02-01-2013 04:47 PM
Hey guys, thanks for that so far.
What applications do you use AC for and DC for? I understand both of those describe which way the electricity flows-- i.e. batteries one way, DC, outlets AC- move back and forth. I am guessing it depends on the metal and surface cleanliness/thickness?
90% of your welding will be with DC. It produces a smoother weld, and is easier to use. AC is basically just for a few specialized rods, and for cutting. However, most DC welders also do AC. When I said AC/DC, I meant over AC alone. The welders I have seen, are not DC only.
I have found one that is capable of 225A in AC and 150A in DC. Should I insist on having at least 200 amps in DC?
That should be more than adequate for anything you will be doing, unless you are wanting to do fabrication of large projects, and if you do that, you will want a wire welder anyway.
Also, I understand duty cycle, but you guys made good points about weld strength, if welding is slow and the molten pool cools. Whats the minimum duty cycle that you would even consider using and expect a strong weld?
That kind of 'depends' on how thick the metal you are welding is. The duty cycle listed (you say you found one at 20%) is for the welder at the highest rating. That is why I suggested a 225 or bigger welder. You probably will be doing most of your welding in the 150-200 amp range, and you will get a higher duty cycle at lower settings. What limits duty cycle, is heat build up within the welder. The less amps, the less heat build up. At some point, there will be a setting where the ability of the welder to cool itself, will equal the heat created. For example, my brother has a Century welder, that is 10% duty cycle at 250 amps, but continuous duty at 180 amps, and 80% duty cycle at about 200 amps. 80% duty cycle is about all anyone can expcect to use, even welding large projects, simply because you have to stop for at least a moment to change electrodes, and chip slag. For most people, they won't use much over 50-60%. So, a 225 amp welder, (which will be somewhere in the neighborhood of 50% duty rating at 180- 200 amps ought to be enough for most farm shop projects.)
at 25 VAC and 225 A, and if I was welding out in a field, my generator would be operating at almost 90% capacity... Funny thing is, when I bought it, I thought it was an overpowering generator! I am likely going to have to go to 230/240V plug in to make this work on power and my generator. Otherwise the power switch will kick off.
Remember, you probably will only turn the welder up that high a couple times a year, if that. I can't remember the last time I did any actual welding above 200A
finally, any suggestions on ones I should look at? Been looking at some from Miller-- either too small or too big. Hobart-- only 20% duty cycle on their biggest model. I'm going to continue my search here on the net. If you guys know what works well, that certainly helps.
Aboout any welder in the 225-250 max amp range from a good maker should be fine. Most common electrodes are 1/8 inch, and you rarely need over 180-190 amps with that size of rod, so you will have adequate duty cycle for most any job, but with the ability to run just a little 'extra' heat, on the rare occasions you might need it, like for cutting. If you don't mind an ugly cut, a high powered arc welder will out cut a torch for speed.
I definitely don't want to go MIG, as my mech says most guys can't clean the surface well enough, and wind becomes a severe issue for a lot of guys. He uses only stick, and strongly suggests stick for my application. Of course, he does all his work outside in the elements, so obviously he is using stick.
Using flux cored wire, will eliminate the wind problem, but you still can't cut through the rust and crud that a stick welder would. However, I personally, am willing to take that trade off, but some people like to just scrape off the big chunks, and start welding. I know the suggestion below, was to get some 6013s, and just go from there, but I urge you to practice a bit, so you feel comfortable welding with 7018 rods. They are a little stronger than 6013s, and are better for fusing dis-similar steels to each other, without becoming brittle. An example of this, would be welding cattle panels to sucker rods, or pipes to make gates. The 6013 welds in these cases will be more brittle, and will 'pop' much sooner than a weld with 7018, which will have more 'spring' when an animal hits it. Myself, I only use the 6013 for a root weld, or when welding upside down (or sometimes a 6011). The 7018, I use for pretty much everything else.
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