Tough time with lap welds

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I've been trying desperately to do some lap welds with .063 3003 aluminum.  I'm using a synchrowave 250 with 3/32 green tungsten and 1/16 4043 rod. I have electrode negative 15 cfh argon. I've left the tip of electrode flat and ball it through use. I have the amperage at 80.  I can do butt welds fine. I inevitably end up melting the edge on the top piece. I'm wondering if I should be starting on a thicker piece of aluminum or perhaps someone has some suggestions on overcoming this...Steve
Reply:

Originally Posted by benchracer1

I've been trying desperately to do some lap welds with .063 3003 aluminum.  I'm using a synchrowave 250 with 3/32 green tungsten and 1/16 4043 rod. I have electrode negative 15 cfh argon. I've left the tip of electrode flat and ball it through use. I have the amperage at 80.  I can do butt welds fine. I inevitably end up melting the edge on the top piece. I'm wondering if I should be starting on a thicker piece of aluminum or perhaps someone has some suggestions on overcoming this...Steve
Reply:Do you have a picture? Sent from my SM-G973U using Tapatalk

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Reply:Foot pedal. I have some .045 for steel but nobody in town had .045 aluminum. I'll try a point on my tungsten.
Reply:The biggest issue you are going to have is holding a tight enough arc. At those thicknesses, you can't be more than 60 thousandths away from the bottom plate or you will overheat the edge of the top plate. You are going to need to keep your arc length less than the thickness of what you are welding. I am not sure it can be done. I know I couldn't do it.Miller Multimatic 255
Reply:

Originally Posted by benchracer1

I have electrode negative 15 cfh argon.
Reply:Oh sorry. I did use ac. Brain fade typing
Reply:

Originally Posted by StandarDyne

Why not use AC?    Focus your heat on the bottom piece, right next to the edge of the top piece. Once you start a puddle on the bottom piece, work it over to fuse with the top piece.
Reply:Ditch the green tungsten and get some 2% Lanthanated. And forget balling it back or leaving a flat. It will ball back slowly on it's own. This will help you keep a tight arc. Increase your balance to 80% EN and if you have some try 5356 filler. The filler is much stiffer and will not wick back the top plate as much. Now I know what others say but I use 3/32 diameter filler to somewhat layrod tie the seam together. You will never be able to keep up filling with real thin filler. Remember that alum saturates with heat really fast and gets away from you. You need to catch that upper plate melt back with filler and amps to melt it into the base plate. I would recommend that you lay rod the beginning of the weld and when going cram the rod and jam forward. Cram and jam, cram and jam. Haul azz to the finish. 4043 is really junk rod in my world. It originated as a brazing filler that just happened to work as a tig/mig filler. It is wholly dependent on base metal dilution for any strength and 3003 has little in the way of alloys to mix in the puddle. 4943 is way better as it is not dependent on base metal dilution, and 5356 beats all the 4000 series fillers. Keep trying and speed yourself up.Weld like a "WELDOR", not a wel-"DERR"

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Reply:

Originally Posted by Louie1961

I would start with thinner filler first (045 wire perhaps?), and sharpen the tungsten to more of a point. Are you using a foot pedal or just a straight 80 amps?