Why does FilletEdge create the surfaces, without modifying the solid?

[Stefano_Menci]

Create a fillet edge selecting the two edges as shown in the snapshot, and the fillet surfaces are created, but not used to modify the solid. The result is two additional surfaces, without changes to the solid.

FilledEdge fails.3dm (705.8 KB)

[martinsiegrist]

When the trimming fails inside the command you can use the surfaces to do it manually

[Stefano_Menci]

Hi Martin, thanks for the reply.
The problem is that I have many similar details.
I tried changing radius and other parameters, but didn’t help.
I recreated the whole solid from scratch, and it works. Faster than creating each fillet manually.
Any idea about what could cause this issue? Two solids seemly identical, one fails and one succeeds.

[martinsiegrist]

I looked at your file. If you fillet in two steps, the concave edge radius needs to be smaller than the 1 mm radius for Rhino to fillet the edge. The thing to do in your case is to fillet all edges you want R = 1.0 at once.

[jeremy5 (Jeremy)]

Or you can fillet the short vertical edges first, then the long horizontal.

Rhino copes better with filleting smooth curves than pointed vertices as created by the OP’s original fillet.

Unless you want the pointed corner, of course, in which case you have to do the extra construction or use a nominally smaller fillet as you said.