Hi krass, sorry I didn't see that your model was attached later in the thread.

Yes, that's a particularly difficult case to fillet. Fillets shrink down to zero width at spots where 2 surfaces are tangent to each other and you've got that situation just at one point right in the middle of where the fillet wants to go.

That's an unusual situation and I don't expect that MoI's filleter will be able to handle it. Probably it will be difficult in many CAD programs because they don't really expect to process a discontinuity right in the middle of the fillet.

So for that kind of situation you would need to use some other method than the regular edge fillet. Filleting curves and doing a loft as you already did is a good way. You could also cut away some space and put in a blend surface, like this:







- Michael