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Re: [TowerTalk] Choice of aluminum

Subject: Re: [TowerTalk] Choice of aluminum
From: K8RI <>
Date: Sun, 14 Oct 2012 01:52:56 -0400
List-post: <">>
On 10/13/2012 8:44 PM, Grant Saviers wrote:
DX Engineering sells Yagi-Mech which calculates wind loads for yagi
elements.  Generally, gravity is less stress than wind so you can get
some estimates of what is needed for diameters and wall thickness for a
self supporting vertical.   (zero wind will reveal the gravity stress

A problem with stock tubing from mass metal suppliers is a .250 wall is
.250 +/- some tolerance which may preclude telescoping at the stepped

That's not "May Preclude"telescoping, stepped diameters in half inch steps and 1/4" wall should not fit! Period. If they do fit they are mis sized because the numbers would give you what is called an interference fit. With Aluminum you'd need something like never seize(DP?) and the pieces would have to be pressed together.

A word of warning: I don't know your altitude, but for those who live in more Northern (and Southern climates)and you are next to Argentina... If you machine a piece to fit tightly into the base of the vertical and you live in an area where freezing occurs even on occasion, put in plenty of drain holes. Aluminum and steel are no match for freezing water.

My daughter was down there 6 months ago, ice climbing in Argentina.

 You won't know until you try it for each tube. Note that DXE
(and Texas Towers) sells tube made especially for telescoping and the
walls thickness is reduced appropriately so the draw tolerance can be
accommodated.  I've asked DXE for longer lengths than catalog - no
dice.  Apparently, they have to order mill lots to get the thinner wall
and have it cut to length by the supplier.

Either they or maybe Texas Towers have 12' lengths which must go motor freight and are still only half lengths as standard mill lengths are 24 feet. I've seen the 12 footers advertized with the freight warning.

Normally 12' is plenty long for even 40 meter elements and you can build splices for the boom. The same goes for verticals. You either need a flat bed truck or pick up with pipe racks to move the stuff. I live on a short street that one of the big freight trucks can only back as far as our driveway. There is absolutely no way they can get into the driveway even though its wide and paved. They can't make the turn off the street into the drive. They can barely make the turn onto the street. Also, standard mill finish is not the smooth, shiny, reflective shine we see on the stuff specifically for antennas.

I usually have stuff delivered to the local airport and then hire a tilt bed used for hauling cars and trucks. That's about $80 a shot and considered very cheap. The steel and aluminum suppliers usually deliver via a flat bed for sheet, tube, and plate and do so free for good sized loads or if I'm willing to wait until they have a load headed this way. Of course when you consider the time it took to get the milling machine off the big truck and onto the tilt bed made the expense well worth it. Then I made a platform out of 2 X 12's and used 1" steel pipe rollers under it. It still took me over a full day to get the mill from the front of the shop to the back. I've been running conduit (EMT) from the contactor box to the breaker box for the last two days. I only have one short piece to go from the breaker box to the long run, but it has 3 bends...2 shallow and one 90 degree and bending conduit is not my best suit!. Now I need a "soaper" to feed the cables into the conduit while I pull. Hope to get that done tomorrow, Sunday afternoon.

I may just let the cable hang down to the breaker until I can get to town and pick up another piece of 3/4" EMT.

One of the problems with the big trucks is they completely block the street or road while unloading. There is also the problem of unloading really heavy stuff. They don't like to be setting there while you unload 20 or 30 pieces of tubing

The only way I can get it is mill lots, or wait and get it as part of a lot so I don't have to pay the extra. A mill lot is a lot of tubing.

Also most of the sizes are for antenna elements and are not structurally sound for unguyed verticals.

 I've found that the
"guarantees telescoping" wall thicknesses are hard to find in stock at
Jorgensen, Tube Service, Thyssen, etc., but it is always worth a call as
they can check the entire USA inventory online.  You always have the
choice of machining some couplers from very thick wall material, also
known as Holobar.  The good news is stocks a lot of
sizes and will sell it in 12" lengths.

My former QTH 80m top loaded vertical failed from fatigue after 6 years
since I guyed it at the top and 50% - a bad idea as it oscillated like
crazy in winds greater than 15kts.  So plan to guy at heights that won't
couple oscillations between sections through guy points.  My failure
point was like it was laser cut.  Note that Al has NO threshold fatigue
stress level, whereas steel has a threshold that if not exceeded the
fatigue life is infinite.

Consider what it will take to erect the mast - a 50% height falling
derrick will likely work or a sign truck crane might be able to handle
the weight.

