're doing a sweep make sure that you're not doing something like only selecting a single profile just on one side of the sweep - if you want a sweep to match up in between 2 different shapes then you need to select both of those shapes as profiles for the sweep so the sweep has not just a start profile but an end profile as well.

When you have both a start and an end profile for the sweep, the sweep will gradually morph between the 2 shapes through the traversal of the sweep.

If you give it only a single profile on one side, then the other end of the sweep is generated purely by movement of that one starting profile along the sweep rails, and that may result in some other kind of shape at the end of the sweep.

If you're still having a problem with it or the above explanation does not make any sense to you maybe you could post an example single surface that's not working like you expected so that I can look at it and give you some advice.

- Michael