Gas welding Aluminum...Any tips?

I'm trying to gas weld some aluminum. It's reasonable thick, about 1/4" or so. I'm using my O/A torch with a neutral flame, Al. filler rod, and aluminum brazing flux. The metal is fresh ground, so it should be clean. It doesn't seem to be going well. Any tips for a novice? Thanks.

-Jeff

 

The two rules to welding aluminum.

Clean it untill it SHINES.

Pre-heat it to a VERY high temp.

After that it's almost like welding steel, except that it puddles all-of-a-sudden, like without warning.

 

I don't do much but my buddy does and he said to get a new stainless steel wire brush and use it ONLY to clean the aluminum joints just prior to welding.

 

Keep the torch moving back and forth,when it gets bright and shiney,it's about to run onto the floor.Go like hell,you gotta be fast.Watched an old time instructor one time,after the demo,none of us wanted to try it.Best advice is practice on scrap,or get it heli-arced

 

I could never do a decent job with a big torch. Bought a Henrob and it is as easy as soldering.

You also have to match the rod to the material, there are many alloys and one size does not fit all.

 

I'd start with using a welding flux instead of the brazing flux. It should make a big difference.

--Matt

 

What's the difference between an aluminum welding flux, and an aluminum brazing flux(thats what the can calls it)? I have 4 jars of "Al-Braze aluminum brazing flux" an no other welding flux except for regular steel brazing flux. How do you braze aluminum anyway? Do you then need a special aluminum brazing rod? Thanks.

-Jeff