[ATM] Re: Second Thoughts on Mirror Support

[mikell at optonline.net (Michael Lindner)]

On Friday 06 February 2004 08:55 pm, Steve Houlihan wrote:
> Such is the nature of a mailing list I guess.  Never the less, I am really
> enjoying the discussion.

Me too. Welcome!

> ...This puts a 3.5 pound force into the mirror and another 3.5 pound
> force just 2 inches away in the opposite direction. 

I agree that you want the moment arm to be as small as possible, but I think 
your numbers are off a little bit. Yes, there are 7 inch pounds of torque, 
but the moment arm for each pad is about 7/8 (a factor of 
1.75/sqrt(1.75^2+1)) of 1/2 that or about 3 pounds. Furthermore, the force 
vector is at an angle, and the push component of that is about 1/2 (a factor 
of 1/sqrt(1.75^2+1)) or about 1.5 pounds. As usual, corrections to my math 
are welcome.

That's still a bit of bending force, but you'd have to do some finite element 
analysis to figure out what effect that would have on the mirror. Does anyone 
know if Plop can be coerced into doing this kind of thing?

-- 
Michael Lindner
http://www.starastronomy.org *** http://home.att.net/~mikel
http://www.atmsite.org *** http://www.atmlist.net