RE: [ATM] Grinding questions

["Nate Jones" <njones@newlintech.com>]

As far as the Celestron 8" Schmidt-Newt, it is not going to be an easy first
mirror.  8" f/5 - f/6 ratio would be better.  If your goal is to improve the
optics, lose the corrector plate and make the best parabolic mirror
possible.  Of course this means replacing more stuff (tube, secondary, etc.)

If you call United Lens, ask for Ken Plouffe at (508) 765-5421.

What to ask for?  A standard 8" Pyrex blank would be fine.  Curve
generation?  I would not bother on a small mirror, but if you want to spend
extra money to save a couple days of rough grinding, have the manufacturer
pre-generate the curve.  The edge will have a slight bevel from the factory
but you will need to bevel the edge a little more with a whetstone and
continue to occasionally through grinding.

Making a telescope mirror can be challenging, requiring perseverance but
very rewarding in the end.  There are plenty of people on the ATM list
willing to help you through the process.

--Nate

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
John Stephen
Sent: Friday, October 08, 2004 12:03 PM
To: 'ATM List'
Subject: Re: [ATM] Grinding questions

What sort of things will places like this need to know, or more 
specifically, what do I need to ask for?  I feel a little intimidated about 
approaching a serious manufacturer like this (or any others suggested by the

group) since I'm just a beginner ATMer.  I'm sure I'll have to know what 
type of glass, the diameter, and the thickness, but how do I ask for an 
initial curve?  ATMer's call it hogging out, but what do the professional 
optical shops call it?  Will they want to know the desired F ratio or SAG or

what?  Also, are there any services I'd be wise to ask specifically for such

as edging?

In case you can't tell, I'm a mild sociophobe which is why I'm going at this

'alone' with only the web, books, and this group to guide me.  A couple of 
months ago I contacted RF Royce about simply making a finished mirror for me

and he declined to make it.  I felt pretty awful about having someone judge 
me as unworthy of their services (or quality) and don't want a repeat of 
that.  Of course that was sort of a blessing since it put me on the path to 
making my own mirror which has been pretty cool so far :-)

Thanks,
- John
----- Original Message ----- 
From: "Nate Jones" <njones@newlintech.com>

> I have used (3) United Lens Co. Pyrex blanks and they turned out fabulous.
> I have also heard that Willman-bell kits are nice because they give you 2
> blanks (one as a tool) so you could make a plaster tool and then you could
> make 2 mirrors (binocular scope??) ;)


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