From: "Mike and Sara" 
To: 
Reply-To: "Mike and Sara" 


Hello!

    No, I don't use her method.  I just wanted to point out that in
experienced hands, her method (or John Dobson's method, as she ascribed it)
can yield good mirrors.  Of course, with lots of mirrors under one's belt,
a lot of mirror making can become feel, which seems to be what she was
describing.  After so many mirrors, she had developed the experience to
know how much to deepen the center during final fine grinding, during
polishing, etc.  Me?  Nope, so I'll stick with the foucault test, star
test, etc.  Best regards.

Mike

----- Original Message -----
From: "Jerald F. Wright" 
To: "Mike and Sara" 
Cc: 
Sent: Sunday, December 22, 2002 3:30 PM Subject: Re: ATM HELP! mirror
making crossroads


>
>
> Mike and Sara wrote:
>
> > Hello!
> >
> >     I met Jane Houston Jones, president of the Astronomial Association
of
> > Northern California, last year, here in Alice Springs for the Leonids
> > observation.  I was in the midst of grinding my fist 4.25 inch mirror
for my
> > children.  I described my frustrations with the grinding and polishing
> > errors I encountered, since no one else in my club makes their own
mirrors.
> >
> >     Anyway, she described her long career of making mirrors with the Jon
> > Dobson method.  She described herself as a tele-evangelist, an
evangelist to
> > get people to use their telescopes.
> >
> >     She described how she made 10 inch mirrors in a day, 4 hours to
rough, 4
> > hours to fine grind, and 4 hours to polish.
> >
> >      When I asked her about testing, etc. to make sure of the figure,
she
> > said she regularly obtains 1/4 wave optics by slightly deepening the
center
> > during the final stage of fine grinding, then polishing and star
testing!
> >
> >     To me, as a Newbie, such skill is far down the road, but I can
> > understand the letters to date about the philosophy of John Dobson about
> > getting making telescopes to be used.  Jane's comments underscored to me
> > what a skilled worker can do, though at my newbie level, I want as many
aids
> > as I can, both to ensure quality optics, but also to learn, and perhaps,
> > just to have fun with the hobby or mirror making.
> >
> > Best regards,
> >
> > Mike
>
>
>
>     I suggest you forget everything she said if you want to make telescope
> mirrors. Her method is ridiculous.  Was it the first of April that you
talked to
> her?
>
> Jerry
>

--- BBBS/NT v4.00 MP