Re: [ATM] Ronchi interpretation and corrective action for highzoneatedge

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

-----Original Message-----
From: Jerry
To: 'Polk, Tom'; atm@atmlist.net
 

Since you have that area in the center that is not quite polished, It might
be a good idea to stick to MOT to work the center quicker. But it might be
just as good or better an idea to continue what you are doing and see if the
crest keeps going to the edge. Since it is slow, maybe by the time you have
fully polished it will be pushed off the edge and you will no longer have a
turned edge.

***********************



I have reconsidered that advice. I was concentrating to much on the Ronchi
description and so missed the most reasonable choice here.

The center is not polished out. And the shape is the oblate with the crater
in the center. So it is reasonable that the unpolished area is in the
crater. The oblate shape is from the center area (the wide hill) not being
worn as quickly. 

You really do not want to finish the mirror and not be fully polished out.
And certainly on a first mirror there is a chance of doing that.

So to work the center more and bring it along to catch up with the polish
farther out, I would say that MOT is the thing to do and get the wide hill
worn down and that will take care of the central 2" unpolished area too.

You did improve the shape, and the edge just slightly with that last work,
and that is nice. But your foremost mission right now should be to get it
polished. MOT will do that for you. And as Mike has said, it would be better
to have it less oblate, so as you polish adjust your stroke to bring it more
spherical. There are little w's and there are big W's and in between. Adjust
the scale of your W stroke to get a sphere.

Don't trust anything I say. I'm self taught with Texereau's and the ATM 1,
2, and 3 books as guides. I could have missed a lot. I present my logic so
it can be questioned and corrected. I like to hear what others think or
know.

Jerry


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