[ATM] Tubing for Trusses

[kurt.clement at flashmail.com (Kurt Clement)]

Torquil,
In reference to your 4.5" truss tube scope question.
Paul LeFevre has a description of his 6" travel scope truss dob on the web 
which is the idea I am working toward.  His well illustrated web site is at:
http://www.lefevre.darkhorizons.org/tvscope/travelscp.htm

Paul indicates that he used 1/2" Al trusses, but not the type of 
tubing.  As someone suggested to me in response to this thread, wooden 
dowels or strips could be used for a small size scope.  For either of the 
4" or 6" sizes perhaps a system with only two tubes could work well.  There 
are several on the web.  The key would be to use larger tubing diameters to 
gain the stiffness needed with only two tubes.

Kurt Clement
Nixa, MO



At 03:33 AM 2/6/04 -0700, Stuart Hutchins wrote:


>----- Original Message -----
>From: "Torquil MacCorkle, III" <torquil@chemist.com>
>To: "Stuart Hutchins" <stuart452@earthlink.net>
>Sent: Thursday, February 05, 2004 10:01 PM
>Subject: Re: [ATM] Tubing for Trusses
>
>
> > Hello,
> >
> >     I am currently trying to build a 4.5" truss tube scope, can you give
>me
> > some websites with info on how i should do it?
> > I have yet to find any websites with real info about build a small truss
> > tube 'scope.
> >
> > Thanks,
> > Torquil
>
>Hi Torquil,
>
>Well, the truss tube designs for amateurs came about with the bigger
>Dobsonians, with 12 to 20 inch mirrors, in the late 1970's. and early 80's.
>The whole purpose was to make these bigger scopes portable, because a big
>solid tube is heavy and doesn't fit in a car.  But the truss is more
>complicated and harder to set up.
>
>Size 4 to 6 inch mirrors were common before the 70's.  An 8 inch was a
>biggest scope most people made, and all the tubes were solid cardboard, wood
>or metal because it is easier to build that way.  That's why you don't see
>designs published for small trusses.  If you really want a 4.5 inch truss
>tube to carry in your day-pack, you'll probably have to scale down a larger
>design.  The balance point, though, will wind up near the middle, not down
>near the mirror.
>
>I'd check out some older classic books.  Build Your Own Telescope, by
>Richard Berry is one.  Making Your Own Telescope, by Allyn J. Thompson is
>another.  Surf to SkyandTelescope.com or Astronomy.com or Willmann-Bell.com,
>or visit a library.
>
>http://www.atmsite.org/  is one of the places I started surfing from.  Do a
>Google search for Amateur Telescope Making.
>
>BTW,  your e-mail came only to me.  I think to reply to the ATMList, you now
>have to use "Reply All".
>
>Have fun,
>
>Stuart Hutchins
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