How to stick weld: Flat Lap joint with 7018's

Summary

This video provides a detailed guide on stick welding a lap joint, a common and practical technique used in applications like truck body repairs. It emphasizes the advantages of the lap joint, such as not requiring precise fit-up tolerances. The tutorial covers key techniques like proper rod angles, arc length, and travel speed to achieve a strong, clean weld. The process involves multiple passes to ensure adequate fill for thicker materials. The video also provides practical tips on maintaining consistency, preventing undercuts, and selecting the right rod size and amperage for different joint thicknesses.

Takeaways

• 😀 Lap joints are a commonly used joint in various applications, especially for truck bodies and repairs.
• 😀 One of the biggest advantages of a lap joint is that it doesn't require precise fit-up, unlike a butt joint.
• 😀 In a lap joint, you can simply measure approximately an inch or half an inch oversize before welding.
• 😀 The most critical part of welding a lap joint is setting the proper rod angles for each pass.
• 😀 For the first weld, use a 45° angle with a 15° to 20° drag angle for best results.
• 😀 Maintaining the correct arc length and travel speed is key to achieving a consistent and clean weld.
• 😀 If the arc length is too short, you risk porosity, and if it's too long, you risk excessive spatter.
• 😀 In the second weld pass, change the rod angle to be closer to perpendicular to the joint for better coverage.
• 😀 For the third weld pass, adjust the rod angle further to avoid undercutting along the top edge of the joint.
• 😀 Each weld pass should overlap the previous one by 60-70% to maintain strength and consistency in the joint.
• 😀 For thicker base metals (over 1/4 inch), multiple passes are required to ensure proper weld penetration.

Q & A

What makes lap joints a common choice in welding?

Lap joints are commonly used because they don’t require precise fit-up tolerances, making them easier and quicker to weld. This is especially useful in repairs and applications like truck body welding.

Why is the rod angle critical when welding a lap joint?

The rod angle is crucial because it affects the heat distribution and weld fusion. Incorrect angles can lead to undercuts, poor fusion, or inconsistent beads. Proper angles ensure good penetration and smooth welds.

What is the recommended rod angle for the first weld in a lap joint?

For the first weld, the rod angle should be around 45° in the joint, with a slight drag angle of 15° to 20° to ensure proper fusion and a smooth bead.

How does the rod angle change for subsequent weld passes in a lap joint?

For the second weld, the angle becomes steeper, closer to perpendicular (about 20° off). For the third weld, the angle should be further from perpendicular, pointing more toward the top plate to avoid undercut.

What is the importance of maintaining the right arc length when welding a lap joint?

Maintaining the right arc length is important to avoid issues like porosity or excessive spatter. The arc should hover just above the puddle to ensure proper weld formation and clean results.

What should be considered when determining the travel speed during welding?

Travel speed should be slow enough to allow the puddle to spread and the filler rod to melt properly, but not too slow to avoid excessive buildup or heat concentration in one area.

How much overlap should be maintained between each weld pass on a lap joint?

Each pass should overlap the previous weld by 60-70% to ensure a consistent, strong weld with good fusion between the passes.

What is a common mistake when welding a lap joint and how can it be avoided?

A common mistake is creating undercut along the top edge of the joint. To avoid this, ensure that the rod angle is shallow enough to allow proper fill along the top edge without standing the rod too upright.

What is the proper technique to follow when making a lap joint weld?

The proper technique involves dragging the electrode steadily, maintaining the correct arc length, and controlling travel speed to allow the puddle to spread evenly. Overlap each pass by 60-70% and ensure the weld bead follows the line of the previous pass.

What type of electrode and amperage are typically used for welding a lap joint?

A Lincoln Electric Excalibur 33 3/32" electrode is used, with amperage typically ranging from 100-110 amps. The size of the electrode and amperage may vary depending on the material thickness.