New question for another's model


Hi , I have been playing around with the attached model because it seems to me a good exercise .
But I have to admit I am stumped about how to create a face where I deleted the previous one. It is not as easy as it at first seems. A sweep 2 rail will not work. Nor will a network srf. It is the two fillets at the top corners which cause all the trouble. There are a few other approaches I tried also without success…

Has anyone got any ideas ? Thanks if you have … Would be interested to know.
ChristopherProbem Shell.3dm (2.4 MB)


Its easy enough to make the missing surface with eitherloft or edge surface.

There are 2 fundamental problems with this model

  1. the crappy small fillets. Its easy to ,make clean fillet surfaces, but its even better to just leave the fillets off and add them after the rest is complete. (see file below)

  2. The other problem is tolerance. The tolerance is too loose for what you are trying to accomplish

Probem Shellx.3dm (49.8 KB)

(David Cockey) #3

You are correct the fillets at the top are causing the difficulties. A general strategy is to avoid adding fillets until necessary.

Another very useful strategy is to incrementally save your project so that you can go back to an earlier version. Then you can either back-up to an earlier version, or open an earlier version to retrieve a component. I start by adding two or three digits to the file name the first time I save a project; for example Skiff001. (Note, commands are from Rhino for Windows.) Then after making significant changes that would not be easy to reverse I use SaveAs and increment the name to Skiff002, and repeat after signficant changes. I also frequently Save in between significant changes so that I have a current copy available.

An approach for your current situation:

DupEdge for edges of the large surfaces around the opening (not the fillet edges).
Connect to close the gaps.
EdgeSrf using the new curves for a surface.
Try using Trim to trim the corners of the new surface to the fillets. You wll find it doesn’t work.
ExtendSrf for the fillets.
Trim the new surface and extended fillets to each other.


Thanks for the advice.

I have completed the second approach and it worked well.
I did’t DupEdge though. I have not been quite certain of the purpose of DupEdge
command yet. I have used it a number of times when following the training videos
… I suppose it will become clearer one day.

I will look at doing the reconstruction with Jim’s approach next.



Just realised that I did dupEdge as David suggested.

(David Cockey) #6

DupEdge creates a curve which exactly matches the selected edge of a surface.