GD&T - Concentricity tolerance

[[Da...]]

Not really a Calypso issue, but always found good answers here. I have a project with a drawing that does not include any spec for position, but it appears to me it should. I think concentricity should work here, just not sure what the 'correct' tolerance should be. I have one part with an OD of 4.620-4.623 (inches) and a hole shown with and ID of 4.628-4.638. Assuming I have the correct filters applied, what would be the correct acceptable tolerance here. I am going with .005, which would be the difference between the worst case parts. Am I going the right direction here?

[[Br...]]

Concentricity should almost never be used. It's so useless in fact that in the 2018 revision of Y14.5 it was completely dropped from the standard. If you want to locate a feature of size, a Position tolerance is usually the most effective. For coaxial features of revolution, some form of runout may be desirable to control the location. Runout is a closer tolerance to Concentricity if you want to go that route, but Position is a perfectly fine tolerance for controlling coaxality of features as well.

As far as calculating your tolerance goes, It depends on the application. The purpose of the Y14.5 standard is to have interchangeability of manufactured parts, ensuring that all the assemblies fit together no matter where the pieces of the assembly came from. So this is why you select datum features that represent the mating/interfacing features of each part, then tolerance all the features back to that Datum reference frame. What you would want to do is look at all your limits and fits to then determine what your tolerances will be to avoid interference. For a position tolerance for example, there are Fixed/Floating fastener formulas you can use to determine your tolerance where you will take the size of the fastener, and size of the clearance hole into consideration to come up with a tolerance value.
https://www.tec-ease.com/gdt-tips-view.php?q=110