What's inside
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Expanded steel is a tough test for a plasma cutter. The raised strands and open gaps interrupt the torch’s path, so the arc can go out just as you reach a crossbar. A contact-start cutter can handle the job, but a pilot-arc machine usually makes it easier to keep cutting through a grille without stopping to restart.
How expanded steel changes the cut
Unlike solid sheet, expanded steel alternates between metal strands and empty openings. The torch may cut a strand, cross a gap, then meet another strand at a different angle. That can break the cutting arc, especially if the torch is moving quickly or the work has paint, rust, oil, or mill scale.
Strand thickness matters more than the overall sheet size. A light expanded-metal panel may have strands around 1/16 inch thick, while heavier grating can have strands several times thicker. Check the thickest strand and choose a cutter with capacity for it; do not assume the open area makes the material equivalent to thin sheet. Leave room above the machine’s advertised maximum thickness, which is often a severance rating rather than a comfortable production-cut rating.
Contact-start and pilot-arc, explained
A contact-start torch needs its electrode or nozzle to touch the workpiece to initiate the arc. Some cutters require a drag tip to stay in contact while cutting; others strike an arc on contact and then maintain it as the torch moves. When the torch crosses an opening, the arc can extinguish. You may need to stop, reposition, and restart on the next strand.
A pilot-arc cutter first creates a small arc inside the torch. That arc can stay lit across a gap until it reaches conductive metal, where it transfers to the workpiece and cuts. This is useful on expanded steel, perforated sheet, rusty material, and painted or coated surfaces. It does not mean the machine can cut through empty space: the pilot arc has a limited reach, and a long gap or slow travel can still cause a stall.
On some machines, the pilot arc runs continuously while the trigger is held; on others it is timed or controlled electronically. Check the manual for the duty cycle and pilot-arc operating limits. A pilot arc that is convenient for repeated short cuts can consume consumables faster if left running unnecessarily.
Which type fits the job?
| Feature | Contact-start | Pilot-arc |
|---|---|---|
| Expanded steel with frequent gaps | May go out at openings; expect restarts | Usually bridges short gaps more reliably |
| Clean, solid sheet | Often works well | Works well, with extra capability you may not need |
| Dirty, rusty, or coated work | Arc starts can be less consistent | Generally more forgiving, but still needs a sound electrical connection |
| Cost and complexity | Typically the lower-cost, simpler choice | Usually costs more; controls and torch design may be more complex |
| Consumables | Wear depends on starts, contact, and cutting conditions | Pilot-arc use can add electrode and nozzle wear, especially with excessive trigger time |
For occasional cuts in clean expanded steel, a properly rated contact-start cutter is a reasonable budget choice. Work slowly enough to maintain the arc, use a drag tip if the torch is designed for one, and expect to restart at some openings. If you are making many cuts, working with rusty or painted panels, or need uninterrupted cuts around a shape, a pilot-arc unit is usually worth considering. Compare pilot-arc plasma cutters by their rated output, duty cycle, and torch consumables—not just the largest thickness number in the listing.
Match the cutter to the material and power
Check the cutter’s output amperage, rated cutting thickness, and duty cycle at the voltage you actually have. A machine advertised for 1/2-inch metal may be able to sever it, but that does not promise a clean edge at a useful speed. For repeated work near the machine’s upper limit, choose more capacity than the minimum. On thinner expanded steel, a lower amperage setting can reduce kerf width and distortion, but too little power or too much travel speed can make the arc drop out.
Air supply is just as important. Follow the manufacturer’s pressure and flow requirements while air is flowing; a static pressure reading at the compressor can be misleading. Water, oil, or low airflow can cause erratic cutting and rapidly damage consumables. Drain the compressor, use the specified filtration, and avoid undersized hoses or fittings. For home use, compare 120-volt pilot-arc cutters only after confirming that the machine’s duty cycle and output suit your strand thickness. Many higher-output cutters need 240 volts.
Cutting technique and common problems
Support the expanded panel securely, but keep it electrically connected to the work clamp. Attach the clamp to clean metal on the workpiece, not to a painted frame or a separate piece that may not conduct. Keep the torch perpendicular unless the cut requires an angle, and move at a steady pace. On a pilot-arc cutter, do not pause over one strand: dwelling enlarges the cut, heats the surrounding metal, and wears the consumables.
If the arc repeatedly stops at openings, slow down slightly and make sure the machine is not being asked to bridge gaps beyond its pilot-arc capability. If it sputters on solid strands, inspect the air supply, ground connection, and torch consumables. A worn nozzle produces a wider, less controlled kerf; a damaged electrode or loose torch connection can cause unstable starts. Replace parts when their condition warrants it, rather than trying to compensate by raising amperage.
For intricate shapes or thin mesh, use a guide or template and test the setting on scrap first. The open pattern can make it easy to lose your line, and the cut edge may have sharp burrs. Wear a properly rated welding helmet, gloves, and clothing, and control sparks and hot droplets: openings let them pass through and can ignite material below the work. If expanded steel is galvanized or coated, account for hazardous fumes with suitable ventilation and follow the coating manufacturer’s safety guidance.
A practical buying decision
Choose contact-start when the work is occasional, the material is clean, and saving money matters more than uninterrupted cutting. Choose pilot-arc when gap crossings, surface condition, or production pace make repeated restarts a nuisance. Before buying either type, verify that its torch and consumables are available, its air requirements match your compressor, and its input power matches your shop. Those details determine whether the cutter works reliably more than a headline thickness claim does.