Brazing or welding thick copper?

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I will be making a gate for the entrance to a house and will need to
join some thick copper rectangular bar. The 0.5" x 1" 110 copper bar is
for the gate frame and the infill of the gate will mostly be .5" x .5"
square copper rod.

I've successfully fabricated copper grillworks for other gates using my
Thermal Arc 185TSW. The grillworks were a mix .75" x .1875" flat bar
and .1875" round bar and I've been very pleased with how the Thermal
Arc works on copper.

However, I made some copper hinges out of .1875" x 2" sheet and found
that my 185 amp welder is at the very limit of what it can do.

So knowing that my Thermal Arc won't be anywhere near able to handle
the .5" x 1" bar, I was wondering what would be the best way to make
the gate frame?

I have an O/A welding setup with #2 and #3 tips (and a 175 CuFt
Acetylene tank) and was considering pre-heating the metal until it was
red before trying to tig it. I guess another person holding the O/A
torch would be useful?. But even preheating it, I'm afraid that won't
be enough and I doubt I could get close with the tig torch to that much
red hot copper.

I've been experimenting with tig brazing 3/16" copper using silicon
bronze and haven't had very much luck. The bronze has been balling up
-- I didn't have that problem when tig brazing steel.

So would it be best to mitre the joints on the thick bar stock to a 45
degree angle and braze it using O/A? Will my O/A setup be enough to
braze copper this thick? Using coarse thread screws seems problematic
since I doubt soft copper
would hold screws well.

Thanks for any insight. (Yes, I was a fool for getting copper this
thick, but that is what the homeowner wanted and I couldn't find square
copper tubing).


Re: Brazing or welding thick copper?
Make that a 75 CuFt acetylene tank... Only reason I mention this is
that I'm not sure I can use a #3 or higher tip with that small of a

Re: Brazing or welding thick copper?
You might want to look into MAPP or Propylene.  It is a LOT cheaper
than Acetylene.  It is sold in moderate-pressure bottles filled with
liquid.  So, you get many times more fuel in the same size cylinder,
due to the liquid and the lack of packing needed to keep acetylene safe.
It works great for brazing.

Jon wrote:

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Re: Brazing or welding thick copper?
Interesting question. I will be following this one because it seems
impossible. My vision shows forging end cap T's onto the copper.

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Re: Brazing or welding thick copper?
On 20 Oct 2005 14:01:56 -0700, wrote:

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  It might be possible with the TIG if you can insulate and preheat
enough but copper is such a good conductor of heat that it wouldn't be

  As for brazing it's definitely possible if you use the right filler
rod. If this is really copper (and not brass or bronze) then I'd
recommend using Sil-fos, Sil-flux or any of the other trade names for
the 90-95% copper, 5-10%silver, and trace amounts of phosphorus for
fluxing rods. Refrigeration contractors use this rod for joining
copper tubing and it's great for that job. No flux is needed do to the
phosphorus in the rod.

Wayne Cook
Shamrock, TX

Re: Brazing or welding thick copper?
Hello Wayne,

Thanks for the suggestions. I really am using 100% copper (Alloy 110).

I already figured out the insulating bit when I made the hinges. When I
was welding the hinges on the metal table, I couldn't get a puddle.
When I put the hinge in a little cave of fire bricks, I was able to get
a puddle.

I can try welding two 1' sections of the bar. However, considering that
copper seems to just suck up the heat, I'm not sure it would be a good
test considering that I'll actually be joining a 4' length to a 6'

I like the end cap idea, but not sure how I would fabricate those. I
can always screw on gussetts to the bottom since there will be a copper
panel on the lower portion of the gate that would hide the gussets.
However, gussets on top would be ugly.

When/if I finish this, is this the kind of thing people would like to
see in the drop box?

Re: Brazing or welding thick copper?
On 20 Oct 2005 15:30:16 -0700, ""

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I'm no expert, but there was once a time when I had to weld copper. It
was 3/4" thick, 4" wide, and a little over 2 feet long. No way could I
weld it with a 300 amp tig torch. I called the welder who usually did
our fancy stuff and he said a good pre-heat would do it. So, using
fire bricks I was able to fill in the 1/2" deep 1" wide goof in the
part using copper wire as filler. It seems to me that after heating
the bar I covered it with fire brick. I for rested my hand on it while
welding. Even with the preheat I think it took at least 250 amps. And
I may have been using helium. We used helium for some aluminum jobs
and ran the torch DC. The metal had to be real clean but boy, could
you really lay in the rod.

Re: Brazing or welding thick copper?

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Seems a little odd to me that nobody has asked why you are doing this.
I'm not a history buff, but I'm sure the bronze age was a long time ago
and the copper age was earlier.

