Jewelry ring polysurface boolean or splitting issue

I seem to be running into this kind of boolean issue a lot as I’m learning rhino to create jewelry. This is a ring design with two objects and I plan to put stones along the surface in the future but I’m having difficulty either joining or cutting away the intersecting portion of the band. Boolean is giving errors and trim or split doesn’t seem to work as expected. Surely there is a simple fix I’m missing here. Any help?

boolean issue.3dm (1.1 MB)

boolean issue scale.3dm (1.0 MB)
I scale up the ring just very little.
There good post on how Boolean works. It is about the intersection. I try to find it

Hi Joshua - do you have the input curves to the ring body?


boolean help 2.3dm (5.4 MB)
Here’s the file with all the curves. I used Sweep 1 to create the surfaces and then Flow along curve for the ring.

Hi Joshua - I’m kind of making stuff up here but is this what you are after?

boolean help_maybe 2.3dm (556.0 KB)


That is a reasonable result Pascal. How did you get it?

Hi Joshua - in my file you’ll find a helix and two squares - those are combined in a Sweep1. that is capped then cut (BooleanDifference) by the cylinder. The cylinder is made over-sized to the inside of the ring and trimmed to the circle of the ring (WireCut). The hard edges are softened last, with FilletEdge.


Hey Pascal, I gave this a shot and got a similar result so thanks for that. I realized a couple things though. First, there is an issue on the underside where the shank meets the head, the fillet interrupts the joint area leaving a gap with a sharp edge. Second, this process works for square cross sections only. I have a similar design with a round cross section and if I try to cut it using wire cut it will only cut in one plane, not 3D to fit the two curved surfaces together. Any thoughts how to fix these issues?

Thanks for this Eddyf, it does work though I was hoping to find a solution that wouldn’t impact the scale as that can create anomalies. That being said I found if I scale the original sweep shape by 1.01 it’s barely noticeable and theres no visible outside issues in this particular design. This definitely seems like the easiest solution I’ve found.

Hi Joshua - as always, please post a file, it’s impossible to know what is going on without it.