[ATM] help with 15"

[Shane LaPierre]

Jerry,

Have you tried Kriege's book for building Obsession-like telescopes?

It has step-by-step for building a solid mirror mount for the  
primary.  You would need steel (you could get from home depot), cutter  
(hacksaw & file are fine), a small drill press, some hardware, and  
find a local shop to weld it up.  I built one many years back, took it  
to a welder, and he did it for free when I told him what it was for.   
I did this when living in a small condo with very little room to  
work... so it can be done.  If you bought a mirror mount commercially,  
you would pay $200+ (I suppose) but I bet you could do the whole thing  
for 1/3 of that yourself if not better.

For mounting a secondary, consider purchasing the holder & spider.  I  
know this is an ATM list and sharing DIY methods is the point... but  
then again no reason to let your mirror sit unused because you can't  
build that part of your telescope well enough to your standard.  You  
can always go back later and build the parts that you purchased  
commercially if you really feel compelled.

Let us know what you're doing.  I'm sure you will get through it.

Now that I've typed this mail, it's clearer to me that wood-working  
skills are not really a perfect match for these 2 components of a 15"  
Newtonian.  Maybe you can build the majority of the scope, and  
consider "outsourcing" 1 or both of these pieces.  I bet that's what  
many ATMers do.

Shane


On Oct 10, 2009, at 9:55 PM, Jerry Hillman wrote:

> Hi all,
> I have not made an appearance on the list in a long time, although I  
> have been watching it.  My 15' mirror is still waiting, freshly back  
> from recoating 2 years ago.
> Every design I have tried for primary and secondary mirror mounts  
> has failed.  I have the ideas. I just lack the ability to execute  
> them.
> I need help with reliable designs, for primary and secondary mirror  
> mounts.
> Primary is 15" 1.5 inches thick, pyrex.  Secondary is 3.125 inches  
> minor axis.
> Both are excellent, and expensive, commercially made mirrors.
>
> With a few hundred thousand dollars, and qualified machinests to run  
> them, I could build the mounts I envision.  But my woodworking  
> tools, as good as they are, are not up to the task, so I need  
> designs I can build.
> Thanks, Jerry H
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