O/A welding aluminum. How much flux ?

No. Aluminum is sort of nasty - it conducts heat so well that the puddle often ends up larger than you hoped - and very runny, so you can go from "no puddle" to "general meltdown" faster than you might think possible. Set aside some practice time. I'd suggest putting that practice time into the MIG, but if you'd prefer to put it into OA, you'll either get it, or decide based on that experience to try the MIG after all.

Are you using acetylene for a fuel?

Yes I am. I have read that Hydrogen would be a better choice, but I don't have a cylinder at the moment.

-Joe

Check:

White is the seeming guru of O/A welding aluminum. I've watched him work and it seems like magic. But, he will tell you it's: practice, practice, practice! He does sell all of the materials and a video on how to do it.

Clean the aluminum first then apply a thin coating of flux. Dip the rod in flux. Add more if it seems necessary. Only practice will get it right. Experiment.

I learned to weld aluminum with O/A. I got some 4043 bare rod and some aluminum flux from my welding supplier and went to the dump and picked up some discarded folding aluminum garden furniture. These are usually tossed because the corners failed. I cut out and welded in some gussets in the bottom corners. The welds were pretty ugly at first but "practice makes perfect". The ones I *really* screwed up, I simply returned to the "supplier" but the good ones are better (stronger, more stable) than new. We have a dozen or so folding chairs that I repaired over 20 years ago. Nowadays, I do the welding with TIG.

One thing I found that you have to push the rod into the work - though the crusty flux and spooge layer. If you wait for a nice clean puddle like with steel, then the whole work turns into a puddle :-( I found a pair of cobalt blue glasses help a lot with cutting the sodium flare from the flux geoff

Thanks.. I'll give it a try. I have not had the time lately to fool with it but as soon as I get a chance i will try your suggestion. I have been waiting for a nice clean puddle to form and then adding the filler, but like you said at that point the whole piece is a second away from collapse. I am also afraid that if I introduce the filler too soon it will melt and just lay on top of the work.

-Joe

Move the torch away momentarily when you touch the rod to the work. The work has to melt the rod, not the torch flame. Pull it back before it sticks.

Gary

You can tell if it is to cold, as the rod won't push into the work. You are still heating the work, but pushing the rod through the surface. It takes a bit of practice Geoff