Hi Duke, surface/surface filleting works pretty good for a part there, but then has some problems with some other areas.

Another thing that the filleter doesn't really like (as you may be figuring out now, it can be pretty temperamental) are areas where surfaces are fairly close to being smooth to another but are really about 5-10 degrees creased instead of fully smooth, like here is one such area in this shape:



For filleting, it is a lot better if a piece is actually smooth with each other, or more distinctly creased with one another.

Another related area is having things be planar that can be planar, instead of slightly warped, this one is like that:



I tried to rebuild that with a simple trimmed plane there, but that outline is just slightly warped and not actually flat.

- Michael