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 … Read more

14. Peaks, Valleys, and Skewness

Many of our surfaces have symmetric peaks and valleys that follow a normal or bell-shaped height distribution. But often we may want that distribution to be stretched, or skewed, toward the peaks or valleys. The Rsk parameter, which is widely used to report this skewness, has some serious issues baked into the math which can … Read more

13. Measuring Short Surfaces

How much of a surface do you need to measure in order to accurately describe its roughness? But if you are measuring a narrow feature or part, such as an O-ring groove or washer, the surface may be smaller than the length suggested in the standards. In this video we show you how to determine … Read more

12. Surface Texture and Wear

Thank you for all your suggestions for new Notepad Series topics! We’re going to get to one of the most requested topics now: how to assess wear. If you dug a hole in your yard, you likely wouldn’t assess how deep it was by describing the roughness at the bottom of the hole. In this … Read more

11. 2D vs 3D (Areal) Texture

Is a 3D (areal) texture measurement “better” than a 2D (profile) measurement? There are strong opinions on both sides. But the truth is that there may be some common ground. In fact, there are cases in which each type of measurement may be the right choice. In this video we discuss the properties of 2D … Read more

10. Stylus Tip Radius

Is a smaller stylus tip radius better for measuring roughness? Is a larger tip more durable? The stylus tip radius influences what we see in surface texture measurement data. Since every tip is a little different, the resulting roughness values can be different even when you are trying to use the “same” radius. To make … Read more