aluminum tig welds w/ 250P

[bmichaelk]

Here are a few pics of some corner welds i made with my new Super 250P. I am very pleased with the unit so far.

[everlast_support]

I take if you have welded before as most people do not start with aluminum.

Nice work. And thanks for the photos.

[bmichaelk]

yea, i've been welding my whole life. just not much tig experience and not much aluminum work either. burned a ton of 6010's though. still playing around with the settings some on the super 250p trying to get the porosity out of the weld. i've read on here that the arc force knob is actually working all the time, regardless of whether you're in tig or stick mode? is that the case, and if so, should you just keep it all the way up on 50A while tig welding?

thanks

[everlast_support]

As far as I was informed, the Arc force is only on during MMA, but you can turn it all the way up when using TIG just to be safe. Also, the MIGs have arc force as well.

[hildstrom]

Nice job on the aluminum. I'm getting more proficient with it on every new piece, but I still have to break out the grinder to fix mistakes. =

ARC Force affects _ALL_ processes on the Super 250P. I explained this in great detail in my review thread and on my Super 250P review page.
http://geocities.com/hildstrom/projects ... index.html

The advice of "turn it all the way up" is not quite right. You should turn the arc force up depending on how much total current you actually need for the weld; unless you want to use the foot pedal and visual feedback alone to limit the current from absolute maximum. I do not necessarily like welding with full power on tap all the time because it is easier to melt through things and it requires much more precise pedal control, which I have not mastered yet.

Figure out the maximum amount of current you need for the weld using tables or material thickness and use this formula to determine your settings. I derived the following formula from actual current measurements on my welder and it takes into account the fact that the Super250P's current specs are peak and not continuous. My review page has another formula to determine the actual plasma cutting current.

ActualWeldingCurrent = PeakCurrent/250*140 + ArcForce/50*40

For example, mild steel is generally considered to require 1A for every 0.001" thickness in a single pass weld. So, 1/8" or 0.125" would need about 125A to weld in a single pass. The additional 40A of current provided by the ArcForce reserve is not needed in this case, so it can be set to zero. Solving this equation for PeakCurrent shows that the PeakCurrent (LED readout) on the welder should be set to 223A using the front-panel knob or the limit knob on the foot pedal.
125 = PeakCurrent/250*140
125/140*250 = PeakCurrent = 223A

For another example, let's assume a 5/32" or 0.156" mild steel plate. This would require 156A to weld in a single pass. The PeakCurrent setting alone cannot achieve over 140A, so some of the additional 40A current reserve from the ARC Force is needed. In this case, turn the PeakCurrent setting all the way up on the front panel or foot pedal so the LED readout shows 250. Now we can solve for the ARC Force, which shows that setting the ArcForce to 20 will provide the additional 16A of continuous current necessary for a total continuous current of 156.
156 = 250/250*140 + ArcForce/50*40
156 = 140 + ArcForce/50*40
16 = ArcForce/50*40
16*50/40 = ArcForce = 20

The Super250P cannot weld with more than 180A of continuous current.

Here is an Excel spreadsheet that you can use to help figure out the actual welding and cutting currents from the Super250P's settings. Just pay attention to the maximums depending on whether you are solving for welding or plasma cutting current. Be sure to push the foot pedal all the way down when setting its limit knob.
http://geocities.com/hildstrom/projects ... urrent.xls

Hope this helps. -Greg