Switching out Reference Spheres

[[Aa...]]

I know there have been other threads on this subject, but I just want to see if my understanding is perceived to be correct by everyone else, since I've been in a conversation with an engineer at Zeiss who seems to disagree with me. Generally, the Calibration Certificates for the Ref Spheres supplied with the machines have a much higher uncertainty than the stated accuracy of the machine. This is not a problem, since that sphere is used for qualification in the ISO 10360-2 verification of the machine. (The CMM and RS are verified as a unit.) For that reason, using a different reference sphere for qualification breaks the chain of traceability through the verification artifact. I believe this is supported by the first paragraph of the attached notice.

ref spheres.pdf

[[Ma...]]

The stated uncertainties on the certificates for the spheres we have from Zeiss are:
Diameter 0.0003 mm
Roundness 0.00004 mm

[[Aa...]]

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Right. It's the same for the one I'm looking at. (Except mine doesn't list roundness or roundness uncertainty, and it says the radius is outside the Lab's scope of accreditation.)
The certificate for the machine lists a base uncertainty of 0.0001 mm.

So basically, I could use the machine to measure the radius of the RS, and that measurement would be of greater value than the one listed on the Certificate. 🤣

[[Is...]]

I have the impression that you are mixing concepts:
















etc, etc, etc...

[[Aa...]]

Okay, thanks. So, which concepts am I mixing, exactly?