Rail revolve question: Keep width constant

I’m not super familiar with this function.

I am trying to revolve this profile curve around an eliptical shape

I dont understand why the width of the part is not staying constant. I want an elliptical torus shape, I dont want the profile the deform during the revole.

Here are some of the things Ive tried:

  • revolve around a center line
  • revolve around a different center line
  • revolve around the outside rail
  • revolve around the inside rail

Could someone help here a little bit?
lamp.3dm (1.2 MB)

I don’t think this is a situation where I would use rail revolve.

I’d use Sweep1 instead. If the section does not remain constant, I’d use four sections and not just one but the result looks good with just one. The section outside of the rail avoids problems with self intersections near the foci of your ellipse.

If you take a look at the example shown in the help files, you’ll see the kind of shape which is created with rail revolve. I added an example to your file.

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

lamp.3dm (1.9 MB)

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Hello Martin,

Thanks for your help. I didn’t know the sweep function!

I guess RailRevolve always scales the shape of the profile curve relative to the distance from the rotation axis by design? It is a little hard to wrap my head around.

I’ve been working with Rhino for all sorts of things for over a decade and I have not bee using the rail revolve command more than a handful of times…