Keeping a welder working

Every weld is a circuit: machine, lead, torch or holder, arc, work, return clamp, back to the machine. A fault anywhere in that loop shows up at the arc, which is why a bad weld is such a poor guide to what is wrong. Working around the loop in order is faster than guessing, and it puts the two things that fail most often first.

This page describes what maintenance is; it does not give settings, and it is not a substitute for the safety position on the welding page — particularly on fume, which is the hazard that matters most and the one no maintenance routine addresses.

• Contact tip — The commonest cause of erratic wire feed and an unstable arc. It wears from the inside as wire passes through it, and a worn one gives an arc that wanders and a bead that is inconsistent for no visible reason. They are cheap and are meant to be changed often.
• Shroud or nozzle, and spatter — Spatter building up inside the shroud restricts gas flow, and restricted gas is porosity. Cleaning it is routine rather than remedial, and anti-spatter treatment makes it a great deal easier.
• Liner — The tube the wire runs through inside the torch. It fills with swarf and shavings over time and produces feed that stutters or birdnests at the drive rolls. Blowing it out is maintenance; a kinked one is a replacement.
• Drive rolls and tension — Wrong groove for the wire, or tension set too high, flattens the wire and makes everything downstream worse. The usual symptom is feed that works until the torch is bent round a corner.
• Electrodes and their storage — Stick electrodes and tungsten both degrade in storage — coatings absorb moisture, which affects the arc and the weld. Keeping them dry and sealed is most of their maintenance.

• The return clamp is half the circuit — Clamping to paint, rust or a workbench rather than to clean metal on the workpiece is the single most under-diagnosed fault in home welding. A hot clamp or a hot lead is telling you the same thing.
• Leads and plugs — Check for heat, discolouration and stiffness. Heat anywhere other than the arc is resistance where there should be none, and resistance in a welding circuit becomes a fire risk rather than merely a poor weld.
• Gas: bottle, regulator, hose, and draught — Porosity is nearly always gas. Work along the path — bottle contents, regulator setting, hose condition, connections — and then look at the room, because a shielding gas is defeated by a draught from an open door as effectively as by a leak.
• Cooling and duty cycle — Vents blocked with grinding dust is how a machine overheats, and a machine that cuts out mid-weld and comes back a few minutes later is usually doing exactly what it should. Blowing out the case periodically, with the machine unplugged, is the whole of it.
• The helmet — Not the welder, and easy to forget. A scratched or spattered outer lens costs visibility, which costs weld quality, and auto-darkening helmets have batteries and solar cells that eventually stop working — usually noticed the hard way.

Before a session: look at the tip and shroud, check the clamp is going onto clean metal, check the gas is on and the bottle has something in it. After a session: clear spatter, turn the gas off at the bottle, and coil the leads rather than dropping them. Periodically: blow out the liner and the case, and look at the leads properly.

That routine removes most of the faults above before they appear, which is the point of it. The alternative is diagnosing a machine in the middle of a job, which is when everything looks like a broken welder.