I have no first-hand knowledge of these towers, but I am currently
working with an experienced aluminum welder (military aircraft) on a tower
project. Presuming arguendo this is not a "buttering" problem (cold weld
with no penetration) it sounds as if the completed units are not
heat-treated to bring them back to the original tensile strength.
An example- I asked my welder friend about the practicability of welding
a center-sleeve of 1 1/2" OD 1/4" wall aluminim tube into a 2" OD 1/4" wall
tube so I could have a travel mast with two 8 foot sections that would silde
together & bolt on just one side. He told me the tube stength would be
compromised unless the welded portion was "baked" at the appropriate temp
for 24-36 hours, and that in his shop (a gov't facility with top of the line
gear) the "oven" can only fit 3ft long objects. To wit: "In some
applications it is better to just use hardware and this is one of them".
Why do I get the impression that the critical welded areas of these
towers are not re-heat-treated?
N3DB
----- Original Message -----
From: <HansLG@aol.com>
To: <towertalk@contesting.com>
Sent: Friday, August 15, 2008 1:33 PM
Subject: [TowerTalk] Fwd: Heights Towers Aluminum??
>I am glad to get this information. The Height tower I have in my yard just
> now is old. I noticed that some of the weld or the Z have opened and was
> going
> to fix that before I put the tower up. Now I may get all the welds
> inspected
> before I put it up. I looked at the welds before and wondered if they were
> OK, but as I am not an expert I thought they were OK. The welds that
> brook were
> under high tention after the Z itself bent at these places.
>
> Hans N2JFS
>
>
>
> ____________________________________
> From: k8isk@comcast.net
> To: towertalk@contesting.com
> Sent: 8/15/2008 2:00:39 A.M. Eastern Daylight Time
> Subj: Re: [TowerTalk] Heights Towers Aluminum??
>
>
> Hi all,
>
> As being the lucky person to clean up the mess left by Owen's tower
> failures, I can tell you first hand that all antenna weights, wind load
> specs,
> lengths, etc. were passed on to Heights before Owen put them up, anyone
> who knows
> Owen knows he goes by the book and documents!! He was told that his
> loading
> was within spec.
>
> I am no expert on aluminum welding but I do a fair amount about steel
> welding and what I have seen is a failure of welds on his towers.
> Normally, a weld
> is stronger than the surrounding material. If there is a failure, the
> weld is
> intact but metal is ripped away around the weld. A sign of a good weld is
> a
> slight cutting away of material right at the weld. This is the point
> where
> the material starts to melt and becomes one with the welding rod
> material. Some
> of the failed welds on his HF tower that came over first look like they
> just
> poped off, like a cold solder joint.
>
> His second failure, just a couple of weeks ago, occured at 36 mph as
> measured by his Davis wx station and verified by the local airport which
> reported
> only a 31 mph gust. The top section failed right where it went inside the
> next
> section. A leg buckeled in and it was all down hill from there. Once
> again,
> as the leg that was receiving all the downward pressure (opposite the
> legs in
> the wind) pushed inward and the Z bracing which is supposed to keep it
> from
> collasping, didn't. I did not see the Z bracing buckle, the welds just
> broke.
>
> All the discussions thus far seems to be centered around just self
> supporting foldovers, not crank ups as Owen's was. I'm sure there is a
> difference
> between the way the load is distributed down the tower.
> At K8GP, we use a lot of Univeral self-supporting towers that pivot up
> from
> atop our school buses. Our towers take a lot of abuse from being
> overloaded
> (it's only 5 days twice a year!) and riding around on bumpy roads on top
> of
> school buses. Our towers have survived 80+ mph winds and when we have a
> break,
> it's usually a fatigued Z brace and NOT at a weld and we only go up 30 to
> 40
> feet.
>
> I'm not passing judgement on Heights towers or aluminum towers in
> general,
> just adding to the discussion of what I saw. For most of us, a tower is a
> pretty good size investment in time and money, and since my tired, old,
> fat butt
> is climbing up, I want nice heavy, thick, galvanized STEEL under me!
>
> Terry
>
> -------------- Original message --------------
> From: <donovanf@starpower.net>
>
>> Hi Dick,
>>
>> Unlike K3CB's recent experiences with the catastrophic failure ofboth of
> his
>> Heights crank-up towers (one in dead calm weather and the other in light
> 30 MPH
>> winds), the collapse of the Heights tilt-over tower was the direct
>> result
> of an
>> inexperienced tower owner significantly exceeding the maximum dead
>> weight
>> specification.
>>
>> I suspect he isn't alone in failing to appreciate the importance of not
>> exceeding the dead weight specification for tilt-over towers.
>>
>> 73
>> Frank
>> W3LPL
>>
>> ---- Original message ----
>> >Date: Thu, 14 Aug 2008 16:40:33 -0600
>> >From: "Dick Williams"
>> >Subject: Re: [TowerTalk] Heights Towers Aluminum??
>> >To:
>> >
>> >I have seen several interesting comments on the reflector concerning
> Heights
>> >Alum towers; and in fact, I posted a couple myself.
>> >
>> >As I mentioned in a previous post, I have three of them and they all
>> >tilt
>> >over in the center (80 ft towers with the fold over at the 40 ft
>> >level).
>> >
>> >Obviously, weight is a concern, you can't put 400 lbs of antenna and
>> >acessories on the top and expect it to work.
>> >Alum masts certainly help; in fact I have a nice 20 ft, 1/2 inch wall
>> >one
>> >sitting on the ground that I am not using right now (150 bucks picked
> up).
>> >
>> >As far as size, I have not found that to be a problem (just weight). I
>> >put the antenna together (or take it down to work on with the boom
> parallel
>> >to the ground (elements vertical). If the elements are too long, I just
>> >start removing element sections as I lower it down until the boom is
>> >low
>> >enough to work on.
>> >
>> >It is too bad that Glenn Martin Engineering does not produce the
>> >Voyager
> any
>> >more. It is the similiar to the Hazer except it is on a external track
>> >on
>> >the side of the tower. I have one on a 120 ft Rohn tower. Have a Force
>> >12
>> >Mag 620/340N on it with a M2 R2800 rotor. Works great; brings the
>> antenna
>
>> >right down to the ground ready to be worked on when needed. And all it
>> >takes is a 1/2 inch electric drill to raise and lower it.
>> >
>> >All said and done, I like the Heights towers and the Voyager system for
>> >"ground level" antenna work.
>> >
>> >Dick K8ZTT
>> >
>> >
>> >
>> >_______________________________________________
>> >
>> >
>> >
>> >_______________________________________________
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>>
>>
>>
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