When I sweep a circle with one closed polyline x-section, it seems like sometimes the resulting closed polysurface is broken into 4 segments with seams at the quads as depicted in the picture attached.
When I sweep two rails, the result is a single surface. I can’t explain why there is this difference in the outcomes. Can someone explain this to me. I’m uploading a sample file too.
Surfacing Question.3dm (281.2 KB)
Hello - I don’t know why Sweep2 does not keep the rail structure in this case - you can get a single surface from Sweep1 by setting ‘refit rail’ in the dialog. That said, if the path is a circle, a Revolve may do just as well.
-Pascal
Thanks Pascal. In most cases it is more desirable for me to end up with a single surface so “Refit Rail” is what I was looking for. Interestingly, before I understood curve degrees, I used the second rail trick to get nicely uniform surfaces on a degree 2 curve. Maybe don’t change that! 
I always use “Revolve” for anything that needs an exact radius shape, because both “Sweep 1 rail” and “Sweep 2 rails” produce some unwanted deviation and can’t preserve the intended constant radius.
… it would be great to have the simple-Sweep option back, as discussed at several threads/ topics in this forum - and it would be great to have an analytic feedback if it fails…- just search “simple sweep” and you will get many topics…
and others…
thanks for some improvements regarding those very basic surfacing commands.
kind regards - tom
