I cannot get this Sweep1 to act correctly

I’m attempting a Sweep1 to create a subtle curved surface with an elliptical border, but my sweep result has this weird anomaly at the center. I think it may have something to do with my input curves.

Rhino_Forum_01.3dm (130.0 KB)


yes, it is about the way your curves are swept around the external axis. _-revolve would be the command you’re looking for.

If you insist using sweep, you need to make another (very tiny) rail curve in the center and use sweep2, however, revolve will work way better and will respect the curvature contrairy to the sweep solution.

or another way would be to split the ellipse /circle with the cross sections and build 4 separate surfaces with _EdgeSurface

I don’t think I can really do a revolve because of the shape of the curves.

I saw indeed too late it was not a circle, sorry about thatt. try the last option then.

It’s like I need a revolve sweep command

You can move the four control points at the center a tiny bit away in each direction and create a circle through these four section start points. Then create a Sweep2 and add a planar surface in the tiny circle…

Or use RailRevolve with just one of the sections as profile :slight_smile:

Rhino_Forum_01.3dm (158.3 KB)

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Rhinoceros Help - RailRevolve | Rhino 3-D modeling (mcneel.com)

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