MIG on some thicker steel. Is it worth getting 100% CO2?

[MOS3522]

Have a project where I need to join 1/4" wall square tube to each other and also to some 1/2". All of it is mild steel, either ASTM A500 or A36. I'm going to use my Miller with some solid core 0.35 ER70S wire.

So I have a tank of C25 on the MIG but technically I'm supposed to use 100% CO2 for this stuff. The welding is structural but it's not aerospace, just some support framework.

Is it worth the effort to get a CO2 tank, or can I get as good a result with C25 mix?

(Frustratingly we've been under Stage 2 fire restrictions in my county for weeks, so no welding or grinding is allowed. Even in a shop! But that will end soon as we've gotten some rain)

 

[Beerhippie]

Have a project where I need to join 1/4" wall square tube to each other and also to some 1/2". All of it is mild steel, either ASTM A500 or A36. I'm going to use my Miller with some solid core 0.35 ER70S wire.

So I have a tank of C25 on the MIG but technically I'm supposed to use 100% CO2 for this stuff. The welding is structural but it's not aerospace, just some support framework.

Is it worth the effort to get a CO2 tank, or can I get as good a result with C25 mix?

(Frustratingly we've been under Stage 2 fire restrictions in my county for weeks, so no welding or grinding is allowed. Even in a shop! But that will end soon as we've gotten some rain)

Maybe you just don't tell the authorities you're welding in the shop? Keep the doors shut?

 

[MJD1]

I wouldn't hesitate to use C-25. Proper joint prep is more important in that scenario than the small amount of extra penetration ( or fusion) that CO2 provides.

 

[PCustoms]

Have a project where I need to join 1/4" wall square tube to each other and also to some 1/2". All of it is mild steel, either ASTM A500 or A36. I'm going to use my Miller with some solid core 0.35 ER70S wire.

So I have a tank of C25 on the MIG but technically I'm supposed to use 100% CO2 for this stuff. The welding is structural but it's not aerospace, just some support framework.

Is it worth the effort to get a CO2 tank, or can I get as good a result with C25 mix?

(Frustratingly we've been under Stage 2 fire restrictions in my county for weeks, so no welding or grinding is allowed. Even in a shop! But that will end soon as we've gotten some rain)

What welder/setting?

What application?

1/4 shouldn't be an issue. I've welded 3/4 using C25 on a couple Lincoln's 180 size machines. Bevel the joints correctly and run multiple passes, if I did it out of sequence I'd get a Pringles chip...

For what's it's worth the old ProMIG units seemed to punch way above their class.

 

[Beerhippie]

I wouldn't hesitate to use C-25. Proper joint prep is more important in that scenario than the small amount of extra penetration ( or fusion) that CO2 provides.

I forgot to mention that I've welded mild up to 1/2" using my Millermatic 180 and 75/25 by using deep bevels, a proper gap, and multiple passes. Still standing after twenty years.

 

[MOS3522]

Yes on deep bevels for sure. The miller has recommended settings which I will adhere too. I was planning on just some normal fillets (root and cap).

 

[vpd66]

How many amps is your Miller welder is more important then your gas choice.

 

[MOS3522]

How many amps is your Miller welder is more important then your gas choice.

250 amps (Millermatic 252), should be ok for this work.

 

[MOS3522]

Maybe you just don't tell the authorities you're welding in the shop? Keep the doors shut?

Yikes! We had a good soaking rain the last 72 hours which put out two of our three giant forest fires and allowed the third to be contained 90%. One of which was the fifth largest fire in Colorado history.

But if I'd welded and set the shop on fire before that rain I think the fire would have taken out half the city. I would be in big trouble.

 

[nadogail]

250 amps (Millermatic 252), should be ok for this work.

About one Ampere per thousandth of an Inch, but not having a "Wire Feed" I stick with "stick"; in my case 7014, because i don't have to keep it dry and use DC, like 7018.

 

[PCustoms]

250 amps (Millermatic 252), should be ok for this work.

Yeah that should be plenty!

 

[PCustoms]

But if I'd welded and set the shop on fire before that rain I think the fire would have taken out half the city. I would be in big trouble.

People weld in shops every day.

Why the big concern?

I agree outdoors in fire weather probably isn't a good idea.

 

[MOS3522]

People weld in shops every day.

Why the big concern?

I agree outdoors in fire weather probably isn't a good idea.

I'm very careful, I have welding blankets and two fire extinguishers on the welding setup, namely a 2.5 gallon pressurized water and a 10 pound CO2. But law is the the law.

Wildfire risk is getting so bad that I am doing some preliminary work to see if I can put a fire suppression pond on the property.

