Re: [ATM] Favorite Spider Designs

[Daniel Fundo <fundo@bellsouth.net>]

<<  That's why I use two pieces of wire for my spiders - one piece makes
two of four vanes.  So, if there's one failure the secondary doean't
fall on the primary or the ground - it will only hit the cage. >>

I make 8 individual wires for my spiders.  If it works for bicycle
spokes, it should work for telescopes!!!  I make them on a jig, and
always make 2 extra, just in case.  "Just in Case" has never happened,
but I did change one out just to see how long it would take.  It took
less than 5 minutes, and alignment was close enough afterward that I
couldn't tell the difference.

I can move my telescope around using the sky end of the assembly and not
affect alignment.  If a wire/vane did break, there wouldn't be any
danger of pieces falling to the mirror, or of the entire secondary
coming loose.  Another point is that extreme tension on the wires
doesn't improve stability (do a vector analysis on it!).  I assemble the
whole thing just finger tight at the acorn nuts on the outside of the
UTA.

*****-----
Dan F.
Memphis, TN
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