Silver Brazing Copper to Stainless

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Hey guysCan anyone tell me if this looks like a feasible operation. I have lots of arc experience but I must say that my oxy fuel knowledge is not up to par. The stainless is about 22 to 24 guage to 2 inch copper. I have 56 percent cadmium free (this is for a homebrew operation) but was not positive this was the best as I read something about 45 % being better for some joints. I did roll a sleeve from stainless and welded it into the top of this bowl to better support the pipe but am leary of screwing this job up at this point after all the fab work. The first time I attempted it like a dummy I didn`t put my smallest tip on and needless to say it was a little hot.  I think I repaired all the damage and was gonna try it again but was hoping someone might help to guide me so that i know I am doing it right. ( I was never shown how to braze unlike TIG/MIG/Stick ) Thanks for any helpBrianThe last picture shows a test I did where I attempted to "tin" the copper before I fluxed the inside and out of the SS and tried to then join them. It has a lot of little pinholes and just looked like such garbage compared to the TIG I am used to that I was not sure I was doing everything correctly. Attached Images
Reply:Pre-tinning not necessary.Fit the parts, clean the parts, apply flux, assemble the parts, start applying heat.  Let the heat of the parts melt the brazing metal and let the capillary action of the melted filler let it draw into the joint.Brazing is (typically) more like soldering than welding, because you are heating the parts and letting that heat melt the added filler and then the molten filler flows into/onto the joint.  It's not called soldering though because it is hotter though.    The best laid schemes ... Gang oft agley ...
Reply:OK ....that is what i had done but I had the wrong tip on the first time around....Would I want to focus the heat on the copper and flow the material towards the stainless or am i going to apply heat more directly to the joint?   Sorry if the answer is obvious,   guess I`m a little gun shy still after almost screwing up and haven`t really seen it done up close.
Reply:Edit: I misread the original post.Opps, missed the part on the SS being so thin. Looked thick from the picts. I'd heat the copper now that I see that.Last edited by DSW; 11-06-2009 at 01:01 PM..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:that is a tough setup for brazing.  you have the correct filler.  I would concentrate the heat on the copper.  They also make a black flux for stainless.  I would clean the hell out of the stainless and copper, then apply the white flux to the copper and stainless at the joint, then apply black flux around the area to be brazed on the stainless(this will act as a bit of a heat sink so the stainless doesn't end up looking burnt when finished)  Like I said before, concentrate the heat on the copper, when the copper is hot enough to braze, start pulling you heat towards the stainless, ut don't leave it on the stainless for to long because you will burn it and then it won't take silver very well.2 Trailblazer 302's2 HF251-D1'sDynasty 200DXLincoln Powermig 140CHypertherm Powermax 30Airco Torches out the a$$
Reply:Thanks guys! Cryowelder thank you that was what I needed to know. I was worried about over cooking the SS because it just seems so easy to do if you are at all unsure about what you are doing as i am. Guess its gonna take some Jedi skills and black flux here.
Reply:Homebrew, huh?.....maybe a still?Sinner.We want to see something like this in the signature line:Lincoln Ranger 250Miller Auto-Darkening Elite HelmetLincoln 100Lincoln MigMiller Spectrum 375Craftsman 8 galllon gas powered compressorLongevity 200amp Tig Welder LT-200D
Reply:Stack of Dimes....maybe yes.  Me a sinner???     You bet!Now thanks for all the help guys.   Think I got it successfully.  Just wanted to tell you all about an awesome product my Airgas guy turned me on to when I told him my problem.It is called Heat Fence and is a paste you apply where you don`t want the heat to conduct and it stops it.   Quite amazing and I don`t think this job would have been possible for an inexperienced brazer like me without it.  Here a a couple more pics. Attached Images
Reply:Glad it worked out for you!  Now you have to polish the metals.  After all, this is for "food grade" use.  The best laid schemes ... Gang oft agley ...