[ATM] grinding with tool

[Jerry]

Continue grinding.

You want four things from your rough grinding work. 

1) the proper sag
2) the curve all the way out to the edge. 
3) all pits from coarser grit removed
4) the curve spherical as possible

In the beginning you mostly work for the sag. Then you add the requirement
to get the curve to the edge. Then the pit removal requirement is added and
then smoothing the curve to spherical. When all 4 conditions are met it is
time to go to the next smaller grit. 

In fine grinding you will also want those 4 conditions before going to finer
grit. But you will already be close to 1, 2, and 4. But you can get closer
at each finer grade of grit. Maintain those while meeting #3.

I think you are close enough to your desired sag that you can add some Tool
On Top work to spread the curve to the edge. 


Jerry


-----Original Message-----
From: atm-bounces at atmlist.net [mailto:atm-bounces at atmlist.net] On Behalf Of
horace r davis
Sent: Sunday, February 04, 2007 3:04 PM
To: atm at atmlist.net
Subject: [ATM] grinding with tool

I started grinding my 16 inch mirror. mirror on top which should deepen
center I have between .005 to .008 to go to reach .200
it appears most of the grind is in the outer 2/3 not in the center is
this because I have not reached truly spherical shape. Am using 1/3
stroke over center overhanging mirror by about 3 inches. the outer titles
have made contact first I cased the tool on top of mirror.
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