Guys,

One thing to check on AC welding (aluminum only) is the waveform. I know the Lincoln is a true square wave which uses high frequency. I don't know about the Miller. It may use a low freq. square wave.

The reason I mention is because in aluminum welding there two things working for and against you. The AC signal cleans the oxide from the surface when it is negative and provides penetration for welding when it is negative. The high frequency wave form is good for strong cleaning, arc stability/ignition and good penetration.

In case you were wondering about my penchant for Lincolns, I worked there a few years ago as a field sales rep so I have been brainwashed.

As a quick example, we were able to weld aluminum foil with the SWT175.

If you find one on a buy-one get-one free sale, send the free one my way!

HTH,
Scott