Sorry about your tower.
Re; the attachment to existing concrete base. There are some very good
epoxies made to use with concrete coring. About two months ago, I core
drilled the old concrete base at K7SS (which was originally installed by
our own K7LXC) when Danny wanted to use it to install a different 48
foot self supporting tower for his new SteppIR. And then we epoxied in
some "legs" LXC gave me for a base.
I checked with the epoxy people (Covert Operations in Los Angeles) and
used their recommendations for type of epoxy.
We drilled three 3" or 4" holes (I can't remember exact diameter) about
a foot deep and then set the legs. About a week to cure and up went the
I happen to own a construction company, so I borrowed one of my best,
most experienced concrete superintendents and he "helped" me with the
task. (In other words he did most of the work. He did let me drill one
of the holes.)
My superintendent and the epoxy people laughed out loud when I
questioned the strength of the installation. "It will be a hell of a lot
stronger than the concrete!" was, I believe, their exact quote.
I am not recommending anything here (my corporate counsel made me say
that) but I would suggest you look into core drilling and epoxy for
mounting some legs for a new tower in your existing concrete base. Any
good local concrete installer should be able to help you with the
And using a licensed PE to design the installation would be a very good
Best of luck!
Kim - K7IM
From: Mike Rhodes [mailto:firstname.lastname@example.org]
Sent: Thursday, June 27, 2002 6:06 PM
To: Tower Talk Reflector
Subject: [Towertalk] Lost My Tower Tuesday
The title says it all... We had an apparent microburst or severe
downdraft or whatever they want to call it. Anyhow, it took out a
perfectly healthy 60 foot Oak which took out a set of guys which in turn
took down my 60 foot tower and assorted antennas.
My dilemma is, since my bottom section was a piece of 25g that had
been cut off at concrete level by the previous owner and, my tower bent
at about the 5 foot level which - of course - is just below the first
joint, what are my best options. I suspect that sawing the remnants off
at concrete level, plugging the holes, and installing a mounting plate
is going to be a lot less painful than trying to jackhammer a yard of
lazy aged concrete into manageable sized chunks. I notice that Rohn
offers a Pier Pin mount and also a mounting plate with 4 mounting holes
and stubs for the first section to mount to. There is about $50
difference in the price so that is not a real issue. Just wondering if
anyone has any pros and cons to offer on the choices.
As for loading, I intend to return to the previous 60 foot level and
the tower was (will be) loaded as follows: Force12 C4 or maybe a C4SXL
(C4 was the previous installation); Cushcraft A505 6 meter 5 el beam or
equiv.; M Squared 2M7 7 el 2meter beam; FO25 25el 432 beam; and a
Hustler G6270R 2m/440 vertical on top. The mast was about 19 feet of
1026 alloy .180 wall tubing with about 5 feet of it in the tower. A
wooden bearing was on the top plate and a thrust bearing was on the
rotor shelf, with the rotor 2 rungs below that. Guys were at the 35 foot
and top shelf levels.
Back on the subject of the mounting plates, what is the proper
procedure for attaching something like this to a concrete base and where
do you look for whatever materials are required. I know this has been
discussed before but I naively thought I would never need to know that
sort of thing since my tower was going to stand forever. Oh well, I
imagine that's what that 60 foot Oak thought too.
Mike / W8DN
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