A common joint found in auto repair work, the lap joint is a piece where two pieces of metal overlap each other. An ideal lap weld should have a good amount of weld bead penetration without the upper edge melting back or overlaying. If the upper layer melts too much, the lap joint will be too weak and thin. Making lap welds takes a good amount of practice to get it right, so experiment with your welding angle, arc length and rate of stitching welder travel to find the best combination for you.
When you are welding a bead onto your lap joint with your stitch welding electrode, using a weaving pattern by zigzagging back and forth across the joint can help avoid melting too much of the upper edge, make the process easier. The trick is to allow the melted metal at one end of the welding weave to solidify only partly before adding more. It is important to be careful not to allow the bead to cool too much, as that can disrupt the strength and flow of the weld. Practice on different pieces of scrap metal to make lap joints before performing the weld on any work piece.
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