340 Ultrasonic Wall Measurement Sanity Check

None of those sonic testers come with the correct probe to measure grey cast iron. None of them. It takes a larger diameter probe. I did research for about a year before I bought mine. Talked to several machine shops north of here ans in the Atlanta area and that's what they all told me. So, when I got mine, I also got the larger probe for grey cast iron and it works very well. I've double and triple checked it on things I can also measure with a micrometer and it's spot on. You gotta have the correct probe.