Sweep2 surface folds over its self in some places

Hi, ive noticed recently that sometimes when im using sweep2 the resulting surface zig zags a little bit over its self, typically where ive used the add slash feature. Does anyone know why this is happening and what i can do to fix it.

post a 3.dm file please, and maybe a screenshot of your sweep2 options used.

Sweep2.3dm (65.6 KB)

just for others that have a look at tommy 's file - the s-style-self-intersection happens here

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dear tommy
If you really need a single surface (building 3 surfaces would be simpler)

  • i think the main challenge is to have a corresponding / equal nurbs structure for both rail curves. As far as i understand nurbs, you’ re asking for a unequal distribution of knots along the upper curve regarding its length. This will somehow cause the wavy s-shape - try to build a _interPCrv through the 4 points - it will be super wavy and somehow show the un-intuitive behaviour of nurbs.
    notice that your surface is a ruled surface - you can also build it with _loft. (no cross / shape needed)

i would recommend the following workflow if you don’t want to dig to much into CV-Editing and don’t need a super clean result:
_extractIsoCurve (magenta - at positions where you want the crest / apex / peak of curvature)
build two
_loft surfaces
_blendsrf (G2) between the 2 lofts
_mergSrf (smooth yes - this is the big cheating i know)
_matchSrf (multiple, position, positon, closest point = yes, refine = yes, presever isocurve direction ) the Surface to your initial curves

Sweep2_tp.3dm (168.4 KB)

hope this helps - kind regards -tom