Fillet edge operation failed

Hello, everybody!

A solid body (Brep) was obtained by extracting one solid from the other. An error occurs when creating chamfers (R=750) on all vertical edges using the “Fillet Edge” command. The maximum number of edges for which this command works is 6. When adding the seventh edge the failed message occurs “1. Fillet edge operation failed”. What could be the problem? (53.1 KB)

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Dear @Mary5
bake your geometry - also _filletEdge outside Grasshopper / in Rhino Modelling fails.
there are small kinks in the neighbouring edges:

use _edgeContiuity to see the tangential deviation:

my guess - it is more a geometrical problem.

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That would be @Mary5


Thanks for quick response, Tom
I’ve corrected the geometry of the edges by the _edgeContinuity command.
I tried in Rhino the _FilletEdge command – as a result the face chamfers are distorted (Fig. 3).
If I use the _BlendEdge command chamfers are created on 2 edges, and on the 3rd edge everything breaks completely (Fig. 4-5).
Brep_03-10.3dm (3.8 MB)

I would really like to use the capabilities of GH, since I use parametric modeling.

maybe you should use another approach to create the breps ?

  • or do some rebuilding / clean - up before fillet ?

a fast and simple approach would be:
dupEdge (the main edges of the curved bar)
rebuild (with same parameters for all 4 curves)
loft (option straight section)
→ fillet will work

Brep_03-10_tp.3dm (4.2 MB)

rebuild violett curves…
version at top

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Fillet Edge is fragile and often breaks, unfortunately. I added ‘40’ to the list of edges, then reduced radius until it appeared to work (200) but the result is “Invalid Brep”.

Unless your object must be exactly as it is, I would highly recommend rebuilding it.

I baked your object and extracted two sections with the YZ plane, rebuilt the curves in Grasshopper and created a new Sweep2. The resulting polysurface can be capped and has 12 edges. (19.4 KB)


Hello Mike!

Thanks for the answer! I repeated your method of modeling in the Grasshopper.

This shape is half of the pylon.

Precise geometry is very important for further design and reinforcement.

On the pictures you can see the difference in concrete volumes (300 m^3) as well as differences in geometry.

Can you suggest how to rebuild the solid body (as in the 1st post) and get the correct pylon chamfers?

Please post a file with the solid body that needs to be rebuilt.


For a superscript 3, type ALT+252

…³ (72.3 KB)

Here’s a slightly different approach which leads to a volume nearly identical to your original shape. (110.1 KB)


Thank you very much, Martin! Everything worked out!

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Hello, Martin!
I have chosen my input geometry and this script crashed. What did I do wrong? (39.1 KB)

The problem with your rebuilding approach is that you need to manually type in the edge numbers. The current polysurface contains one small edge you forgot. Even with that edge, sorting the curves is challenging.

I think the rebuilding could be automated:

  1. cull the edges of the top and bottom surfaces
  2. join the +/- vertical edges
  3. align all four edges so their start point is at the bottom
  4. sort the curves
  5. create edge surfaces with two pairs
  6. loft the edge surfaces

The four edge indices for the fillets can be found by extracting all edges that aren’t part of the top and bottom surface and then it’s the set difference… (61.8 KB)