For example if a bunch of parts are manufactured and measured several times, I would expect the standard deviation of the measurements to be similar from part to part however the mean would be expected to be different for each part. Both the manufacturing and measurement process are expected to be normally distributed. How would I calculate the expected range for future measurements on a specific part given a few initial measurements and the standard deviation from a much larger sample set?

Could I calculate the confidence interval (95%) of the mean and then add 3*sigma?