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NURBS [message #1143] Sun, 31 August 2008 22:45 UTC Go to next message
avatar jefffhaynes  is currently offline jefffhaynes
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I've been spending some time in 3ds max trying to get some nurbs models to result in water-tight meshes with no luck. No matter what I do, I can't really close the nurbs to the point where I've eliminated all holes. So, my question is two-fold. 1.) Does anyone know any tricks for pulling this off? The "cap" surface doesn't seem to work since I can't "join" the surfaces, which leaves holes. 2.) If not, I noticed that shapeways now supports nurbs (no export to mesh). If so, what file format should I be using for that? All the formats I've tried don't support nurbs and simply convert to mesh. Thanks for any info or leads!

- Jeff
Re: NURBS [message #1149 is a reply to message #1143 ] Mon, 01 September 2008 07:39 UTC Go to previous messageGo to next message
avatar kreator  is currently offline kreator
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I'm not sure I can answer but I would like to see your problem, can you post a picture ?
Re: NURBS [message #1156 is a reply to message #1149 ] Mon, 01 September 2008 21:33 UTC Go to previous messageGo to next message
avatar jefffhaynes  is currently offline jefffhaynes
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Sure, here's the wireframe to give you an idea of the overall object (which is an arch ceiling). You can see the nurbs is closed at two ends and open at the other two, making a sort of loop of tape. Next I'll post with surfaces drawn.

  • Attachment: nurbs1.PNG
    (Size: 30.14KB, Downloaded 228 time(s))

Re: NURBS [message #1157 is a reply to message #1156 ] Mon, 01 September 2008 21:35 UTC Go to previous messageGo to next message
avatar jefffhaynes  is currently offline jefffhaynes
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In this second picture you can see that the ends are capped. However, this leaves holes between the surfaces (which you can easily see here). Since the cap is a cutout surface, it cannot be joined to the existing surface. As a side note, I've since abandoned these and recreated them with meshes.

  • Attachment: nurbs2.PNG
    (Size: 31.77KB, Downloaded 218 time(s))

Re: NURBS [message #1168 is a reply to message #1157 ] Tue, 02 September 2008 04:03 UTC Go to previous messageGo to next message
avatar Neffy  is currently offline Neffy
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Not sure on your process, but once you have the mesh try converting to an editable poly (all parts attached) and use the bridge function to join edges up or Weld to join vertices.

Alternatively you can try using the Shell modifier which wont close the holes, but give the mesh thickness and hopefully intersect it enough that it wont matter when printing. Just a theory
Re: NURBS [message #1169 is a reply to message #1168 ] Tue, 02 September 2008 04:09 UTC Go to previous messageGo to next message
avatar jefffhaynes  is currently offline jefffhaynes
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Yeah, I'm not sure about the first bit, I'll give that a try although I think it might be a little messy...maybe not, I don't know. I may be wrong but I *think* the servers will still error even if the meshes are watertight after intersections have occurred. I was under the impression that all individual meshes had to be watertight on their own. I could be wrong.

Thanks,

Jeff
Re: NURBS [message #1170 is a reply to message #1169 ] Tue, 02 September 2008 06:07 UTC Go to previous messageGo to next message
avatar Neffy  is currently offline Neffy
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Shell modifier will make anything water tight but how cleanly that is depends on the mesh
Re: NURBS [message #1172 is a reply to message #1157 ] Tue, 02 September 2008 07:50 UTC Go to previous message
avatar kreator  is currently offline kreator
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An answer from a CAD (Pro-E) user, not 3Dmax:

1- looking at nurbs2.PNG: I would make the brown surface with a function/feature based on the edge of the red surface, then they should perfectly match.
OR
2- do not add this brown surface (I guess to make your shape thick) but turn the red surface into a sheet with adjustable thickness.
OR
3- copy the red surface with an offset down and join edge vertices with vertical edges (to make the side brown surface).

I would prefer 1 or 2 but maybe 3Dmax can only do 3 (check its functions).

 
   
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