Set Amperage vs. Actual Amperage XMT 350

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I received the Red-D-Arc 360 Extreme today which I bought based on this thread-http://weldingweb.com/vbb/showthread.php?t=43540I cleaned it out when I received it, there were a lot of bugs and dust inside, as well as it smelling like smoke, but it does weld well. My question is, when I set the amperage on the machine, and I look at the panel right after I'm done welding, there is sometimes a large difference in the two values. For instance, on dirty 1/4" mild steel with old 3/16" 6011 rods (probably slightly wet) with the machine set to 210A and 70% dig, it showed the actual output amps on one pass as 353A. Is there a problem with the output control on the welder, or is this a normal variation caused by arc length, rod type, dig settings, etc? The person had the machine set up funny as well. He has 20' of 2/0 for the stinger lead and about 20' of #4 for the ground connection. I was assuming this would all be Dinse, but Red-D-Arc used Tweco connections so I wasn't able to use the cables I had purchased. Would the small ground cause this due to increased resistance or a significant voltage drop?Thanks
Reply:Well, I did notice something else after trying to run it again. I used an old, and once again most likely wet 3/32" 6011 rod at a set value of 44 Amps. I ran that rod about 1/4 of the way down, looked up, and the machine registered 191 Amps. It also cut a 1/4 deep groove into the edge of a 1/4" plate I was welding on. When using the 3/16" 6011 rod. The first arc I started severed the 1/4" plate for about 1 inch. I'm assuming this isn't normal, and I know the 3/32" rod shouldn't have acted as a gouging electrode.
Reply:Alright, I ran the 1/8" 7018 on cleaner 1/4" plate at a set 140A. It would consistently register 181A or 176A, arc length didn't have an effect. Turned down to a set value of 90A gave me 136A actual output. I then tried this same technique on 5/32" 7024 at 140 A to get about 190A, and it gave me 124A, 136A, and 180A over three tries. This rod was in an old shop and I picked it up and baked it. Do you think the inconsistency is from the rod?
Reply:Thanks for the help with this. Do you know what Airgas or a similar store would charge for calibration?
Reply:"He has 20' of 2/0 for the stinger lead and about 20' of #4 for the ground connection"That is one H of a mismatch - running 350 amps through 20 feet of #4 !!!Heck I have a #4 ground cable on my 130 amp MIG welder.Neglecting all the calibration talk, I sure would change out that ground lead for something heavier.The welding current makes a complete loop - through the 20 feet of 2/0 stinger lead, arcoss the arc, through the weld/base metal and returns to the welder by way of that 20 feet of #4.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:I'm going to try swapping the tweco adapter onto the larger cables I have tomorrow and see if it is consistently off at all amperage ranges. Also, I believe this guy was a smoker, and that is what the smoke smell is. Unfortunately, I don't have a wire feeder, so it's stick until I can find one.
Reply:You could calibrate your welder with a coil of steel wire.Details are in post #38 of this http://weldingweb.com/vbb/showthread.php...+car+batteriesBut is is quite simple and here is the essence of what you would do.Buy 50 feet of 5/16-inch diameter galvanized steel cable. Wind the steel cable around the outside of a deep plastic bucket.e.g. In my case, average 11-inch diameter (bottom was about 10.5 inches widening to about 11.5 inches near the top). This gave about 16.5 turns around the bucket. To keep the turns of un-insulated steel cable from touching each other, I wound 5/16 inch yellow plastic rope between the turns of steel cable. This also gave me a nice even spacing between the turns. The hight of the coil ended up as 11 inches.Pass a known current of say 1 amp DC through the coil while measuring the voltage drop across the coil.  You could use a 1.5 volt alkaline flashlight battery with a resistor in the circuit.  You will need two multi-meters, one to measure the amps through the circuit and a second one to measure the voltage across the ends of the 50 foot cable.e.g. In my case, I used a 12 volt car battery and some resistors.  I passed currents of about 5, 10, 15, 20 and 25 amps (pure DC) through the coil while measuring the voltage drop across the coil of cable.  The resistance over that measured 50 feet was constant at 0.06 ohms. What you are trying to do is measure the electrical resistance of that 50 foot of cable.  Suppose it is 0.06 ohms.OK, hook your welder up with that 50 foot cable in the circuit: the cable between the welder and stinger cable, or between the welder and your ground cable, or between the ground cable and the work-piece.  Use a muli-meter to measure the voltage drop across the 50 ft of steel cable as you weld with different settings on the welder.The true welding currrent in amps is given by: I = V/Re.g.  Suppose the 50 foot of cable resistance is R = 0.06 ohmsSuppose you set your welder on amps = 100 and weld.Let's say you see a voltage across the 50 foot cable of V = 7.6 voltsThis means the real welding current is: I = V/R = 7.6 volts / 0.06 ohms = 126 ampsRick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:Alright, after swapping the ground to a 3/0 cable, it didn't change the way it ran the 1/8" 7018, but significantly improved the 3/32" 6011 performance so it is once again only jumping around 30 to 40 amps from the set values. the 3/16" 6011 still runs about 75 to 100 Amps over, but I'm going to say it's because the rod is around 10 years old and was not stored well in the shop I got it from.