Welding Tips and Tricks

Hello I am new here and have a question about mig welding aluminum. I have been welding steel for a few years now and I am a pretty competant welder. I have just bought a spool gun for welding aluminum and have been practicing with info gained off of the weding tips and tricks videos. I have my welder set so that I get a nice spray transfer and my welds are actualy not that bad looking but I seem to get a cold start and the first 3/4"-1" of my weld is balled up but once the heat starts they smooth out and the welds are actualy not bad, but the end of the bead gets too hot and melts out. I have a millermatic 210 with spool gun using 5352, .030 wire, welding 1/8" material. What am I doing wrong.

I have the same machine. Try preheating your aluminum.
http://www.youtube.com/watch?&v=8AT4cEHtMn8#!

(QUOTE from Jody)
Just a slight preheat of aluminum makes a huge difference in the way it welds.
The first bead could be too cold, and the second bead, too hot..
conductivity is the reason. Aluminum is much more conductive than steel.

Thanks. I have watched that video before but must have missed the pre heat part. I will give it a try. What should I do about the too much heat at the end of the weld bead.

Stomper.

My first thoughts concerning the excessive heat at the 'weld ends' was the size of the pieces you are welding.

I understood that you are welding 1/8" thickness plate.
If the pieces are too small, then too much heat will build up in the plates before finishing the weld.
In production work, you might consider using temporary run-off tabs that allow you to continue past the end of the joint.
Another possibility would be to put an inch of weld at one end of the joint, then start welding from the opposite side.

Independent of the 'weld ends' difficulty, practice filling craters at the end of a weld.

Tanks.
Alexa

Yes that is correct, I am using 1/8" material. Thats a good idea. I think that would work. I will try it. Just to recap, I am going to preheat (to keep the first part of the weld from balling up because it is to cold) then weld the last inch, then weld the first part up to the last part. sounds kind of confusing so I hope this makes sence. Thanks for the replys.

You could try lowering your voltage and slowing your wire feed the preheat is important on aluminum. I always used %100 argon gas on aluminum and make sure after you preheat to brush with a ss wire brush.