AC or AC/DC?

[Rayrla]

Trying to determine which type of arc welder to buy. Uses are to repair equipment and some fabrication. Have ruled out MIG because most repair work to be done outdoors and with "dirty" metal. Is AC/DC worth the extra cost? Your opinions.

 

[RickB]

I opted for AC/ DC. I bought a Miller Thunderbolt and am very happy.

 

[wdchyd]

Rayrla,

Definetly AC/DC.....No Question for repair work I use DC- for strong welds all the time.....

If you have the money AC/DC/Tig HF covers all the bases....(light duty, heavy duty, stainless , aluminum) but comes with addl costs (argon tank refills), but you'll do everything......

AC/DC welding is definetly where to go for strong repair work without all the changeovers needed with Mig.....

Don't get me wrong I have Mig also...and its good for fabricating (fast and clean welds), but my vote for strong repair work on steel is DC-......:thumbsup:

 

[EddieWalker]

The DC setting will give you more control and less splatter. The rod wont stick as much and the results will look better. DC make arc welding easy.

Eddie

 

[yomax4]

DC opens you up to a whole new world of Electrodes that when ran on DC give you Out of Possition options like Vertical and Overhead that are difficult with AC. And Yes Aluminum. Just remember when using Aluminum Rods, 1 = Pre Heat to 500 degrees. Run the Aluminum Rod 90 degrees to your work and go like H--l. You can get to 500 degrees by using a Temp Stick or, Take a Oxy/Acet. torch and turn on only the Acetylene. Smoke the area that you wish to weld with Acetylene Smoke. Then turn on the O2. Pre-heat the area and when the Black Smoke goes away, You are at 500 degrees. Now lay a great bead with the Aluminum Rod. If you dont pre-heat and or run at a 90 degree angle, You will get Bird Crap looking Aluminum Welds. Take the extra step and enjoy repairing Aluminum. :thumbsup:

 

[Mark @ Everlast]

If you can find a DC only inverter, you won't even think back to welding with AC. It costs a little more, but they certainly are worth the extra $ to invest. They are much lighter and more portable.

 

[Spudland_Dave]

If you can find a DC only inverter, you won't even think back to welding with AC. It costs a little more, but they certainly are worth the extra $ to invest. They are much lighter and more portable.

Couldnt have said it better...I absouletly LOVE my Maxstar 150 for so many reasons...

 

[wvpolekat]

I am noticing that most DC machines are lower amperage than AC machines. Does DC need less amperage?

 

[Mark @ Everlast]

Not necessarily. The DC inverter machines can be bought up to 600 amps if you want and have the money. But like the Everlast PowerARC 200...It sells for $350.00 , weighs less than 30 lbs, scratch start tig capable and is a commercial class machine. 200 amps is way more than enough to handle 95% of the welding jobs most commercial customers have even in the oil fields.

BUT transformer machines that have AC/DC do have much less amp capability in DC just because of the way they are manufactured with the rectifying system that is administered to the AC current.

DC current is much more stable and yes, because of the DC polarity, the electrode gets the majority of the heat concentrated on it so melting is smooth and regular. On AC, the heat is shared 50/50 60 times a second. During the time the arc cycles or "reverses" the arc literally goes out and then reestablishes. There are very few real reasons anyone will ever need an AC current when stick welding. It makes a much lower quality weld with more slag and inclusions in the weld. One time that AC is usually touted to be superior is controlling arc blow. But proper cable and clamp arrangement and a little skill can prevent this rare occurance in DC as well.

 

[rjkobbeman]

Not necessarily. The DC inverter machines can be bought up to 600 amps if you want and have the money. But like the Everlast PowerARC 200...It sells for $350.00 , weighs less than 30 lbs, scratch start tig capable and is a commercial class machine. 200 amps is way more than enough to handle 95% of the welding jobs most commercial customers have even in the oil fields.

BUT transformer machines that have AC/DC do have much less amp capability in DC just because of the way they are manufactured with the rectifying system that is administered to the AC current.

DC current is much more stable and yes, because of the DC polarity, the electrode gets the majority of the heat concentrated on it so melting is smooth and regular. On AC, the heat is shared 50/50 60 times a second. During the time the arc cycles or "reverses" the arc literally goes out and then reestablishes. There are very few real reasons anyone will ever need an AC current when stick welding. It makes a much lower quality weld with more slag and inclusions in the weld. One time that AC is usually touted to be superior is controlling arc blow. But proper cable and clamp arrangement and a little skill can prevent this rare occurance in DC as well.

Can't argue with anything you said here, but man, I got a 35+ year-old monkey-ward (Montgomery Ward) AC buzz-box that flat-out can lay some rod. I think the duty-cycle on it is 30% at its max current, but I have seen the ol' man go through boxes of rods non-stop for hours. Thinking back on it, it really was a sight to see. I remember watching him for hours after school with the extra shield he bought just for me. Well, I'll stop before I reminisce too much more...

Ah..., I love the smell of 6011 in the morning...

 

[Mark @ Everlast]

I have an old Penncraft 230 amp AC box as well, from that time period. Its copper wound with a 35% duty cycle. The problems: 1) Very little rod versatility. They say 7018's will run on AC, but whats the point? 7018's aren't run for code work or serious repair on AC... I have used the 7018AC rods successfully, but found that (IMHO) they still run better on DC...even better than regular 7018. You're stuck with primarily 6011's but then again, its a great GP rod. And lets not forget AC capability of the 6013, but well....its a 6013. Even a monkey can weld his butt crack shut with a 6013. 2) Not a quality weld...Even though it may appear so externally. But put it side by side in a destructive test or ultrasound, the differences will be revealed. I am not saying AC won't pass, but in general, it takes way more patience and skill than the average person has. 3) If you've never welded with DC, then its kind of hard to 'splain how much better it is. But if you have only welded with DC, then go to AC, you IMMEDIATELY know something is WRONG. 3) Show up on the job site with an AC only welder, and it will be more embarrassing than walking around with visibly used toilet paper hanging out of your pants all day long...You will likely be asked to leave and come back when your toy welder grows up a little.lol

Of course, I am joking a little, but the point is that AC is not generally accepted as the "best" method. It will work, no doubt. But DC welding is so much smoother, quieter, and generally higher quality.

