Re: [ATM] 6-pole

["Scott Ewart" <scotte@frontiernet.net>]

Thanks Rob,
	No, the wood tube clamps were NOT easy to make.  I had to learn
enough of a CAD program to virtually build the truss assembly in 3D, then
have it tell me the angles I needed to drill.  Since the top and bottom ring
diameters were different, so were the sets of blocks.  I needed to know not
only the departure from vertical, but also the horizontal departure from
straight, i.e. inward toward the center.
	Fortunately, my friend's mill had the necessary tooling to find
these angles.  I too considered Moonlite hardware, but I wanted to do it
myself.  And I would think they weigh more than my clamps, but oh, how
simple it would have been.

Scott

-----Original Message-----
From: Rob O'Toole [mailto:albireo13@comcast.net] 
Sent: Wednesday, April 09, 2008 6:05 AM
To: Scott Ewart
Subject: Re: [ATM] 6-pole

Scott,

    Nice scope !   Very clever engineering and metalwork.
Funny, bit I like your wood tube clamps.  Were they easy to make?
Looks like you used 1" thick pieces of birch ply for the UTA tube  
clamps.
I may try this.
   I seem to be getting hung up mostly on how best to do the upper  
and lower tube clamps.

I've looked at just buying Moonlite ball/socket tube clamps but they  
are not cheap and they are
bulkier than I like for the UTA.


Rob

On Apr 8, 2008, at 9:43 PM, Scott Ewart wrote:

> Rob,
> 	I built my 12.4" split ring using 6 poles.  It saves weight, it fits
> better with my three-vane spider, and with my round "bucket"  
> allowing a
> rotating tube, there are no mounting point issues.  Looking in the  
> front
> end, "down the barrel", you can easily see what Richard refers to.   
> It's
> much more striking than with 8 poles.  The tubes appear to "bend"  
> inward as
> they cross by the aperture, so you do need to account for that in your
> design and be sure there's enough room in between the middle of the  
> 6 poles.
> 	Alex also brings up an important point about a shroud.  Keep in mind
> that at each end of the scope,  there are essentially only 3 points
> supporting the shroud, allowing it to cross into the light path.  I  
> solved
> this by adding 6 strings (ultra-thin bungees) between the poles.   
> If you're
> looking for quicker set-up time or simplicity, this may complicate  
> things
> too much for you.
> 	I've had mine a few years now and still haven't tired of any of the
> complications.  I really love the scope.  It's up to you.
>
> Scott Ewart
>
>
>


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