Re: [ATM] Help with TDE

[Mike Lockwood <melockwo@uiuc.edu>]

Hannes,

Hannes van Niekerk wrote:
> I am a novice in the ATM game, busy with my first project,
> a 203 mm f6.2 (at this stage) mirror. I went through the
> grinding and polishing stages alone, based on what I could
> learn on the internet. The first Foucault test was not too
> far off the mark, so I thought, well this is going to be
> plain sailing. Well I must have missed some vital piece of
> information, as I now have a mirror you can scare the kidds
> with. Can someone please point me to an article that will
> help me, step by step, to correct a horrible edge, even how
> to return the mirror to a sphere again and start the
> figuring all over.

Well, we'll need more information about what happenned.

What did you do just before you noticed the edge issue?
What was the figure of the mirror before this happenned?
What strokes did you use and for how long, with what type of pressure? 
  How hard is the pitch - I usually ask how long the channels take to 
close under normal polishing to quantify this.
Can you post images and Foucault readings?

Not sure if my figuring page will help, but here's the link:
http://bi-staff.beckman.uiuc.edu/~melockwo/mirror_making/full_lap/full_lap.html


Everyone,

I had a very lucky friend/mirror making student finish his 6" F/6 
mirror in two figuring steps last night, starting from a fairly good 
sphere.  The pitch was fairly soft.  I hope to add that mirror as an 
example to the end of my figuring page, right after the 6" F/6 that 
took me four figuring steps.  :)

We even got to observe Saturn (without freezing our rears off) and a a 
few moons through my 10" F/5.5 scope between figuring spells.  An 
excellent evening overall.

	Mike Lockwood


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