Brazing large copper piece?

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I am working on a copper cowboy hat, full size.   I have been struggling with TIG welding it, and decided to try brazing, with silicon bronze rod.  (The dome is one piece, I am trying to weld or braze the brim on). I tried with a number 2 welding/brazing tip on my Victor 100FC torch.  I was working a test piece, maybe 6 inches in diameter, so much smaller than the hat.  Apparently I am not even close to having enough heat to braze something that large; the copper seems to pull the heat away faster than I can deliver it.  If I look at the application chart for the #2 tip, it says it should work on 3/64" to 3/32" thickness, but presumably those numbers are for steel.  I am using 32 oz copper, about 0.040" or 1 mm thick.  I tried to braze some small pieces with the #2 tip, and that worked fine, no surprise.  I tried using my cutting tip, but I think that I got the tip too hot; I could see the flames go in strange directions, probably will need to replace the tip.  I tried braze welding with my TIG torch, but had the same problems that I had with TIG welding.  Should I try a rosebud?  Am I just kidding myself that I can braze such a large piece of copper?Maybe it did not help that I was clamping the pieces together using a 1/4" steel plate.....I rarely braze, and when I do I usually braze weld with my TIG torch.   Any comments on off brand vs. Victor welding tips?   The price of the off brand on ebay is dramatically less than the Victor tips.  The number 2 tip is the largest I have, but I see that larger tips are available.  I have a Victor 100FC torch handle.Comments?  Thoughts?  Experiences?Richardhttp://www.fergusonsculpture.com
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Originally Posted by richardferguson

I am working on a copper cowboy hat, full size.   I have been struggling with TIG welding it, and decided to try brazing, with silicon bronze rod.  (The dome is one piece, I am trying to weld or braze the brim on). I tried with a number 2 welding/brazing tip on my Victor 100FC torch.  I was working a test piece, maybe 6 inches in diameter, so much smaller than the hat.  Apparently I am not even close to having enough heat to braze something that large; the copper seems to pull the heat away faster than I can deliver it.  If I look at the application chart for the #2 tip, it says it should work on 3/64" to 3/32" thickness, but presumably those numbers are for steel.  I am using 32 oz copper, about 0.040" or 1 mm thick.  I tried to braze some small pieces with the #2 tip, and that worked fine, no surprise.  I tried using my cutting tip, but I think that I got the tip too hot; I could see the flames go in strange directions, probably will need to replace the tip.  I tried braze welding with my TIG torch, but had the same problems that I had with TIG welding.  Should I try a rosebud?  Am I just kidding myself that I can braze such a large piece of copper?Maybe it did not help that I was clamping the pieces together using a 1/4" steel plate.....I rarely braze, and when I do I usually braze weld with my TIG torch.   Any comments on off brand vs. Victor welding tips?   The price of the off brand on ebay is dramatically less than the Victor tips.  The number 2 tip is the largest I have, but I see that larger tips are available.  I have a Victor 100FC torch handle.Comments?  Thoughts?  Experiences?Richard
Reply:What kind of flux are you using?  As mentioned above, some brazing and soldering rods are self fluxing.  If you over heat it, it will burn the flux and the filler won’t flow and bond to the copper.  Start over and shine things up.   Most HVAC people that braze copper would use an acetylene-air turbo torch.   OA may be too hot, so be careful with the heat.  If I was welding steel that thick with a Victor torch, I would use a 0 tip.
Reply:Have you compared temps of base metal and filler?  You call it brazing probably welding.  Are you expecting it to flow without melting the base metal?
Reply:I agree with the Sil-Fos recommendations,, PLUS,,,,add a source of heat other than the torch.You would be amazed at the change if you tried brazing while the hat is sitting on a large propane cooking grill, with all burners set to high.Or possibly use a weed burner propane torch.Load up the heat from the "other side" so that you can get on to doing the brazing with your torch.There is no law in the welding books that says heat must come from one source,,,
Reply:#2 tip should be more than adequate.  I've Sil-Phos brazed 2" buried copper pipe with less while water was held 8"-10" away by a Dutch finger.  I think your project would require less heat so something must be going wrong with your method.  Try directing flame so that as much stays on work as possible instead of burning up in surrounding air.
Reply:Were you Tig welding it with Copper and didn't like the results? I feel like copper Tigs pretty well... (I haven't done a whole Lot of it, maybe like so many other metals, there's a larger variety of copper alloys than I realize)


