Split mesh with curve; appears to work but mesh is still one piece?

When using the split mesh with curve command I get new polygon edges added to my mesh along the curve used for splitting, this is what you would expect , but the mesh is still one piece. How can I get this command to work?

SplitMeshWithCurve first pulls the curve onto the mesh, then splits the mesh. If the pulled curve does is not continuous between edges of the mesh then the mesh will not be fully split. Instead the mesh will be partially cut. Try using Pull to separately pull the curve onto the mesh and check that the pulled curve is continuous from edge to edge. Is that what is happening with your curve and mesh?

Also, depending on your intent you might want to first Project the curve onto the mesh and then split the mesh. Project and Pull give different results.

@Pascal Is it intent or a bug for SplitMeshWithCurve to sometimes only partially cut the mesh rather than split it? If intent perhaps a note about it should be included in the documentation.

Hi David - All of the mesh splitting and trimming tools are quite limited. It is not uncommon for a mesh split to look like it has done nothing, but if you look closely, the polys are split and then rejoined, sometimes in a peculiar order. In short, it is not Rhino’s long suit at the moment…