Offsetting a closed curve thats set at an angle?

Hey guys, i’m pretty new to Rhino and i’m still learning so sorry if this is easily resolved or impossible! (it feels it)

I am wanting to offset a curve inwards but because the curve is set at an angle the offset is not in the middle of the initial curve, it is both above and below it.
I hope the images illustrate this abit better…

The third image is how i want the offset to be, but in line with the intital curve if that makes sense,

Also i would ideally like to make this shape by just turning the curve lines into solids so they would print like thick lines if that made sense, to create and open structure, but have no idea how i would go about that either.
Thanks in advance for any help!

I don’t seee an image, but I surmise what’s happening is that you have a non-planar curve in 3D.

Offset is basically a 2D operation, and it is relative to the active view’s CPlane. Planar curves, even if they are not parallel to one of the principal planes will normally offset in their own plane correctly - there is a command line option to use the curve plane and not the view CPlane.

However, a curve in space that is not planar will have to use the view CPlane for the offset, as the curve itself does not have a definite plane. This may produce a result that is “unexpected”… If the curve has kinks, there may even be separate parts to the offset.

Edit, having seen your images now, I think my theory is correct. 4 lines in space are not necessarily coplanar.


You might want to try Pipe and pipe all the curves, the joints will always be problematic, I often put a small sphere at the joint points, slightly bigger in diameter than the pipes…

Not sure this is exactly what you are after, but what I often do in cases like this is use EdgeSrf to get a surface strung between the curves, then use offsetCrvOnSrf, finally trim the results.

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Nice procedure Sam, I’ll try to remember that… --Mitch