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What's the best way to weld copper?

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  • #16
    GTAW: typically 11000 degrees F
    OFW-A: typically 6000 degrees F

    Those are ballparks, and they vary with many factors, but I don't see how you can say the O/A is hotter than TIG. Or were you saying something else?

    Solarflux is available for protecting the back of a TIG weld on things like stainless. Does it work for copper, too? Might be worth checking into.

    Comment


    • #17
      Originally posted by MAC702 View Post
      GTAW: typically 11000 degrees F
      OFW-A: typically 6000 degrees F

      Those are ballparks, and they vary with many factors, but I don't see how you can say the O/A is hotter than TIG. Or were you saying something else?

      Solarflux is available for protecting the back of a TIG weld on things like stainless. Does it work for copper, too? Might be worth checking into.
      MAC,
      your correct I should have been more specific. I should have said the average temperature of the cross section of the arc/flame. The TIG arc temp can be quite high in the center, but cools off a lot in the outer envelope of the arc. I should have said somethin likeenergy imput. Yes there is a copper flux, its been around for years before TIG. I think you can get it from allstate, as well as kent white. As far as your listed Tig arc temp, If you hold a gap of about 10mm at 100 amps ( with the tungsten as the cathode) the center of the arc at the tip of the tungsten will be about 20,000K, and about 6,000K at the work (anode). Note that this does not mean that the tungsten is getting more heat, this is where we get into cathode jets, heat flux input to annode and all sorts of things in the arc plasma. Simplified, the OA flame has a lot of energy input for its physical flame size, and works perfectly for copper, and in some ways better then TIG, just one of those things thats hard to beat no matter how many red and blue machines we throw at it.

      -Aaron

      Comment


      • #18
        he is working with verry thin copper, the pipe is under 1/8" or there abouts.
        i would skip the econotig but the syncro200 would be a decent TIG for your uses. a syncro180 would also work and most likely be findable at a decent price if you can find one near enough shipping dose not kill you. a new syncro 200 compleat ready to weld package is about $1900 shipping included so dont get caught up in a bidding war and go to high.
        if you want to go with an inverter for lower imput power option or smaller size the TA-185's are about $2000 ready to weld, the dyn200 is about $3000 ready to weld both including shipping.
        although i think O/A is still the best starting point as it should handle all your needs with a lil practis. add a TIG later when you feel the need or want if thats the case, but the O/A setup is verry versatal and lends its self to art quite well once you start to lern all its abilitys.

        Comment


        • #19
          Originally posted by makoman1860 View Post
          MAC,
          your correct I should have been more specific. I should have said the average temperature of the cross section of the arc/flame. The TIG arc temp can be quite high in the center, but cools off a lot in the outer envelope of the arc. I should have said somethin likeenergy imput. Yes there is a copper flux, its been around for years before TIG. I think you can get it from allstate, as well as kent white. As far as your listed Tig arc temp, If you hold a gap of about 10mm at 100 amps ( with the tungsten as the cathode) the center of the arc at the tip of the tungsten will be about 20,000K, and about 6,000K at the work (anode). Note that this does not mean that the tungsten is getting more heat, this is where we get into cathode jets, heat flux input to annode and all sorts of things in the arc plasma. Simplified, the OA flame has a lot of energy input for its physical flame size, and works perfectly for copper, and in some ways better then TIG, just one of those things thats hard to beat no matter how many red and blue machines we throw at it.

          -Aaron
          This discussion is why when doing weld procedure qualification records we record the interpass temp at various points starting at the center of the weld moving to the toe and then calculate the total Joules of energy input.


          Not that I can realy talk to this subject.



          As to welding copper with GTAW the stuff I have welded required pushing a SW350 to the max using 1/4" tungsten and that was for .125 thick sheet copper. The filler was cut from the same sheet. I had much better result when the company sprang for a SW750and a 1000amp torch. It made welding 1"Inconel a lot easer as well.


          So with out many thousands of dollars and three phase power i think you are limited to braise or silver solder and I would opt for the silver as with the right joint you could hide all the silver.
          Last edited by Fat-Fab.com; 06-06-2007, 09:20 PM.

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          • #20
            you have to keep in mind he is not doing structural weld but rather art work requireing only that it atach for decoration, not to hold a load. so wile all the advice is good it dose not all fit his need.

            Comment


            • #21
              Originally posted by fun4now View Post
              you have to keep in mind he is not doing structural weld but rather art work requireing only that it atach for decoration, not to hold a load. so wile all the advice is good it dose not all fit his need.
              I doubt that any power source hooked into a 1 phase 220 outlet would eaven get a puddle going on standard copper pipe say 1/2" id.

              Ill give it a try tomorrow on my dynasty 200 and let you know how I do.

              Comment


              • #22
                cool that would be verry helpfull.
                like i said i think O/A and most likely brazing is going to be the best fit.

