It make me think about different side of this subject.
A friend of mine said, long time ago: "in metrology, the only thing that I'm certain is the existence of the uncertainties !"
This subject is as close to accuracy than it's to phylosophy !
When a part or a dimension is bad, who doesn't begin by re-measuring it ?
When a part or a dimension is good, who begins by re-measuring it ?
When a tech calibrates the cmm, he measures (ISO10360-2) 5 lengthes in 7 locations three times.
If you can, just take a look at a location measured with a Koba-step, by measuring all the steps.
If you choose the same lengthes than the tech ,you will find few deviations.
If you choose different lengthes than him, ou will see more important deviations.
In both cases, the cmm is generally "in the tol". but not at the same place !
What can I say as conclusion ?
Still be confident in your cmm, according just the right place to uncertainties, and don't talk about this to your boss, you avoid some questions
!
Ah !
It's friday, happy week-end !
