Unable to offset Spiral curve

Hi I have drawn a flat spiral with an radius of 1000mm, I select a new layer to offset the spiral curve, the offset completes however only about half of the curve offsets. Unsure why?

Any pointers are appreciated, file below.


Coiled Strip.3dm (1.7 MB)

Yeah, I see that. Your original spiral curve has 33,000 control points, maybe Rhino just can’t deal with that many… Seems to be even worse in the current WIP. @pascal - one for the pile?

I guess the easiest way to get a result in this case would be to make a new spiral with +0.6 on both the inside and outside radii and the same number of turns (926).

Try Clipper.

Does Clipper work on NURBS curves higher than degree 1? I thought it only worked on polyline-type curves…

Yes it’s for polylines but the clipper offset could be converted into an interpolated curve again. Depending on the requirements this might be an option?

Bit pedantic, but I think that’s 925.

Also FWIW, in terms of dealing with large numbers of control points, Rebuild maxes out at 5000 new points.


Split into several curves. Offset the separate curves. Join the results into a polycurve.

Continuing with curves with a very large number of control points is likely to continue to expose limitations of Rhino.

PS: was able to look at the file now and clipper definitely does not make sense. Instead of offsetting the spiral, you could create a second spiral with offset start and end points.

What are you going to do with this curve?

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