GD&T
GD&T Position vs Concentricity: Practical Selection Notes
Understand why position and runout controls are often more practical than legacy concentricity concepts, especially when working across ISO and ASME conventions.
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Open GD&T Reference →Do not treat similar-looking controls as interchangeable
Position, runout and concentricity describe different tolerance concepts and inspection implications. The correct control depends on the functional requirement and the governing drawing standard.
ASME Y14.5-2018 context
DraftFit intentionally removes concentricity and symmetry from the ASME Y14.5-2018 mode because those characteristic symbols were removed from that edition. Existing legacy drawings can still require interpretation against the edition specified on the drawing.
Related standards
DraftFit guides are engineering educational content and do not replace the controlled standard, project specification or responsible-engineer review.