 

[rjkobbeman]

I have an old Penncraft 230 amp AC box as well, from that time period. Its copper wound with a 35% duty cycle. The problems: 1) Very little rod versatility. They say 7018's will run on AC, but whats the point? 7018's aren't run for code work or serious repair on AC... I have used the 7018AC rods successfully, but found that (IMHO) they still run better on DC...even better than regular 7018. You're stuck with primarily 6011's but then again, its a great GP rod. And lets not forget AC capability of the 6013, but well....its a 6013. Even a monkey can weld his butt crack shut with a 6013. 2) Not a quality weld...Even though it may appear so externally. But put it side by side in a destructive test or ultrasound, the differences will be revealed. I am not saying AC won't pass, but in general, it takes way more patience and skill than the average person has. 3) If you've never welded with DC, then its kind of hard to 'splain how much better it is. But if you have only welded with DC, then go to AC, you IMMEDIATELY know something is WRONG. 3) Show up on the job site with an AC only welder, and it will be more embarrassing than walking around with visibly used toilet paper hanging out of your pants all day long...You will likely be asked to leave and come back when your toy welder grows up a little.lol

Of course, I am joking a little, but the point is that AC is not generally accepted as the "best" method. It will work, no doubt. But DC welding is so much smoother, quieter, and generally higher quality.

I get all our points and appreciate the razzin'! I also have a MIG, set of torches and plan to get a TIG soon... but I can't forget the memories and utility of that ol' indestructable buzz-box.

I think I first experienced the quality of DC back in high-school (mid to late 80s). Back then, unlike now where I can afford to just go buy whatever I need, school had all the neat stuff.

I am amazed that in this day and age, there are still folks out there that don't have a basic buzz box. Even the "inferior" AC box is still king when the alternative is nothing! A lot of metal has been melted together with them!

By the way Mark, I'm Rob. Nice to meet you.

 

[doall]

I have about a 25-30 year old Lincoln that has melted a ton of rods. Not just 6011's either. I Like it a lot. I always thought I was only missing out on aluminum. Now you guys are really making me wish I had AC/DC. Thanks for the info.

 

[Gary Fowler]

One of the benefits of DC is that you can hold a shorter arc than with the AC machines. There is no practical way that you can run a root pass in a butt joint in all positions with an AC machine and get a quality weld. AC is OK for flat and vertical welding, but overhead gets extremely hard to do simply because you need to hold a short arc to weld overhead and if you try this with AC it will stick a lot of times. I too have used 7018 DC rods to weld in an AC machine but you need super steady hands and lots of patience as the arc will just go out a lot of times. I have a Miller 350 amp AC/DC CC/CV machine and never use AC for anything but it is there just in case I ever want to rig up to weld aluminum. I would certainly never use it for AC stick rod applications.

 

[woodlandfarms]

So, refresh my memory, what is better, DC+ or DC-. Ooops, Let me rephrase, why would I use one of the other? Felt like I was talking to my wife, didn't want a fight to start...

 

[Gary Fowler]

Your best welding characteristics for stick welding with DC is DCRP-with the electrode on the positive side and the ground on the negative. This give less spraying of the arc and better transfer of molten metal. The metal wants to travel to the negative piece. DCSP where the electrode is negative is used for TIG welding since you dont want to burn up your tungsten electrode. If you tried to TIG weld with the welding leads set for stick rod welding the tungsten electrode would melt off just like a piece of stick electrode/ DCSP can be used if you want really shallow penetration. One can tell when a welder is using DCSP by the hissing sound it makes. I have never seen an ASME qualified welding procedure that specifies using DCSP.
By the way, there is no way to change the polarity on an AC machine as it is alternating current, the polarity changes 60 times a second where as DC is constant.

 

[Mark @ Everlast]

DC- is really limited in uses. For shallow penetration for items like sheet metal, it works fine. Many rods will weld with DC-, but again not real well. The 6010 will not, unless you like jerking your rod loose more than you weld. The 6011 is probably the best performer on straight polarity along with the 6013.

 

[Iplayfarmer]

I welded a ton of rod with my old Montgomery Ward AC stick welder. I had to use 6013, 6011, or 7014 rods. Then, I got a newer Lincoln 225 AC/DC machine. I haven't used it much yet, but the few times I have I've noticed the arc is much easier to start and maintain, I can use any rod, and the weld seems to look better. I'm still learning the machine and what settings to use for what welds. Overall I think DC is easier to use.

The only advantage I see to AC is the upfront cost. Old used AC machines are a dime a dozen. I traded mine for an old broke-down lawn mower if that gives you an idea what its value to me was.

 

[Rayrla]

I appreciate all the information that this post has provided. Lots more than I expected. Great forum! Thanks to all. Definitely will get a machine with DC. Which one?

 

[Iplayfarmer]

I appreciate all the information that this post has provided. Lots more than I expected. Great forum! Thanks to all. Definitely will get a machine with DC. Which one?

Honestly just about any of the brand name machines will do equally as good of a job.