[Dick Linn]

If you were TIG welding aluminum it couldn't have been DCEN or DCEP. TIG welding aluminum is only possible with AC high frequency with that machine because DCEP pulls oxides from the aluminum surface but will melt the tungsten with 2/3 heat on it. DCEN provides 2/3 heat to the work without melting the tungsten. AC changes between the two 60 times a second but the HF is required to maintain the arc between cycles.

DCEN welding aluminum is only for stick welding which is recommended for 1/4" and thicker.

Hope this helps. Sounds like someone set the machine up and didn't really explain everything. If all else fails there's the machinist's response, "the answer is in a book somewhere". I would recommend finding a copy Welding Principles and Applications by Larry Jeffus.

Edit: I've tried Spazdemon's suggestion many times for balling the tungsten but really only to save time or guarantee a good tip.

-Tan Linn