[ATM] New Tool?

["John K. LaShell" <grace.community@rcn.com>]

Hi, Everybody.
I'm working (slowly) on a 12.5" alt azimuth Gregorian. I plan for the focus to come out through the altitude bearing. I am almost done rough grinding with a tile tool. (I had to put a second layer of tile on it a while back.) Here is my question. The tool is 9.5 inches in diameter. Should I keep on using it or should I make a new tool the same diameter as the mirror? If I use the 9.5 inch tool, what kind of stroke should I use to get a spherical surface without a turned down edge?
John LaShell
P.S. The reason I'm making a Gregorian is that I don't want to attempt a convex secondary such as a Cass. uses.
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