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Author Topic: Bending copper tubing for folded dipoles  (Read 3925 times)
KC2ZPK
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« Reply #15 on: October 19, 2012, 04:17:08 AM »

What frequency are you building for?
The higher the frequency, the smaller the tubing can be.
It's for 440 MHz

Quote

Depending on the radius of the bend, size makes a difference.
The tighter the bend, the smaller the tubing you should use.
Pack sand and use a spring bender on the tubing for best results.

Tubing material also makes a difference in the radius of the bend.
NAPA sells a corrosion resistant brake line that is a copper/nickel
alloy which is soft and easily bent.
Air conditioning tubing is also a softer alloy and bends well, too.

Aluminum is difficult to bend, unless it is alloyed for it.
However, aluminum holds up better than copper, unless,
as noted above, you use a corrosion resistant alloy.

If strength is needed, you may want to heat treat after bending
to increase the strength. But it does cost to have it done right.

If you don't need the bandwidth larger tubing has, use wire.
Aluminum wire is light and strong, and easily worked.
Another benefit of wire is, water doesn't get inside to freeze or corrode.
I was trying to bend 3/8 utility grade copper tubing. They also had a different grade, which might bend easier.  I was also thinking of using 10gauge copper wire, that should be stiff enough to hold up.


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John
KC2ZPK.com - A work in progress
SWMAN
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« Reply #16 on: October 19, 2012, 07:26:20 AM »

 Why not get some copper 90's of the same size, 2 of these would make a bend that you need,just couple them together with the size of bend that you need with piep.
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KC2ZPK
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« Reply #17 on: October 19, 2012, 08:12:01 AM »

Why not get some copper 90's of the same size, 2 of these would make a bend that you need,just couple them together with the size of bend that you need with piep.

I guess it would be more of a rectangle than an an an elongatged oval, but does it matter?
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John
KC2ZPK.com - A work in progress
W5DQ
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« Reply #18 on: October 19, 2012, 08:59:31 AM »

Benders for conduit and pipe might give you a bend radius of like 12" in 3/8 material. But most start at the 1/2 (trade size). http://www.mcmaster.com/#conduit-benders/=jr0v74

If you need tighter, buy 4 of the 3/8" copper elbows and solder :-).  The reason you are making the antenna out of copper in the first place is because you can solder it, I guess?

Copper elbows in McMaster-Carr catalog: http://www.mcmaster.com/#catalog/118/216/=jr0udl

I bend 3/8" aluminum tubing with a radius of about 2" with the little cheapo tube bending set from Harbor Freight. I haven't tried copper but works well with aluminum. I see no reason it would not work with the untreated copper tubing and piping.

Gene
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
N1CX
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« Reply #19 on: October 20, 2012, 03:43:15 PM »

Trombones and musical instruments are made by filling the pipes with water and freezing...then bending...
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