How to close a Loft Geometry? - Patch does not work properly

Dear Community,
I have a problem that I need your help with.

I have an inital geoemtery which is a connector between different beams.

I want to close the geometry with interpolated surfaces. When I use ‘Patch’, I was not able to close the geometry. I tried different properties for the command but whitout any success.

Maybe someone has an idea how to deal these geoemtries? Maybe with a Mesh, SubD or even in Grasshopper? My final goal is to 3d print the geometry, so it has to be closed.

Would love to read your thoughts and ideas! Thanks a lot !

220110_ExampleFile.3dm (400.6 KB)

The best way to get help is by posting a 3dm file with the relevant geometry.

Sure! Sorry I forgot to attach it.

The quickest way to create a closed polysurface is by untrimming the patch and the moving it inwards so you get a clean intersection with the other surfaces.

Another way would be to untrimm the patch and extend the surfaces.

220110_ExampleFile.3dm (757.1 KB)

If you want a more organic looking knot, a good way to start is with the SubD Multipipe command.

220110_ExampleFile_SubD.3dm (752.3 KB)

Thanks Martin for your fast answer! I tried this already but with this method I always had a change of the intial geoemtry. If I compare the area of the inital and the final cutted polysurface they are different.

Do you have an idea how to force the Patch to the boundary of the polysurface?

Thanks !

Multipipe is great but for this case not possible. I have to use the intial geometry, which I am not able to edit.

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You’ll have to increase the spans of the patch and lower the tolerance. Attached is a file with a closed polysurface.

220110_ExampleFile.3dm (1.2 MB)

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One way could be to make a SubD with this topology, crease the outer top edges, then adjust the open ends to meet your beams.


looks like a case for the plugin xNurbs

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ah yes this would be a good chance to test it.

one quick and dirty method without fiddling much could also be to create a mesh as dense as your tolerance may require, then fillmeshholes, might not be pretty though, then i certainly would prefer patch as Martin suggested.

xNurbs is a great way to close the polysurface!

i assume so, it unfortunately can not be installed on macs. i just wished Rhino would get a more powerful native patch, that would be a real gap filler.

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