What mistake I am making on some solids?

Ring solid.3dm (151.6 KB)

When I create a ring solid such as the example, often I find that the surface and edges are not continuous. I usually create it by extruding two coplanar closed circles or a flat surface or use a solid offset. What causes the model surfaces and edges to not be continuous as with the attached example?

I asumme by “not continuous” edges you are referring to the individual surfaces of the polysurface being only 180 degrees instead of 360 degrees.

Without the input curves/surfaces used to create the solid any comments on the cause would be speculation.

If you click the ‘MergeCoplanarFaces’ command, it will be fixed

MergeCoplanarFaces will merge the flat surfaces on the ends of the ring, but will not merge the curves surfaces.

The curved surfaces can be merged using MergeSrf
Explode the ring
MergeSrf Smooth=No Roundness=0
Select the two inner or outer surfaces to merge
Enter to complete

After merging Join sto create a solid