my first attempt at oxy-propane welding aluminum

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I had to put back together the aluminum cover of a motorcycle muffler that I'm now really regretting having sliced in half to remove.I'll have to fix that. I've never tried welding aluminum before, but I guess it might work with propane and oxygen...I even have some AL tig rods (not that I've ever TIGed in my life...) and some oxyacetylene flux. It might work.I have no idea how I'm supposed to apply this flux. Well, here goes.By my standards, this might be considered a success.Clearly, I have no idea how to apply the filler rod, either.Actually, it came out looking pretty good...for my first ever attempt at something I have no idea how to do...at least once I grinded out the stuff from the inside so that it would actually fit around the muffler again. Last edited by Skippii; 05-14-2010 at 04:25 AM."To tell which polarity to use go to the bathroom and pour some water down the drain. If it runs clockwise use straight polarity. If it runs counter-clockwise use reverse polarity. Or if it just gurgles use alternating current." -RandomDave
Reply:You have the wrong gas for welding anything.  Propane isn't a welding gas.  It is fine for heating and cutting.  If you want to weld with gas, use acetylene instead.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Got any pics of the whole bike?Rex
Reply:Originally Posted by DesertRider33You have the wrong gas for welding anything.  Propane isn't a welding gas.  It is fine for heating and cutting.  If you want to weld with gas, use acetylene instead.
Reply:Originally Posted by rode2rouenGot any pics of the whole bike?Rex
Reply:Originally Posted by SkippiiConsider yourself warned....http://advrider.com/forums/showthread.php?t=577613
Reply:Originally Posted by DesertRider33You have the wrong gas for welding anything.  Propane isn't a welding gas.  It is fine for heating and cutting.  If you want to weld with gas, use acetylene instead.
Reply:Originally Posted by SkippiiConsider yourself warned....http://advrider.com/forums/showthread.php?t=577613
Reply:A comments I've read elsewhere in regards to gas welding aluminum, maybe they'll be helpful. " The trick is to keep your gas pressures set low.  If you needmore heat then change to a larger tip but keep the oxy and acetylenepressures no higher than 4 psi.  The other thing that you will need issome flux for your aluminum rods and a good set of special goggles forviewing the weld properly.  A few years back everyone was using thesecobalt blue goggles but they weren't that good for your eyes.  I usegoggles that have a gold reflective surface on them. I picked them upat the welding shop and they work really good.  Welding aluminum is abit tricky because the color doesn't change when the metal heats uplike steel does.  Aluminum is a bit like plastic, one minute its thereand then all of a sudden the floor drops out and you have a big hole.The trick is to look for when a skin appears to form on the surface andthen push your filler rod in and a way you go.  Without the specialgoggles, you won't be able to see the skin effect.  Practice on lots ofscrap stuff first before getting into some more serious work.  You'llget the hang of it in no time."TheGrooveking
Reply:Another fine example of doing what can not be done. I hope even with acetylene my first AL welding attempt is as functional looking as yours.
Reply:Who says you cant weld aluminum with oxy/propane?? It was done in production, acetylene, hydrogen, city gas, and propane were all used as fuel gasses. The flux prevents oxidation. Acetylene is the only fuel gas for fustion welding steel, stainless, and cast iron.
Reply:I doubt nothing. I've seen mild steel welded to alum., with s-6 wire. I guess if you don't know better, then the rules don't apply.200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Nothing wrong with oxy-propane - in fact I've heard it's actually preferable for welding aluminum, because you get a clearer view of the weld puddle than with an oxy acetyelene flame.  I have only used oxy acetylene (and TIG) on aluminum, though.Cleaning the aluminum, way way more than you did would have helped a lot.  In fact I'm surprised you got anything to fuse at all with how dirty that aluminum started.  Must be done decent flux you found...  Anyway after cleaning all the oxides off the surface, (and this is not a trivial task) then you generally want to proceed to weld right away, before the oxides have a chance to come back.Not sure if you applied flux to the back side, but this would be a good idea.  Some dipped in the filler doesn't hurt either.Make sure you remove all the old flux after welding is done.  The stuff is really nasty, salt-like stuff that will attract water from the air and corrode the aluminum if you don't remove it entirely.  It's not easy to get off, either!  This is my main reason I prefer the TIG process for aluminum over oxy-fuel welding.  (TIG also allows more heat control, and focused heat.)If you could apply a copper strip underneath the butt weld, I think it would have helped the metal not sag/melt through as much.  And helped shield the back side from atmosphere, and kept the flux from dripping out through the crack.  These steps do take extra time (as well as cleaning the alum) but are important I believe for getting good results.Congrats on actually getting a weld in spots.  I had the darndest time oxy welding 16 ga aluminum tubing together... real "hit and miss".  I was able to successfully weld thicker stuff though.
Reply:Originally Posted by jakeruNothing wrong with oxy-propane - in fact I've heard it's actually preferable for welding aluminum, because you get a clearer view of the weld puddle than with an oxy acetyelene flame.  I have only used oxy acetylene (and TIG) on aluminum, though.