Offset curve; offset is not equal


i made a curve. from this curve Iwant to create an offset off 65mm.
When I checked the offset with __analyze curve deviation__I found out the offset isn’t 65mm at all! (detected by my client:tired_face:)

when I exploded the curve and make the off set, then it works well.offset curve.3dm (45.2 KB)

why is this happening and what to do against it, as this is quit dangerous.

looking forward for your reply,

Hi Baasab
I suspected your model curve was not planar, so I projected it onto the CPlane, then offset it at 65 mm and it came out nice and even.

Hi Costel,

I did the same, doesn’t work.

when I explode it it does work

so there must be something else wrong

Hi Baasab - running FitCrv on the curve before offsetting should help (keep a copy so you have the original simple curve. - I think the problem lies in the very long sparse span there in the middle - I’ll check with the developer- thanks for the example.

Hi @pascal, why not _SimplifyCrv ? This seems to fix the ugly arcs and offset behaves.


Oh, yes, simplifying may work fine as well and keep things cleaner.



You are right. In fact I should come clean about it and it may be turn out to be Rhino bug after all.

In fact I projected the curve onto an arbitrary CornerToCorner plane. But then, since that plane was to going to be built in CPlane, I figured what difference was going to make if I’d say I did it in the CPlane or an arbitrary plane( built in CPlane).

So projecting on CPlane does not work, but project it on a random plane works.