Cumulative Radial Runout

[[La...]]

I am having trouble with the Cumulative Radial Runout below. I've never had to deal with Runout much, so I am not sure what I need to do on this. They indicate it in the lathe at about .0005". I thank you in advance for help!

[[SH...]]

Measure datum a and b as cylinder with high density (scanning).
For first runout create a 3D line using two cylinders, calculate runout with respect to it.

Second case calculate with respect to datum A cylinder.

[[Cl...]]

To add, you need to probe/scan the entire surface of both OD cylinders.
In addition A-B is one datum from two, if you weren't aware.

[[Er...]]

Creating a line between datum A and datum B and using that as a datum will not be correct. Use a step cylinder as datum since you have plenty of surface at the datums to work with.

[[An...]]

Exceeding the limits of CMM.
See attached.

Contribution_28_08_2020_c.xlsx