http://cgi.ebay.com/DIGITAL-ULTRASONIC-T...=item45f3671185This looks just like the sonic checker I have. Works great. I radiused the probe to use on cylinder walls. Purchased after scrapping the above mentioned block so I don't know what that block wall thickness was.
The blocks I've checked (230,250) have thick walls on the thrust side, .250 inch or so. Thinnest spots are between cylinders, typically around .120 inch. The smallest reading I've seen is one block has a very small spot that shows about .080 inch with .120 or better all around. That spot is about 2/3 the way down the bore and between cylinders. I think that particular block was already at .060 over.
CNC, I'm interested in your experience regarding what sonic readings are cause for concern relative to location in the cylinder and planned usage.
