What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
Plasma cutters make quick work of aluminum angle, but the right machine depends on the angle’s thickness, the available power supply and how clean the edges need to be. Aluminum conducts heat quickly, and its bright surface can make the arc less forgiving than a cut in mild steel. For occasional brackets, a compact 30-amp cutter may be enough. For frequent work on thick angle, a 40- to 50-amp machine with a suitable air supply is a better fit.
Choose by aluminum thickness
Check the thickness of each leg of the angle, not the outside dimension. A 1/8-inch-thick angle is a different job from 1/4-inch stock, even if both pieces are 2 inches wide. Cut ratings are usually stated for mild steel; aluminum may cut more slowly or require more amperage because it pulls heat away from the arc.
For occasional cuts in aluminum up to about 1/8 inch, a 30-amp cutter can be a reasonable, lower-cost choice. At roughly 1/4 inch, look at 40 to 50 amps and favor a machine with a clear, realistic rated-cut specification. If you plan to cut thicker stock regularly, compare the manufacturer’s rated capacity rather than relying on its maximum severance rating. Severance means the machine can part the material, not necessarily make a clean, square edge at a useful speed.
Compare cutter types
| Type | Good fit | Trade-off |
|---|---|---|
| Compact 30-amp, 120V | Thin angle and occasional repair work | Limited speed and thickness capacity; may trip a shared 15-amp circuit |
| 40- to 50-amp, 240V | Regular shop cutting and thicker angle | Needs a suitable 240V circuit and usually costs more |
| Air-compressor plasma cutter | Buyers who already own a capable compressor | Cut quality depends on dry, steady air at the cutter’s required flow and pressure |
| Built-in-compressor cutter | Portable work where external air is inconvenient | Often trades cutting capacity or duty cycle for portability |
What to look for when buying
For light-duty work, compare 30-amp 120V plasma cutters. They can be convenient for a home garage, but verify the outlet requirements and the manual’s recommended breaker size. Running a cutter through an undersized extension cord can cause voltage drop, poor cutting and nuisance trips. A dedicated circuit is preferable; do not assume a standard garage outlet can deliver the machine’s full output.
If you expect to cut angle stock often, shop among 40-amp or higher 240V plasma cutters. Check input voltage, duty cycle and consumable availability before buying. Duty cycle describes how long the unit can cut within a 10-minute period at a stated output. A machine rated for a 40% duty cycle at its top setting can cut for four minutes, then needs six minutes to cool under the test conditions. That may be fine for a few brackets, but frustrating when making a batch of parts.
Air quality matters as much as nominal pressure. A compressor must supply the cutter’s specified airflow continuously, not just reach a pressure number on its gauge. Water or oil in the air can damage consumables and make the arc sputter. Use the cutter’s recommended filtration, drain the compressor tank and check the air supply before blaming the torch. If you need to work away from a compressor, compare plasma cutters with built-in air compressors, while checking their aluminum capacity carefully.
Cutting aluminum angle cleanly
Mark the cut and clamp the angle so it cannot shift. Keep the work lead connected to clean, bare metal on the workpiece or a solidly connected table; paint, oxide and a loose clamp can interrupt the arc. Aluminum’s oxide layer melts at a much higher temperature than the metal underneath, so a hesitant start can leave an uneven kerf. Remove heavy paint, grease and contamination around the cut, and follow the cutter maker’s guidance for pilot-arc starting and torch distance.
Move at a steady pace. Going too slowly widens the kerf, heats the angle and leaves heavy dross underneath. Going too fast can make the arc fail to pierce the full thickness, leaving the back of the cut attached or ragged. On angle, each leg can affect torch access: position the work so you can keep the torch square to the surface and maintain a consistent path across the corner. Make a test cut on a scrap piece of the same thickness before cutting a finished part.
Plasma cutting throws hot metal and intense light. Wear a correctly rated welding helmet, gloves and nonflammable clothing, and keep flammable material away from the cutting area. Aluminum does not produce the same visible color cues as some other metals, and freshly cut edges can remain hot. Let the part cool before handling it, then deburr sharp edges with a file or grinder.
Common problems and sensible compromises
If the cut bevels heavily, first check torch angle, speed, consumable condition and air supply. A worn nozzle can produce a wandering arc; replacing consumables is often cheaper than buying a more powerful cutter. If the machine cannot keep up on a long cut, check its duty cycle and circuit before upgrading. A cheaper 120V unit is still a sensible buy for short cuts in thin angle, especially if occasional cleanup with a grinder is acceptable. For repeated cuts, thicker legs or less rework, the extra capacity and 240V supply of a shop-class machine are usually worth considering.