15. Why Not Repeatability?


How good is my surface roughness gage? There’s an old tale of three blind people describing an elephant based on the small portions of the animal that they each experience. It’s a great analogy for surface measurements: we may get very different information about a surface just by slightly changing the measurement location.

In this Notepad Series video we look at how measurement location can account for poor “repeatability,” and why repeatability is not a good judge of a stylus instrument’s condition or capability. In fact, good repeatability may indicate a bad instrument!