<snip> > >2. High-speed dental drills use air bearings. That's how they can >achieve such high speeds (~50,000 revolutions/minute) without the >bearing burning up. > <snip> Hmmm.... are you sure about this? We have sold countless bearing balls (very small size) for dental drills. They have much longer life than steel ball dental drills, and can be repeatedly steam-sterilized. Andy