AC or DC for stick welding.

[propane1]

Which would be better. I have an AC stick welder. I’ve seen videos on how to change them to DC welders. Now, I know nothing about welding, have never had a course in it. But I weld stuff at home to fix or make stuff. Mostly rusty metal. Some days things seem to weld reasonable and other days it doesn’t.
If switched to DC, can I still use the same rods. And what is the advantage of changing polarity.
Thanks for your knowledge.

Noel

 

[poncho62]

Following this, as my 50+ year old welder is likely just AC

 

[Paul F]

i'm not an expert, but what i've learned over the years is DC polarity and DC rods are used for more penetration in thicker steel since the electricity (polarity and heat) is flowing from the rod into the steel to be welded. AC polarity alternates flowing the current both ways so you end up with more heat in the welding rod itself, requiring AC welding rods. AC is good for thinner materials where you don't want a lot of distortion.

i always suggest welding on clean, ground steel and making sure your ground clamp is clean and on freshly ground steel nearby your weld. you'll see a big difference in the quality of your welds.

 

[California]

Instead of modifying an existing welder I would buy a similar AC-DC unit off Craigslist.

After selling the old one, I doubt you could have modified the existing unit for as little as your net cost difference will be after this upgrade.

 

[sonny580]

Not sure about modifying one but You need rods that are for use with dc. Some rods are ac only!--some work for either.

 

[Yomax4]

You can't add DC to your AC machine. One of the benefits of DC is better ability to weld out of position like vertical up. You can pick up a DC stick inverter on Ebay for $90. I'm not suggesting anyone should buy a $90 welder but it's just where the prices start. Good Luck !

 

[California]

Back when transformer AC welders were common there were optional external rectifier units to output DC.

 

[Yomax4]

Back when transformer AC welders were common there were optional external rectifier units to output DC.

Never have seen. How did the Rectifiers connect to the AC Machine?

 

[California]

I don't know much about the external AC > DC accessory. My cousin offered to lend me one, and sent a photo of a box on top of his AC stick welder. It had the logo of some known company, Lincoln or something. He's a serious tech (he sets up physics lab experiments for university students) so I don't doubt the unit works as described. I assume it's simply in series with the welding leads.

 

[sonny580]

this shows how to wire a unit to make ac welder into a dc unit. --- I have NO idea if it would actually work, but enjoy the vid at the link above.

 

[Thirdroc17]

Simple electronics will change AC to DC, no matter the application. I've looked into it, the actual costs of parts usually seem to be a lot more than most claim. You also have to be half way familiar and handy with wiring.

DC needs different rods? Huh. I recently picked up a small DC welder, and use the same rods I always have. Guess they were already AC/DC rods.

A lot of professional welders will have a dozen different rods, I have 2, using only 1 of them the vast majority of time. What one uses for home projects is not nearly as critical as welds in the high stress, high use applications, the pros are used to. No need to over complicate things if you're not doing it for a living.

I will say this, after welding with DC, I highly recommend it.

 

[California]

The comments following that vid convinced me that buying an AC/DC welder on Craislist then selling the first one, will work out better.

 

[dstig1]

I have never seen rods that won't work on DC. It is the other way around. 7018 is a common example. Regular 7018 won't run well, or at all, on AC but there is a 7018AC version that will run on either AC or DC. 6010 is the one that causes a lot of problems as it requires DC and further not all DC machines can even handle it for some reason. That is where 6011 comes into play as it is pretty close to 6010 but will run on either. Both are deep penetrating fast freeze and can be used on "rusty" items. When I took a welding class at the community college they started us off on 6010 for everything, but we were using Miller XMT304's as the power source and they are impressive.

 

[Gary Fowler]

I constantly see folks referring to "use stick rods on rusty metal". While a stick rod like 6010 or 6011 will usually weld over rusty or dirty metal, the only real way to weld, regardless of the process is to clean the metal down to bare, shiny metal. Any rust, grease, dirt, etc. is going to negatively affect the weld metal strength, make it hard to strike an arc (and hold an arc). Only in extreme circumstance when it is impossible to get a cleaning tool into an area to be welded should you weld on dirty metal.
Some rods like 60XX will weld over rust and dirt with only minor effect. 7018 on the other hand will cause porosity, under bead cracking, lack of fusion and other problems with the weld if the metal isn't shiny clean.

Best to always take a few minutes to clean the area well before striking an arc regardless of the process.