 

[PCustoms]

I'm very careful, I have welding blankets and two fire extinguishers on the welding setup, namely a 2.5 gallon pressurized water and a 10 pound CO2. But law is the the law.

The law says you can't weld indoors?

 

[MOS3522]

The law says you can't weld indoors?

Technically you can weld indoors but my summer ranch shop is open and classified as outdoor ag space. And I back up onto the national forest too, so a fire could be really bad.

 

[ching0n]

I'd say yes. I picked up a 20lb soda bottle from facebook and refilled it for another 20 (I think). C02 is liquid so you get way more bang for your buck (and shop space).

I want to eventually have a big argon and my liquid bottle using a gas mixer to DIY gas mix but I have been putting it off.

 

[vpd66]

Your Millermatic 252 has enough amps but I would look into dual shield flux core wire for welding thicker steel. It is not the same has the gasless flux core wire. You still use a shielding gas and it run much hotter then regular solid wire,

ref=sr_1_1

 

[William Payne]

Have a project where I need to join 1/4" wall square tube to each other and also to some 1/2". All of it is mild steel, either ASTM A500 or A36. I'm going to use my Miller with some solid core 0.35 ER70S wire.

So I have a tank of C25 on the MIG but technically I'm supposed to use 100% CO2 for this stuff. The welding is structural but it's not aerospace, just some support framework.

Is it worth the effort to get a CO2 tank, or can I get as good a result with C25 mix?

(Frustratingly we've been under Stage 2 fire restrictions in my county for weeks, so no welding or grinding is allowed. Even in a shop! But that will end soon as we've gotten some rain)

First off, I have done jobs like that with C25 no problem. It is all in the weld prep. I don't consider that to be thick.

But I do have some questions. You say they are structural. Structural for what? Is there a weld procedure requirement? Why are you supposed to use 100% CO2? Is it because that is what the weld procedure, customer requirements say?

If there is specific customer requirements or a specified weld procedure, you follow that like gospel and do not deviate, because that is what they are asking you to do to those requirements.

 

[no704]

I use CO2 for everything. Much cheaper and the spare bottle can also go in the kegerator.

 

[Beerhippie]

I use CO2 for everything. Much cheaper and the spare bottle can also go in the kegerator.

OTOH, I don't have to worry about pub staff stealing my mix bottles to push beer!

 

[MOS3522]

First off, I have done jobs like that with C25 no problem. It is all in the weld prep. I don't consider that to be thick.

But I do have some questions. You say they are structural. Structural for what? Is there a weld procedure requirement? Why are you supposed to use 100% CO2? Is it because that is what the weld procedure, customer requirements say?

If there is specific customer requirements or a specified weld procedure, you follow that like gospel and do not deviate, because that is what they are asking you to do to those requirements.

No gas spec in the drawing or in the customer request for that. I just know that CO2 is recommended for thicker steel welding due to penetration. All things being equal of course.

I think I will weld with C 25 and see where it goes. It’s not structural in the sense that failure will endanger anything. Just support beams for a metal sculpture thingee.

 

[PCustoms]

No gas spec in the drawing or in the customer request for that. I just know that CO2 is recommended for thicker steel welding due to penetration. All things being equal of course.

I think I will weld with C 25 and see where it goes. It’s not structural in the sense that failure will endanger anything. Just support beams for a metal sculpture thingee.

Pretty sure the 252 is rated for 1/2" single pass with C25...

 

[whateg01]

About one Ampere per thousandth of an Inch, but not having a "Wire Feed" I stick with "stick"; in my case 7014, because i don't have to keep it dry and use DC, like 7018.

But you don't set amps with MIG.

All the "real welder" I know would probably run a dual shield wire. I am not a real welder though so I would do that with my 180 and c25.

 

[KwikFab]

I weld thick stuff with 75/25 all the time without issue.

If you're going out to get a different gas, get yourself a bottle of 85 argon mix and run some spray.

 

[William Payne]

No gas spec in the drawing or in the customer request for that. I just know that CO2 is recommended for thicker steel welding due to penetration. All things being equal of course.

I think I will weld with C 25 and see where it goes. It’s not structural in the sense that failure will endanger anything. Just support beams for a metal sculpture thingee.

oh in that case you should be fine if your welds are good. It’s all in the prep. Don’t be afraid to do weld prep to get penetratio.

 

[whateg01]

If you are unsure how well it will do, build some coupons then cut and etch them.

 

[Beerhippie]

oh in that case you should be fine if your welds are good. It’s all in the prep. Don’t be afraid to do weld prep to get penetratio.

Damnit. Which Shakespeare play was that?

 

[William Payne]

Damnit. Which Shakespeare play was that?

