I've seen several low cost import ultrasonic thickness testers on Ebay. I'm wondering if they could be used to measure engine cylinder wall thickness. They cover the thickness range, but all seem to have flat probe tips. A 3/8" diam. flat probe tip inside a 4" bore would have ~ 0.009" clearance at its mid point, and I'm concerned this might prevent coupling even with glycerin or silicone gel. Anyone have any experience with this situation?
These things get used for inspecting old steam boilers (for which they are an absolute Godsend...). There is often at least 0.01 roughness in the surface. A smear of Vaseline seems to work. On the other hand, it depends on the degree of accuracy you need. For a boiler, an error of a couple hundredths is not a problem. If you are expecting 0.325 and get 0.297, you're probably quite happy. But if you get 0.082, you have a big water-cooker you don't dare put a fire in...
Jerry
What metal are you measuring? If it is cast iron it will be a problem.
Geometrically I would prefer to take the readings on a cylinder on the O.D. surface instead of the I.D.
Mark
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