Chris,


Is your end cap fitting over your tube like a sleeve or is it just a coin shaped turret punched slug? There are some differences in prep between lap joints and butt joints.

At lunch break I ran out to my Aerowave and duplicated your parameters and found your 10 amps reverse polarity to be a bit minimal. Some folks prefer a very tight etch line but I suspect we are seeing the result of sacrificing mechanical quality for the sake of appearance. If you double the amount of amps on reverse polarity you will find a noticeable improvement with wetting at the toe of the weld. With a water cooled torch you can still run a 1/16 inch tungsten with a pointed tip for extra control, and I bet your inspections will be more consistently favorable. Also unless access considerations require you to use a very small cup, you might consider running your argon a bit higher, possibly up to 20 CFH.

Variable polarity Machines can open a real can of worms when setting production parameters. Since we have paid all that money for a fancy machine, most of us want to use the whistles and bells. The problems arrive when we take things to the limit of performance and than go that little step beyond, only to find diminished returns and rework.

Wouldn't it be nice if the manufacturers of these Hybrid machines published more thorough and in depth text, going beyond one page data sheets and citing real time production samples and industrial testimony. For the most part we are left to ourselves to reinvent the cart and fit it with the new reinvented wheel we have purchased.

Here are some further suggestions that will benefit anybody working with asymmetric power sources for manual GTA welding. Not particularly in order of importance.

1.) If your tungsten electrode touches the work or the filler or becomes misshapen due to over heat, STOP and re-dress it. None of the fancy waveforms will be of benefit if your electrode is contaminated.
1a.) When GTA welding aluminum, if ever your tungsten is contaminated you must stop! Some see this as a simple rule of craftsmanship while others do not. We must never say "well I would have stopped if I knew it was going to be X-rayed"

2.) Electrode Tip shapes. Rounded or balled electrodes serve a productive purpose only in the area of build up of wear areas and situations when a wide bead profile is desired. A pointed tip will provide greater directional control in nearly every case. If the arc begins to wander or climb up the tungsten, STOP, something needs to be addressed.

3.) To keep a high performance set up on thin Aluminum or Mag, a water-cooled torch and a full length electrode is the way to go unless space considerations prevent it. A full-length electrode will act as a heat sink and you will find you can squeeze a few more amps or a little more (EP) into your weld without loosing your tip to melting.

4.) For high frequency AC GTA welding Cerium and Zirconium are the best choices for electrodes. Miller Electric likes Thorium as a second choice, probably because of its slightly greater current carrying capacity, but the deformation and spitting (tungsten transfer into the puddle) is just too great a risk when working at the edge of the performance envelope. Its preferable for the electrode to begin to round off a bit at the tip (which is what Zirconium electrodes do when overheated) than to have it spit into the work like thorium does.

5.) . When taking performance parameters to the limit (max EN) it is vital to have the best surface prep possible, this includes attention sheared or rough edges, not just the tops of the sheet or tube.

Lastly, people often forget that the Aerowave simply set at *Normal* settings (like an old fashioned square wave) will produce superior welds. The circuitry is so good in those puppies that during regular welding operations the thing switches between EN and EP without need of superimposed High Frequency. The bottom line is that it will perform most jobs just fine in a stock configuration. (It's just not as fun or noisy).

Let us know how you fare.


Lawrence


PS. this is worth printing off and keeping in your toolbox http://www.millerwelds.com/main/ads/tig/articles/TIG_aluminations.pdf

hey,
the only main thing i see is acetone. it isnt a very good thing to clean with. poor degreaser and nasty. use regular rubbing alcohol. i just went to a one day aluminum welding seminar offered by miller and alcotec. it was awesome, at least for me. this was one of the first topics covered. just make sure it evaporates before welding. alcohol also leaves no film. if im wrong someone shoot me. also clean first and then wire brush !! and checkout www.alcotec.com very informative site