[TowerTalk] base insulators

[David Robbins]

I agree with thicker plates if you are doing an insulator like that, the ones i got are probably 1/2" or so and well galvanized.  the standard roof or pier pin plates are meant to be supported on their whole surface not just in the middle.  If the commercial stuff is too expensive i would do something with a 2-3" thick piece of lexan or fiberglass big enough to support the whole base plate... then probably just epoxy it down to the concrete, or maybe put a couple of small bolts sticking up an inch or so from the concrete into pockets drilled in it, and a bolt in a pocket as a pier pin from the top... that would be lots stronger for side stresses than the porcelain like i have.  if i were doing the raised one again i would sandwich something like that between the plates i have and keep the leg braces for lateral support.


Aug 1, 2012 12:02:55 PM, knowkode at verizon.net wrote:

David,

I have pondered using this style insulator but have had concerns as to how well they could survive the forces you experienced which led to failure. One option would be to fabricate a pier pin to bolt to the top of the insulator so that the tower base insulator behaves as a pier pin on which a tower pier pin base plate sits, or better yet, a tapered bottom section of tower. My other concern lies in the relatively small diameter of the insulator with respect to the tower diameter. I would be more comfortable with a wider insulator especially at its base and cap. I have seen 1/4" base plates bent because of the forces applied between anchor bolts and tower legs. The answer of course it to fabricate with thicker plate when the forces cannot be kept linear. 

73,
Jim W5QM



________________________________
From: David Robbins 
To: towertalk at contesting.com 
Sent: Wednesday, August 1, 2012 8:08 AM
Subject: Re: [TowerTalk] base insulators


be careful with repurposing old insulators, or even in applying new insulators in cases that they haven't been designed for. 
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