Reply:What filler rod did you use when you tried TIG brazing it?Check out my bench vise website:  http://mivise.comMiller Syncrowave 250DXMillermatic 350P with XR AlumaProMiller Regency 200 with 22A feeder and Spoolmatic 3Hobart Champion EliteEverlast PowerTig 210EXT
Reply:Try using helium as a shielding has it gives a much hotter arc. Copper is a heat sink for sure and if your machine is maxed out and your not able to get a puddle going without cooking the hell out of the part helium is the answer.
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Originally Posted by Bradley256

What kind of flux are you using?  As mentioned above, some brazing and soldering rods are self fluxing.  If you over heat it, it will burn the flux and the filler won’t flow and bond to the copper.  Start over and shine things up.   Most HVAC people that braze copper would use an acetylene-air turbo torch.   OA may be too hot, so be careful with the heat.  If I was welding steel that thick with a Victor torch, I would use a 0 tip.
Reply:I used solid copper wire with pennies and TIG.  Short welds, let cool and repeat.
Reply:Just an update:  I tried to use my oxy-propane rosebud, but could not melt a piece of rod on the test piece, so not enough focused heat......  That was after I got rid of the 1/4" steel plate, in favor of a lot less thermal mass used in clamping.I am going to think some more about how I could preheat the piece; given how thin it is, heat would probably need to be continuous to be effective.   I am thinking about buying some larger oxy-acetylene tips.Personal note:  This has been a very frustrating project, which seems to have come down to my inability to consistently produce good small weld beads.  So far I have thrown away three brims; I keep trying to save the dome.   I put the project down for several months, and then I try again.  I even got a welding instructor to come to my studio and give me some tips......  I was hoping that brazing would offer a way out,http://www.fergusonsculpture.com
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Originally Posted by richardferguson

Just an update:  I tried to use my oxy-propane rosebud, but could not melt a piece of rod on the test piece, so not enough focused heat......  That was after I got rid of the 1/4" steel plate, in favor of a lot less thermal mass used in clamping.I am going to think some more about how I could preheat the piece; given how thin it is, heat would probably need to be continuous to be effective.   I am thinking about buying some larger oxy-acetylene tips.Personal note:  This has been a very frustrating project, which seems to have come down to my inability to consistently produce good small weld beads.  So far I have thrown away three brims; I keep trying to save the dome.   I put the project down for several months, and then I try again.  I even got a welding instructor to come to my studio and give me some tips......  I was hoping that brazing would offer a way out,
Reply:So you are using oxy propane?  Oxy acetylene works better for directing heat to a specific area.  Propane heat a larger area.  If you use just the inner cone, then you compromise heat input. The max heat input is notPinpoint at the cone but on the outer area of the flameLast edited by tapwelder; 2 Weeks Ago at 03:42 PM.
Reply:This is my favorite tip for silver soldering copper. I use 15% silver solder, and no Flux unless I'm soldering copper to steel. It is a uniweld type 17-15. I use a slight carburizing flame. 15% solder comes out more of a bronze color. I've only used oxygen propane once many years ago and hope to never use it again unless I have to.




