Difference between AC and DC stick welding

Hello all,

I have been welding with an old Lincoln Tombstone welder forever. It is an AC only machine. I do quite well with it but it is needing repair and new cables so I am considering buying another machine.

Unfortunately I cannot afford most mig machines I have seen and I am not sure if the smaller 115V machines will do the trick for me.

I weld trailers and BBQ smokers. Most stuff is 1/4" or larger steel. I so far have not needed to weld aluminum or other materials.

I can get a brand new Lincoln ac/dc tombstone welder for $387 from Home Depot. I can get a new AC only machine for $287 from them also.

Since ALL of my welding history is with AC stick, I do not know how a DC machine will change things. I have always heard that AC is harder to learn but since I can already weld AC I would guess that DC would not be a huge challenge but since I do not know the benefits of DC+ or DC- I was hoping someone here could shed some light.

NOW, I am not against MIG and would like to buy MIG but cash is a crunch and I am not sure if the 115V machines will do the work I want. I weld a lot and the 115V machines just seem like they would not hold up. I was told a Miller 251 would work perfect for me but it is WAY oustide my price range.

My questions:

How is DC- and DC+ different from AC welding? How would it change what I currently do?

What Mig machine would be a minimum for 2hours/day of active welding (the rest is setup and parts but 2hrs of actual arc time) on thick metal?

I know the Lincoln 225 wlil weld everything I would ever want to weld but DC and MIG are interesting to me.

Thanks for any help. I have been a one man show for a long, long time and finding a bunch of people that REALLY know welding is great.

Kimo

Reply to
KIMO
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Where are you located?

GWE

KIMO wrote:

Reply to
Grant Erwin

Where do you live? I can make you a super deal on a Hobart TR250 AC/DC machine, if you live in So. California. This is an industrial duty machine, unlike the box stores machines, and is of course..single phase.

Gunner

"I think this is because of your belief in biological Marxism. As a genetic communist you feel that noticing behavioural patterns relating to race would cause a conflict with your belief in biological Marxism." Big Pete, famous Usenet Racist

Reply to
Gunner

I am located just east of Dallas, TX.

Reply to
KIMO

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Have a look at these. Direct replacements. Don't be afraid to offer $75.

Grant

Reply to
Grant Erwin

If the repair is not cheap (usually is), a used machine is. These things are dirt common and tough, so many are available used, cheap, and often with better setups than a "new" machine (which often comes with cruddy undersized cables and cheap, low quality electrode holder and ground clamp, for instance, if it comes with cables at all).

Reply to
Ecnerwal

But for God's sake don't tell anyone you paid that much "around here , they go for about 15 bucks " was what I was told . BTW , I did pay 75 for mine , but those are in better shape , at least they're cleaner . If you watch ebay , you can catch large diodes (275-500 amp units !) at a reasonable cost and make it dc yourself . Which I plan to do as soon as some come up .

Reply to
Snag

Your useage says mild steel, reasonable thickness, and no issues with high stress or certifications. This is perfect territory for stick welding with 6013, 6011, or 7018 rod on an AC welder. Going to DC on a stick welder will give you smoother welds, somewhat less spatter, and the ability to run a greater variety of rods. Check out a typical list of rods, see which ones do what and which require AC or DC. Sample at

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|2030| If you buy a new Lincoln, by all means go the extra $$ for the DC, it will give you added flexibility. At your stage of knowledge, you will be able to utilitize the DC profitably.

But the Tombstones are really bulletproof. About the only thing that goes wrong is cables and clamps and the rotary switch. Spray the switch with plastic safe contact cleaner and run the switch through the settings for a couple of dozen times. The cables usually need replacing, move the stinger cable to the ground side, add a somewhat longer stinger cable.

If you think you want to go with MIG, your useage will want a 220 volt unit. Can't be beat for a 'production' mode of laying down lots of weld bead. But plan on the $700 to $900 range for what you need. Used should be available for half of new but you take your chances.

I'd just fix the cables and keep > Hello all,

Reply to
RoyJ

I appreciate the replies so far but can anyone explain if I should try to find a used AC only or AC/DC and what Benefits a DC machine may provide?

Reply to
KIMO

Thanks Roy,

That points me in a better direction.

My AC machine needs new cables and probably a new fan. The fan really whines when it is running and really makes a lot of noise when it first turns on. I have not taken it apart yet buy may do so this coming weekend.

