Cannot get a proper fillet

Hi All,

I’m having a helluva time filleting this object. I created it using curves and kinda pieced it together then joined all the surfaces together. There is probably a better way to create it but I couldn’t figure it out because the base of the surface follows a contour, then it has that peak. Anyway, I cannot get it to fillet. Some of the edges I can get to fillet, but not the whole thing (I don’t need to base edges to fillet). Perhaps, it doesn’t like the lower edges I suppose due to where it comes to a point. I included the surface and the curves I used to create the individual surfaces in the file. You can see from the one image, I’m getting a fillet error near the bottom, but no matter what radius I change it to, it doesn’t seem to help. I want to use about an .04 radius for this. Any help would be appreciated. Thanks !!

Fillet issue.3dm (847.8 KB)

Hi Kirk- a couple of things-

  • at the skinny end there is a little bit of srface sticking out past the end plane- you need to clean that up for this to work.
  • it is probably best to make all the planar faces as actual trimmed planes - simpler surfaces than what you have there.
  • the problem area is at the wide end where the triangular surface’s point meets the end plane. I’d clean up as suggested above, then FilletEdge all the edges at once that you want to fillet, then work out how to deal with that one junction and trim all the rest in afterwards. I’ll see if I can make a suggestion on how to do that.


Hi Pascal,

Where you see that bit of surface at the skinny end sticking past the end plane, that’s where the fillet is failing to trim the surface and the fillet preview is showing that corner will not be trimmed. I’m not sure how I would clean that up.
-When you suggest to make the planar faces as trimmed planes, what method would you use to make that happen ? I made the faces by using the “Surface from 2,3,or 4 edge curves” command.

Thanks !

Hi Kirk-

I have the fillets made and almost ready to go on my machine at the office- I’ll send it tomorrow. As for the planar faces- if when you make the surfaces, the loops of curves are planar, use PlanarSrf to make a trimmed plane. On the existing object- ExtractSrf and trim the face in the image above to clean up, Join, then MergeAllFaces - this will replace some planar faces that are next to other, coplanar faces, with single trimmed planes, then ExtractSrf any faces, one at a time, that look like they might be planar and see if Cap on the remaining object fills the gap with a planar face. Like so.


Thanks Pascal, I appreciate the help. I found I needed to use Fillet Surf as opposed to Fillet Edge, as Rhino didn’t like the 3 intersecting surfaces. It took a little more manual tweaking and patching than I hoped for but the end result worked. I was perhaps being lazy, hoping Rhino would do more work for me. But thanks again ! Maybe future versions of Rhino will have some filleting tweaks.