Thanks in advance,
-Sandow
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I've been making copper crowns as the trophy for a shooting competition for a few years and have had persistent issues with weld penetration. The base material is oxygen free copper and the bullet are solid tellurium copper. The welds are all done with ERCu tig rod as rosettes and the ground flush. The because of the way copper conducts heat, I end up essentially melting the back of the bullet into the a puddle with the fill rod contributing a bit of direction and some oxide soaking to the melt pool. The result is very consistent as far as color goes on the finished item but once the welds are ground flush with the interior of the band, I'm frequently finding the seam at the edge of the bullet and band where the weld has failed to penetrate bellow the surface at all. In these cases, I go back and weld another layer of reinforcement (not going to call I a bead cause it really isn't) and then grind it flush again. This isn't really a structural weld but I'm left knowing that where I don't grind through, I'm likely left with many welds that are essentially paper thin. Do any of you have advice for better penetration or flow of the melt pool? Surface prep, flux, tig brazing? I'm open to trying whatever. I would prefer that the result be coherent in coloration though which is why I've avoided the soldering options thus far.
Thanks in advance,
-Sandow
Thanks in advance,
-Sandow
Red-hot iron, white-hot iron, cold-black iron; an iron taste, an iron smell, and a babel of iron sounds.
-Charles Dickens
-Charles Dickens
i havn't done cooper before. but i think the bullet mass will work against you. so i would preheat the bullet, then try not using filler. use to many amps and be hot and fast. at least get a couple of points of good pen. then come back with filler and fill up any low spots. i'm assuming the bullet is cut to shape first.
other things that can help is to bevel each part and then fill that with weld.
even if its just a bit in the center where the ring can handle some heat. ie trim the bullet on the sides so you have a groove to weld on each side in the center of the ring. that should give enough strength and weld around the rest of the bullet for looks.
other things that can help is to bevel each part and then fill that with weld.
even if its just a bit in the center where the ring can handle some heat. ie trim the bullet on the sides so you have a groove to weld on each side in the center of the ring. that should give enough strength and weld around the rest of the bullet for looks.
tweak it until it breaks
The thermal conductivity and heat capacity of copper means that after the first weld the entire piece is essentially preheated and stays hot until quenched. I have played with quenching after every weld and that does blow off the black oxides and gets you clean metal but then the dwell time to get a melt pool and my welders 200 amp max is abysmal.
Notching the band pretty much solved the issue I was seeing. Basics of welding stuff right? Maybe I've been spending too much time casting and forging...
To explore a few more options I played with using brazing flux between welds and found the results to be absolutely miserable. I'm not sure if the cleaning action of flux is dependent upon the environment of gas welding but I saw a bit of porosity when I used it and found the clean up to be significantly worse. I wonder about using borax like in welding at the forge but that can produce a glassy coating that is occasionally a PITA to scrub out of corners.
If anyone is wondering about the coloring, I simply feather a torch across is and at the right temp the surface oxides produce the color variation.
-Sandow
Notching the band pretty much solved the issue I was seeing. Basics of welding stuff right? Maybe I've been spending too much time casting and forging...
To explore a few more options I played with using brazing flux between welds and found the results to be absolutely miserable. I'm not sure if the cleaning action of flux is dependent upon the environment of gas welding but I saw a bit of porosity when I used it and found the clean up to be significantly worse. I wonder about using borax like in welding at the forge but that can produce a glassy coating that is occasionally a PITA to scrub out of corners.
If anyone is wondering about the coloring, I simply feather a torch across is and at the right temp the surface oxides produce the color variation.
-Sandow
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Red-hot iron, white-hot iron, cold-black iron; an iron taste, an iron smell, and a babel of iron sounds.
-Charles Dickens
-Charles Dickens
That's really cool looking. You make it sound so casual how you get the colors, and maybe you just had a happy accident, but it does take some experience to get some positive looking flame coloring on copper. I know from experience. It's extremely easy to overheat it and just get a sickly brownish green color.
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With thick copper, it is actually pretty easy to get a spectrum of colors. Once the piece is hot it is just a matter of waving the torch across for a couple seconds. If you go too far you just let it cool a bit and try again. I used to blow compressed air on it to selectively cool it but I just freehand the torch now. Color is based on time and temp in an oxygen environment so you can stop the color drift by cooling. Water will quench off the surface oxides but you could probably stop the color change by plunging into an argon purged bucket.
-Sandow
-Sandow
Red-hot iron, white-hot iron, cold-black iron; an iron taste, an iron smell, and a babel of iron sounds.
-Charles Dickens
-Charles Dickens
Guy at work keeps asking me to tig weld his cymbals. I keep telling him every single video or forum blurb I've seen about it says it's a terrible idea and he's better off cutting the cracks out of the edge, or drilling the cracks out of the center, but he keeps asking, so I finally told him I'd take it home and try to spot tack it with no filler and see what happens.
I am not optimistic.
I am not optimistic.