RE: [ATM] overshot sagitta correction stroke

["Jerry" <wa4guu@verizon.net>]

I know what you mean. But .....!
 
	It would stand to reason the same holds true with the tool as the
mirror. It has more area on the outer zones to wear to make the mating
shorter curve. Shouldn't it be equal work to go either way? To shorten the
radius would have the same sum of tool and mirror glass removal as going
back to the starting longer radius. That is one reason I feel it is more
perception than reality that 50-50 MOT-TOT doesn't hold the radius stable.

I haven't missed the ROC by much so just work them back to what I want
rather quick. The next time I do one on a full sized tool I will test my
idea that most all the change "appears" in the first wets of a finer grit
and that once the surface is finer 50-50 will actually hold the ROC while
continuing with the same grit. Maybe tile vs. glass makes a difference. 

Might be a while before I find out. I think my next grinding project will be
a 16". I might use a full size tool but probably not.	

Jerry 

-----Original Message-----
From: Ken Hunter 


--- Jerry <wa4guu@verizon.net> wrote:

> Either there is an error of measurement (on the long
> side) when on rougher grits, or just a tendency for
> the radius to get shorter even with 50-50 MOT TOT. 

50/50 won't work very well... There's a lot more area
in the edge zones and it takes 5-10 times longer to
change the radius (by the same amount) when working
the edge TOT...

Keep at it, it'll eventually show some progress.




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