I have been investigating comparator calibration, only to find out that there is no industry standard which outlines acceptance criteria. I have asked comparator calibration companies, and they comment that nothing exists, and its up to you to determine acceptance. I understand that an R&R study can be performed to verify if it is an acceptable instrument for use in inspection, but what about gage tolerance? Does anyone know what is accepted as a tolerance for comparators? If know one knows, how can it be called calibration?