Welding copper with oxy fuel

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I got a bunch of 4/0 copper wire at a garage sale and am thinking about making some sort of copper sculpture.  I tried welding it with my oxy fuel setup, and it reminded me of welding steel with a similar puddle.  I used some 10 AWG bare copper as filler.  It looks like it's welded, but I don't know much about it, so maybe it only looks like it's welded.  Am I going about this the right way?  Here's a pic.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:Looks lika a weld to me too. I looked up copper welding in one of my old O/A welding handbooks. Long story short, it recommends neutral flame, filler wire with some phosphor as that works as a flux on copper, and also using additional powdered flux (type not specified) to protect the surface from oxidation (mostly when the torch is removed and air comes in contact with the hot copper). There are also some recommendations on hammering the weld on larger objects while it is quite hot (650-800 degrees centigrade) to counter the shrinking effects of cooling down, and warns to not hammer it at lower temperatures as the copper is too brittle then. Probably not useful for welding wires.Since you are not working on structural stuff I'm guessing you can make a good enough weld with common copper wire as filler and no flux, as long as it's clean and you don't have any obvious problems when you weld. On the other hand, you may also want to solder/braze it, as is done with copper plumbing - should be easy to find that kind of stuff.
Reply:not critical what happen when his two ton  sculpture falls over and crush's a kindergarten class on a field trip!!!
Reply:That's ok, the bus load of nuns with puppies will stop it. Nuns are supposed to be very forgiving about stuff like that. .No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Teaching the puppies to bite is the hard part.Does anyone know if one can arc weld copper?  Maybe use bare copper with separate flux?Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:You can DC tig copper. No flux required since the argon shields the weld from the atmosphere. Copper is a great heat sink and it will take a lot more amps than say steel would to do the weld..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I'm making a square out of 1 inch copper pipe.  Thickness M, the thin one.  The local building supply only has a code for 3/4, and they're charging me that amount.  16.70 per 10 feet.  Pretty cool.  My friends and family have always been supportive, but have never been so pleased as when I showed them welded copper.  It's a lot cooler looking than steel.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:I've ground some of the crappy welds down, and it looks pretty good.  I'll upload pics soon.  Here's what I want to know.  I heat the copper up a ton, weld it a bit, and it turns a blackish color.  While it's still super hot, I spray water on it, and the black stuff comes off, and it becomes a mottles copper color.  What's going on?  Thanks.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:The copper is oxidizing.  Keep the weld in the flame envelope, as there's little oxygen there.  You can clean it up using a "pickling" solution:- Vinegar, salt & hydrogen peroxide- Sodium bisulphate (PH Down from a pool supply co.)- Citric acid- Sulfuric acid- Bar Keeper's Friend- Ketchup"USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Avoid salt or muriatic acid, they promote corrosion. Sodium bisulfate or 10% sulfuric are best for pickling copper.A few weldersA lot of hammersA whole lot of C-clamps
Reply:I finally set up my DC only TIG machine.  It's a chinese plasma cutter combo unit.  It has no foot pedal, just a switch on the gun.  This is my first TIG'ing ever.  I haven't really started watching youtube videos and reading up on TIG yet, I just went for it.  I was able to weld two copper pipe sections together when I didn't bother using a filler rod.  Penetration seemed pretty good doing that.  I tried using some filler rod, and got bird guano.  Here's some pics.I have a 20 cubic foot argon tank, and I think I used up maybe $5 of the $40 refill cost.  Is this how expensive TIG is?  Is a larger tank a necessity? I probably had an arc going for only a total of 90 seconds. The machine was set to keep the gas going for a few seconds after I release the trigger.  Do I need the gas to continue at all with TIG?  Thanks.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:Your bird dropping "welds" look like you were melting the filler with the arc, not the puddle. That's a fairly typical newbie mistake with tig.As far as the gas flow, yes it's required. The argon gas helps shield the tungsten until it cools sufficiently after you turn off the arc and it also helps cool the power line and torch, WIth a water cooled torch, you can cut some of the post flow time but with an air cooled torch you need that flow time. As far as a bigger cylinder, You most probably will need a bigger one. Usually we have students set their flow meters to about 20 CFH, so your cylinder might last about 1 hour. Gas is less expensive per cubic foot the bigger the cylinder is. That's usually because wrapped up in the price is all sorts of "fees" for hazmat, shipping and handling charges, hydro testing and so forth. That cost is usually the same if you are getting a 20 cf cylinder or a 200 cf one. So that fixed "fee" isa large percentage of your cost with a small cylinder and a tiny one with a big cylinder, plus you only pay that fee 1/10 of the time ( using that 200 cf cylinder as an example).Most places will allow you to "upgrade" your small cylinder when you go to exchange it. My place simply charges you the price difference between what you have and the next size that you want if you upgrade. The only time really small cylinders are useful is if you need to drag them some where for portability, then you just have to pay the extra for fills..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks for the great reply.  I'll look into a larger tank, because I'd like to be able to practice a lot without the scary feeling I get as the regulator gauge dial goes down too quickly.  The little bit that worked OK looks great to me.  Not a stack of dimes tilted over like is the ideal, but it looks like a row of dimes layed flat, which is still pretty fun for me.Peregrine FisherCave Junction, Oregon1981 Miller Thunderbolt 225VOxy/AcetyleneSome broken shovels and rakes
Reply:I'm always on the lookout for used cylinders at yard sales and CL cheap, even if the gas in them isn't what I need. My place will swap similar size cylinders for any gas. I've often swapped my "spare" nitrogen cylinder for argon or mig gas if I know I may need a 2nd cylinder for a big project over the weekend, and swap the empty back later for nitrogen. I've done the same thing with acetylene and O2 as well. I'm sitting on 4 40cf acetylene B cylinders right now that I got off CL for less than it would have cost me for the gas in the cylinders. When I find a need for a small cylinder of gas, say argon for my Maxstar 200 for a portable tig job, I'll probably swap the empty 40 of acetylene for argon. That or I'll exchange 2 40's for an 80 cf cylinder.I wouldn't go any smaller than an 80 cf cylinder and I try and go as big as possible..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I think you need Helium for copper TIG.