OFW aluminium

[cavala]

I have part that's cast aluminium that a friend needs repaired. Of course I take the work before knowing if I can do it. I can weld Al with a tig but I don't have one and I don't have a spool gun for my mig. So my option is oxy acet. I've tried brazing Al in the past but this part needs to be repaired ie good penetration. I picked up some rods at the weld supply warehouse around the corner (they recomended me buying a tig) they gave me a good price for a one pound box because they said noone buys them.
Like I said I'm comfortable welding Al just not this process are there any tips or technics that differ that might make my life easier and not destroy this guys part. The part is cast about 3/8" thick and the rods are flux cored about 3/16"

Also one more thing who is comfortable with pot metal. I restore slot of antique lighting and I see a ton of broken pot metal parts and struggle trying to repaire them.
Hope you guys can help thanks Marc

[jeremy k]

You'll be better off triing to find a local welder that may let you use his tig welder or let him do the repair.
"Pot metal" or cast zinc is weldable also with tig - I have made many repairs of this sort over the years on door handles to lighting fixtures. Although it can be done - cast zinc takes a very good touch to be able to weld it, anyone who has done it knows. Over 20 yrs experience helps in my case - but it can be done with the right equipement. - JK

[cavala]

"Better off" ... I guess my question wasn't clear I realize a tig machine would be easier but I have an oxy acet torch. I was More looking for advice or technics tip size, oxy fuel pressure etc not give up and let someone else do it. That's not in my vocabulary. Now if your saying it's so difficult that id be better of tig welding it then I appreciate the challenge.

Thanks Marc

[Bentiron1946]

Lindsay's Technical Books These guys have a book on using O/A for welding aluminum. I haven't tried doing it personally but a friend of mine has with limited success but then he went and bought a TIG to make life easier.
http://www.lindsaybks.com/bks7/airweld/index.html Edited November 4, 2009 by Bentiron1946

[Rich Hale]

For decades I have welded aluminun, with an O/A torch. I am pretty confidant with it and take care of my needs as they arise.
trust me if I can do it anyone can. So let me give a couple of my thoughts based on my experience: I also use the flux cored rod from thelocal welding supply, Use a larger tip than youthink it will take. You need tolocalize the heat, if you use a small tip it will heat a larger area of the metal to fall away from the piece ins search of your toes. The metal is almost ready to weld when after you have blackened the piece with an acetalene flame and then go back to a feather and as the black area disappears you try and add a touch of the rod...piece has to be really clean before you start,,,including the outside of the rod. Keep trying You will get it. Practice with different shapes and thicknesses,,every day if you can. Rod is pricey but you will need alot of it..I would not try an important piece for at least a year or so..When you get good penetration slice the piece open so you can look at the weld in cross section and see how you are doing.
If you can find anyone near yu for hands on tips and guidance it may help....If you have other things in life that you need to do then you may have to add some time to the learning timeline. If you can easily handle almost all welding chores with a O/A rig on steel then it MAY shorten the time a bit. If you were closer I would offer to demo a couple of welds for you here.....However I would not have the time to teach you ,,just demo....I have used a tig a few times..seemed easier to me......

[cavala]

Well I've tried some practice passes on some scrap 3/16x1" I blackens it like was suggested and shockingly it it welded. I did melt the ends but as I started to get the hang of it I was able to build it back up. Now these aren't pretty welds but from what I can tell I'm getting good penitration. I guess my only question now is does cats aluminium weld like the bar stock. Knowing the weldabilty difference in cast iron and steel.
Thanks Marc

[JeremyP]

Depending on the grade, cast aluminum generally does not weld as nice as your typical t6 extrusion. A lot depends on what the cast aluminum has been exposed to. It will soak up oil and grease and other contaminates over time. Cast aluminum also is more likely to have voids and contaminates in it from the casting process. A very thorough cleaning is recomended. Wash with acetone and brush with a stainless wire brush, use a lint free cloth. If its still not welding well, stop and clean it again.

[cami]

In addition to crap in the castings, aluminum used in casting is often alloyed with Zinc to help it flow into the forms better; you might notice a more "liquid" puddle.

For general repair of aluminum with a torch, I braze, or braze weld it with Alladin 3-in-1; it's a nice product.

[BIGGUNDOCTOR]

Never OA welded aluminum, since I have a TIG, so I can't help you there.

On potmetal there are low temp rods out now that use a propane torch. I usually see them at the automotive swap meets to repair chrome parts. Flows nice, and really strong. It can be used on parts as thin as a beer can on up to heavier castings. Works on aluminum too.