With non uniform thickness, it's more about technique than settings, but here are a few things to point you in the right direction. AC balance 20-30% since everything is nice and clean. AC freq 100 to 120, this will help you pinpoint the arc which is where technique comes in. You will have to direct the arc to the spindle as it will take a lot more heat than your tubing. Let the cleaning action work on it and get some heat into the part even before you try to form a puddle. You can even preheat the part beforehand if you want. Once the thick piece starts to wet, then move the arc to the tubing and put a little heat there until it starts to wet out, only then add filler and work more heat on the thicker material. If the filler balls up you don't have the piece quite hot enough. One trick is that if you do get a little ball of filler in the joint but not fused to either side, you can direct your heat to that ball as you don't have to worry about blowing a hole in the ball. Once it's hot enough it will flow into one or hopefully both parts. Getting them joined will allow the heat to even out between them. At that point you will need to back off on the amps to keep the puddle under control. You might start off with 150-200 amps and be down to 100 or less by the time you complete the weld. That is the nature of aluminum. However, you will still want to work your torch angle to direct more heat into the thicker part. It just takes practice. The foot pedal is your friend for things like this.
Long arc, short arc, heliarc and in-the-dark!
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Originally Posted by inthefrey
