We are a job shop manufacturing turned parts on screw machines and CNC lathes for a variety of customers and industries.
On parts with multiple diameters some customers call out a concentricity specification. Others will use run-out and some show a position requirement. Aren’t they really all asking for the same thing? Why do they say it three ways, and can they be used interchangeably?
Runout tolerances (circular runout and total runout) control the form, orientation and position of individual features - datum axis required.- Circular runout is a two dimensional, surface to an axis contol.- Total runout is a three dimensional, surface to an axis control.
Concentricity tolerances control the location of opposing median points of a feature (datum axis or median plane required)- Concentricity is a three dimensional tolerance.
Position for coaxial features is a three dimensional, axis to axis control.
I suggest you refer to ASME Y14.5M-1994 http://catalog.asme.org/Codes/PrintBook/Y145M_1994_Dimensioning.cfm
Understanding the differences in these specifications will allow you to assure compliance.
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