Level 3 · TIG: aluminum, stainless, and welds you meant to look like that

Everything below this level is about getting metal to stick together reliably. Level 3 is where the weld itself becomes part of the design. It is also where the honest answer to "should I?" is genuinely "it depends what you want to make" rather than "yes, eventually".

TIG is not an upgrade to MIG in the way MIG is an upgrade to flux-core. It is a different craft with different strengths, and a great many extremely competent home fabricators never own a TIG machine because nothing they build needs one.

What TIG actually is, and why it is harder

In MIG, the wire is both the electrode and the filler — it melts into the joint as it feeds, so one trigger controls everything. In TIG, the electrode is tungsten and it does not melt. It exists purely to make the arc. The filler is a separate rod you hold in your other hand and feed into the puddle manually, and the amperage comes from a foot pedal.

That separation is the whole point. Because heat and filler are independent, you can put exactly as much heat into a joint as it needs and exactly as much metal as it needs, which is what makes TIG work on 22-gauge stainless where a wire process would blow straight through.

It is also why it is hard. Three inputs at once, plus the discipline never to let the tungsten touch the puddle — which contaminates it and means stopping, grinding and starting again.

AC versus DC: the one specification to get right

If you read nothing else on this page, read this. DC TIG welds steel and stainless very well and cannot weld aluminum usefully. AC TIG welds aluminum.

The reason is oxide. Aluminum instantly grows an oxide skin that melts at roughly three times the temperature of the aluminum beneath it. On AC, the electrode-positive half of each cycle blasts that oxide apart — the cleaning action — while the electrode-negative half does the heating. That alternation is exactly what aluminum needs, and it is why AC/DC machines cost more than DC-only ones.

So the buying question at Level 3 is not really which machine. It is: will you ever weld aluminum? If yes, buy AC/DC and accept the price. If genuinely never, a DC machine will save you real money and weld steel and stainless beautifully. AC versus DC TIG works through it properly, and TIG welders for aluminum covers the machines if the answer is yes.

The controls that actually change the weld

Budget AC/DC machines advertise a long list of adjustable parameters. Three of them earn their place.

AC balance sets how much of each cycle is spent cleaning versus penetrating. More cleaning for dirty or anodized aluminum; more penetration for thick, clean material. This is the control you will actually reach for.

AC frequency tightens or widens the arc cone. Higher frequency gives a narrower, more focused arc, which matters on fillets and tight corners.

Pulse alternates between a high and low current many times per second. On thin material it lets you put in enough peak heat to fuse without accumulating enough average heat to burn through.

Everything else on the panel is refinement. A machine with fewer controls and better defaults is often the better first TIG machine, which is the real case for the name-brand options over the parameter-rich budget ones.

Everything that is not the machine

TIG has the longest supporting-cost tail of any level here. You need 100% argon, a regulator and a bottle. You need tungsten, and a dedicated grinding wheel for it, because sharing a wheel with steel contaminates the tip and ruins the arc. You need filler rod in the right alloy for the metal, which means stocking more than one. And you need a helmet that triggers reliably at low amperage — a budget lens that fires fine on a 100-amp MIG arc can fail to darken on a 15-amp TIG arc, which is exactly the situation you do not want to discover experimentally. See auto-darkening helmets for what to check.

On power: a 200-amp class machine on a 240-volt circuit is the normal home setup, and the circuit comes first. What size breaker a welder needs is the page to read before you order anything, and circuit work belongs to a licensed electrician.

The signal that you have outgrown Level 3

This one is not about welding at all. It arrives when you notice that the slow, annoying part of every project is no longer joining metal but cutting it — when you are spending forty minutes with an angle grinder to produce a shape you could draw in thirty seconds. That is Level 4 · Plasma, and it is the only rung on this ladder that is about shaping rather than joining.