Fit cylindrical NURBS to trimesh

Rhino
1

I optimized a quasi-cylindrical triangular mesh with deformations in separatae software and need to post-process my geometry into a smooth B-Spline or NURBS so that I can export as STP or other parametric/CAD equivalent.

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I know I’ve used Rhino to do this “fit’ sometime back in 2018 but I can’t seem to find the right option. If I recall correctly, the option involved me selecting a “cylindrical” base or something to fit a spline accordingly. The rendered cylinder preserved the dimples and “extended’” over the missing mesh points since my geometry isn’t a perfect cylinder (helical cut at top, jagged bottom). The end result was a smooth surface that I could export as STP and use as a split tool in Inventor/Solidworks.

mesh.stl (1.2 MB)

2

I played with this. The bottom sawtooth should be pathed up a bit.

I use path single face on the mesh to get this edge:

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Then the Quadremesh command can be used fto convert it to a subd:

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Then run ToNURBs to get it to a IGes surface that might work.