Sweep 1 Issue - Overlapping Surfaces


I am having an issue with sweep 1 command on rhino.

It gives me this overlapping surface:

It’s probably because of the large number of control points, so I rebuilt the curve and the resulting sweep is perfect, but I prefer not to rebuild this curve (as other things in my model depend on the same curve…)

Any other options?

Thank you

sweep 1 issue.3dm (756.7 KB)

Dear @shhifa
(please next time you post a file with a problem, mark the position in question with a _dot)

your rail curve is a complex polycurve
will show that the curves only have G0 (position continuety) at the position where the waves / overlapping occurs.
you should make sure that the curves have (or the polycurve internally) at least G1 (tangent) better G2.
you can also add additional shape/cross curves exactly at this position or do separat sweeps for each section.
kinks (G0) at the rail might work well for planar curves - in 3d it is not 100% predictable even if Rhino try s its best.

kind regards



Hi -

I’m not seeing that here with your curves:
(your surface in black, mine in blue)

Please run the Rhino SystemInfo command and copy-paste the result here.

dear @wim … there is multiple curves in the file.
the problem is not the system, it s the rail curve as described above.
i managed to reproduce the wavy, overlapping result:

attached file only has the bad curves that will produce the waves in my case.
wavy-sweep1.3dm (81.0 KB)

I apologize…I should have organized the file better

okay… had no idea about this concept of position continuity… thanks so much!

@shhifa - see


1 Like

thank you!!!