Welding Tips and Tricks

Hi Guys,
Im new to this forum and pretty new to TIG welding. So, sorry to start with a question.
I have been doing a fair bit of Mild and Stainless work and im really pleased with the results:) I have a 150A Migatronic Tig welder with a fair few controls (but no frequency control, its fixed to 50Hz i think).

Now, the problem i am having is when i come to weld Aluminium, I can only describe it as trying to solder with no flux:) the metal balls up when it melts rather than flowing into a nice weld-pool. I can get it to form a weld pool, its just rather erratic and looks like crap.

Do i have the settings wrong?

I have a fairly big aluminium job to do tomorrow so any help would be much appreciated:)

Cheers,
Ed (from the UK)

I am very much a novice, in fact probably the least experienced here. But on my machine I usually reduce the arc gap to fix this (distance between workpiece and electrode). Also, remember that the arc melts the base metal and the weld puddle melts the filler. One other thing that might be contributing is too small filler rod diameter (ie. rod melting before the base metal is wetted)...

Sometimes that can just be torch angle or filler rod angle. Your rod is melting before the pool is formed. You want to keep the rod under the gas but not the flame and only dip the rod in as you advance the puddle thats forming on the base metal. Watch Jody's video's, I'm sure they will solve your problem.

Thank you for your quick replies,
How can i watch jody's video?
The problem im having is getting the pool to form in the first place, once i get a pool formed and i can start feeding in the filler rod it all goes more smoothly, its just getting that initial pool to form and join the two pieces of metal.
cheers.

Make sure you have the machine set on a/c and check the high freq settings...and make sure gas is on...made that mistake before

Definitely on ax and gas on, what would good over all settings be for Ali?

How are you prepping the metal?

How thick is it?

WildBill, go to millers website and use their online tig calculator to get you in the ball park for your tig settings. I like to slam the pedal when I start and I have the torch nearly vertical. Once the puddle starts to form I angle the torch back and sort of push the puddle along. Depending upon the thickness of the Al and the outside temps you may need to pre-heat. If there's high humidity or the Al is cold you'll have hard starts and moisture accumulation standing in your way. A MAP Gas torch is all I use to preheat and I just heat until I see the moisture line dissappear. It's highly visible with a torch which is why I switched from using a electric heat gun.

Thank you all for the help!
I realised that i just wasnt using enough heat:( my tig only have 150amp max and i only had it set to 100 so it was really struggling. I went back to the job the other day, i preheated the metal with a blow torch and gave it the full 150amps, also i used about 75percent -ve electrode. It worked, just about. I still found that i had to work too slowly so the puddle started to splay out after about half an inch.
I think i really need a pedal for alu so that i can start with high amps and lower them as i go along to stop the puddle getting out of control.
In hindsight could i have used pulse to control the heat a bit?? or would that have made the heat input even less and i would be back to not melting the metal?