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@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@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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