Closed sweep2 has a crease

Hi All,

I’m trying to model a shoe last in Rhino, for which I follow this example in which a 2 rails sweep is used to create the last surface:

As can be seen on page 18, this gives a nice and smooth surface:

However, if I try to replicate those results, my surface appears to have a ‘crease’ at the front of the shoe last:

I tried many things but none of them seem to work. After hours of searching I decided to ask the experts. So does anyone know what causes this crease and how I get rid of it?

I’m planning on replicating those results in Grasshopper, however since both give the same result I figured it was best to fix the Rhino model first.

Thanks a lot for your help, I really appreciate it.

shoe_last_from_curves.3dm (1.3 MB)

I believe the difference in your model from the page in the tutorial is that you have different shaped curves and the surface traveling through them gets twisted on itself due to too little information in the middle. I’d suggest using the Csec command to make a closed profile that travels through the four existing cross sections. Follow that with NetworkSrf and you’ll get what I think you’re after. You can also record history with NetworkSrf and then tweak the curves to fine tune the result.

Thanks a lot! That is exactly what I’m after. Any thoughts on how to implement this into Grasshopper?

Sure, it would require two crv components each assigned multiple curves and then a network surface component like this…

Really nice to see how simple a solution can sometimes be. This is absolutely perfect, thanks a lot!