Jeff,
Warning this is long as I didn't know how to better describe things!
First of all, I would NOT guy anything to a chimney. Most chimney masonry I
have seen is not necessarily all that strong and it was not designed to have
large forces put on it. I would stay away from that.
I just put up 50 feet of tower and while I could hide 2 of the guys deep
into the wooded part of my back yard, that left my third guy running into my
front yard which I didn't want. My solution was to create a guy point in my
roof. Not an idea situation, but life isn't ideal. Here is how I did it:
First of all, I reinforced the roof joists in the area of where the anchor
would be with 4 foot pieces of angle iron. I think I did a total of 8
joists. After this, I took a 12 foot 2x12 and lag bolted it into the
joists. This way, my load gets spread across many joists. Furthermore, I
reinforced the 2x12 with more angle iron on top and bottom in the area where
my anchor point would be. Finally I took several 2x4s and tied the joists
near the anchor point to the rafters below (just above the 2x12). I did
that with 4 1/4" carriage bolts in each 2x4 (2 per end).
Now, came the most difficult part. In order to get a good angle for my guy
wire, I had to put the anchor point on the opposite side of the tower. In
other words, the pitch of the roof is in the same direction as my guy wires.
I did not want to just drill a hole through at a 90 degree angle as that
would mean that there would be a twisting or bending force on my guy anchor
bolt and not a lateral force. I wanted my guys pulling along the anchor
point. So I got a long wood bore bit and drilled at approximately a 45
degree angle to the ground into the roof (approximately what I need the guy
anchor to be). Once through the roof, I then continued that angle into the
2x12.
My guy anchor bolt was a piece of 3/4" threaded rod about 3 feet long which
I cut to length. Back inside the attic, I needed to add some washers and
bolts. The biggest issue was not that everything was difficult to attach
since the rod was coming through the board at an oblique angle.
Nonetheless, it was doable. In order to further strengthen the board and
prevent the guy rod, washers, etc. from ever pulling through the board, I
attached a piece of flat steel bar stock to the 2x12. I had to drill an
enlarged 3/4" hole in it (roughly 2 3/4" holes edge to edge and filed out)
so as to accommodate the slant of the bolt. The bar stock is 3" or so long.
This I then screwed into the 2x12. So the 3/4" rod passes through the board
and through the bar stock. Then of course it was fastened in with washers
and bolts.
Back on the roof, I used a couple of short green treated 2x4s to make a
"level to the ground" platform that my modified equalizer plate would fasten
to. One of these was sanded down so that when put against the pitch of the
roof, the top surface was parallel to the ground. The other just went on
top of that piece. These had 3/4" holes in them to pass the rod. After
lots of roof tar, they got screwed into place in the roof (not much force on
these pieces, they just make placement easier). Then I fastened my
equalizer plate to these and now I had my guy point!
If you can get away with guy point on the same side of the roof as your
tower, that is much easier as you can just come straight out from the roof
and don't have to go at the odd angle that I did, etc.
Also, you can buy a long heavy duty, 5/8" or 3/4" threaded eye from Sears
Hardware. Yes, Sears Hardware has heavy duty forged turnbuckles and eyes.
I was amazed myself - they are the only hardware store that does. Using the
long threaded eye would work as well too.
Now for the yard anchors, I have seen what you talk about, even at
professions installations. Here is what I can tell you from what I know:
1.) You'll need to go at least 4 feet into the ground like you would for any
deck pier or anything like that. This gets you good into the ground, avoids
frost and you'll probably be resting on rock and clay. The bigger the hole
the better. You can get 12" augers which is probably pretty good.
2.) For the post, one option is to get a long I-beam. I would guess that
you could probably go 4 to 6 feet above ground - so that would make it a 10
foot I-beam.
3.) Or you could do what another ham I know of has done. He purchased large
diameter pipe (couple inches wide), put it in the hole filled with concrete
and then filled the pipe with concrete. He obviously drilled his anchor
bolt hole and put his guy point in place prior to putting the concrete down
the pipe.
Really though, if you can get your wife to agree to guys, they aren't all
that bad. But a free standing at 40 feet isn't necessarily that large
anyhow. Either way, you'll end up spending plenty of money. There is no
such thing as a free or "cheap" tower.
Your final option is the house bracket thing we've talked about. If you
have a 20 foot high roof, you could easily do a 40 foot bracketed tower w/o
guys.
73,
Jon
NA9D
on 10/3/02 7:53 PM, Jeff Burns at jhburns@attglobal.net wrote:
> The one restriction my wife has put on my plan to install a tower is "NO Guy
> Wires." Despite this I sill think a slender tower with a few guy wires may
> look better that a massive self-supporting tower.
>
> If I use a guyed tower the anchor points will be a challenge. The tower will
> be just behind the house. Our masonry fireplace is along the same wall. How
> might guys be attached to a fireplace?
>
> To keep the other guys from being a nuisance in the yard I would like to
> attach them to post at least seven feet tall. Can anyone suggest how big a
> post is needed and how much concrete is needed to hold it in place?
>
> I am thinking of a 40ft tower.
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Life Member: ARRL, NRA
Member: AMSAT, DXCC
http://www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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