[ATM] Re: Mirror cells - some professional literature and ideasforamateurs

[SHO at SURFNETUSA.COM (Steve Houlihan)]

Thanks for the great links, Tom.

> 
> My $64 question:  Can I make whiffletree cells for large/thin mirrors
> that serve as both axial and lateral support...in other words combine
> the two functions of axial and lateral support in one mechanical
> structure.  

An attempt to combine the two into one is what started this thread.  When using a laterally supported whiffletree and bonding it to the mirror, that is exactly what you are doing.  In my case I got worried about the large moment applied to the back of the mirror.  John Anderson-Lee suggests using multiple spots of RTV to attach to a rigid plate.  This also combines axial and lateral support together.  Both of these schemes have been used many times and seem to work.  How good is the real question.

In the literature you reference, one seems to bore a hole in the back of the mirror so the mounting surface is in line with the center of gravity.  This has some promise.  Another uses supports that exert a force that goes through the CG and the other uses a center bonded mount that has counterweights to ofset the bending moment.  I admit I don't understand that one very well.

So, from this limited study of the problem, I suggest a whiffletree with a ball joint pivot that is forward of the mounting surface and resides in a recess in the back of the mirror.  Piece of cake!

I sure I can come up with a few more crazy ideas if I read some more.

Steve