From: "Tom Krajci" 
To: 
Reply-To: "Tom Krajci" 


>From: "J&S" 

>> is the best approach to holding the
>> mirror - silicone caulk?

In most cases there is seldom one best approach.  It depends on your
performance goals and design approach, and multiple approaches may meet
your needs.

RTV silicone *can* work.  All my ATM secondary mirrors have been held that
way.  All my ATM main mirrors, up to 16 inch (25 pounds) have been held
that way too.  (The converse is true...if you are sloppy in technique and
application...silicone *won't* work.  You can say this about practically
any mirror mounting method, or any ATM technique.)

>...(FYI Bob: There have been heated
>discussions on the list about the pro's and cons of gluing optics to
mounts
>on and off for years - there are the dyed-in-the-wool mechanical types,
and
>there are the sili-cone-heads.)   :O)

And then there are those non-dogmatic types that apply an appropriate
technique, not because it fits dogma...but because it provides the
performance they need.  As I learn more about mirror cells and mounting
mirrors...in certain future designs I may use something other than RTV
silicone.  No guilt, no remorse...only better performance.  ;-)

>...Okay, I'll bite:  I would never glue an optic I wanted to use for
high
>resolution - over one or two inches anyway, but that's my preference
and >the way I do stuff. Others differ, and that's fine. (I think most
folks
>agree to disagree.)

This is an example of style over technique.

Style is often dictated by non-rational factors...personal taste, public
opinion, habit, etc.

Technique is often driven by an objective assessment of methods versus performance.

Style does not necessarily guarantee performance because that is not the
first consideration.

Technique is aimed squarely at performance...whether it is maximizing it or
'satisficing' it.

As you become more interested in objective assessment of performance...you
will find yourself more and more concerned with technique.  Style will
gradually fall off your radar scope.

As you use technique more, you'll be less likely to say things like
"...that's my preference and the way I do stuff. Others differ, and
that's fine. (I think most folks agree to disagree.)"  Instead you'll
say things like "...based on experience/analysis/etc....this approach
will meet my performance goals.  (And perhaps this other approach will also
meet my performance goals, etc. etc.))

There is a great deal of opinion spouting on this list, and not enough
digging for objective evaluation of techniques and performance.  Sadly,
that leaves this list (and ATM websites) often sounding like 'on-line oral
tradition' instead of the 'valuable resource of ideas, principles, and
techniques' that could be possible.

Have a good weekend!

Tom Krajci
Tashkent, Uzbekistan


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