Mig Welding lap joints, Lift Arc TIG, and Walking the Cup

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The first part of the video above shows mig welding a 1/4" carbon steel lap joint.

And since the welding machine I used was not just a mig welder but a MTS (MIG,TIG,STICK) welder that also does lift arc TIG and Stick welding, I also showed some Lift arc TIG and walking the cup technique.

An MTS (MIG,TIG,STICK) welder like the primeweld mts200 gives you a lot more options than a standard mig welder. 

I use it primarily as a MIG welder but it sure is nice to have the option of stick and lift arc TIG.

I highly recommend the PrimeWeld MTS200 as opposed to a mig welder that strictly does MIG. 

MIG Welding a 1/4" lap joint using a primeweld mts200

How to MIG Weld a 1/4" Thick Carbon Steel Lap Joint – Step-by-Step Instructions

1. Materials & Tools Needed:

• 1/4" thick carbon steel plates (cleaned of rust, oil, or mill scale)
• MIG welder (preferably 220V for thicker material)
• ER70S-6 solid wire (0.030" or 0.035")
• Shielding gas: 75% Argon / 25% CO₂
• Welding helmet, gloves, and safety gear
• Wire brush, grinder, or flap disc for prep

2. Prep the Metal:

• Clean both pieces where the weld will go using a flap disc or wire brush.
• Remove any contaminants like paint, oil, or rust.
• Make sure the lap joint has full contact with no major gaps.

3. Machine Settings (Starting Point):
For 1/4" steel with 0.035" wire on a 220V MIG welder:

• Voltage: 20 Volts
• Wire Speed: 310 IPM (all machines are a bit different so adjust wire speed up or down based on puddle and sound)
• Gas Flow Rate: 25–30 CFH
• Use DCEP (Direct Current Electrode Positive ) and push or pull  technique based on your preference. Both angles work provided you limit gun angle..in fact a 90 degree angle works well too.

4. Tack Weld First:

• Tack weld the plates on the ends 
• Ensure the pieces are flush and clamped down if necessary.

5. Technique Tips:

• Use a slight drag (pull) technique for deeper penetration or push for better visibility and wider bead. You will read all kinds of discussion on whether pushing or pulling gets better penetration. Most of it applies to spray transfer mig welding as you would do in  heavy manufacturing
• Keep a consistent travel speed—too slow causes buildup, too fast leads to insufficient weld.
• Maintain a wire stick-out of about 3/8" for good arc stability.
• Hold your gun angle at about 10–15° from vertical.

6. Welding Pass:

• Weld in a single pass for lap joints on 1/4" plate if using 220V and correct settings.
• Use a slight manipulation or tight circles and play the arc to the leading edge of the puddle to ensure penetration and sidewall fusion.
• Watch the puddle and don't undercut the corner of the top member

7. Post-Weld:

• Inspect for proper bead shape, penetration, and minimal spatter.
• Clean the weld area using a wire brush or  wire wheel if needed.