Good evening!

Trying to get a thicker version of this polyline.


For that I try to sweep a circle with a fitting radius around it. The result is not what I expected, the sweeped body doesn't follow the polyline but goes all over the place.



Is there a way to just use the polyline as rail for a circle in order to get a thicker version of that polyline?

Hi NaN, it's happening because your curve is not quite planar, some areas of it are swooping around a little bit in 3D space.

If you go to the Back view and squish it flat using "flat" snap as shown here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3378.4

then it should work ok after that. That's what i have done in the attached version.

The reason why that happens is that when you do a one rail sweep on a rail that has sharp corners between curve segments, it will try to do mitered corners. Mitered corners are created by extending surfaces and then intersecting them with each other. That intersection process can be difficult if the path is not planar.

One thing to note though is that your circle doesn't fit on that path, the corners of the path have a radius of curvature that is smaller than the circle size so it will get bunched up on itself as it tries to go around that corner, like this type of thing:



If you want to thicken it and have a curve as the result you can use Construct > Offset to generate offset curves after you have flattened it.

- Michael

Hi,

The problem is on your construction of your curve with hard corners very near.
Is it normal that your curve is not planar ?
You want it or is it an error during construction ?

If it what you want, you can use the ReconstructCurve script to have soft curve non planar. 200 points are ok for example to have nice sweep.

If you want a planar curve, resize it to have a flat curve. The sweep will be OK next.

Thanks you Michael and Phiro,

Making the polygon flat (and reducing the circle radius somewhat to get rid of the mitered corners) solved the problem indeed!

The polyline was drawn around an existing body, some points probably snapped to close-by points of that body that were not exactly on the plane.

Great help - as usual!