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oxy-fuel welding of aluminum I am interested in learning this skill to hopefully repair a trailer of mine and learn something that many new welders are not using/interested in. I understand that its somewhat tough, and that proper heat input is hard to get right. practice. What would be some of the parameters to follow and technique as well? I can gtaw on al fairly well, and oa welding too. Any help appreciated. Do I need the special 'blue' lens ?Owner - Certified Welding & Fabrication / 22yrs in businessSteamboat Springs, Co(970) 879-5491AWS structural shopHMI 70t iron worker2 field trucks specailizing in structural steel, aluminum and stainless steel
Reply:You will need to run a 3x flame ( feather three times as long as your cone)  you also need welding flux paste to paint on your joint.  Pure aluminum is not too difficult but alloys are considerably more.    There is no clear puddle.  It is much like stirring a spoon in porrige.  Also just a slight overheating and everything melts away creating a big hole :'((  The flux has to be completely cleaned off or it corrodes the surface.
Reply:thanks for the info...any more info on this? do i need the blue lens?Owner - Certified Welding & Fabrication / 22yrs in businessSteamboat Springs, Co(970) 879-5491AWS structural shopHMI 70t iron worker2 field trucks specailizing in structural steel, aluminum and stainless steel
Reply:It has been many years since I did any gas welding of aluminum.  I didn't have a blue lense and got by.  It definitely makes things easier.   Expect to do a lot of practice before you get a decent weld.  Remember that the flame envelope is what is keeping the oxygen away from the molten aluminum.  If you pull away with the flame you get instant porosity/aluminum oxide.
Reply:A long time ago when I was a kid, I had a Harley-Davidson crankcase with a broken motor mount lug. I took it to a Diesel truck reapair station that also did welding. The mechanic used an Oxy-Acetylene torch with a white flux paste and some bare aluminum rod. I watched as he pre-heated the crankcase for a couple of minutes. He then proceeded to do a really nice job. When it cooled, all I had to do was to reshape the lug with a file and re-drill the hole where the bolt went. It's possible to do a good job when you have some pure aluminum. At that time, Harley was using almost pure aluminum for their castings and I think that's one reason it worked so well. I'm not sure what would happen with more exotic alloys but the process is certainly simple in any case. It's a lot like brazing although you have to be more careful not to overheat and melt the part since it is a parent-metal weld.Last edited by gnm109; 10-27-2006 at 11:28 AM.
Reply:zapster - got any input?Owner - Certified Welding & Fabrication / 22yrs in businessSteamboat Springs, Co(970) 879-5491AWS structural shopHMI 70t iron worker2 field trucks specailizing in structural steel, aluminum and stainless steel