                Comment


                • #23
                  Originally posted by Anti-GMAW View Post
                  Keep in mind that only certian grades of copper are weldable, although most are able to be brazed, soldered etc.... The econo tig and the 200 wont have the power for any real welding on copper. You would be prety limited on the thikness. We push our sync. 350's at work nearly to the breaking point on the copper/nickle stuff we do.
                  Looks like I will for sure start out with OA and deoxidized copper welding rod. I will keep one eye open for a TIG while I'm at it (depending on my results).
                  From my research, the copper sheet metal shouldnt be a problem with OA. What about plumbing pipes? Just looking at the 1/2" & 3/4" rigid copper pipe at Home Depot.

                  Are there any good sources of info online for welding copper with OA?

                  Once again, I want to thank everyone for their input! Lots of good info.

                  Comment


                  • #24
                    Originally posted by subzero View Post
                    Looks like I will for sure start out with OA and deoxidized copper welding rod. I will keep one eye open for a TIG while I'm at it (depending on my results).
                    From my research, the copper sheet metal shouldnt be a problem with OA. What about plumbing pipes? Just looking at the 1/2" & 3/4" rigid copper pipe at Home Depot.

                    Are there any good sources of info online for welding copper with OA?

                    Once again, I want to thank everyone for their input! Lots of good info.
                    SZ,
                    The plumbing type pipe welds just fine, in fact we buy ours from home depot for engineering projects. Kent White has some copper info at his site in the technical area, He has a good booklet on the subject as well. Otherwise the guys at www.metalmeet.com in the forums talk of welding copper as well.
                    Good Luck!
                    -Aaron

                    Comment


                    • #25
                      welding copper to copper

                      If it is decorative, Oxy-acetylene does the job...parent metal as filler....I do it all the time....practice makes perfect....weldress

                      Comment


                      • #26
                        [QUOTE= only certian grades of copper are weldable, although most are able to be brazed, soldered etc.... You would be prety limited on the thikness. We push our sync. 350's at work nearly to the breaking point on the copper/nickle stuff we do.

                        How can you find out what grade is weldable? I never had any problems with a torch, why with a TIG?

                        Also I am interested in buying a Tig for welding copper on copper. What about the Dynasty 300 DX. I think the 200 DX just doesn't have enough amp power to puddle it. Unless you go to Helium/Argon mix??

                        Any imput would be great, thanks,

                        Kim

                        Comment


                        • #27
                          I've done this

                          When I got my first TIG welder I did exactly what you are inquiring about. I was just experimenting, welding razorblades together and such. I thought I'd try welding 1/2" copper pipes. I melted the first one down, but then I got the hang of it. It needs to get very hot, nearly to the point of melting the copper, then you hit for a second and it welds. The puddle doesn't last long enough to really see it. The whole tube just oops out before that happens.

                          That welder was a $200 (on sale) Harbor Freight 130A scratch start inverter tig welder. It doesn't take a lot of heat to weld 1/2" type L copper pipe.

                          Yes, you need a lot of heat to weld copper sheet because every inch the heat travels, it gets an inch further away from the arc... but on small diameter pipe, when the heat travels an inch - well, it's almost right back where it started. Or in more thermodynamic terms, it cant utilize it's thermal mass as efficiently as a sheet because it can only move up and down the axis of the pipe instead of radiating outward in all directions on a sheet.

                          I found the best way to do it was to make an autogenous weld by melting the edge of the fittings over and onto the pipe. I held the torch with the right hand and used my left hand to rotate the amperage control like a "poor man's pulse".

                          The results were very aesthetically pleasing. The welds were virtually indistinguishable from the rest of the pipe. I showed my sister the completed fittings and she seemed to think they'd make excellent drug paraphernalia. I didn't set out to make a dope pipe, so I broke it and chucked it in the scrap pile, otherwise I'd show you pictures.

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                          • #28
                            Copper

                            Why not use silver solder and braze it? I use it all the time for copper to copper, copper to steel, and copper to brass. It's strong on withstands temperature changes. It won't be good for sheet metal. My friend works for a flashing manufacturer and they use plumbing solder or tig with copper or brass rod.
                            Lance
                            Last edited by lanceman73; 09-16-2008, 09:30 PM.

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                            • #29
                              copper TIG

                              When I was in the automotive industry, I welded over a million welds. Mostly aluminum. I tried experimenting with lots of stuff.
                              Copper water pipe welds fine with a 350 miller, only had AC, as the place I worked didn't want to spend the extra $ for DC machines......I used #14 electrical wire, and it welded just like aluminum. Never needed over 200 amps.
                              I also repaired a copper sink with a different machine, same wire, but with DC, and it sucked. I got it done, but it was much more difficult. I was tempted to switch to AC, but was told by someone who was supposed to know, that DC was best, and I didn't want to make it look different as it was about a $5,000 sink.

                              Comment


                              • #30
                                I was able to TIG weld 1/16" copper with my Dynasty 200 DX. I agree that a larger machine would handle larger or thicker pieces. Here is a link to my original post:

                                http://www.millerwelds.com/resources...68&postcount=1

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