When you know how to weld, you can repair the rusted hand railing on your front stoop or a broken tractor hitch. You can build machines or simple workshop aids, such as heavy-duty shelf brackets. When you get good at it, you can even restore old cars. That’s a lot of applications for a single skill. At its most basic, welding joins two pieces of metal using melted steel as the glue. Here we demonstrate that process with a flux-cored wire-feed welder. When the powdered flux inside the wire melts, it emits a gas that condenses to form a thin shell of slag. This protective layer prevents contaminants in the air from polluting the cooling molten metal and reducing the strength of the weld. Most projects require five steps: prepare the metal; clamp the pieces in position; tack them together with blobs of metal; finish-weld the parts; and clean up the assembly. Get that down and you can handle a project like the C table at the end of this article.