When a shop begins the manufacture of rotating shafts, they frequently turn to their conventional CMM for part validation. However, this is often a case of using the tool that is at hand, rather than one designed for the job. A screwdriver can be employed as a center punch, but a tool dedicated to the task gives much better results. So it is with a traditional CMM vs. a dedicated shaft gage.
While a CMM can get the job done on turned parts, there are some very good reasons for switching to a gage which was specifically designed for the measurement of shafts and other turned parts.