From: "Jim Miller" 
To: "Russell Jocoy" ,
,
        
Reply-To: "Jim Miller" 


all explained in gory detail on the website. in short...no flexure due to
overkilled connections...

take a look at www.jtmiller.com and ask any questions.

jtm

----- Original Message -----
From: "Russell Jocoy" 
To: ; ; 
Sent: Thursday, July 24, 2003 8:46 PM Subject: Re: ATM Truss design thoughts.


>From: "Jim Miller" 
>To: "Russell Jocoy"
>,,
>Subject: Re: ATM Truss design thoughts.
>Date: Thu, 24 Jul 2003 08:52:02 -0400
>
>i used a $10 surplus aluminum alloy bicycle road racing rim, some bits of
>aluminum, hacksaw, drill and handfile to make my secondary structure.
>www.jtmiller.com
>
>jtm
>



("atm{at}shore.net")

      Jim,
  This is a fantastic idea and right  down the ATMers roadway.   But how
have you made connections?
If they are bolted or riveted, they will flex, and thus we are back to
movement. I feel that this felx is only critical in large mirrors, since
the truss system needs to be longer. When dealing with extended truss &
cage systems I would think that welded joints and connections would be less
apt to flex.
I may be wrong but I have a little engineering know how and welds do flex
but only with temperature.
Once the weld is made, it is usually stronger than the metal itself... This
is only my opinion..


                                               Russ Jocoy
("atm{at}shore.net")
>----- Original Message -----
>From: "Russell Jocoy" 
>To: ; 
>Sent: Wednesday, July 23, 2003 11:00 PM
>Subject: Re: ATM Truss design thoughts.
>
>
>
> >From: Clive Milne 
> >Reply-To: Clive Milne 
> >To: atm{at}shore.net
> >Subject: Re: ATM Truss design thoughts.
> >Date: Wed, 23 Jul 2003 10:14:26 -0700 (PDT)
> >
> >
> >
> >"John Sherman"  wrote:
> >    Thus I think
> > > that the upper and lower trusses can be made out of
> > > much smaller diameter tubing saving a lot of weight.
> > > Anybody have any thought about reducing the left and
> > > right truss diameters?
> >
> >    Tom K has done some interesting research on various different
> >truss configurations and has posted real performance data on his
> >web page (absolutely worth reading).  One comment I will pass though,
> >and this is not to be implied as criticism of Tom's work, is that
> >asside from any conclusions that you might draw from the _RELATIVE_
> >performance of any given truss, be mindful of the _ABSOLUTE_
> >deflection values given (even in the worst case).
> >From this data and the experimental work of myself and others, we
> >can conclude that a (properly designed) truss made from tubes of a
> >diameter sufficient to resist buckling, will be plenty strong enough
> >to make a supremely rigid telescope.   ie) For a 20" telescope,
> >anything larger than 3/4" (19mm) is just a waste of materials.
> >    So to answer your question. Yes, by all means reduce the
> >diameter of ALL the truss tubes. (3/4" will be fine) If your scope
> >still vibrates, I'd wager it's not the truss tubes at fault.
> >It might be time to take a good hard analytical look at the whole
> >design from the ground up.  Just because everyone has built them
> >basically the same way for for the last 15 years doesn't make it right.
> >It's high time we moved on.
> >    ~Clive.
> >
>
>
>
>("atm{at}shore.net")
>
>            Here, here.... I agree, How can you blame vibration on supports
>when you are using
>primative secondary cages made of wood and rocker boxes of thick Plywood.
>But at what cost are
>you willing to go to more exotic materials?  Most ATMers are on a budget
>and
>are ready to deal
>with these inperfections of design. Hey we all want the best but sometimes
>the wallet (or wife) makes
>us settle for a little less than our dream.  Just a thought.. I would love
>to have a Jaguar automoble but
>I own a Dodge Caravan.. dratt.....
>                             Russ J.
>
>("atm{at}shore.net")
>        Russ J.
>("atm{at}shore.net")
> >__________________________________
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