"Jon Elson" wrote: (clip) the grinding creates hot spots, the thermal
stress cracks
the glass. (clip)
^^^^^^^^^^^^^^^^^^^
This correct, but generally the piece doesn't crack apart. Little chiops
keep flaking off, so you never wind up with a smooth surface. Often flakes
come off ahead of the cut, spoiling the part you intended to keep. You can
actuaslly see "fire" if you do it dry. DAMHIKT.