Re: [ATM] starting grit size

[Jonathan Lavoie <atm@lavoielactee.net>]

----- Original Message ----- 
From: "Greg Jones" <gregj888@comcast.net>
To: <atm@atmlist.net>; <atm@lavoielactee.net>
Sent: Friday, April 15, 2005 11:59 PM
Subject: Re: [ATM] starting grit size


> Jonathan,
>
> I'm sure I am coming into this late, but why are you grinding at all?

You're not too late, you are the only to reply!

> Assuming a classical Gregorian you need very little figuring to change the
> parabola to the Hyperboloid of the RC, just a pitch lap.
>

Two reasons I have to grind. First is that I will begin with the secondary
because this is the hardest part to accomplish. Then I will optimize the
primary to match what I've done on the secondary. Second reason is that I
have tini scratches on the primary that I didn't remove in the first time.
My curve was so perfect that I decided to live with those scratches. Now I
have e reason to remove them :)


> If you have too grind, I would probably start with 120/220 grit... but
then
> again I would be hard pressed to grind at all.  If the issue is design,
send
> me the ROC of your current primary and your final desired effective focal
> length and I can give you a starting point.
>

I have 220 on hand. So I will not have to buy other grit, good news!
About the desing, Richard is helping privately right now. I'm at final
tweaking right now.

Thanks Greg,

Jonathan

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