AC vs. AC/DC

[Ender]

I did my damnest at searching the boards for this question, but came up with nothing definitive.

What are the benefits of using an AC/DC arc welder as opposed to an AC unit?

There is currently an AC/DC Lincoln on eBay that is calling my name. Its not too far (NY state) that I wouldn't be able to drive and pick it up either (shipping is $125) Its already up to 150 though, with 2 days left on it.

But then, there is a listing on craigslist, very local to me, with a 220 AC lincoln, same piece of equipment, but AC only for 125.

What are the positives and negatives of burning with each?

[Me!]

it's night and day when using an AC only stick and a DC one, I had an AC only buzz box for a long time and it welds just fine. But the DC is a lot smother and less splatter, its also better to control.

Get the AC/DC... You will not regret it and most likely will not take it off DC.

[WelderBoy]

You have more options of what rod to use when you have AC/DC as well you can achieve different weld profiles with the flip of a switch. More rods are available for DC. I believe AC runs burns rods up fast, which can be good or bad depending on what you are doing. Not positive as I never run AC.

Most people use DC only. I prefer DC. In fact, I NEVER weld with AC except for aluminum TIG welding.

AC is usually messier, harder to keep a stable arc.

With DC you can run DCEP and get much higher penetration than with AC. You can also run DCEN and get low penetration for thinner material.

[Ender]

So the ultimate concensus is to save up the few extra measily bucks it will cost and jump for the AC/DC unit.

[Me!]

Yep.

What are you looking to weld?

[WelderBoy]

Originally Posted by Ender

So the ultimate concensus is to save up the few extra measily bucks it will cost and jump for the AC/DC unit.

Bingo.

[tapwelder]

I use a/c a lot at my shop. I have an old 20th century 295amp welder. A/C will do what you want. I also have two DC inverters and my engine driven welder is DC. I use them onsite. I use mostly 6013, occasionally 6011 and 7014 I use the rods on both machines. I have never compared the rate at which the rods burn, though I haven't noticed any significant difference. Rod selection and technique has a lot to do with messiness, too.

Definitely a difference in the way they weld. You'll probably have a more stable low end with DC. That said, I think I would find a cheap AC welder and then find a DC inverter with more than 125 amps and higher duty cycle.

You should be able to find an AC machine for less than $150, possibly less than $100. You should be able to get a used ac/dc welder for less than $300. If you want go just DC, then you might find an inverter for around $450.

[cheeseclip]

also if you get the ac/dc unit youll be able to do tig also(i think)

[Ender]

Originally Posted by Me!

Yep.

What are you looking to weld?

At most, 3/8" plate.

I'm going to take the little crafstmen 85amp welder I've been trying to use and turn it into a dedicated sheetmetal piece. No more strain on this old girl.

So that leaves me with a need for something bigger and stronger

[gnm109]

Definitely I would get the AC/DC. With both currents you open up the whole spectrum of rods that you can run. If the current is a bit low, you could try 3/32" rod for general welding. Those Lincoln Buzz Boxes are bullet proof. Some people even convert them to a rudimentary TIG machine.

[tresi]

At least for me the puddle is much easier to control on out of position welds with DC.

[WelderBoy]

An advantage to AC is when welding on magnetized steel. If steel has a magnetic current it will try to push your filler material away and will give a bad weld. A lot of steel in the field can be magnetized, usually on equipment.

[Joe H]

I did some stick welding earlier today at a buddy's house with his AC only tombstone. I guess I am spoiled because it drove me bananas! The welds were fine and all, I guess the sound annoys me more than anything. After welding DC so much, that AC buzz is unsettling to me. When TIG'n aluminum the sound gets on my nerves too.

Personally, I would go for a DC capable machine. It gives you some more flexibility, and welding is definately alot more pleasant. A person can get by with an AC stick welder though.

[Ender]

I actually found someone not too far away with a lincoln AC/DC for a hundred beans. Doesn't sound too bad, compared to the prices I've seen elsewhere.

He claims "its used, but in great condition and a great machine", which, i've come to understand, means it fell off the tailgate of his truck while he was doing 95mph down the Garden State Parkway and he picked it back up and it still MAY work on a good day.

I'm going to ask about more details, maybe some pictures.

[David R]

Try it. Tell him if it works like he sez, you'll buy it.

Be sure to try every amp range and setting.
For one hundred beans, you can decide for your self which is better.

David

[Ender]

Just happened to notice that in a few pictures of the welder (not the one specifically for sale, but same model), the duty cycle of the welder, in both AC and DC config is %20.

Is that pretty standard for a stick machine?

And just so I understand this properly, thats 2 minutes of welding to 8 minutes of rest?

[tresi]

Originally Posted by Ender

Just happened to notice that in a few pictures of the welder (not the one specifically for sale, but same model), the duty cycle of the welder, in both AC and DC config is %20.

Is that pretty standard for a stick machine?

And just so I understand this properly, thats 2 minutes of welding to 8 minutes of rest?

At max setting most of the entry level buzz box welders run 20% to 30% duty cycle. Most Major brands run up to 100% at lower setting. If not marked otherwise the amp number that is circled is the 100% duty cycle limit. If you time yourself changing rods, chipping flux, wire brushing, repositioning, ect you'll seldom exceed 50% duty cycle with most home projects.