I’m not even going to correct that typo. That’s awesome. I am going to write that down. I made up a word.

 

[Beerhippie]

I’m not even going to correct that typo. That’s awesome. I am going to write that down. I made up a word.

You made up a character!

"I am Penetratio!" "Prepare to ..... (edit for family values)"

 

[William Payne]

You made up a character!

"I am Penetratio!" "Prepare to ..... (edit for family values)"

I wonder if he has a friend named “Insertio”.

 

[dnschmidt]

For steel that thick the correct answer is neither of the above. Use flux core wire as it has better penetration and no gas cost. For 1/8" and smaller C25 is the answer but for something that thick There is no need for gas. Dual Shield is another option and that typically uses C25. Personally, I would use stick and 7018 or 7024 probably in 1/8" rod.

 

[William Payne]

For steel that thick the correct answer is neither of the above. Use flux core wire as it has better penetration and no gas cost. For 1/8" and smaller C25 is the answer but for something that thick There is no need for gas. Dual Shield is another option and that typically uses C25. Personally, I would use stick and 7018 or 7024 probably in 1/8" rod.

May I kindly ask what you base your opinion on regarding this? I am not asking to be negative, just as a welder myself I always like to hear people’s opinions on their techniques.

The options you mentioned are completely valid of course, however C25 and solid wire is used daily in many weld shops throughout the world on things far more critical and as thick and thicker than the original poster is doing.

1/8” and thinner with mig is tiny stuff.

I think the original poster is going to be fine.

 

[MOS3522]

I would have used stick but my tig/stick unit was borrowed by a stranger out of my truck while I had lunch and has still not been returned. I need to replace it.

 

[William Payne]

I would have used stick but my tig/stick unit was borrowed by a stranger out of my truck while I had lunch and has still not been returned. I need to replace it.

That *****.

 

[giles45shop]

With a 252, you could always bump up the wire size to 0.045 for the thicker stuff with C25. My 251 was set up with 0.045 wire and a 20' whip when I bought it used from a heavy truck repair place. It would weld 1/2" in one pass w/o issue.

 

[dr_clyde]

But you don't set amps with MIG.

All the "real welder" I know would probably run a dual shield wire. I am not a real welder though so I would do that with my 180 and c25.

Sort of. Wire welders don't have a knob that says "amps" on it, but you do set the weld parameters around the amperage.

Amperage is the volume of current flow, and in a wire weld, the volume is dictated by the wire size and feed rate. The voltage setting is there to maintain the arc at a given feedrate. To increase amps, either up the diameter or feedrate.

If you look at a welding procedure specification, you'll see the procedure specify all variables, but under the wire feed speed space it'll be labeled (amps). This signifies that the wire feed speed should be adjusted to whatever is required at the given voltage to achieve the specified amperage.

As far as what gas to use, it will depend on the wire and process. Has almost nothing to do with "getting more penetration" and has everything to do with getting predictable results with a given wire and process. Some will require a blend, some will take 100% co2 and some will be self shielding.

 

[MOS3522]

This dual shield wire is interesting. I have known it exists, but I have to confess to never having used it. But looking at some parameters the main advantage seems to be me it will work better with .045 wire (I can do .045 on the gas shielded solid core, but I prefer to work in .035 and make 2 passes on joints like this).

Can someone recommend a good brand of dual shield wire? I want to play with it. The only wire that it seems Amazon sells that is ER71T-1C or M has some really mixed reviews. I will get over to the welding supply house next week, I can see what they have at that point. I know airgas sells a variety of this.

 

[dr_clyde]

This dual shield wire is interesting. I have known it exists, but I have to confess to never having used it. But looking at some parameters the main advantage seems to be me it will work better with .045 wire (I can do .045 on the gas shielded solid core, but I prefer to work in .035 and make 2 passes on joints like this).

Can someone recommend a good brand of dual shield wire? I want to play with it. The only wire that it seems Amazon sells that is ER71T-1C or M has some really mixed reviews. I will get over to the welding supply house next week, I can see what they have at that point. I know airgas sells a variety of this.

Dual shield usually wants to be ran in the spray transfer mode, which takes a machine with some nuts. You can run it on a MM252, but it will probably be on the upper end of what it wants to do.

You can get it in .035" diameter, which will help.

I like Lincoln UltraCore and Hobart FabCo Excel-arc. But we run it on 350 or 450 amp power sources. Not sure how well it will run on a 252.

 

[MJD1]

I like the esab 7100 dual shield wire. I run the .045 size on a miller 252 with c-25 gas. If running at the higher end you will burn up the factory miller gun. I use a Bernard q-300 gun which handles the high amperage just fine.

 

[dnschmidt]

Lincoln or ESAB dual shield.