This may be obvious, but I will say it anyway. Due to the sample parts actual geometry, your results can be skewed. The sample block that came with your CMM is probably not very precise. It is an OK tool to use for this comparison only if you are able to probe the same number of points in the same orientation at the same Z height.

I do a round robin correlation between 7 Zeiss Eclipses, 1 Zeiss UMM550, 1 Mitutoyo, and 1 Brown and Sharpe. I take very special care to probe the part the same for each machine.

For all the Eclipses, we run the same probe and program. I get correlation closer to .0002" - .0003".

A good test would be to measure the features you are using to do your correlation with a large number of probing points and determine the form of each feature. If the form is significant, you need to take this into account when you measure the same feature on the other machine.

This is difficult to do when you are using a manual machine to compare to a DCC machine. Probing at Consistent angles is difficult when you are probing manually. But I have found if the measure the features 5 times or more and average you measurements before you compare, the results are usually much better.

I hope this helps!
Bryan Sorensen
Quality Manager
Tosoh Quartz Austin
503-605-5667