Re: [ATM] Help with Strut Flexure in my 3 Truss DOB

[Tom Conlin <tomc@cs.uoregon.edu>]

not crunching any numbers here but with the smaller diameter tube
the thickness may be a liability. a larger diameter thinner wall
tube is the surest way to improve the stiffness in your 3 pole design.

if the tubes you have are going to stay,
perhaps non stretching tension members (cords) from the tops of each tube
to the bottom on the opposite side if the mirror (in both directions around)
would improve stiffness .
pro:  would add little weight
       would form a truss
con:  different expansion than tubes may cause OTA warping
       cords may obscure mirror
       change the look/simplicity of the scope

RP Sutton wrote:
> Hi John and Mike -
> 
> the scope was built on designs but Albert Highe - please see here:
> 
> http://pw2.netcom.com/~ahighe/home.html
> 
> I have emailed him asking for help as well but I have not heard back from him 
> yet. the three single pole design has worked succesfully in may scopes just not 
> mine and I cannot figure out why.
> 
> Thanks again -
> 
> Patrick
> 
> 
> On Thu,  1 Jun 2006 17:29:21 -0400, John Sherman wrote:
>> Hi Mike,
>>
>>> As I understand it from the original message, there are only
>>> three (nearly parallel) tubes supporting the upper cage,
>>>
>> That's how I read it, too.
>>
>>> not actually trusses, they are simply cantilevered beams.
>>>
>> Ya beat me to it! As a solution I would add poles or strings at
>> diagonal points to make trusses. That would keep the original
>> structure intact.
>>
>> John
>>
>>
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-- 
           ... nice weather     eh          tomc@cs.uoregon.edu

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