oxy/fuel problem

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I'm trying to put back together a weld on a wrought iron table.  I'm using a bronze stick with flux.;  Out of the four legs that I've weld, only one is in tact.  I'm a newbie and I'm sure I'm making all sorts of mistakes.  I did grind it down to the shiney bare metal.  It seems as if I'm using way to Ox.  I've heated up the metal, then tried to weld the bronze at the joint.  The one that did weld has a huge glob holding it together.  My local Lowes guy said to set the Ox at 20 and the acetylene at 5.  Any suggestions?  At first I was using a small tip that came with my Lincoln torches.  I switch to the bigger tip but am having problems connecting it to the handle.  Seems with the bigger tip that came with the package it doesn't allow the Oxy to flow.  What size tip should I use and why does my weld stick on one part of the joint but not the other.Thanks for the help.Jim
Reply:You've got a lot of issues here, and practice and experience count for a lot in this sort of thing.I'll give you a few pointers in the right direction, and I'm sure that plenty of people will chime in with the safety concerns (of which there are many for someone unfamiliar with oxy-acetylene).So, first off, you're brazing, not welding.  Its brazing, when you're using bronze rod (that's rod, not stick).It sounds like you're using oxygen and acetylene, since you mention pressures of each.  That's not absolutely necessary for brazing, but its a good choice.For welding and brazing, your gas pressures should be just about the same on the oxygen and acetylene sides.  You would only want significantly higher oxygen pressure for cutting (which you're not doing).  Do you know how to adjust for a neutral flame?Brazing requires enough heat to get the bronze to flow into the joint.  If its all blobby and not sticking to one side, it sounds like you need to work on your heat control.  In order for a braze to stick to both sides, you need to get both sides hot enough for the bronze to flow out on them.  It should be a dull red, and if done right, the bronze will appear to creep away a little from where its applied.  More importantly, you don't want to apply too much heat to the bronze rod.  That will melt drips off, without any good attachment.  You want sufficiently to heat both sides, and then touch the rod to the joint a little away from the inner cone of the flame, and it should melt onto the surface and flow into the joint. The Lincoln torches look like Victor clones.  Not bad.  Are the o-rings on the bottom of your larger torch tip sitting correctly?  Maybe there's something wrong with the tip.You should be able to get the oxygen, and the acetylene to both flow separately to see if its clogged.  If you don't hear the gas coming out, you could put the very tip into a cup of water and look for it bubbling.
Reply:bronze stick with flux?  maybe you want to try RG-45 as filler.  You sound just like me 8 months ago (which is why i never heard of bronze stick with flux).its frustrating, i know, but keep it up, you'll get it.
Reply:Brazing is sort of like soldering. You need flux which can be seperate or on the rod. This is brazing flux not soldering flux like they sell for plumbing. As said you need to get both pieces red hot then add the rod..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:rlitman   Thanks for your advice.  I do know how to adjust to a neutral flame.  From what I'm gathering, I probably haven't heated up the sides enough.  Most of the time it seems I would melt the rod.  It would make a ball and roll off or get blown off by the torch.  If my memory serves me right, when connected the fuel would flow but the oxy would not.  This was late last night.  I'll double check it again.   I'm using a bare bronze rod and a separate jar of flux.  Little granuals.  What size tip should I be using?  Sounds like my biggest problem is not getting it hot enough.  You said I should have both my oxy and fuel at the same psi?  Should it be around 5?I appreciate everyones help here.  To take time out to help me with my problem is much appreciated.
Reply:the most important lesson you need to get is not to ask the guy at lowes..he might have been selling shoes the day before. by the way as rlitman said he told you  wrong, this time you didntget killed from the wrong advise. even for cutting a 4:1 ratio aint correct. more like a 5:1 or 6:1, but check mfrs website for proper settings for the tip you are using. with most smaller welding tips 3-4 psi of each wont be too wrong. the gauges only get you in the right park, you still need to adjust to get just the right flame. if you're not getting a puddle in 3 seconds you are too cold.thisironically will result in using too much heat, because you'll stay too long in one spot and get distortion.
Reply:Thanks weldbead.  "by the way as rlitman said he told you wrong, this time you didntget killed from the wrong advise. even for cutting a 4:1 ratio aint correct. more like a 5:1 or 6:1"  You mean the guy from Lowes told me wrong?  Or rlitman?  I'll start with 3-4 psi with each and adjust as needed.  The other tip was for a gas/air .  Explains why there wasn't any oxy. Going to give it another shot tonight.  Thanks for all the input.
Reply:rltiman good, lowes bad.
Reply:Originally Posted by weldbeadrltiman good, lowes bad.
Reply:It came with the port-a-torch.  Its called a gas/air connection.  I'm going to take your advice and give it a shot tonight.  Again I appreciate all your help.  I'll let you know how it goes.  I tend to get my mind made up on learning/doing something.  ThanksJim
Reply:There has got to be a better way?  Can I put it back together with a mig or an arc welder?  I got it to braze on both sides.  But its not very good.  Loose.  Seems I can't get it hot enough for the melted rod to run.  It wants to rollo up in a ball and only stick on one side of the joint or braze on both side but not solid.   I think I'm using too much oxy/fuel yet it seems to takes too long to heat and yet still not getting hot enough.  On some scrap metal I can get a nice puddle but with this it never really turn bright red.  I guess if it were easy, everybody would be doing it.
Reply:One problem is once you've got the brass on it, welding will be a PITA. You will need to get rid of all the brass to attempt to weld. As Iron is porous it gets in the metal a bit and you will need to do some grinding. Learned that the hard way after someone else did a braze repair that didn't hold and just lightly ground it and brought it to me. Cast Iron has a tendency to crack as it cools along the weld. Castweld has had several good posts on welding up cast iron. Take a look at his stuff. I would try and mig it if I couldn't braze it. Preheat the area on both sides well and let it cool very slow. Some bury it in kitty litter or wrap it in a welding blanket to slow the cooling. Your best bet is usually with a high nickel rod or wire, but thats probably more money than you will want to spend. You might be able to find small packs of nickel stick rod at tractor supply or some place like that. and use stick..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:If you can't get it hot enough, you've probably got too small a torch tip.The catch, is that with Acetylene, there is a limit to how large a torch tip you can put onto your torch, which depends on the size Acetylene tank you have.If you have an MC tank, you may not be able to get anything larger.  With a B size tank, you could be ok to get something larger.Anyway, do you have another torch available?  Maybe even a propane torch (like a bernzomatic for plumbing).  If you could set that up, kind of clamped in place, heating the part from behind, that could help.
Reply:I agree, a bigger rig is in order. I also must advise you use a flux coated rod. This is the better way to go for someone new to the process.Bill LambertArgon WeldingABQ NMSic gorgiamus allos subjectatos nunc
Reply:Thanks guys.  Neighbor is coming over tonight with his torch.  In discussing it with him, he seem to think it wasn"t getting hot enough.  He travels all over the world.  He came home at the right time.  Thanks again.