On Thu, 25 Sep 2008 13:00:56 -0400, Leon Fisk
wrote:

On Wed, 24 Sep 2008 16:50:27 -0500, "Robert Swinney"
wrote:

snip
Drop a 1" diameter ball bearing from a height of 10". It should rebound back up to 9" if the anvil
surface is properly heat-treated. I'm not sure I believe this. Can someone confirm?

I've heard of building your own hardness tester using this
method.

You need some known items of hardness for calibration
though. Find some glass tubing maybe 10-20 inches long that
you can make marks on and your steel ball will easily slip
into. Using a known surface drop the ball (from the same
height) and note (mark) how high it bounces up. Repeat
several times and take the average. Repeat process on
another known item. Test your unknown item and note how high
the ball bounces.
See: http://en.wikipedia.org/wiki/Schmidt_hammer
Just before I retired, the technical data centre manager showed me one
and asked if it was worth keeping or if I wanted it, wish now I had
taken it instead of explaining (and showing him on one of the exposed
building columns) how it was used to estimate the strength of
materials.
Gerry :-)}
London, Canada