You can use the Rhino Convert command for this process, commonly called “Arc Fitting”. Approximating splines by a series of tangent (or nearly tangent) arcs is generally preferable to just polylines, because they allow a more accurate cut with a smaller file and less possibility of slowdowns along the curves, especially with older machines. Control the approximation tolerance by using the correct settings during the conversion process. By convert, we mean that the spline curve is approximated by a polyline or polycurve containing only arc and line segments. So, to cut parts sucessfully, it is necessary to convert any free-form NURBS curves ( splines) in your file into a series of arcs and lines. A great many industrial cutting machines and software only understand lines and arcs.
