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Aluminum angle is easy to distort and unforgiving of dirty surfaces. A suitable TIG welder needs stable AC output, adjustable cleaning action and enough amperage for the thicker leg of the angle. For occasional brackets, a basic AC/DC machine can be adequate; for repeated work or thick sections, duty cycle and input power matter as much as the headline amperage.

What to look for in a TIG welder

For aluminum, the essential feature is AC TIG. The alternating current helps break up the aluminum oxide layer while the arc melts the base metal. A DC-only TIG welder cannot do this job properly with conventional TIG technique.

For angle sections around 1/8 inch thick, a machine with roughly 150–200 amps of AC output is a practical starting point. For 1/4-inch material or long welds, look at machines rated around 200–250 amps, and check the duty cycle at the amperage you will actually use. A rating of 200 amps at a 20% duty cycle means only two minutes of welding in a ten-minute period at that output.

Useful controls include AC balance, AC frequency and a foot pedal or other reliable amperage control. Balance lets you trade oxide-cleaning action against penetration; frequency affects arc focus and feel. These controls help, but they cannot compensate for oily, oxidized metal or poor fit-up. On a budget machine, simpler controls may be fine for short, straightforward repairs.

Compare the main machine options

For a first machine, compare 200-amp AC/DC TIG welders by duty cycle, input voltage, included torch and pedal, and warranty support. Do not assume a machine can deliver its maximum output from an ordinary 120-volt outlet. Many higher-output welders need 240 volts, and some offer reduced output on 120 volts.

Set up the angle before striking an arc

Clean both pieces mechanically and chemically. Remove paint, oil and oxide, then wipe with a clean solvent suitable for the material and let it evaporate. Use a stainless-steel brush reserved for aluminum; a brush that has touched steel can embed contamination. A dirty joint can cause black soot, porosity and an unstable puddle even when the welder settings seem right.

Fit the angle tightly. Gaps force you to add more filler and heat, raising the risk of burn-through and distortion. Clamp the work, tack it at several points, and check that the legs remain square before welding the full seam. For thin angle, short welds separated by cooling time often produce a straighter result than one continuous pass.

Use pure argon for most aluminum TIG work. A starting flow around 15–20 cubic feet per hour is common with a standard cup, though drafts, cup size and gas-lens setup change the requirement. Excessive flow does not improve shielding; turbulence can pull air into the arc. Choose filler based on the alloy and service conditions. When the alloy is unknown, avoid treating one filler rod as universally suitable; identify the base metal if the joint is structural or safety-critical.

Torch, electrode and filler choices

A machine that includes a torch and pedal may be the lower-cost route, but inspect the torch rating and connector compatibility before buying. A torch that is undersized for sustained current can overheat. A foot pedal gives fine control as the joint heats up, which is useful on angle corners where the puddle can suddenly run away. A torch switch is cheaper and less bulky, but offers less direct control during the weld.

For a general-purpose setup, compare compatible TIG torches and foot pedals against the machine’s connector and control specifications rather than buying by appearance. Use the electrode diameter recommended by the welder manual and sharpen it for a focused arc. Aluminum TIG commonly uses a balled or slightly rounded tungsten tip, depending on the electrode type and machine settings; follow the manufacturer’s guidance instead of allowing a large, unstable ball to form.

Common failures and how to avoid them

Black deposits or pinholes: Check cleaning, gas coverage, leaks and drafts before changing amperage. Keep the filler rod inside the gas shield and avoid touching it to the tungsten.

Burn-through at the corner: Reduce heat, move steadily, use a pedal to taper current, or weld in shorter sections. Thin angle can lose its edge quickly once the corner becomes molten.

A wide, wandering arc: Check tungsten preparation, electrode stick-out and gas setup. A higher AC frequency can tighten the arc on machines that offer the adjustment, but it is not a substitute for a clean electrode and sound technique.

Weak weld despite a neat bead: A shiny surface does not prove fusion. Watch for the puddle to wet both legs of the angle, and test settings on matching scrap first. If the work is load-bearing, use a qualified welding procedure or have the joint assessed; appearance alone is not a reliable strength test.

Which welder makes sense?

For occasional 1/8-inch aluminum angle, an entry-level AC/DC inverter with a usable pedal and adequate household or shop power can be enough. Pay extra for a midrange machine if you weld frequently, need longer runs, or want better control over AC balance and frequency. A multiprocess unit is worthwhile when its other processes will actually be used; MIG capability does not make its TIG function better.

Before ordering, confirm the machine’s AC output range, duty cycle at your working amperage, required circuit, torch and pedal compatibility, and local service options. Those details matter more than a long feature list when the job is a square, clean aluminum angle joint.