Re: [ATM] PLOP Calculations

["Nils Olof Carlin" <nilsolof.carlin@telia.com>]

Scott,

> Thank you for the analysis of the edge support.  This is a topic I
> have been concerned about for a while.  PLOP is very nice but I think
> it leads to over-optimized back support without dealing with more
> serious problems that might arise from faulty edge support.

so do I....
>
> My most recent Dob cell used wiffle tree support for the edge.  Would
> you like to speculate about the best placement of support for this
> system?  The center of each wiffle tree was +- 45 degrees.

I'd suggest as evenly spaced along the lower half - at say +-30 and 60 deg
from vertical - it ought to balance the forces best, but until there is a
"PLOP" program to calculate edge supports, we don't know - the optimum
angles may be slightly different.....
>
> An alternative to the ubiquitous sling (which I don't like very well
> because it isn't clear to me that it positions the mirror precisely)
> might be two short slings. Consider three posts arranged at the
> bottom and +- 60 degrees of the mirror.  Now put a sling over the +-
> 60 posts and under the 0 degree posts.  The mirror would rest between
> the two slings.  This may be needlessly complex, but it would hold
> the mirror firmly in the XY plane.  It would be a two point support,
> but a slightly loose sling would give you continuous contact over two
> parts of the mirror's edge.

My ideas at:
 http://w1.411.telia.com/~u41105032/sling/threepart.htm
are not unlike yours here, I believe (I just uploaded that page, it isn't
linked from my main page yet).

Nils Olof


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