Hi Jeff, so I learned from browsing that thread a bit more that there is actually the concept of an arc object in SketchUp, and that certain operations like entity info or dimensioning are able to get at that original arc center and radius information. That's kind of strange that they did not make offset make use of it as well though.

That's pretty confusing to have only some tools recognizing the arc information and others just using the polyline approximation.

- Michael