BREAKOUT DIAMETER

[[Jo...]]

I am trying to measure a break out diameter for size.   basically it is a ring type part that has a center bore, a plane and web.  The web has radius that is less than 60degrees of an arc that is intersected with the plane.  Where the plane and radius meets is the diameter I need.  The radius is part of a line profile (several around the part) measured with a curve.  So i have the curve points.  I recalled those points into individual diameters.   If I was just measuring the radius, it would just constrain the size to get location and constrain the position to get the size... in this case I need both at same time. I tried using a theoretical diameter and formulas to input the location and size of the recalled points and then intersect with the plane.  When i do this I get a diameter that does not make any sense. Any ideas on why?