In recent columns I’ve commented on information requests accompanying calibration orders. Some of these are common and effective but some are not. Occasionally, they are brought about due to their inclusion in one standard or another but are misrepresented. In some cases, the standard they are from relates to in-house systems rather than calibration activities by outside parties.
One of my readers had such a dilemma on his hands and asked my advice on dealing with it. My reader calibrates gages and instruments for a number of groups within his organization and had to ensure his calibration uncertainties did not exceed a ratio of the tolerance for the item calibrated. This would seem to be a straightforward matter to figure out, but on reflection raised the following question: If the tolerance is plus/minus 1, is the ‘tolerance’ 1 or 2? After much qualifying, I told him that since there was no definition, I would take all the uncertainty I could get and consider 2 as the tolerance.