[DSM8]

Ok so if I understand this correctly.
Dual shield is using both a FLUX CORE wire AND an Argon/CO2 gas mix.

If this is correct then my question is can you use ANY flux core wire or is there one that is meant to be used with CO2 vs. one that is not?

[MinnesotaDave]

There is self shielded flux core wire and gas shielded flux core.

Self shielded is not designed to be used with shielding gas as well.

Side note, gas shielded flux core often is rated for 100% CO2 or 75/25 mix.

[DSM8]

OK that is kind of what I thought but thank you for the clarification.
At least now I know what wire to put into the machine.

[Oilman]

I will have to check a few things about what I have used doing dual shield welding. I didn't set the machine up nor buy the wire.

I stopped over to a friends metal fab shop and got roped into welding for 3-4 days on some outdoor wood stoves.

Welding was done indoors. Single pass welds on 3/16" and 1/4" plate. Absolutely had to push weld. Drag welding resulted in monstrous porosity. (I at first insisted on drag welding despite his mild objection, and had to listen to his laughing while I ground out bad welds for a few inches) Welds were baby bottom smooth with almost zero porosity. We were using a 400 amp Miller, and had to take breaks to let the gun cool off. Yes the welds were made significantly on the hot side. horizontal mostly.

His reasoning was that you have almost no water leaks when leak testing, using dual shield. I have seen boat builders use the same process for the same obvious reasons.

After reading up on the process on Lincoln's website I will have to ask him what wire he was using. I notice that Lincoln recommends drag welding dual shield???

http://www.lincolnelectric.com/en-us/su ... rodes.aspx

There is always a conventional way of thinking with each welding process. In my world, we developed new weld processes through experimentation when attempting to weld unconventional thicknesses/fit-ups/materials. Some of our weld techniques are in Lincolns library. So just because there is a conventional way to weld something there is sometimes a better way to get the job done.

[christhewelder75]

One other thing to note when using self vs dual shielded is polarity. Dual uses electrode positive (dcrp) self shield u have to switch to electrode negative (dcsp) for it to run right.

As far as pushing dual shield I'm of the opinion u can push or pull depending on the situation and your technique. Tho pushing you are increasing the risk of inclusions

I'm not sure tho why you would have porosity by dragging maybe too much gas flow? Or a draft that was blocked by your body positioning?

[Oilman]

Absolutely no issues with positioning. Like I said I will have to check into the variables in my friends set-up. He may have been using regular flux core wire rather than wire made for dual shield. All I know was that there was no way you could drag weld with the set up. Whereas push welding resulted in a very nice bead with very good penetration in the root. This was a very hot weld. I've done structural welding on heavy plate (1" and 2"), of course multi-pass, and didn't have the torch heat up like It did welding that stove. It could very well be that he simply experimented with the variables until arriving at a good formula. I think we had something like 2-3 minor leaks on the completed stove. As I remember those were on the few welds we had to do with a vertical up pass.

[Cbking]

The Stick out of dual shield also take a bit of time to get used to. That wire needs to preheat before hitting the puddle. These are 3G bend tests on 1/2 plate with a 1/4" backing bar.




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