FilletEdge error - 'Failure in building corner'


Not the first time I’ve have filleting problems like this before. The error ‘Failure in building corner’ pops up when I try to fillet an edge as show in the image below. Can someone explain to me why it won’t fillet this and possible workarounds?

I’ve attached the Rhino file as well:

shell concept.3dm (1.2 MB)


Hi Raymond -My guess is that is is due to the edge in the middle there being tangent but the surface are not tangent. I’ll see if I can find a workaround.

FilletSrf and ‘hand trim’ but you’ll see you need to fix the fillet surfaces up where they meet in the middle at the tangent but not tangent location.


Thanks Pascal,

I have tried FilletSrf prior to FilletEdge, as you said I’m left with a mess in the middle. I tried patching it up after and I couldn’t get a clean finish with no naked edges.

I’ll give it another try and see if I can get it working.


Hi Raymond - to clean up,FilletSrf, Extend=Yes. Untrim the result. Split >Isocurve snapping to the Int of the edge where they cross in the middle. ShrinkTrimmedSrf. ExtendSrf the open ends to make sure they pass through the flat face. MatchSrf the middle seam for tangency, with Average set. Trim back the extended end with the flat face. Trim the main surfaces…

shell concept_PG.3dm (198.0 KB)


wow… That’s a lot to go through for a fillet. Will certainly give it a try. As for the file you attached, did you go through the same procedure or was there a workaround?

I did it as I described, but it is really quite fast, even with a couple of miscues on my part in trimming:


Thanks! You’re a life saver. Its all so clear now.