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Dimension Circularity dialog box
One hit, plus the feature's minimum hit requirement is necessary to determine the roundness of that feature. Additional hits provide a better representation of the roundness of the entire feature.
The Insert | Dimension | Circularity menu option determines the roundness of a circle, sphericity of a sphere or the conicity of a cone. This dimension type is considered one sided, meaning a single positive value tolerance is applied.
For legacy Circularity and Cylindricity dimensions as well as a Location dimension's RN Line, the feature solution is used to compute the dimension. By default this is Least Squares. However, you can choose to solve the feature using Minimum Separation, Maximum Inscribed, Minimum Circumscribed, or Fixed Radius regression algorithms.
FCF Circularity and Cylindricity dimensions on the other hand are computed using the Chebychev algorithm (Min/Max) as required by the Y14.5 standard. Because of the change in calculation, Circularity and Cylindricity FCF dimensions will generally compute to a slightly smaller value than their legacy counterparts.
FCF form dimensions that use the Chebychev algorithm include flatness and straightness.
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