ac tig arc rectifying problem

By siriskymarine Date 06-01-2007 04:09

I've been welding anodized aluminum for years and run a 75 he 25 argon on an early 90's miller syncrowave 250 with a wp20 watercooled with the lead extension to 40'. I have the darndest time with the arc rectifying, it does fine on the anodized but once the metal is clean the arc will sometimes rectify ( stumble and sputter kinda making a wierd puddle but not welding ) and on mill finish its really bad. Does anyone have any idea what may be causing this issue ? Could it be the lead extension ? or low primary power ? Thanks for any feedback on this.

By Tommyjoking (****)

Date 06-01-2007 10:40

I am guessing here so bear with me....but 40' seems awful long for a a/c+ high freq.....I have always been taught that the longer the lead the more your Freq control dissapates..

Is this a marine application....why use the more expensive gas...why not 100% argon? Then again I always remove anodized coatings from the weld area.

I see the symptoms your describing usually from a dirty cup or tungsten. Also a tungsten diameter that is not large enough for the amount of heat being used will cause a spattering unstable arc on a/c. Sorry I don't have a definitive answer for you.

By 357max

Date 06-02-2007 19:01

What is the alloy, the thickness, joint configuration? Measure the primary voltage at the fuse box, the outlet, at the terminals of the primary connections on the terminal board in the machine. Pretty close to the same values - fantastic. Excellent choice for shielding gas although he and he mixes are harder to get the arc started especially on thin materials at low amperages. Set the machine's ac balance control at maximum penetration and sharpen the 2% ceriated/thoriated tungsten to a point.