There is really no need to c'bore anything. I had a homebrew 55 foot
freestanding vertical in Aruba and the larger sections make clanking noise
in the constant wind. So I drilled a 1/4 " hole though each joint. I then
took it apart and drilled a larger hole though one wall of the outer tube,
large enough to clear for the head of a socket head cap screw. So the bolt
does not squeeze the outer tube, it just forces the inner tube to one
wall. The head of the screw is still visible and easy to tighten. I
suppose with a large enough clearance hole you could even use a hex bolt.
This stopped the rattling and it worked well.
John KK9A
To: Jim Thomson <jim.thom@telus.net>
Subject: Re: [TowerTalk] Shorty Forty Hose Clamp thread
From: Stan Stockton <wa5rtg@gmail.com>
Date: Thu, 13 Aug 2015 08:53:16 -0500
After about 40 years of making my own antennas I learned something a few
years
ago when faced with assembling 65 tribanders (520 elements) we made for
WRTC2014.
I was introduced to the element joint attachment method I am told is used by
Optibeam. I was skeptical when I heard the verbal description, having
settled
on pop rivets after every other conceivable method about 20 years ago.
I made one element with pop rivets and another with a single stainless steel
socket head cap screw with a counterbore (head clearance on socket head
screw)
for one wall of the larger diameter tubing for each joint, then grabbed each
one in the center and violently shook them back and forth. The one with SHCS
joints felt like one solid piece of tubing as compared to the pop riveted
one.
It is so easy and so solid, I will never mess with pop rivets again.
A V block fixture with stops, drill press and some of these bits along with
straight bits for the smaller diameter tube drilling are all that is needed.
http://www.wttool.com/index/page/category/category_id/14686/
make the job easy in comparison to many methods. The counterbore is
important.
Use stainless nylock nuts.
YMMV but I'm sold on it.
73...Stan, K5GO
Sent from Stan's IPhone
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|