[ATM] Sharpie Test , Mating Spheres Blank/Tool Query...

[hermit at outofoptions.org (Ken Lowther)]

The Sharpie test is a guide.  If the lines "grind away" you are good.  Make sure
your strokes are 1/3 total.  For 6 inch mirror that is 2 inch travel with 1
inch overhang per side.

Look very closely at the surface to see if it looks consistent in the 'frosting'
from center to edge.

ken

Quoting "Satish K. Pagare" <asatsi@yahoo.com>:

> Hi List,
>
> I am done with rough grinding for my 8" (planned F/6)
> and now moved onto #120. After a number of wets I
> did the Sharpie test on the blank. And the lines
> near the edges take longer time to go away. Basically
> Sharpie test failed. Going by my reference site
> at http://www.stellafane.com , if the lines at the
> edges are still there for sharpie test. Then I need to
> do more 1/3 center over center with MOT. But my main
> worry after doing quite a few wets, with MOT and 1/3
> center over center, I have already overshot the
> sagitta
> and the sharpie test is still failing for me.
>
> I just want to clarify my doubt here. Is it possible
> for me to do TOT 1/3 COC strokes and flatten my
> overshot sagitta as well as get the perfect mating
> sphericals of the blank and the tool?
>
> Thanks in advance you "Beautiful People" :)
> Regards,
> Satish/
>
> =====
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Hermit, holed up in Youngstown, Ohio