Well I was going to experiment with a truss made out of 12 large salamis wrapped in pasta for rigidity, but I'm afraid I would get hungry and eat my telescope. Cast concrete sounds like the way to go.
As a side note. Many laser collimators are out of alignment themselves. Both of mine required adjustment before they were of any use.
-------------- Original message --------------
From: "Michelle Stone" <litebkt@No-Spam>
> Personally, I feel that the stiffest arrangement is a steel
> reinforced cast concrete tube. I think that you could reduce your
> tube flex by at least half with this material.
>
>
>
> Michelle
>
> On Thu, Mar 13, 2008 at 8:01 PM, wrote:
> > Certainly triagluar cells would be stiffer, but that doesn't mean that
> parrallel tubes aren't stiff enough.
> >
> > We can speculate all we want, but until we measure what's happening, we won't
> know.
> >
> > That also brings up the question of what's stiff enough. How stiff does a
> telescope need to be for visual use, etc.
> >
> >
> > -------------- Original message --------------
> > From: "Richard Crisp"
> >
> > > the truss tube designs I have seen on the typical dob aren't structurally
> > > very rigid from twisting
> > >
> > > parallel tubes just have that property
> > >
> > > triangles arranged properly are far stiffer
> > >
> > > might that be it?
> > >
> > >
> >
> > > ----- Original Message -----
> > > From: "Michelle Stone"
> >
> > > To: ; "The Astronomy Connection"
> > >
> > > Sent: Thursday, March 13, 2008 7:47 PM
> > > Subject: Re: offlist Re: [TAC] Collimation question!
> > >
> > >
> > > > How much is it moving Mark? I've noticed in most dobsonian designs
> > > > that there is a combination of reasons that add up to some flex in
> > > > collimation. (Yes, even on the scopes that I build). No system will
> > > > be perfectly rigid. The key is to not let it interfere with the
> > > > views. So it at least needs to be stiff enough to provide pleasing
> > > > images for the majority of cases. If you collimate at the 60 degree
> > > > mark, then you are pretty well covered for most of the observing
> > > > range. You rarely observe down parallel to the earth... that's where
> > > > you want it to be the worst.
> > > >
> > > > Michelle
> > > >
> > > > On Thu, Mar 13, 2008 at 7:43 PM, Mark Wagner
> >
> > > > wrote:
> > > >> Richard Crisp wrote:
> > > >>
> > > >> > the sling type cell support seems to be hard to guarantee to not move
> > > >>
> > > >>
> > > >> Its not in a sling. The mirror is a conical, center bolted, onto a cell
> > > >> that has six support
> > > >> points to the OTA. Its seems very securely mounted.
> > > >>
> > > >>
> > > >> --
> >
> >
> > > >> GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
> > > >> Who's observing where? - http://observers.org/OI-calendar/
> > > >> Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
> > > >>
> > > > --
> > > > GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
> > > > Who's observing where? - http://observers.org/OI-calendar/
> > > > Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
> > >
> > > --
> > > GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
> > > Who's observing where? - http://observers.org/OI-calendar/
> > > Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
> > --
> > GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
> > Who's observing where? - http://observers.org/OI-calendar/
> > Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
> >
> --
> GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
> Who's observing where? - http://observers.org/OI-calendar/
> Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
--
GSSP Web Page updated 3/4/08: http://www.goldenstatestarparty.org
Who's observing where? - http://observers.org/OI-calendar/
Mailing list preferences: http://seds.org/mailman/listinfo/sf-bay-tac
Received on Thu Mar 13 21:19:39 2008