Re: [ATM] Small Dob truss question

[Scott Carson <scottcarson@austin.rr.com>]

Thanks to everyone for your inputs.  Now just need to decide whether I 
prefer the traditional truss or am willing to live with the "X" 
configuration tradeoffs  (dual plane, larger footprint, etc.). 

Thanks again.

Scott

 


Scott Carson wrote:

>
> I'm assembling a small 8" f6 dob and elected to use a truss tube 
> design to familiarize myself with the dob design characteristics.  
> Hopefully I'll someday attempt a larger one.
> My question... I'm curious why the traditional dob truss has the 
> paired tubes meeting at the top ring (secondary cage bottom ring) 
> verus having the tube pairs (two tubes on same side of mirror box) 
> cross in the middle (form an "X") and attach at the top ring with a 
> geometry comparable to tube arrangement at the mirror box? 
> Seems the "X" tube configuration would significantly increase the 
> rigidity for a small increase in tube length, and especially if the 
> tubes are physically bolted together where they cross (middle of the 
> "X")?  I've taken a quick look at the geometry I'm evaluating for my 
> 8" (secondary cage 8.5" IN x 11" OD) and didn't see problems with the 
> truss poles crossing into the light cone.
>
> But given I'm inexperienced in this area, I suspect I've missed 
> something.  Appreciate hearing from others that have already explored 
> / answered this question.
>
> Thanks
>
> Scott
>
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