Trouble with smooth transition

I am having difficulty doing something properly.

This is the model I am working on

For the green section, I created an arc that runs from the larger circle at the bottom to the smaller circle at the top, using the arc: start, end, direction at start command . I used the Quadrant and Near snaps. I then did Pipe with 1 mm diameter at the top and 1.3 mm at the bottom. The transitions of the green section look just the way I want them.

Since I need two more like these on either side of the center band I tried to do something similar. I have tried several things. First I tried to run an arc between these two circles, again using arc: start, end, direction at start, and Quadrant and Near snaps, after which I tried to make a pipe again.

The result was not smooth, and not want I want. (Red objects)

I also tried to create two circles and a connecting arc,

after which I ran the Sweep 1 command, which gave me this result.

The transition on the top is again not what I want.

What am I doing wrong, and what do I need to do to do this properly?

I have added the file in case anyone want to take a look at it.

Cage ring.3dm (3.0 MB)

Use Blend Curves > Adjustable Curve Blend to make the center curve and then use the pipe tool with the centerline curve you just made.

There is a video a couple posts down titled “Simple jewelry design with Rhino for Mac” that illustrates this technique perfectly.



Thank you! That worked beautifully.