Dual shield rookie

Puts down a nice weld.
What gas mix are you running with it-

It is an 80% Argon, 20% CO2 mix. Can also use it for solid wire I believe, but not tried it yet.

I have been building a few of these and welding them with self shielded flux core is a pain.

Done some more experimentation with Dual Shield. I found horizontal fillet welds with 1.2mm (0.45) wire, you need heaps of amps 250+ to get it to penetrate into the root as the deposition rate is to great if you go too slow you end up having the arc on the puddle rather then the leading edge.

Vertical up's are like cheating though. Just hold it straight and zip it up and it is counter intuitive in that you want fast wire feed for vertical up, not slow.

Here is a cut and etch when I finally got things sorted out.

.RC. said:

Done some more experimentation with Dual Shield. I found horizontal fillet welds with 1.2mm (0.45) wire, you need heaps of amps 250+ to get it to penetrate into the root as the deposition rate is to great if you go too slow you end up having the arc on the puddle rather then the leading edge.

Vertical up's are like cheating though. Just hold it straight and zip it up and it is counter intuitive in that you want fast wire feed for vertical up, not slow.

Here is a cut and etch when I finally got things sorted out.

View attachment 312049

Click to expand...

My last machine Millermatic 252 was crank voltage very high, turn up the feed speed a LOT. Imediately I burned up my hand, then I burned up the gun. Bought a massive Bernard gun & heat shields for my hand. Heat shields melted.
Dual Shield is a HOT process! it also gives nearly certain bond with parent metal. For me, its ability to give certain bond while running a lot of deposit uphill makes it very desireable. It has not been easy for me to work the bugs out. I've watched many videos, none addressed the problems I had.

My problems were birdnesting, a snarl around the feed rollers, and porosity. Several people on Welding Web contributed, especially Oscar. I still never made headway.

Maine Oxy manager figured out the wire I was using needed 85/15 gas. sold me different wire for 75/25 gas. He sold me little felt cylinders & lubricant to put on the wire as it entered the feed rollers.
I tried in vain to figure out what liner my gun needed, then discovered a "jump liner" I already had.

My birdnest problems are solved. My porosity problems are solved.

.RC. said:

Done some more experimentation with Dual Shield. I found horizontal fillet welds with 1.2mm (0.45) wire, you need heaps of amps 250+ to get it to penetrate into the root as the deposition rate is to great if you go too slow you end up having the arc on the puddle rather then the leading edge.

Vertical up's are like cheating though. Just hold it straight and zip it up and it is counter intuitive in that you want fast wire feed for vertical up, not slow.

Here is a cut and etch when I finally got things sorted out.

View attachment 312049

Click to expand...

Curious why your welds have a pinhole at deepest part of the root? I ran .045" dual-shield and didn't find it that hot using a 300 amp Bernard gun. If you want hot burn some 3/32" Innershield NS3M E70T-4 at 400 amps+. You need the heat shield on the gun. Even the smaller guns for self shielded flux-core come standard with a heat shield. I think I've seen optional heat shields for standard guns though. The biggest Lincoln Innershield gun is rated at 600 amps for burning 1/8" wire! That's got to be pretty insane.

Welder Dave said:

Curious why your welds have a pinhole at deepest part of the root? I ran .045" dual-shield and didn't find it that hot using a 300 amp Bernard gun. If you want hot burn some 3/32" Innershield NS3M E70T-4 at 400 amps+. You need the heat shield on the gun. Even the smaller guns for self shielded flux-core come standard with a heat shield. I think I've seen optional heat shields for standard guns though. The biggest Lincoln Innershield gun is rated at 600 amps for burning 1/8" wire! That's got to be pretty insane.

Click to expand...

I wander if it isn't a small slag inclusion considering it's past the edge of the plate

That is the major issue with dual shield at lower power levels.

I had endless trouble with root penetration, and further research revealed it is a common problem with horizontal fillet welds.

The fix is to get the arc on the leading edge by going faster and do not put the arc on the puddle.

Here is a photo showing what was happening when I started out doing some testing. Also here is a video showing the problem with dual shield flux core on horizontal fillet welds if just done in a blase manner.

I built and repaired RR cars with it . I thought it was a very good thing . I often thought if i could have dual shield at home i could speed up some projects.

.RC. said:

That is the major issue with dual shield at lower power levels.

I had endless trouble with root penetration, and further research revealed it is a common problem with horizontal fillet welds.

The fix is to get the arc on the leading edge by going faster and do not put the arc on the puddle.

Click to expand...

I have an old edition of the Lincoln welders bible, there was a loose insert about a technique developed during the early stages of WW2, that showed just what you did with etching. run fast enough to use the arc force to dig into cold steel.

Click to expand...

Arc force blowing on the liquid puddle is absorbed much shooting a gun into water.

Well I am a convert on the dual shield now. Gone through nearly 15kg of it. Been welding up some galvanised stuff, including stuff like 3/4" water pipe. The self shielded stuff, so much smoke, noise and spatter you nearly have to weld it by braille. And you have to run it hot, then it blows holes in thin stuff. This dual shield, it seems to take the best of solid wire and self shielded and combines them. Gal stuff is no problems.

Finally got back into it myself. Ran a lot of Lincoln 71M several years ago at my last job but have been away from it a while. Guy at the welding store talked me into Hobart triple 7 .045 wire this go round. Rebuilt a bucket on a 980G loader and that triple 7 seems so much more forgiving on the settings. I couldn’t hardly buy a wormhole with it and it was always a problem on the upper settings with 71m. Different power source and feeder so that could be part of it. The 71m was ran with a miller xmt350 and recently I ran the Hobart with a Lincoln vantage 500 and an ln-25. Did a lot in the 6-700 ipm range maxed out and it just laid it in there. 100% co2 and the new 400 amp profax gun I just bought never got hot enough to stop. Ran through over 40 pounds on the last day to get it out the door. Verticals did well in the 400ipm range.

These were 600 ipm stringers with the bucket rolled back for a little uphill then flattening out at the point of the edge.