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Welding/Dual shield welding

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Question
QUESTION: How do you set up the welding machine up for dual shield welding. Is the gun (-) or (+). I am using 75/25 gas and 1/16 inch wire. I am pulling the wire. I am getting a lot of spatter and cracks in the weld.

ANSWER: Hard wire MIG and Dual Shield are Electrode Positive.
Self Shielded Wire is Electrode Negative.

1/16" wire has a happy place at 23 volts and 200 amps.



---------- FOLLOW-UP ----------

QUESTION: I have seen pictures of dual shield welding and beads all look smooth and shiny. I can do this with flux-core, but not dual shield. Is that because of the heat or feed. Is it technic. This really bothers me. Sometimes it is hard for me to get good penetration.

Answer
Dual-shield is dead easy.
Set the machine correctly and weld back-hand (pulling the gun, not pushing).
Move slow and steady, and the weld should just flow.
If your dual shield welds look choppy, or rough, there must be something off with your setup.
Could be your gas, or polarity.

Electrode Positive, C25 gas (75% Argon/25% CO2)

Also you can't leave flux-core wires on a machine uncovered for too long our they will get moisture in the flux.

In industry the wire is usually used up before this happens, but hobbyists often have this problem.
If your wire is on a wire spool you can bake it to dry it out, but if it is on a plastic spool, that is trickier.  

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Ernie Leimkuhler

Expertise

Questions about Oxy-Acetylene welding/cutting, MIG, TIG, Flux-core, Stick welding, brazing and soldering, bike frames, air frames, motorcycle frames, structural welding. Also questions about Welding Certifications and Inspections. All questions about fabrication of metals (stainless steel, steel , aluminum, brass, bronze, copper). Basic questions about underwater welding. TIG is my strongest subject.

Experience

Extensive background in most welding fields. 18 years fabrication of metal theatre scenery, 16 years structural steel, 2 years pipe welding, 9 years as a Welding Instructor at South Seattle Community College, and 5.5 years as a Welding Instructor at the Divers Institute of Technology. 16 years Industrial Welding Consultant for fabrication shops in the greater Seattle Area. 11 years Architectural Metal Fabrication. 8 years in Film/TV; SPFX/construction/set-deco/props/. 33 years Blacksmithing and Knifemaking. Currently a Field Welding Inspector for Otto Rosenau and Associates.

Organizations
American Welding Society - Certified Welding Inspector Washington Assoc of Building Officials (WABO) - Special Inspector - Structural and Reinforcing Steel.

Publications
Do a search on google groups for "Ernie Leimkuhler" in the rec.crafts.metalworking and sci.engr.joining.welding groups. http://www.stagesmith.com/ http://www.metalwebnews.com/ Blacksmith's Gazzette - Anvil Making

Education/Credentials
BA Theatre Technology - Purdue University.

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