[ATM] 16 mirror

[Jarvis Krumbein]

OK, keep up what you're doing until the ground area gets to the edge and
then make a new tile tool.  Use this to true up the curve to a sphere and
further deepen the curve.  This will also true up the tool. 

Jarvis

On Wed, Jan 17 Jarvis Krumbein jkoptic at juno.com writes:
>It sounds like you are at the point where it's time to make a new full
>(or near) full size tool.  If the grind is now out to the edge then make
>a tile tool to conform to the shape of the hogged out mirror and
continue
>with 60 grit (80 would probably be better) with the mirror on top and
>fairly well offset until the center depth is around .190.  This should
>wear in and true up the new tool and get you close to spherical.  Change
>to center over center strokes with about a 6" stroke until a sharpie
test
>shows good contact and spherical surface.  Switch to your next finer
>grade of abrasive and continue.  Alternate tool on top/mirror on top
when
>proper depth is reached in the center to maintain the desired depth. 
>You're on the right track.


On Thu, 18 Jan 2007 13:56:29 -0500 horace r davis <hrd9 at juno.com> writes:
> I probably did not make my self clear the out side 2.5 inch are flat. 
> I started working on the center 2/3 I have increased my stroke to 
> over hang the edge by 1 inch trying to fix that I think will be a 
> problem. I ground for 1 hr and it seams to be working the center did 
> not deepen but the edge of the flat has moved out 1/2 inch toward 
> the edge.
> 
>