Hi Shazbot, it's better for filleting to not have any unnecessary extra edges in your objects. For your case here that means you don't want these edges here:



It would be much better in your case here if those cylinder pieces sticking out were made up of just one single cylinder surface rather than fragmented into a couple of different sections.

The reason why it gets hard for filleting is at juncture areas where many fillet pieces are coming together and need to be trimmed with each other and possibly have a "corner patch" filled in, like in your case you have juncture areas here with 5 edges coming out of that point with many of the edge nearly tangent to one another where they meet up:




That kind of "nearly tangent" geometry also makes things difficult for filleting as well because when 2 surfaces are nearly tangent to one another when they get intersected with each other the intersection is kind of more of a fuzzy region of overlap rather than a distinct intersection curve.

So I'd probably try to replace those fragmented cylinders with just one cylinder surface and that should probably help a lot. You also may want to make the base shape for something like this to be made of one side profile that then uses Construct > Revolve, rather than lofting through many different sections, it's just a bit easier to control it when drawing just one curve for the revolve.

- Michael