Stylus Standard Deviation

[[Jo...]]

I wanted to get some thoughts on this stylus system. I was informed that it has always qualified at .010mm or higher. It has recently been providing inaccurate results. The horizontal shaft is ~8 inches long.

Today, we inspected the tips, and they appear to be in good condition (no visible flat spots or aluminum buildup under microscope). We verified all connections are tight. Both tips qualify at the same sigma value and radius (.005 mm oversized). We then tested qualifying each of the tips at a 20-30% probing dynamic, and that yielded .001mm. We also tested adding a counterbalance to the system, and that made no difference at the 100% probing dynamic.

Does this seem right to you guys? Could there be something else causing issues? I have limited experience with stylus systems like this. We also have a couple other setups like this, and they qualify around the same sigma value. My leading theory is simply that the shaft length causes it to “shake” during probing, so the lower dynamic slows this movement down, allowing for more stability.