RE: ATM Truss Tubes - Flare Fittings are superb!

["Bertapelle, Ken" <Bertapelle.Ken@tci.com>]

Kurt, Paul, et. al.,

FWIW, my opinion is based on observing what's doing the holding of the
bottom ends of the tubes in the two cases.  Using the compression inserts,
the tube is held by: 1) the flared sides of the inserts  pressing against
the insides of the tubes; 2) the threads of the machine screws that run
into the inserts; and 3) the bottom perimeter of the tube being held 
against the blocks.

Using the Obsession style clamping blocks the tube is held all around its
circumference by the close fitting hole that accepts the tube.  The mating
surfaces are between 2 and 4 inches deep, depending on the size of the 
blocks.  The clamping surface is about 1/3 this length.  

Imagine holding a tube in your hand using the two different styles of
attachment.  There is much more bearing surface in the second case than
in the first, and this is why it seems to me that the second is more
rigid.  Don't get me wrong, however.  I'm not saying that using inserts
wouldn't work.  And other considerations, such as compactness might make
it more attractive.  But still, IMO rigidity of the OTA is the primary
consideration, and so if it were me, I'd use the clamping blocks.

- KenB

> -----Original Message-----
> From: Paul Shankland [mailto:pshankland@flakeysol.com]
> Sent: Friday, July 16, 1999 8:47 AM
> To: atm@shore.net; Bertapelle, Ken; NGC704@aol.com; 
> sayre@foothill.net;
> donovan@bravoz.com; 'pshankland@flakeysol.com'
> Subject: Re: ATM Truss Tubes - Flare Fittings are superb!
> 
> 
> >> Kurt,
> >>
> >> IMO this approach to anchoring the lower ends of the truss tubes
> >> would not be as rigid as the Obsession style clamping blocks.
> >> This is based on nothing scientific, but just my view of the
> >> size and shape of the two kinds of connectors.
> >>
> >> - - KenB
> >> > -----Original Message-----
> >> > From: NGC704@aol.com [mailto:NGC704@aol.com]
> >> > Sent: Thursday, July 15, 1999 11:40 AM
> >> > To: atm@shore.net
> >> > Subject: Re: ATM Telescoping truss tubes
> >> > In a message dated 7/15/99 10:32:21 AM Central Daylight Time,
> >> > donovan@bravoz.com writes:
> >> >
> >> > > This seems like an almost "too easy" solution for attaching
> >> > truss tubes.
> >>
> > ------------------------------ Date: Thu, 15 Jul 1999 
> 13:06:44 -0700 From: "Bruce
> > Sayre" Subject: RE: ATM Telescoping truss tubes Kurt Maurer 
> asked: "I'd be most
> > interested to hear if anyone has [used threaded tube 
> fittings], and if so, what
> > comments might be made." Although I haven't used them, I 
> think they would work very
> > well. http://www.foothill.nt/~sayre/
> 
> Hi all,
> I'm kinda in 'da middle' of a conversation, but my 2 cents 
> is, my toa agree strongly
> with Bruce Sayre - the threaded fittings work well (I have 
> used them), and the flared
> compression fittings work in simply outstanding fashion! 
> Having used all the
> variations on Obsession-style block clamps on the same scope 
> first (& not quite
> satisfied), I'll tell you, I feel the flared fittings are 
> much better, IMHO. Take a
> look here to note the methodology, or my ATM page... I also 
> looked at telescoping
> poles for my 8" f/8 travelscope, but it's a stretch (pun 
> intended) using LLOOONNNGGG
> poles on an f/8 as it is... kinda... 'limer'... try:
> http://home.att.net/~JEKasunich/truss.htm
> 
> Good luck!
> Paul
> --
> Best Wishes / Dark Skies,
> Paul Shankland
> Key West, Florida, US
> ARS - NT3L
> 
> Home email: <Paul & Vic> pshankland@flakeysol.com
> Work: <CDR Paul Shankland, USN> pshankla@jiatfe.southcom.mil
> Home Page:         http://member.flakeysol.com/shanklan/index.htm
> ATM Page:         http://member.flakeysol.com/shanklan/ATM1.htm
> 
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> questions?
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> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 
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