A mast and hand winch for a falling derrick will also work, but it can be slow and tiring.

  Or rent a 40' 4WD boom lift as they usually have 500#
capacity so you and the mast hopefully won't exceed that ;-) .  They're
a lot of fun/exciting and easy if you go slow and get the delivery guy
to give you the basic operating course.

Many companies will not allow any one to operate their equipment other than their employees due to insurance. I used to operate the things where I worked (before going to college) but my license has long since expired. One place locally would let me run theirs, but it was well over $1000 for the week end. Another place 20 miles away was just over half their price, but I had to use their operator and it was "portal to portal" for both the machine and operator.

Grant KZ1W

On 10/13/2012 5:02 PM, Jorge Diez - CX6VM wrote:
Hi Rudy,

You are lucky!, I am considering something for CW/SSB J

There´s some commercials self supporting towers. Also a Rohn 25 is
good for
a guyed tower. My problem is shipment cost and handling.

So looking for instructions about how to build one J

How about TV towrs? they are generally light and fairly cheap, but I don't know how they'd go in that part of the world.

A steel tower will work well for an antenna that size, but they do require some equipment to put up. 60 feet should go up in one push, but I'd not want to go much taller than that. I've even climbed a 90 foot TV tower (that was well guyed) it depends on what is available in your area. The problem with building your own tower is that pipe is generally far too heavy (as well as soft) and once welded up they need to be galvanized or well painted, inside and out.

73 and good luck,

Roger (K8RI)




De: Rudy Bakalov []
Enviado el: sábado, 13 de octubre de 2012 21:46
Para: Jorge Diez - CX6VM;;
Asunto: Re: [TowerTalk] Choice of aluminum


This is a great question that has been on my mind for a while. I was very
tempted to try to model it, but never found the time to do so. I also
thought that all I care about is the CW/RTTY portion of 80m.

That said, I decided to see what DX Engineering offers on their site
for 80
m. Two very interesting observations from the 80m vertical installation

1) they use very small size tubing, not even close to what I am
(my current 40m vertical uses better tubing!!!)

2) they claim a very wide bandwidth

So if their 80m verticals are half as good as they claim, the much
size tubing I am considering should do very well.

Rudy N2WQ


From: Jorge Diez - CX6VM <>
To: 'Rudy Bakalov' <>;;
Sent: Saturday, October 13, 2012 7:36 PM
Subject: RE: [TowerTalk] Choice of aluminum

Hello Rudy

What´s the bandwidth of this verticals compare with towers?


-----Mensaje original-----
De: TowerTalk [] En nombre de Rudy
Enviado el: sábado, 13 de octubre de 2012 21:04
Asunto: Re: [TowerTalk] Choice of aluminum


Thanks for the comprehensive answer. I didn't realize that 6061-T6 is
expensive than 6063 as I was looking online prices in chunks of 12 and

Just for kicks I prices a 4-Square set of verticals made of 24'
sections of
3", 2.5", and 2.0", 0.25" wall thickness. $2,300 delivered for the set.
Doesn't look that bad compared to dealing with towers and tower crews.

Rudy N2WQ

From: "" <>
Sent: Saturday, October 13, 2012 6:36 PM
Subject: Re: [TowerTalk] Choice of aluminum

Hi Rudy, 6061-T6 aluminum has a yield strength rating the same as
that is sold by Texas Towers and others.
The 6061-T6 costs more than 6063-T832 because of the extra
heating/quenching steps needed to reach the rated yield strength.
reaches the rated yield strength by work hardening the material in the
If you want a self supporting vertical, then you would need to go through
the same process as designing a 80 meter beam element with most of the
weight left out of the calculations. Just as a guess I would expect the
section to be about 4" diameter with a .25" wall.
This is not a trivial structure! Please proceed with caution!
If you want a guyed vertical, there are a number of them that have
been on
the air long enough to think about duplicating one. W5UN is one that
Gerald K5GW
In a message dated 10/13/2012 4:09:30 P.M. Central Daylight Time, writes:
I was  wondering if anyone can help me select the right material for
full-size 80m  verticals. My questions are as follows:
1) offers
   6061-T6 aluminum, but not T8. Is there a difference between T6 and
T8 for
2) Should go for the 0.125 or 0.065 wall thickness?
3) Is 1"
   tubing OK for the topmost segment? Too stiff for the wind at 70'? Not

I am aware that many ham stores offer 6061-T8 tubing, but I
   do want to buy it local in VE3, close to my QTH, in 12' lengths
   6') and avoid shipping complications due to length or clearing
73 Rudy



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