Re: ATM 3" Surplus Shed Project Up-Date

["Great Goo" <greatgoo@baysidenet.net>]

I have a couple of those mirrors and they are very nice.
I wondered about some way of combining them to form
and 3" f20 device. Never could get it to work. Now I am
working on a parallel tube mount for an odd pair of 
astro binoculars using those mirrors.

I have found that many of the ready made optical
components are matched by plumbing parts. I made
a focuser tube from 1.25 chromed drain nipples and
PVC drain line. The nylon seal rings make a very smooth
draw bearing. Once i get it set I tighten the nut and I'm
there.

I made a little refractor from a surplus Achromat from
the Surplus Shed and some plumbing parts. I have used
it with a 4mm piece, where it is used with difficulty, but it 
is best with a 10 mm eyepiece. Good field of view.

BTW: A 3/4 inch slip copper coupling is perfect for a .096
focuser, if you make your own eye pieces.

David

----------
> From: Joe Mayenschein <mayen1@mwt.net>
> To: ATM! <atm@shore.net>
> Subject: ATM 3" Surplus Shed Project Up-Date
> Date: Monday, December 18, 2000 4:10 PM
> 
> 
> 
> 
> Ok the mirror just left the test stand, and I was
> quite surprised. As specified it is a f-10 sphere.
> And a very nice one I might add. Both using  standard
> foucault it greys evenly and completely with no trace
> of   err. well anything.  And using the ronchi rulings
> set all lines are perfectly straight and parallel in
> all positions and number of lines.
> 
> I then removed it from the cell and measured the
> thickness and it's 3/8ths thick so that's a 8 to 1
> ratio in the thickness department..
> 
> So i guess it's thick enough. The way the mirror is
> held in the cell is quite cheap but it works.  The
> cell is made of a plastic pipe looks like black ABS It
> it ever so slightly larger than the 3" mirror. This
> extra slop is taken up by them wrapping the mirror is
> several turns of a yellow paper. the ring that
> surrounds the mirror is ever so slightly thicker than
> the mirror. the same bolts that are the collimanation
> bolts are also used to hold the mirror in place..
> hhmm,, it's hard to describe,, I'll get the web page
> made with some close-ups.
> 
> But optically the mirror looks excellent a better
> sphere than I ever remember making he he he.
> 
> Joe
> --
> Ridgetop Stargazers
> http://clubs.yahoo.com/clubs/ridgetopstargazers
> 
>