1: Both are OOS failing, so who cares about the 0.003 delta?! They both verify parts are bad, well beyond each devices' uncertainty levels, and well beyond the delta you are seeing.
2: Use the technology to your advantage. Do a form plot to see where the CMM is picking up the high spot, or what kind of pattern the bore is exhibiting. My guess is, you will find that the diameter is likely smaller as bore gets deeper, which is indicative of tool wear. Which is a very logical reason for the smaller diameter. Your bore mic can measure bigger very easily if you're not perfectly square to the bore's axis.
3: The CMM should be more reproducible than the bore mic. Human error is real. Do yourself a mini MSA and test out which one has lower measured variation.
1: Both are OOS failing, so who cares about the 0.003 delta?! They both verify parts are bad, well beyond each devices' uncertainty levels, and well beyond the delta you are seeing.
2: Use the technology to your advantage. Do a form plot to see where the CMM is picking up the high spot, or what kind of pattern the bore is exhibiting. My guess is, you will find that the diameter is likely smaller as bore gets deeper, which is indicative of tool wear. Which is a very logical reason for the smaller diameter. Your bore mic can measure bigger very easily if you're not perfectly square to the bore's axis.
3: The CMM should be more reproducible than the bore mic. Human error is real. Do yourself a mini MSA and test out which one has lower measured variation.
