Object won't split?

Im a high school student who is in his second year using rhino, so I am relatively new to the software. Attached is a model I want to be able to split into segments, however the split tool will not work. The explanation of: “split failed objects may not intersect or intersections may not split object” appears every time I attempt to.Need Help Splitting.3dm (8.8 MB)

Hi Peppermonty - can you please post the curves used to generate this…? I am certain there is a better way to make it. What you have is a polysurface made up of hundreds and hundreds of skinny little strips, some of which are near or even below the file tolerance in width.


Hi @pascal,

To make this model I generated a number of curves from a shoe-last shaped mesh (using the project curves tool) . This resulted in something which looked like a contour drawing. I then used the loft tool and selected approximately 15 random curves from the ‘contour model’ to loft from. After several attempts I resulted ended up with a form I was happy with.

Are the skinny strips of width below the file tolerance what is preventing the model from being split?

CheersLast and Contour line models.3dm (2.6 MB)

Yes, that is almost certainly the case… How does the attached look to you? Is that more or less what you are after?

Last and Contour line models_PG.3dm (1.8 MB)


Hi Pascal,

Yes that is perfect thank you very much :slight_smile:
Just for future reference can the width of those strips below the file tolerance be extended above the file tolerance just by increasing the scale of the model?



Well, yes, but just to pound the point in, the result that I sent back to you is one surface and what you made was hundreds of surfaces, not to mention going all over the place- I would try to get a hold on why that is and understand what is going on when you loft an arbitrary set of curves.

  • Sectioning or Contouring a mesh results in a polyline, not a smooth curve.
  • Lofting curves with hard corners in them, like polylines, makes a polysurface by default - multiple surfaces.
  • Non-matching curves (all the polylines have different point count in this example) will make matters worse as has to increase the complexity of the surface it makes to accommodate the different curves. You need to do something special, in the case the Rebuild option in Loft to get around that. Curves rebuilt together at the same settings will be compatible for Loft and other commands that use the curve structure to generate the surface structure directly.
  • Take a look at http://www.rhino3d.com/download/rhino/5.0/Rhino5Level1Training/ & http://www.rhino3d.com/download/rhino/5.0/Rhino5Level2Training/