I was going to show a tutorial on this, but my path to the intended goal was tricky.
I had to jump back and forth a few times with copy and paste.
Either fillets did not work or surfaces did not Union.
I got this one to work though...
This could be a cool looking port for a turbine or high power fan.
You could also take this route for a nice wheel rim.
I had several criteria: The bridges between the outside and the center spindle had to smoothly transition between the two surfaces.
The had to have a curved swoop to the shape, and narrower on top than on the bottom.
(Before Fillets)
There are many ways to attempt this kind of shape which is good for sports rims.
Blending from holes in a top surface to a bottom surface is one good way. Lofting, Blending and whatnot.
Here is how I made this:
1) Profile shapes made and Revolved to make the outside cylinder and the inside spindle.
2) Profiles made for the bridge element. - The part between the cylinder and the spindle.
3) Made a few copies of those bridge profiles, scaling some to make the one near the center more narrow and the one on the outside wide.
4) Positioned the profiles to make an overall curve to the Loft progression and a dip in the shape's top.
5) Lofted the profiles to get a nice shape for the bridge.
6) Copy Rotation of the bridge pieces.
7) Boolean Union welded the bridges, spindles and cylinder.
8) Fillet the joints as much as it will allow. Blending surfaces can work as well.
Note, the bottoms of all the pieces should be planar (flat) so that they Union easy.
If only one part Fillets due to something funny in the geometry, and the others do not: Consider trimming to just the one good part and Rotating copies of it to make a complete round.
I still want to try other methods, lofting and so forth. But a shape like this is more complicate then is often obvious.
I am open to and grateful for suggestions to making a shape like this and to alternate methods.
