1 Advance Notice of Proposed Rulemaking. 2  This optional step entails publishing the agency's initial analysis of the subject matter, often asking for early public input on key issues. 3  Any data or communications regarding the upcoming rule would be made available to the public for review.
Concentricity tolerance zone controls the median points of a feature of size. Concentricity tolerance is a condition in which the axes of all cross-section elements of a featureâs surface of revolution are common to the axis of a datum feature.
The flatness tolerance references two parallel planes (parallel to the surface that it is called out on) that define a zone where the entire reference surface must lie. Flatness tolerance is always less than the dimensional tolerance associated with it. Tolerance Zone: Two Sets of Parallel Planes where the entire referenced surface must lie. Gauging / Measurement: Flatness is can be measured using a height gauge run across the surface of the part if only the reference feature is held parallel.