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Reply:I have read that oxidizing flame work for copper, bronze and zinc.
Reply:I was bending metal last night on this rare occasion using heat with acetylene tank connected.  Decided to try some copper /silicon bronze.  Used MECO weldmaster torch .  I had .025 copper and 1/16 sb.  Used acetylene/oxygen.  #1 tip.  The melted bronze seems to add mass and no melting occurs where sibr is added.  Issue I had was tip too large it would overheat shortly after flow. I will try a 0 or 00 tip.  I think the proximity or the melting point. The copper melt everywhere else after the sibr flows.  I think propane is the issue for you, not allowing heat concentration.  Interesting in hearing your result.
Reply:Correction I had #2 tip on last night.  Tried a 1.  Much better control.  Nothing pretty,  though.  Seem like it start to flow then overheat and piles up?  I am just speculating. Oh, I guess I should try flux.
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Hope this photo works.  Added flux.  However the part where it began to stick there was a large mass of flux.  Again, speculating the first part there was not enough flux and it kept balling and would not adhere at all to the lower plate, like not enough heat, but I think it is oxidation..  Notice the color difference.  I used Esab brazo flux added water but it did not make a very good paste.  Thus it distributed unevenly.
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Here is another photo.  Inner cone almost touching added filler.  Caked on a large volume of wetted esab flux.!dried it in place  with the torch before brazing.I also, tried Harris staysil silver solder white paste and oxidizing flame. No conclusion on how it works since there are too many other variable for me to correct.I brazed on top of a piece of square tube. I think heat wicking ,due to a mass ,was not a huge issue compared to wicking due to proximity of directing heat to where I wanted the filler applied.  If the cone is too far away, then the filler balls or only adhered yo the vertical plate.  It often will not move/flow.
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Alright, alright alright. Last one, maybe. Photo does not represent well.  CloseCone and small tip, oxidizing flame.  Flowed well.  I was not comfortable, hesitated and burned hole the end.All joint are fillets.  All are curved so they stand freely.  The last one is straight.Last edited by tapwelder; 2 Weeks Ago at 01:56 PM.
Reply:An oxidizing flame produces a slightly higher flame temperature, but whereas flux is there to dissolve oxides and improve wetting, while an oxidizing flame promotes oxides, I see little reason to use one under normal circumstances. A neutral or slightly reducing flame, with copper or most brasses, will lead to less problems including zinc vaporization on the surface of brass. Here's a site a quick search found that gives basic information about flame characteristics:https://mewelding.com/oxyfuel-flame-...nd-flame-type/
Reply:Yeah,  however the difference in flame temperature is remarkable.  I tried reducing flame with out flux it worked, but input so much heat due slow build up of heat it burned holes later in the process. With neutral flame and flux i could direct the flame cone into the joint and begin brazing almost immediately.  I suspect an oxidizing Flame and flux would be useful on heavier material.  In production application I suspect it would be cheaper, use oxidizing flame rather than waiting for reducing flame to heat up and all the heat transfer that occurs in materials like copper.  I think a reducing Flame would be better for sweating pipe, since it is broader and will wrap.Also, read reducing flame is a safety setting since neutral is balanced and will drift.  It is less likely to become oxidizing.  Anyway to OP. My suggestionsAcetylene would likely work better for directing heat where you want it to go.Smaller tip neutral or oxidizing flame.Lots of flux
Reply:The late Mr. Tig on copper welding. I cast quite a bit of copper but in the foundry you throw your failures back into the furnace and they disappear so I never had the need to weld it.Another source:https://www.brazing.com/Support/Proc...rocedures.aspx---MeltedmetalMore nonsense from "MrTig" (this clown names himself despite not being much of a Tig welder

) Welding Copper at .45 sec "Pretty difficult", at 3.25 suddenly "isn't that hard"...I don't know what Helium costs were in 2014, but today his advice is even sillier than it was back then. Use the right size machine, and copper welds just Fine. You can do fun stuff with it too, weld SS and Copper with Romex wire filler!
Reply:Last one.  Cleaned metal with grinder. Used Harris 600 flux is wet slurry/”paste” . Baked flux on to rod. Stopped multiple times to recoat rod.  Used neutral flame.  I switch flux only because I was out of esab flux.  The coated rod flowed betted and eliminated the trash atop the previous welds.  The photo was taken with immediately after welding with zero post weld cleaning.  I did a previous weld with uncoated rod and reducing flame.  The metal flowed the same as the fluxed rod, but still has trash in the bead.Coupon is sitting on 3/8” thick steel table.Next question… have you ever grinded silicon bronze?  It is a bear.

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Last edited by tapwelder; 1 Week Ago at 09:11 AM.
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Originally Posted by BaTu

More nonsense from "MrTig" (this clown names himself despite not being much of a Tig welder

) Welding Copper at .45 sec "Pretty difficult", at 3.25 suddenly "isn't that hard"...I don't know what Helium costs were in 2014, but today his advice is even sillier than it was back then. Use the right size machine, and copper welds just Fine. You can do fun stuff with it too, weld SS and Copper with Romex wire filler!
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Originally Posted by G-ManBart

He passed away a few months ago...kind of poor form to call the guy names, even if you disagree with him.
Reply:Yea, I gotta say, "death" gives everybody a get-out-of-Jail card?Once dead, you can't be criticized? Any misinformation you leave behind has to stand unchallenged? And this is because of some Child Like Fantasy that the dead might be "looking down" on us and unable to respond in defence? I called him a clown when he was alive (and I must say I was unaware of his current status when I wrote it this time) and his passing hasn't changed my opinion one bit!


Reply:For future reference, and I know it is subtle, when I refer to someone as "The late whomever", it doesn't mean he missed lunch. It means he is dead.

---Meltedmetal
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Originally Posted by Oldiron2

I know nothing of the fellow, including his abilities, but see no reason that should cloud factual statements made by others about that ability. If someone thinks he has given bad information or demonstrated poor technique and that might be accepted as being correct by newcomer to the field who see it, a reasonable warning seems to me to be justified. In my case, if someone criticizes me now, it would theoretically bother me more that it could after I'm dead.Besides that, how is everyone supposed to keep track of someone who they only see on the internet and know that he has died?