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Re: [TowerTalk] Adding Expanding Foam inside boom

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Adding Expanding Foam inside boom
From: David Gilbert <xdavid@cis-broadband.com>
Date: Thu, 26 Apr 2018 13:09:05 -0700
List-post: <mailto:towertalk@contesting.com>


Most commonly available foams actually crush pretty easily.  After all, they are just bubbles with a flexible membrane surrounding each bubble.  Another factor is that whenever I've tried to use the foam to fill a really large gap, the bubbles formed are not of uniform size ... the interior ends up with really large bubbles that would have no strength at all.  It's easy to make a big glob of this stuff in a plastic bag, then cut it open to see the effect.

I also agree that the extra weight probably offsets what little additional strength that might result from the foam.

Dave   AB7E


On 4/26/2018 8:42 AM, Charles Gallo wrote:

The foam might not give you ANY extra strength, and even you look at
strength/weight, I'm going to guess it'll be a net negative.  Now if you
know your boom has a vibration problem, we are talking another story.
Even then, there are probably better ways to make the boom stiffer (put an
end cap on both ends, attach a cable that runs inside the boom from end
cap to end cap, and come up with a way to tension the cable - aka put the
boom under compression, or put a metal ROD in, and put the boom under
tension - both will change resonance)



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