The selector switch is a little "Tricky" and I have to select the amps I want and wiggle the switch back and forth to be sure it is in the right position or it does nothing. Probably need a switch also.

Kimo

Reply to
KIMO

This happened to me on a little Miller Thunderbolt buzzbox. When I tore it apart to R&R the fan, I noticed that the mounting screws were loose. I tightened them up and it's run silent for maybe 8 years now. YMMV.

Welding with DC, it's lots easier to strike an arc, and the rod will run more smoothly with less spatter. That means your welds will look better and probably be stronger. On a barbecue that'll acquire a nice rust/smoke patina, do you care much how the welds look? Not really.

If you go looking for a small welder, I agree with the recommendation to look for an AC/DC welder. It's lots easier to find 7018 than 7018AC - I've come across a bunch of rod several times, and usually they were of a type that wouldn't work with AC. Also, many exotic rods e.g. stainless 308 can only be run with DC.

There's a clean Miller Thunderbolt here:

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It's the older kind, where the leads detach. Much much better to be able to remove your leads and hang 'em up. Also, you can then swap the leads for proper sized ones.

GWE

Reply to
Grant Erwin

Roy mentioned the main advantage of DC already. That is the smoother arc and greater range of electrodes. On the negative side you will get to experience arc blow. With DC out of position welding is easier. You mentioned that you have to wiggle you amperage switch. When you are investigating the fan noise and have the cover off. Clean the brass contact points with some fine abrasive paper or small wire brush. Usually oxidation is the problem. Randy

Reply to
R. Zimmerman

Most Electrodes nowdays are designed to run on AC current, DC+ or DC-. The only electrodes that come to mind that require a set polarity are Low Hydrogen and Cellulose electrodes, these electrodes run better on DC+ for capping and fill runs. For general purpose electrodes such as xx12 & xx13 either polarity is fine. All it means is that more heat is generated at the positive pole on DC, about 2/3 as opposes to 1/3 at the negative pole, which means that if you run electrode positive, most of the heat is at the electrode.As said before in this group, DC gives you a smoother arc and better positional welding characteristics. Arc blow can be a problem in Windy conditions or if the Earth clamp isn't positioned correctly. Generally Three Phase AC gives you a more stable arc than single Phase AC so going single phase DC solves this cheaply. I'm from Australia so I'm not sure what type of terminology you guys use for inverter welders, or model types, but they are a great way to go. The benefits are many; lightness, portability, perhaps get a AC/DC HF unit to enable you to weld Aluminium as well as steel as most inverters come with a tig kit as well as a stick setup, here in Oz they sell for around $1100 . Hope this helps

Reply to
Rod Day

A good professional quality AC welder is very sweet to use, especially with 6013. Told, but never tried, that 6012 actually really wants AC. Lower-end inverter can seem to lack the mastery which a good AC machine has, on these rods. The AC copper-and-iron machine would be more expensive to buy that a lower end professionally usable inverter. ("Oxford" oil-cooled AC machine vs. Italian reasonable inverter is 2:1 on cost in UK)

We are definely not talking about "buzz-boxes" here, you understand...

6011 on AC makes crackling sound at mains frequency but works absolutely fine.

Richard S

Reply to
Richard Smith

I've got a diode assembly from a Lincoln 400 amp DC welder. NIB surplus replacement part from John Deere, for sale cheep. Diodes, heat sink, metal box, pretty gray color, ;-). Remove pyrotechnic device from e-mail addy.

Reply to
Tom Wait

Perhaps someone else can use them , I scored some on ebay a few days ago ... or you can email me your price (change snagnone to snagone in my reply-to addy) and if they're cheap enough , I'll sell these and buy yours - lots less work for me !

Reply to
Snag

OK guys, I stumbled upon an AC/DC Miller Thunderbolt that I got for $20. I am going to clean it up and get new leads.

Back to my original question: Using DC to weld.

I have heard of DC- and DC+ to weld. If I am building trailers and BBQ smokers what should I do? Also for mild steel what electrode should I use for DC?

Would I go DC+ (stinger is +) and use a 7018 electrode? It appears that it is an all direction electrode that is also a DC electrode.

Is my question answered this easily?

Last but not least, why would I ever go DC- ? What is that benefit?

Thanks to all, even a 49 years old I have a lot to learn.

Reply to
KIMO

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