Brazing Rod Specific Question

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Hello all, I would like to attempt to a repair a damaged ear of a cast part.  is a non loadbearing part, just a bolt hole to attach the cover to the housing.anyway, i honestly dont know if its cast iron or cast steel.  I was told and have read on here to use silicon bronze rod.  Ideally a self fluxing.  and or buy flux or some say use borax soap.however All i can find locally is solid bronze rods, and a flux covered product simply called Flux-coated brazing rods.i know what you are going to say go to your local welding supply.  I live in the boonies, i could order some, which i might have to do.  or wait until i make a trip the 'BIG" city. ideally i only need 1 rod.  perhaps there is a welder near me who can spare a rod (yellow pages? might help with that)  but what would your recomend for this?  Mostly i am wondering what kind of consumables will work for this repair. I am a brazing newb. I did it a couple times on some sheet steel a couple years ago in school.  that worked out fine.thanks for your help.
Reply:you don't list your location so its hard to say if anyone is close to you or not.i prefer to use uncoated rods and apply the flux seperatly,  but the flux coated rods work.  tractor supply should have both if there is one close,  even the hardware stores out in my part of the boonies carry brazing rods and flux.record the location of the center of the bolt hole(may or may not be necessary depending on if you can transfer punch the location afterwards.grind out the break.  clean up with a burr,  build up with braze.  grind to shape,  lay out center of hole,  center punch, drill,  tap(if threaded) and your done.if its a large ear,  you may want to make a steel tab to braze onto the ear so your not building up braze forever.XMT 350 MPa, w/D52-DTA 185 TSWHarris of
Reply:If you are using a torch those flux coated rods are what you want in my opinion.  Probably there is many times the amount of flux needed but you do need some at the start should you decide to knock most of it off.  That stuff flows into tight areas and spreads out on the surface.  The silicon bronze would be the choice if you use tig.  I am sure lots of tig compatible rods can be used with a flame but without practicing and breaking practice pieces I wouldn't use them.The sparks from a grinder are quite different iron vs steel.  Also if you drill steel you can get twirly shavings where iron is more of a powder.FranLast edited by fran...k.; 01-08-2013 at 10:58 AM.
Reply:Exactly what I was going to say on the grind or drill test you will have a much easier and better result if it is cast steel.....as mentioned the prep is everything....get it sanded or ground down to clean parent metal and position the part so you can get a clamp on it if possible. If you discover it's cast....cover it with kitty litter or some kind of cover to let it cool slower to help prevent cracks.......Good luck I hate cast iron....  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:well i will give it a try. if it doesnt work out, no big loss on this one.i am using a tourch, and will buy those generic flux coated brazing rods.  I will also take to heart all your prep advice.  Mind my preheat and do the best slow cooling i can.Thanks. I will post results, pass or fail.
Reply:Word of advise. When brazing cast iron, use an oxidizing flame to (tin) the parts with brazing material, then go to a neutral flame to build up as needed. The oxidizing flame helps consume the graphite on the surface etc. Also try to use burrs, chisels and such rather than grinding or sanding when prepping the part, this helps limit the smearing of graphite on the surface to be brazed. Silicon, zinc, and tin bronzes can all be used with the O/A flame with good result. The commonly sold flux coated brazing rods are usually a copper/zinc alloy.
Reply:Hello all, you know how it goes with back burner projects.  well i just got to this today finally.  no pics.  but its not the prettiest thing in the world.  took a bit of paitience to get the build up i needed without flooding out.  made some dams from some scrap plate.  beveled edges, clamped pre heat dip dip. slow cool downto the point though, bolted it back on, got it tight didnt crack.  seems to had done the trick.  so calling this good and thanks again!