OffsetSrf Issues - missing faces

I no longer have the TSpline for this object. . .
So with this closed polysurf, when I do OffsetSurf by .5’ edges are jagged and not as smooth as the original.
I’ve tried converting to mesh to offsetmesh, but it’s producing same jagged edges.
I’ve tried to convert to mesh back to tspline, but my computer keeps crashing.
Any help with creating a smooth thickness would be very much appreciated.

many thanks,
RebeccaHelp Me Plz.3dm (1.8 MB)

Hi Rebecca- there are no surfaces or polysurfaces in this file, only a mesh. Are you offsetting out, or in? Looks like out.


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as @Pascal remarked, your object not a tspline object but a mesh made of single unwelded mesh faces, therefore it looks jagged when you try to offset it. I´ve welded it fully using _Weld 180 and then unwelded the sharp edges then _OffsetMesh worked but required a bit of cleanup.

Help_cg.3dm (2.0 MB)

…but it is still a mesh :slight_smile:


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Thank you so much!

I accidentally uploaded the mesh, instead of the polysurf.
I created the tspline first, then converted to rhino polysurf and forgot to make a copy of the tspline before saving.
(looking to do a .5’ inward offset ^^;:wink: Are there some tips on best ways to unweld edges? And, the cleanup work you mentioned, how did you do that? (ie. what methods, commands)

Again, a million thanks for your help and time.

Thank you Pascal for your speedy response.
I accidentally uploaded the mesh, instead of the polysurf. Here it is:

I am trying to offset inward .5’

I have a set form and in process of giving it wall thickness.
The other forms attached to it are all set but I forgot to keep the original tspline for this one and having trouble with it.


the object you´ve uploaded to dropbox is a polysurface but this won’t help much as it is just one converted from a mesh using _MeshToNurb. This command just creates more trouble as it does make the object less editable compared to the original tsplines object. Never use _MeshToNurb !

I´ve used the fixed mesh (the inner one) from my first reply and offsetted each mesh part inward by 0.5, however this created intersecting faces which had to be fixed using commands like _SplitMeshWithCurve, _CollapseMeshEdge, _DeleteMeshFaces, _Weld and _3DFace. Finally i´ve deleted and rebuild a few non manifold and intersecting mesh faces, to seperate the cutouts and create sharp edges i’ve used the command _ExtractConnectedMeshFaces.

To be honest, it quickly can get very time consuming to repair meshes in Rhino and finally obtain a watertight mesh which passes _Check. If you purpose is rendering, the result might be enough, but for 3D printing the mesh would need further cleanup.

Help_cg.3dm (2.5 MB)


really appreciate your help with this.
especially for the insight on the process.
This is more than enough for me to work off of.
thank you again.