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Re: [TowerTalk] aluminum tubing strength with holes.

To: towertalk@contesting.com, "K1TTT@ARRL.NET >> David Robbins" <k1ttt@arrl.net>
Subject: Re: [TowerTalk] aluminum tubing strength with holes.
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Sun, 09 Jun 2013 08:34:41 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>

David,

They make them in 2.75" to 0.625" tubing sizes.  You want 7/8"?
   http://www.dxengineering.com/parts/dxe-ecls-087

The entire list is here:
<http://www.dxengineering.com/search/department/clamps-and-fasteners/product-line/dx-engineering-element-clamps/welded-stud/yes?autoview=SKU>

73,

   ... Joe, W4TV


On 6/9/2013 7:07 AM, K1TTT wrote:
They are made for much bigger tubing, I doubt they would tighten around 7/8” 
stuff.  My updated design is on my blog at 
http://wiki.k1ttt.net/2013%20Maintenance%20and%20Upgrade%20Blog.ashx?NoRedirect=1#bottom





David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net <http://wiki.k1ttt.net/>
AR-Cluster node: 145.69MHz or telnet://k1ttt.net <telnet://k1ttt.net/>



From: Jim W7RY [mailto:w7ry@centurytel.net]
Sent: Sunday, June 09, 2013 01:52
To: K1TTT; reflector -tower; antennas@qth.net
Subject: Re: [TowerTalk] aluminum tubing strength with holes.



Why not use something like this?



http://www.dxengineering.com/parts/dxe-ecls-225





73

Jim W7RY





-----Original Message-----

From: K1TTT

Sent: Saturday, June 08, 2013 5:53 AM

To: reflector -tower ; antennas@qth.net

Subject: [TowerTalk] aluminum tubing strength with holes.



I am assembling 5 of the 5 element 10m longjohns… I just got the first one

to the point that I put on the beta match and am not thrilled at the clamp

arrangement on the element.  On these the driven element is split, the butt

end of it goes into a plastic insulator about 2” long that is then clamped

in the boom-element clamshell thingy.  In their design an aluminum ring goes

around the element and is clamped with a #10 machine screw that also holds

the end of the rod and coax eye lug.  I am considering replacing that ring

with a #10 bolt through the element.  My concern is that the hole will be at

the point of highest stress for the driven element.







My question is this.  What is the relative strength of an undrilled 7/8”

tube vs a 7/8” with ¾” piece inside it with a hole for a #10 bolt through

them.











David Robbins K1TTT

e-mail:  <mailto:k1ttt@arrl.net> mailto:k1ttt@arrl.net

web:  <http://wiki.k1ttt.net/> http://wiki.k1ttt.net

AR-Cluster node: 145.69MHz or  <telnet://k1ttt.net/> telnet://k1ttt.net







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