Hi Jens, the lower part fillets ok over here up to a radius of around 0.75 . So you may have not quite gone small enough.

What I'll usually do is start with a really pretty small radius, like 0.1 and increase it in steps until it stops working.

Often times during this you can kind of see which fillet piece is causing the problem, like in this case there is one piece of a fillet that keeps getting smaller and smaller and when you go to 0.75 it is really pretty skinny - that fillet piece kind of evaporating is when it breaks. Here is a snapshot of the one I'm talking about, with the arrow pointing to it:



Also below that I've circled a different kind of problem - there is an edge in the model down there, and the fillet will be likely to fail if it gets big enough to where it would have to cross over that other edge. This is actually one of the biggest problems that I hope to get fixed up when I can get an update to the geometry library that I'm using.

So try a little smaller yet! One quick note - if you want to type in a bunch of different radius values, it is not necessary to click in the "Radius" box first, just type a number directly and hit enter. Once you start typing, your keystrokes will automatically go to the first numeric entry box in the command options area.

- Michael