17. Measurement Settings

The measurement settings for roughness gages can be intimidating. There are a lot of options, and it’s not always clear what they do. In this video we make it easy for you as we point out the two most important settings: the wavelengths which define “roughness” (filtering and cutoffs), and the length of data we … Read more

16. Why Use a Skid?

To measure surface roughness, a roughness gage (sometimes called a stylus profilometer) traces a small stylus over the surface. A stylus on its own can be very sensitive to not only the surface but also to outside influences. Any vibration or disturbance can make it move, which will introduce errors to the measurement. To help … Read more

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