2025-02-21+08_diameter_bug.3dm (285.5 KB)
The number, not the font, is what is unexpectedly large. Just thought I report this.
2025-02-21+08_diameter_bug.3dm (285.5 KB)
Hi @feklee
You must have snapped to something other than the geometry shown here (or moved it by accident). If you select the dimension and turn on control points (F10), select all and ZoomExtentsAll, you’ll see that the center point is a very long way from “home”.
-Jakob
Edit Aah, I see what you’ve done. This happens if you try to dimension the seam of the torus in top view. I’m guessing the the small size and relatively low tolerance makes the seam curve “not completely flat”, and therefore it has a really huge curvature when seen from the top. It is really the R5 of the cross section, but “placed” in the top view, so you’re dimensioning the wrong curve.
Thanks for your explanation! I didn’t realize that _DimDiameter measures the curvature as projected onto the current cplane. But it makes total sense. Otherwise cruvature would be ambiguous.
It makes sense, yes… but I’d never have thought of it either! Yet another thing to be stored in the “things that might make Rhino act a little weird”-library 
-Jakob