"Vernon" wrote in message
...
What are they good for? I just don't get it although I've done my
homework and have even consulted wikipedia, that ultimate authority!
I understand they will grind down a surface in infinitessimally small
increments and produce a beautiful surface. But on what? And why? V

Sheets of granite. Concrete floors prior to flooring with good flooring.
Lots of "stuff".

Steve