From:  Michael Gibson
2048.9 In reply to 2048.8 
Hi Brian, actually there is one other issue with that tail as well, which is that it isn't very good to try and fillet a very thin "knife edge" type situation like that.

You can see that the vertical section did fillet, but it did not produce a very good result in the back:

It is tough for the filleter to produce a nice corner in such a sharply angled "knife edge" situation like that.

If you want to fillet that well, it would probably be necessary to first fillet that very sharp edge so that it was a slightly rounded edge first (probably actually best to put a small rounded piece in there early on from the initial sweep actually), and then boolean the pieces together, then do a fillet where they met and it would then not have that "knife edge corner patch" type issue.

Filleting things that come to a very sharp angle generally can cause problems for MoI's filleter. You may have some better luck with those particular knife-edged ones in ViaCAD instead of MoI.

- Michael