Re: ATM chasing spheres $%$^&*(%^&$%^!!!!!

["Tom Krajci" <krajcit@det5wg57.barksdale.af.mil>]

> From: Cary Chleborad <bennu@ns.net>
 
> Tom Krajci wrote:
> 
> > How long are you grinding before you look at the graphite pattern to
> > determine you've got this raised ring?  
> > 
> I must have chased my tail around in circle for about 5 hours on 120
> grit.

I understand you spend five hours at 120 grit, but please describe 
how you do your graphite test.  Do you:  draw a grid on the mirror, 
grind one minute, examine the wear pattern?
 
> I can't believe how fast you can grind out a grit size
> compared to working a mirror by hand.  My qustion is, is it the machine
> action or the aluminum tool, or both that make it grind so dang fast?

The aluminum tool makes a big difference, and if you put more weight 
on the tool with the machine compared to hand grinding then that 
helps as well.

> Since the arm is manually controlled, I manually apply pressure during
> the roughing out stages, maybe up to 50 pounds or more( I lean on the
> lever arm), then I switched to 5 pounds at 120 and 220 and from then on,
> just the weight of the tool and arm.

The weight you describe using sounds good, but I've found that with 
the silicon carbide grits (for me that's down to and including 500 
grit) I can use 20 or more pounds with a six inch mirror and not get 
in trouble.  With the aluminum oxide grits (12 and 5 micron for me) I 
use four pounds.  Makes for faster grinding.

Hope this helps,
Tom Krajci

Capt Tom Krajci
B-52 Intelligence Officer
"In God we trust, all others we monitor!"
http://spur.barksdale.af.mil