Slide 002: MIG Welding Technique — Bead Running & Joint Welding¶

Slide Visual¶

MIG Welding Technique — Bead Running & Joint Welding

Slide Overview¶

This slide covers the hands-on technique for MIG welding, from running practice beads on flat plate to welding basic joints. Students will learn proper body position, torch angles, travel speed, and how to read the weld pool.

Instruction Notes¶

Body Position & Stability¶

Welding is a fine motor skill — stability is essential: - Stand or sit comfortably with both feet flat on the floor - Brace your welding arm against the table or your body - Use both hands: dominant hand on the gun trigger/grip, support hand steadying the cable - Position yourself so you can see the weld pool clearly (looking at the joint from the side, not straight down) - Plan your travel path — you should be able to complete the weld without repositioning

Torch Angles¶

Two angles define torch position:

Work angle: Angle between the torch and the workpiece surface, measured perpendicular to the weld direction - Flat butt weld: 90° (perpendicular to plate) - T-joint fillet: 45° (bisecting the angle between plates) - Lap joint fillet: 60-70° toward the bottom plate (more heat to the thicker section)

Travel angle: Angle of the torch in the direction of travel - Push (forehand): 5-15° forward tilt — wider bead, less penetration, better visibility - Drag (backhand): 5-15° backward tilt — narrower bead, more penetration - For beginners: push technique is recommended for better visibility

Contact-Tip-to-Work Distance (CTWD)¶

The distance from the contact tip to the workpiece — also called "stickout": - Short-circuit transfer: ⅜"–½" - Spray transfer: ½"–¾" - Consistent CTWD is critical — varying it changes the effective amperage - A common beginner error is gradually increasing CTWD during a weld, causing the bead to get colder

Reading the Weld Pool¶

The weld pool tells you everything: - Pool size: Should be approximately 2× wire diameter wide. Too big = too slow or too hot. Too small = too fast or too cold - Pool shape: Slightly elongated in the direction of travel. Circular = too slow - Pool brightness: Consistent orange-white glow. Dim = too fast. Bright white = too hot - Ripple spacing: Even spacing = consistent travel speed. Uneven = speed variation

Travel Speed Control¶

Watch the POOL, not the arc — the pool shows what is actually happening
Maintain a consistent pool size by adjusting your speed
A good bead has even width and even ripple spacing
Target: the trailing edge of the pool should be about ⅛"–¼" behind the arc

Stringer Bead vs. Weave¶

Stringer: Straight-line travel with no side-to-side motion — produces a narrow, consistent bead. Best for learning and for thin material
Weave: Side-to-side motion while traveling — produces a wider bead, useful for filling larger joints. Pause briefly at each edge (toe) to ensure fusion

Key Talking Points¶

Stability and body position matter as much as machine settings
Watch the weld pool, not the arc — the pool is your feedback instrument
Consistent CTWD is one of the hardest skills to master — practice deliberately
Push technique is recommended for beginners — better visibility of the pool
Even, consistent travel speed is the hallmark of a competent MIG welder

Learning Objectives (Concept Check)¶

[ ] Demonstrate correct torch work angle for butt, T-joint, and lap joint
[ ] Maintain consistent CTWD within ±⅛" during a 6" bead
[ ] Read the weld pool to adjust travel speed in real-time

Last Updated: 2026-03-19