[TowerTalk] aluminum tubing strength with holes.

[Jim W7RY]

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 at 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 at arrl.net> mailto:k1ttt at 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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