Today copper is a lot less available than other metals like steel. Why
not ask how to coat some steel item with a thick coat of copper? Maybe
the stupid waste of materials and disregard for strength is the point of
your work.

Sorry. Just my opinion after reading what you are up to vs what I would
be inclined to do.

Other than that -- traditionally copper gets soldered. I guess the whole
point here is excess, though. I don't really mean that in a bad way,
just a comment on what you are up to.

Re: Brazing or welding thick copper?
Xray, you don't have anything constructive to say, so why bother
posting? Why is it material I use to make a gate? The customer likes
they way aged copper looks. And if you bothered to google for copper
gates, you would find that there are plenty of gates made out of

By the way, the total cost of copper was $400. I just finished a wooden
gate that cost the same amount in materials. Do you go and complain
about people making furniture out of walnut? Or do you believe
everything should be made out of MDF? And as to coating steel with
copper, do you have any great ideas on how to do that in a small shop?

Re: Brazing or welding thick copper?
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Well, it's usenet, just killfile the people who aren't worth reading.
There'll always be more, but no reason to not keep the signal:noise
ratio as good as you can.

Re: Brazing or welding thick copper?

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True enough. My bad.

Re: Brazing or welding thick copper?
In article <1129847416.285947.302270>, says...
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I'll second Wayne's recommendation of phos/copper brazing.
It's relatively inexpensive and a pretty good color match
for pure copper. I've brazed heavier (though not as long)
sections of copper bus bar than what you're looking at
using oxy-propane.

Ned Simmons

Re: Brazing or welding thick copper?
On 20 Oct 2005 14:01:56 -0700, wrote:

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Piece of cake if you braze it.  Damned hard if you weld it, because of
the conductivity.

Are you going to patinate the copper afterwards?

Re: Brazing or welding thick copper?
Hi Aaron,

Andy is right. Brazing (not brazed) is the best that you can use. I
suggest you use
AWS - Bag-1 Silver Brazing Alloy CD 45. it would cost  $1 in USA.

For more info on How to do Heating and Brazing of Copper with CD 45

Austri Basinillo (Philippines)

Re: Brazing or welding thick copper?

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I agree also. Brazing is the way to go.


Re: Brazing or welding thick copper?
Do you have a rosebud tip for your oxyacetylene outfit?  It generally
works much better that a regular welding tip for preheating.  Even if
you gas braze, you could probably preheat with the rosebud, quickly
swap tips, and fire up the actual torch tip.  The rosebud that I am
familiar with is an entire section like a cutting torch attachment and
not just a tip, although they may make a tip attachment also.

Re: Brazing or welding thick copper?
I noticed that there are actually phosphor bronze electrodes for SMAW.
According to the datasheet ( ), these rods could
be used to weld copper. Has anyone used these? In any case, I'm sure I
would have to buy a minimum of 10lb and I don't need that much.

I think I'm going to try brazing, though.

I have some Stay-Silv 56 from another project. Would that be a good
alloy? Or should I use their phosphor copper alloy? I guess one would
use the phosphor copper for better color matching? However, using the
staysilv 56, I would only have to get the copper to 1200F instead of

If I braze the copper bars, would a mitre joint be the appropriate
joint? It seems there would be more surface area than a butt joint, but
it still seems like there should be more of a mechanical fitup for

Re: Brazing or welding thick copper?
On 21 Oct 2005 17:43:16 -0700, wrote:

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  I think that a lap joint would be the best joint for brazing.
Wayne Cook
Shamrock, TX

Re: Brazing or welding thick copper?
I did some brazing a few weeks ago - been a long time - and long re-learning...

It was on copper sheet - 32oz and 64oz - 110 copper - 99.99999% IIRC.
It was a rough go - using lots of oxy on it.
It was copper to copper with bronze filler and a small torch.

What I found was - used some borax type flux that was around the filler -
but what did the trick - paint the area with electronic flux - then braze
on top of it. Get a nice puddle - and naturally alloy - then add the item
that needed to be added.  This was while it was hot and fluxed.  The white
flux around the filler worked to a lessor extent but worked only in protected
air space - no air flow.

Copper was a pain in the neck.  I did the exact same thing with the sheet of
and the add on part still copper pipe.  Beautiful flowing glob - and adding the
copper, it froze the top, but adding heat, it flowed around both nicely.

I think the real trick is this :  Must get the brazing material to whet on the
surface and flow.  Once it is on one then the other is the job.

Might be best to do two jobs and then heat them together.

Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA Second Amendment Task Force Charter Founder

Wayne Cook wrote:
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