In article ,
"DOC" wrote:

Over the years a number of people have asked (and answered) that question
here.

I see where Scientific American shows the process in their August 05
edition in the Working Knowledge article.

Any photos of the "machine" for checking the balls? IIRC, it's just
a series of anvils the balls bounce across after going down a ramp. The
ones that make it across pass, the ones that fall off are rejects. I've
heard about these things, but I've never seen a photo.

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