How to weld
Practice, step by step: positions, materials, specific jobs.
Practice rather than theory. Each article is a job that beginners lose material on, taken in the order the work actually happens: fit-up, tacking, settings, sequence.
A theme runs through all of them. Most of what goes wrong on these jobs was decided before the arc was struck — a gap that should not be there, tacks in the wrong order, a sequence that lets the shrinkage add up instead of cancel. The welding itself is the easy part to fix.
- Welding thin sheet Settings and technique for 0.8 to 2 mm sheet: stitch welding, backing bars, torch angle, and why the fit-up gap ruins everything.
- Welding a vertical weld Vertical-up and vertical-down welding: how much to drop the current, which weave to use, and which one belongs on which joint.
- Welding square tube Welding hollow section: the tacking order that controls distortion, welding the corner, and settings for 1.5 to 3 mm walls.
Frequently asked questions
Why does thin sheet burn through at the end of a seam?
Because the plate is hot by then. Settings that were right on cold metal are too much for metal that has been absorbing heat for two minutes. Either drop the current as you go, or work in short stitches with cooling time between them.
Up or down on a vertical weld?
Up for anything that carries load — the frozen bead below supports the pool, so penetration is good. Down for thin sheet and pipeline root runs, where speed matters and deep penetration would blow through.
My frames always come out out of square.
Sequence, not skill. Tack diagonally opposite corners first, check both diagonals, then weld opposite faces in turn so the shrinkage cancels. Welding face by face round the perimeter always pulls the frame towards the last weld.