My suggestion would be to flush cut the remaining legs with
the surface of the concrete base. Then drill a hole in the
center of the concrete base for a pier pin instead, provided
they make a pier pin base plate for the Rohn 25.
A pier pin for the bottom section is a much better way to go
anyway. I use them an all my towers. No worries about
getting that first section straight and the resulting stress
you place on the tower when it isn't perfectly vertical.
73
Chuck...K1KW
----- Original Message -----
From: "Tower (K8RI)" <tower@rogerhalstead.com>
To: <kr7x@comcast.net>; "Melvin Brafford" <roadrulz@isp.com>
Cc: <towertalk@contesting.com>
Sent: Wednesday, July 07, 2004 3:31 PM
Subject: Re: [TowerTalk] Broken Rohn 25G Base Section
> WARNING: Welding on tower legs is welding on galvanized
material. This
> gives off a very poisonous gas. Make sure the wind blows
the smoke away
> from whoever does the welding.
>
> I'd do it the way they do on the 45 G and solid leg
towers. Use a sleeve
> similar to the construction of a 45G. They are straight
with no reduction is
> size at the joint.
>
> First, make certain that the portion of the base section
is straight.
> Neither twisted or bent with no welds broken.
>
> Make up sleeves/adapters to fit the bottom of next section
slip an insert
> inside that just nicely fits into the base of the next
section. 25G legs
> are reduced in diameter at the top and enlarged at the
bottom. Your cut off
> section is going to be full diameter at the top. I'd just
use a steel pipe
> to create an adapter that would fit inside, or preferably
outside the base
> legs and a slip fit *inside* the next section. It'd take
two different
> sizes to do this.
>
> An adapter that fits over the base and inside the next
section helps prevent
> water from running down into the inside of the base legs.
>
> There is also the option of making it into a hinged base.
Just look at the
> catalog diagrams of the hinged base. They are just two
steel tabs welded
> onto each base leg with holes to fit the next section.
>
> Roger Halstead (K8RI, EN73 & ARRL Life Member)
> N833R, World's Oldest Debonair (S# CD-2)
> www.rogerhalstead.com
>
> > Mick:
> >
> > A possible fix depending on how you are at welding or
know someone who is
> a certified welder is to trim the legs down to say 12"
long vertically.
> Weld some channel legs to the stub legs say 8" overlap and
have the channel
> legs end about 8" above the stub legs. Weld the legs to
the back of the
> channel sections with the channel flanges pointing to the
outside..... (weld
> on both sides of the leg to channel lap. You can use stich
welding to
> minimize warpage.
> >
> > O[ <------ outside
> >
> > Take a normal tower section and set on top of the stub
rohn legs and drill
> out the channel web to match the bolt holes in the tower
legs. Bolt up and
> you have created a reinforced splice in the leg. The
channel can be C4 or so
> does not have to be real big just a bit larger than the
area of the leg in
> cross section.
> >
> > This is a suggestion and other splice mechanisms would
also work. The load
> in the legs at the base for a guyed tower, even those
embedded in concrete
> is mostly axial not in bending.
> >
> > Your milage may vary but this should work.
> >
> > 73
> >
> > Lonberg Design Group, Ltd.
> >
> > Hank Lonberg, P.E.,S.E. / KR7X
> > President
> >
> >
> >
> >
> > > On May 21 a storm took down my 100' Rohn 25G. All the
"big grip"
> connections,
> > > EHS cable, etc held up ok. When an 80' tall tree fell
on the SE guy
> wires, the
> > > NW guy anchor pulled up out of the ground, and the
tower folded like a
> hair-pin
> > > at the 30' level, and fell toward the direction of the
tree(SE). The
> force
> > > exerted on the tower as the tree hit it also, broke
one of the tower
> legs at
> > > just above the 2' level. The 25G was pushed and pulled
at the same time.
> I'm
> > > left with around 2 feet of tower sticking out of the
concrete base. The
> swaged
> > > ends are gone, and all I have left is the 3 legs which
appear to be ok,
> and the
> > > 2 remaining cross and Z brace sets seem ok. I wonder
if anyone would
> trust using
> > > the remaining base section stub, and if so how would
you attach the next
> section
> > > above it? Thanks, and direct dialogue will be fine, so
as not to clutter
> up the
> > > reflector.
> > >
> > > 73, Mick W4YV
> > > _______________________________________________
> > >
> > > See: http://www.mscomputer.com for "Self Supporting
Towers", "Wireless
> Weather
> > > Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any
> questions
> > > and ask for Sherman, W2FLA.
> > >
> > > _______________________________________________
> > > TowerTalk mailing list
> > > TowerTalk@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/towertalk
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting
Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting
Towers", "Wireless Weather Stations", and lot's more. Call
Toll Free, 1-800-333-9041 with any questions and ask for
Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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