Problem with railsweeps along a curve

Hi Everyone,

I am trying to do a rail sweep along a curve. The shape transitions from square with slightly rounded corners to square but when i use closed sweep it shows wobbles in the corners and issues on the sides.

Here are some screen shots showing what is happening.

I am new to Rhino so any help gratefully recieved,



You will probably have to attach the 3dm file so that people can take a look.
Up front, though, it looks like those surfaces are way way way overdefined. My guess just from looking at this is that it will be hard to get anything clean out of this…

Thanks for the reply, could you elaborate on way way way overdefined? This is the first time i have started using surfaces.

Any advice on achieving these rail sweeps would be much appreciated.

Can you post the file?
The overdefined comment refers to all the isocurves that are drawn on the surfaces in the images.

Thanks again Wim, really appreciate the input, as i said it’s the first time i have worked with surfaces so used the curve network tool to get these surfaces. Maybe this was the wrong tool to use? I am unable to post the file as it is a design that i have to protect but i could make up a file showing just this problem area if that might help at all.

The other surfaces seem ok after i render them, just this particular area i am struggling with.

Square to round Transition…3dm (64.8 KB)

Here is the file for the area that I am struggling with, i managed to put a surface on to the 10 sections starting at the round end by 2 rail sweep tool but after that point is where it seems to go wrong.

Hello simonms,

Is this conceptually what you’re looking for?

Hi OSTexo,

Yes, that’s right but along my specific dims. Essentially a square to round transition along a curve.

Hi simonms,

I took your file and deleted the stuff you don’t need for the sweep2. I also joined some curves together.

Is this what you’re after?

Square to round Transition.3dm (222.3 KB)

1 Like

Since you have the center points, why not use it to make a curve using InterpCrv?
And then use the curve to do Sweep1 the first joined square and end circle.
Square to round Transition_sweep1.3dm (142.4 KB)

Forgot to thanks everyone for there help, all done so thanks!