Hi Sun, what fillet radius are you trying to use?

Since this piece has rotational symmetry, it should be possible to replicate one successfully filleted piece around and trim it into place, if you can let me know what fillet radius you want I can get it on the model that way.

One other thing that you may be running into is also related to short fillet segments - when you have 2 curved surfaces meeting each other instead of having one curved and one straight, then it is actually not so great to have edges between them that come to a single common point like this:



When each side of an edge like that is a curved surface, the fillets will actually get constructed in some separate segments in a case like that, see this previous post for an illustration:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4023.10

That's because fillet surfaces are created at an offset of the current existing surfaces, and when you've got curved surfaces on either side it means that the fillet pieces on either side of that point where the edges touch each other in the original surfaces will be offset slightly, leaving a kind of small gap to be filled. Small gap situations do tend to be a complex area to handle where the filleter can get confused more easily than when it deals with larger fillet sections.


If those side pieces had a "seam edge" that was not in exactly the same spot as the edge on the outer ring surface, that would actually be easier to fillet. That can be done by dragging the seam point markers that show up in the Loft command when creating the loft initially - when you're in the loft command inside the viewport there will be 2 points that show up that you can drag around to control the starting connection point between 2 closed loft profiles.

But I think it should be possible to replicate any one successful fillet piece around to finish off your piece instead of doing any changes to it, if you can let me know what fillet radius you want I can make that for you.

- Michael