Then when you put on fillets as the last step, I used Edit > Trim to cut these edges to make it easier to do the variable radius fillet:



Then when you fillet the top faces (for filleting here just select top 5 faces, quicker than selecting edges), you start with the small radius and then add a point set at these points and use a larger radius for those:



- Michael

So the kind of key line of reasoning is to make a seamless area be more like an extended block of stock material. Then that block will be cut to impose a border upon it but the surface shaping remains the same.

It's kind of similar to how the actual physical machining process might go.

It's difficult to get this type of shaping by building pieces separately and trying to fill in pieces in a "patch by patch" type way.

Basically when you try to fill in a patch the boundaries become a major influence on the resulting surface shape. When you build a simplified and extended piece that forms the final boundary by being cut, the surface shape is not at all influenced by the cut, the surface shape comes directly from the original extended block.

Hope that makes sense!

- Michael

THANK YOU, Michael, for your response and examples.
You are a fantastic reference point for any problems and difficulties. Sincerely thank you.
Mario R.

This is oh-so frustrating when Michael shows how to solve a particular problem. It's always easy, elegant and evident.

And I struggle drawing a circle ... ;)

Thanks Michael

Hi Ditto, it can take a while to get used to the optimal strategy for NURBS modeling.

Usually though it's about constructing larger extended shapes that are cut with booleans. If you find yourself building surfaces by filling in a patchwork between 3D edges rather than primarily using 2D curves that can be a sign you're going in the wrong direction.

It's very different than the strategy used in polygon mesh modeling.

There are some tips here for people coming from a polygon mesh modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael