Fillet created new untrimmed surface

Hi all,
Im new to Rhino and having trouble filleting a surface. I want to fillet the top two edges of a fin. One side works (the inner edge). The outside one creates a new untrimmed surface. Any thoughts or ideas or suggestions on where i went wrong with the modeling? Attached is the file



sorry here’s the file

Fin.3dm (354.3 KB)

Hi Peter- here’s one way out - add a couple of ‘handles’ in FilletEdge as marked in the attached file and then set the ends to zero radius. You still need to manually trim the surfaces with the fillet’s edge curves.

Fin_PG.3dm (1015.4 KB)


thanks that did work, but i assume there is an easier way in the future…? Are there any specific reasons why the original fillet did not trim? Id like to figure this out before i get involved in more complex shapes



Hi Peter - your object could be made a little more cleanly, possibly- I’m not sure what you have in mind exactly, but for instance, rather than bend the one larger surface up to make the side of the fin, I think I might make it as a separate, simple surface and but a fillet between it and the larger surface. The sides can be simple and trimmed off by the top of the fin and the large base surface. It seems lime that might be better but again, I have no idea what the constraints are so maybe you need to build this way.