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[TowerTalk] Al elbows

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Subject: [TowerTalk] Al elbows
From: (L. B. Cebik)
Date: Sat, 10 May 1997 09:00:49 -0400 (EDT)
My thanks to all who took the time to give me enough suggestions to prowl
the local shops for the next several weeks.  Lots of new potential
adaptive uses for existing items and lots of techniques to try either
sooner or later.

Below is a compendium of extracts of various ideas, in case others run
into a variant of my need.
You might try an Electrical Contractor Outlet.
Ie. aluminum conduit.

73, N1MAU
Greville (Sandy) Balzarini, Parts Quality
IIS Varian, Gloucester, MA
  I have seen some cast aluminum elbows used for scaffolding
and hand rails--but they are larger than 1 inch ID and pretty bulky--nothing
like the copper pipe ones in the hardware store.

One option is to make you own by sawing tubing at 45 degrees
and then TiG welding it back together--but you would probably want
to use something like 1-1/4 x .120 wall to get the strength since
welding causes the heat treatment to be negated--resulting in weaker

Another option is to bend something up using relatively softer tubing.
BTW  The heat treating process must be something that continues
over time like curing concrete.  I have taken 3/8 6061-T6 solid rod
and heated it up with an acetylene torch and bent it 90 degrees in
order to make Tee-bars for matching networks at VHF and when 
the tubing was relatively fresh from the mill it works beautifully.  
If I take the same tubing and wait a few years and try the bending 
process I will get cracks!

73  John  W0UN
Commercial electrical supply companies usually carry aluminum conduit. It 
comes in two wall thicknesses. They also have various corners and joints.

If that does not work, a conduit bender can be used. Bending 1" aluminum 
needs a (forgot) 3/4" or 7/8" bender. If a manual one is not available,
look  in the Yellow Pages for a pipe bending shop. They hae all sorts of
dies and  can bend anything. Thin wall aluminum on some machines will
crack, because  the machine moves very fast (unless it has a mandrel). The
solution is to  heat the tubing before (and maybe during) the bend. Tubing
down to .049 can be bent in this manner.
                        Tom, N6BT
                        Force 12 Antennas and Systems
                        (Home Page )
Hi, again.

Just remembered another technique to keep the tubing from cracking or 
compressing on the outside of the bend. You can fill it with wet sand. There 
is also a commercial product that looks like liquid metal. It has a very low 
melting point, I think even less than lead, so it takes very little heat to 
be able to pour it into the tube. It also cools quickly. Of course, the EPA 
probably has it off the shelves in California, but maybe not everywhere!
                        Tom, N6BT
                        Force 12 Antennas and Systems
                        (Home Page )
i have seen aluminum angle sections made for use with railings for
steps.  they are bigger than you probably want though, probably about
2" diameter.
David Robbins K1TTT (ex KY1H)   or
I do not know if there exists ready made aluminium "corners" but I can give you 
advice how to make them yourselves.

We have made similar parts and it is not extremely complicated. You have to get 
some puley with internal diameter of the cut of the outer diameter of the 
tubing. The precision for good results should be within 2mm. Than fill the tube 
with sand and than make the required "corner". It can be any angle. Even for 
"hard" military grade aluminium the results are very good. We have used this 
method for "in phase" driven HB9CV swiss quads which we used as multiplier 
antennas in late 80's at OK5R. We used this almost forgotten antennas due to 
very small dimensions and of course allowable small heights for still 
results. there is the problem that you have to make a 45 deg angle on the tube. 
We used 28mm tubes on 20m and 25mm on 15m - same dimensions as you want to use. 
We have used this method for some 2m stacked constructions also with good 
Jiri Sanda
I have never seen elbows for Al pipe. But, there is some
scaffolding, (sp?), that is made from Al looking pipe and
they have all sorts of slip on connectors. 90s, 45s, Tees,
Xs and etc.
You would need to look at a contractor supply store or maybe
even a rental yard to see what I mean.
The fittings are held in place with small set screws. Quick,
simple and strong. Should be great for antenna playing!
However, cost might be another mater......!

73, Ron,     SOWP 5545M,
.........KU7Y.....ARCI #8829.....Monte "Ron" Stark..... Lake, Nevada....
....QRP-L #17...ARS #49...NorCal #330.....NRA LIFE.....
Suggest you try a Marine supply place for the aluminum elbows...I have seen
elbows of aluminum in such - for use in manufacturing the supporting
framework for covering/tarping boats.  The ones I recall were part of a
system nd included all kinds of interesting angled fittings, 90 as well as
135 degree mating being possible.

To each who sent suggestions for finding or fabricating, my sincere
thanks.  Although I may only use one or two of the suggestions, depending
on local availability, perhaps the ideas will be of use to others, if not
today, then someday.

I shall report what I actually used when I finish testing the antenna,
including what I tried that did not work well.



L. B. Cebik, W4RNL         /\  /\     *   /  /    /    (Off)(423) 974-7215
1434 High Mesa Drive      /  \/  \/\     ----/\---     (Hm) (423) 938-6335
Knoxville, Tennessee     /\   \   \ \   /  / || /      (FAX)(423) 974-3509
37938-4443     USA      /  \   \   \ \       ||    


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