 

[welding seabee]

What rods you use either AC or DC all depends on the application whether it is fabrication or repair work. 7018 is not a good choice for positions other than flat fabrication. As most of us here probably do some of both like myself it pays to stay with 6010, 6011, and 6013. I stock these 3 in 3/32 and 1/8 diameter to use with a 230A AC/DC machine. I will get some 5/32 if working on material thicker than 1/2". They will do 100% of any thing you encounter.

If you are serious about doing the best job possible please spend some time researching welding theory and practice and then practice practice and then practice some more. Practice in all positions, concentrating on vertical, overhead, and horizontal. Flat work comes a lot easier and is where all welding schools start you out. There are a lot of good pubs available on Amazon. The root pass is your key element. Screw it up and the flaw will carry through each subsequent pass. All the low hydrogen rods are moisture sensitive and must be kept in a warm environment, a cost most of us avoid so avoid those rods.

I am somewhat ahead of the game as welding was part of my pipefitting trade of younger life. Never forgot how like riding a bicycle but I am rusty and more shaky.

Ron

 

[Gary Fowler]

What rods you use either AC or DC all depends on the application whether it is fabrication or repair work. 7018 is not a good choice for positions other than flat fabrication. As most of us here probably do some of both like myself it pays to stay with 6010, 6011, and 6013. I stock these 3 in 3/32 and 1/8 diameter to use with a 230A AC/DC machine. I will get some 5/32 if working on material thicker than 1/2". They will do 100% of any thing you encounter.

If you are serious about doing the best job possible please spend some time researching welding theory and practice and then practice practice and then practice some more. Practice in all positions, concentrating on vertical, overhead, and horizontal. Flat work comes a lot easier and is where all welding schools start you out. There are a lot of good pubs available on Amazon. The root pass is your key element. Screw it up and the flaw will carry through each subsequent pass. All the low hydrogen rods are moisture sensitive and must be kept in a warm environment, a cost most of us avoid so avoid those rods.

I am somewhat ahead of the game as welding was part of my pipefitting trade of younger life. Never forgot how like riding a bicycle but I am rusty and more shaky.

Ron

I have to disagree on using 7018 in positions other than flat. 7018 is an all position rod and can be used comfortably in vertical and overhead although it does take some adjustment to the amps used. Granted, rods larger than 1/8" are difficult to weld vertical and overhead which is why I dont stock anything but 3/32 and 1/8". I always found that 5/32 7018 didn't run well due to the flux fingernailing badly. If I was welding flat and wanted more rod, I would skip the 5/32 and move from 1/8 to 3/16" because they run so much smoother than a 5/32".
Through many years of welding pressure piping, I have found that there is not much difference in speed using 1/8 vs 3/32 when using all positions like pipe welding in a fixed position. If you want to practice all position with 7018 start with 3/32 first, master that then move to the larger rods. I doubt any hobby welder would ever need any rod larger than 1/8".

 

[psc1947]

As a very poor welder with failing eyesight (I'm 73 with a cancer bug) I always grind each pass smooth with a side grinder which makes it easier to get a better weld on the next pass.

 

[Gary Fowler]

As a very poor welder with failing eyesight (I'm 73 with a cancer bug) I always grind each pass smooth with a side grinder which makes it easier to get a better weld on the next pass.

That is good if you have humps /valleys in the weld. Welding over a lump just increases the size of the irregularity so grinding down any unsightly objects will make the weld look better. You can also remove any slag entrapment in the process.
Start clean-finish clean!

 

[Motox]

As a very poor welder with failing eyesight (I'm 73 with a cancer bug) I always grind each pass smooth with a side grinder which makes it easier to get a better weld on the next pass.

As a 63 yr old welder. (former pipeline welder yrs ago now hobby) with eyes also going south, I understand but can't give it up. Currently building pipe fence with son in law. crusty rusty pipe. Hope I am still welding when I'm 73.

 

[Gary Fowler]

As a 63 yr old welder. (former pipeline welder yrs ago now hobby) with eyes also going south, I understand but can't give it up. Currently building pipe fence with son in law. crusty rusty pipe. Hope I am still welding when I'm 73.

I am also a former pipe welder (worked petro-chem construction) and at 701/2 years old, I can still run a bead but what I used to do with one hand, now takes both hands and a steady rest. I have just started getting together machines for wire feed welding (FCAW and MIG). Just light duty 110 volt babies but they work fine for my knife making and sheet metal work.