Re: ATM 12 point mirror cell - examples

["Tom Krajci" <tkrajci@san.osd.mil>]

From: Ross Sackett <rsackett00@yahoo.com>

>Oh, ugh.  Both cells look a little nightmarish to me,
>especially the one with the long springy outer
>triangles. 

That's why I asked for feedback and comments.  ;-)  Yes, the skinny
triangle idea is not good for more than one reason (Nils mentioned
another reason).  I've since updated more info and diagrams to my page
at:
http://overton.tamu.edu/aset/krajci/cell-12-pt/cell-12-pt.htm

>Wouldn't a PLOPed Hindle-style
>("Hitler-era") 16 point cell be simpler to build and
>support the mirror better?

Hopefully my examples (with help from Nils) show more practical
applications of a 12 point support that are not difficult to build -
only beams in some examples.  Easier to build than a Hindle 18 point
support?  Actually it looks, in terms of moving parts and
arrangement/layering of them...to be identical...just that it uses 12,
not 18 points.

Will it support better?  I'll let PLOP answer that.  

>Since when did support points become an endangered
>species in need of such radical conservation?  I
>remember a thread a couple of weeks ago about the
>macho  appeal of building the ultralightest ultralight
>on the observing field, inviting a lot of hemming and
>hawing about other reasons to build the beautiful
>creatures, too (low wind resistance, lone-nerd
>portability, etc.).  

My main goal here is to go through a design exercise and learn how to
design better mirror cells.  (Actually, for my 16 inch CCD scope...I
only need a six point support for a 1.5 inch thick mirror....but some
day I'll scale up to a larger mirror, and then I'll need more support
points, with more layers of pivots.)  If you want to...you can think of
my webpage as a design sketchbook that I'm making public...warts and
all.  As my knowledge gets better, I'll make improvements to the
webpage.

As I stumble through this process I'll try and strike a balance between
complexity of the cell, and number of support points.  I will not put
the design criteria of 'absolute minimum of support points' above
mechanical simplicity of the cell design.  (Although I'm not afraid to
design an asymmetric cell that may look strange at first glance.)

>Ok, I guess I finally need to build that one-masted,
>carbon-epoxy 18" with the 5-point cell and
>teflon-sheet groundboard I've been designing :)

Got any diagrams you care to share with us?  ;-)

Tom Krajci
Tashkent, Uzbekistan
 

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