Re: [ATM] 10" sonotube vs. truss

["B. Bainbridge" <brianb@u.washington.edu>]

You might also think about two tube "trusses", for example:
http://www.atmsite.org/contrib/Ravneberg/alice/

On Thu, 10 Nov 2005, Ross Sackett wrote:

> --- Mike Shuken <mikeshuken@value.net> wrote:
>> ,,, I will be using a 10" f/5
>> mirror.  I know that I can
>> build it using a sonotube, but would it be worth the
>> effort to build a
>> truss design instead?
>
> Mike,
>
> I think you have correctly anticipated the tradeoffs
> here.  The sonotube 10" will be heavy--my 10" f/5 OTA
> came in at 70 lbs., even with a thin tube.  But the
> truss is much more work to build, and can be
> frustrating if not made with precision (so yes, plan
> to put in more time).
>
> If you decide to go with the truss, remember that in
> general the smaller the aperture the higher the center
> of gravity.  If you are building an Obsession-class
> truss dob, you will need to make the mirror box deeper
> than on a bigger dob.  You might also find, however,
> that at the smaller aperture the weight difference
> between sonotube and truss aren't significantly
> different.
>
> For an alternative truss design that works well at
> this aperture see Barry Leger's article in S&T
> (December 2000) or Google his name to find a number of
> scopes based on it made by others (I used to have the
> URL of a pdf of his article, but I can't find it).
> Barry's design looks like an easy build and can be
> marvelously compact.
>
> Ross
>
>
>
>
>
>
>
>
> __________________________________
> Yahoo! Mail - PC Magazine Editors' Choice 2005
> http://mail.yahoo.com
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>
_______________________________________________
ATM mailing list http://www.atmlist.net/