How to weld copper?

   #1  

EddieWalker

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I might have a job that will include welding, or maybe brazing, some copper. I will fold it over one inch and I need to connect the bent over part. This will be a cover that will go over a cabinet. It will be 22 mil thick, or 24 gauge. Its pure copper.

What would you do?

I might just take it to a welder and have them do it, but for such a small project, I think I can do this myself.

Thank you.
 
   #2  

Motorboatin

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Brazing the joint is the what I would recommend. You will figure it out with a little bit of practice

If the joints are tight you can easily solder it
 
   #3  

aczlan

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Brazing the joint is the what I would recommend. You will figure it out with a little bit of practice

If the joints are tight you can easily solder it
That is what I would do, I spent a summer working HVAC and brazed a lot of line sets with Copper to Copper connections. We used either a MAPP gas torch or a oxy acetylene torch. I preferred an oxy acetylene torch because it did not spread the heat as much, but in your case you might want a map gas torch as it will spread the heat more and let you warm up the whole area that you're going to be brazing quicker.

Aaron Z
 
   #4  

Industrial Toys

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I was thinking brazing too. The filler will flow over the copper to some extent, which could be a factor, for appearance sake.
 
   #5  

Wilco

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95/5 Solder would probably be fine. I'm not really sure exactly what your trying to do though.
 
   #7  

PILOON

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To solder copper you would want acid flux and using an acid brush you prep the joints and solder away.
Do it outdoors as the fumes are not nice.
 
   #8  

grandpajay

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If you have access to a TIG welder/straight Argon, copper welds almost exactly like mild steel. Just strip some insulation off some solid 14 or 12 gauge wire and use it for fill rod. Practice on scrap first to get the hang of it.
 
   #9  

rScotty

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I might have a job that will include welding, or maybe brazing, some copper. I will fold it over one inch and I need to connect the bent over part. This will be a cover that will go over a cabinet. It will be 22 mil thick, or 24 gauge. Its pure copper.

What would you do?

I might just take it to a welder and have them do it, but for such a small project, I think I can do this myself.

Thank you.

You can do that job in several different ways.
You could use low temp solder like a plumber does... -under 800 deg. F melting - with a mild acid flux. That can be done with any heat source from propane/air on up to Mapp or oxy/acetylene. You can use either old fashioned lead/tin soft solder or one of the newer lead free tin/cadmium types. Downside is that it is difficult to control just exactly where the solder will go and how much to use. Soldering is dependent on clean metal, good flux, and not getting things too hot. Just hot enough to flow.
And the joint won't be very strong. Basically it is just a little bit stronger than the solder itself.

If you are handy with an oxy/acetylene torch you can do that job in several other different ways.
For nicer control you can step up to an oxy/acetylene welding&brazing torch. The copper doesn't have to be as clean, the flux is often a boxax powder rather than a paste, and the filler rod can be any of a dozen types of brass (copper and zinc) , bronze (copper and tin), or either one with enough nickel or silver to make a very hard nickel-brazed joint. The jointing work can be done with beautiful control - it's what jewelers use for tiny work. And a nickel-brazed joint is stong enough to withstand hammering the finished product into shape. All a matter of practice, and you can get the rod for a couple of bucks/lb at the local welding supply shop.

Here are some examples of free-hand welding - there's some brass, bronze, and nickel brazing in these pieces, but not a drop of solder.
rScotty
 

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Tractor Seabee

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You can do that job in several different ways.
You could use low temp solder like a plumber does... -under 800 deg. F melting - with a mild acid flux. That can be done with any heat source from propane/air on up to Mapp or oxy/acetylene. You can use either old fashioned lead/tin soft solder or one of the newer lead free tin/cadmium types. Downside is that it is difficult to control just exactly where the solder will go and how much to use. Soldering is dependent on clean metal, good flux, and not getting things too hot. Just hot enough to flow.
And the joint won't be very strong. Basically it is just a little bit stronger than the solder itself.

If you are handy with an oxy/acetylene torch you can do that job in several other different ways.
For nicer control you can step up to an oxy/acetylene welding&brazing torch. The copper doesn't have to be as clean, the flux is often a boxax powder rather than a paste, and the filler rod can be any of a dozen types of brass (copper and zinc) , bronze (copper and tin), or either one with enough nickel or silver to make a very hard nickel-brazed joint. The jointing work can be done with beautiful control - it's what jewelers use for tiny work. And a nickel-brazed joint is stong enough to withstand hammering the finished product into shape. All a matter of practice, and you can get the rod for a couple of bucks/lb at the local welding supply shop.

Here are some examples of free-hand welding - there's some brass, bronze, and nickel brazing in these pieces, but not a drop of solder.
rScotty

"Old" sheetmetal hand here. TIG will do your nicest looking job and can be polished to match; but w/o that: Soft soldering a butt joint corner does't work, quickly crack. For soft solder you have to have overlapping parts, preferably with a mechanical fastener, you can then sweat solder them together. This project; use 45% + silver content brazing rod, 00 O/A tip turned real low, tack the open corner at the top, get the joint tight together and smooth, work from inside, start at the closed end out toward the tack slowly w/just enough heat to melt and flow the allow. Done carefully there will be just a hairline of alloy visible on the outside. This is not blow and go work.

The brazing alloys for HVAC work referenced earlier take a lot more heat and will distort the thin material plus leaving a heat/alloy stain very difficult to remove. I was a HVAC installer also in my early life.

Ron
 
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