A butt joint is a piece where two pieces of metal are joined by their edges with a weld bead using a stitch welder. The exposed edges of each metal piece heat up quickly, so careful use of the electrode is necessary when welding. An ideal butt weld should have full penetration at the joint with a small weld bead on the bottom surface and a larger bead on the top surface. Butt welds on pieces of metal that are less than 1/8 inch are difficult to control as thin sheet metal can tend to “crawl” apart when it is heated from a weld. A good way to avoid this is to perform tack welds on the butt joint along the entire length of the piece.
When you are welding a bead onto your butt joint with your stitch welding electrode, using a weaving or circular motion can make wider beads, which spread the heat evenly and prevent burn through. Using a stitch welder to make butt welds takes some time and practice to get it just right, so experiment with your electrode angle, arc length and rate of travel to find a combination that works best for you. Practice making weld beads with your stitch welder electrode on pieces of scrap metal to make butt joints before using it for any major automotive project.
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