From: "Tom Krajci" 
To: "'Benjamin Robbins'" ,
         
Reply-To: "Tom Krajci" 


>From: Benjamin Robbins [mailto:benjaminr{at}highwire.com]

>We were planning on using cloth attached with Velcro to the secondary
for
>baffling...have you had any experience with that?

Only experience with setups like:
http://overton.tamu.edu/aset/krajci/dobsonian/dobsonian.htm
As long as the geometry is worked out, this system can work very well.
Black velvet is darkest, but flocking paper is very good, and even flat
black paint will work reasonably well.

>We are noticing some truss droop when the scope is in the horizontal
>position, it does go outside of the 3 ring binder circle we have placed
in
>the center of the mirror.. Any ideas on corrective measures?

A.  Reduce weight in the upper ring.  (Anything lighter than chains you
could use?  Cables?  Kevlar string?)

B.  Increase stiffness of the chain system...to include stiffness of the
fastenings to your plywood.  Would some bracing help here?

C.  Widen the stance/spacing of your chains.  Move the attachment points as
far apart on the scope's mirror box...maybe even modifying the attachment
points so that the chains are held a couple inches beyond the edge of the
mirror box...as long as the attachment points are stiff.

Tom Krajci
Tashkent, Uzbekistan

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