Re: ATM [Fwd: BOUNCE atm@shore.net: Non-member submission from [et@ugcs.caltech.edu (Ernest S. Tomlinson)]]

[spooner@page.az.net (Michael Spooner)]

> The huge, deep scratch that I mention above obviously came from
> some stray particle of dirt, but when I get scratches they're
> usually very shallow lines that are clearly visible only when the
> disk is wet and the light hits them just right.  They grind out
> quickly and tend to concentrate fairly near the edge of the mirror.
> _And_ they all seem to get there when I'm grinding tool-on-top.
>


Have you beveled the edge, perhaps with a stone? Beveling the edge 
with a stone can result in fractures into the glass. As the surface 
grinds away, little bits come loose and leave big tracks. I make 
sure and bevel enough before rough grinding (I confess I still use 
a fine stone but with lots of water and low pressure. Patience is 
rewarded.) But I still have to regrind the finer stages once in a 
while so maybe I should bevel with a flex sanding disk on a drill 
motor. I have noticed many more problems when I rebevel between 
stages with a too coarse stone. 
Just some thoughts mingled with a bit of experience. 
Mike