Odd Edges when doing Screw Lathe spins around Edges


Lately I am having extreme difficulty doing Lathe spins of Edges (splines) with Screw Modifier. I get these odd straight zones and really odd shadows. They also happen intermittently, skipping layers. Here is a for-instance. On the photo, you can see one of those issues popping up. Usually there are 3 or more. This one was lucky, but no matter what tricks I try, I cannot get rid of them, including with SubDivision.

What is causing this?

I use the latest Alphas, so perhaps they are having an issue with the Screw modifer, I am guessing.

Also, I ‘usually’ start with a new Mesh Vert (dot). Last night I attempted using different routes to create Splines to get around this issue.

Such a bummer… :frowning: It seems like its broke.

Could it be that you’re getting inverted normals?
Check with Viewport Overlays > Face Orientation.

If so, in Screw Modifier there’s a Normals > Calculate Order checkbox.

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That was it! A thousand thanks. I didnt think Vertices could get twisted up in a Spline. But they did… Odd how that looked and messed up the Screw modifier.