Conference warhed::astronomy

Re .0
>    1)  Is it cheaper to buy any of the Primary mirror kit materials out
>    	here in the US (living in Connecticuit).

It used to be, but I think the prices are nearer parity now. How much would the
materials cost in the US? I've just spoken to a UK supplier, and 6" blank +
tool would be about �38. If you're going to stick with plate glass, a 12" would
be around �100 and almost three times that if you use Suprax (Pyrex).

>    2)  Am I better off not making the primary at all and buying it in a sale
>    	over in the UK.  (note the reason for grinding my own is not for 
>        saving money ....but for the challenge, however a 14 inch mirror
>    	will take ton of grinding and may be totally non-cost effective, if
>    	not utterly frustrating).

You'd be lucky to find something in a sale, though it's not impossible...I did!
Grinding a 14" is *much* more of a challenge than a 6", and
 
>    3)  Has anyone gone down this avenue and had regrets, ie. The end
>    	result was lousy, It cost you arm & leg or you just never completed
>    	it etc...

I know a lot of people who've produced perfectly reasonable 6-8" mirrors, but 
gave up the attempt to make anything bigger. A friend of mine still has a set
of 16" (ish) blanks he bought about 15 years ago. After grinding his 9" he vowed
"never again". Maybe you should get in touch with him, he's probably open to an
offer!

		Ian G.

    Ian,
    
    Many thanks for your quick reply,
    You are correct about similar costs, but it appears a little cheaper
    here.
    
    Average cost for Eight inch blank/Tool plus abbrasives/lap kit
    ($40 dollars plate $109 Pyrex) given the 1.6 exchange rate tis a little
    cheaper plus you get all the grinding material.  
    However I then have to consider my carry on luggage on the way back!!
    
    Mirror coating it pretty resonable here too;
    $60 dollars for Enhanced Aluminum 92-94% reflective on an 8" or 
    $45 dollars regular AlSio 85% reflective
    
    I am certainly interested in your friends 16" blank if he still has
    it.  I guess I should try doing the 6-8" first though as I may be
    biting off more than I can chew!!
    
    Thanks again,
    
    John
     

    If you are dead set on grinding your own mirror, I'd definitely
    give some thought to doing a 6". You would gain a wealth of
    knowledge on the process and what's involved. After grinding the
    6" go the full distance and complete the rest of the scope for it.
    Having done this, you will have a much greater appreciation for
    the additional effort that would be involved in doing the same for 
    a 14" sized scope.
    Light years ago, in a far-off galaxy...er time, :-) I tried to grind
    my own 6" mirror. When I got done, I wasn't satisfied with the results.
    At the time (when I was in high school), I was a member of the
    Boston chapter Amateur Telescope Makers. They provided a lot of help,
    and without that help, I don't think I would have gone as far as I
    did go with the project. Since then, I've never had the inclination
    again to want to grind my own mirror.
    However, I don't wish to discourage you from trying. Just don't try
    a 14" on your first try. Work up from something smaller, so you can 
    develope the experience necessary to test your patience on a larger
    mirror the next time. :-)
    Good luck.
    
    
    Bob

    Thankyou for the advice Bob ....I am definitely going to start small
    plus I'm looking into amateur clubs for advice, support and sympathy
    when needed ;)
    Strangely enough, I was chatting to a chap today who belongs to the
    same club you did in Boston.  I am aware that there is somewhere in the
    region of 300 in the one club alone but you may know of him;
    
    			Marti Groffman
    
    He was telling me about a chap there who has been making primary
    mirrors for years and he now currently working on a 32" !!!
    
    I'll let you all know how I get on....
    
    Rgds,
    
    John.