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Why pilot arc helps with expanded metal
Expanded metal is a tough test for a plasma cutter. The strands are narrow, and the openings break the arc’s path. A basic torch may cut one strand, lose the arc over a gap, then need to be retriggered. A pilot-arc torch keeps a small arc going before it transfers to the work, making it easier to restart as you cross openings.
Pilot arc is useful, not magic. It does not turn a low-amperage cutter into a fast production machine, and it will not compensate for poor air, a worn consumable, or an undersized power supply. For occasional repair work, a cheaper cutter without pilot arc can be adequate if you can clamp the work securely and accept slower progress.
What to look for when buying
For expanded metal, prioritize a pilot arc that can cut expanded or perforated material without losing its start, a drag-capable torch, and a rated cutting thickness that leaves some margin over your usual stock. A 40-amp machine may handle thin sheet and light expanded metal, while a 50- to 60-amp unit is a more flexible choice for thicker strands and longer cuts. Check the manufacturer’s rated cut, not just its advertised maximum severance thickness: severance is a rough cut made by forcing through material, not a good everyday target.
Duty cycle matters if you are cutting many panels. A rating of 60% at 40 amps means about six minutes of cutting in a ten-minute period under the stated conditions, followed by cooling time. Input power matters too: confirm whether the machine needs 120 V, 240 V, or both, and check the circuit and plug requirements. A dual-voltage cutter is convenient, but it generally cannot deliver its full output from a 120 V outlet.
Air supply is a common weak point. Compare the cutter’s required pressure and air consumption with your compressor’s delivered airflow at pressure; tank size alone is not enough. Water, oil, or pressure drop can cause wandering cuts and short consumable life. A filter or water separator may be needed, especially with a small compressor running continuously.
Cutter types compared
| Type | Best fit | Trade-off |
|---|---|---|
| Entry-level, no pilot arc | Occasional cuts in clean, solid sheet | Can extinguish across openings; more stops and restarts on expanded metal |
| 40-amp pilot-arc cutter | Thin expanded metal, brackets, and home-shop repair | Less speed and thickness margin on heavy strands; may require a 240 V supply for best performance |
| 50- to 60-amp pilot-arc cutter | Frequent work, thicker material, and longer cuts | Costs more and needs adequate input power and air delivery |
For a general-purpose home shop, compare 40-amp pilot-arc plasma cutters if your work is mostly light stock. If you regularly cut thicker material or larger panels, look at 50-amp pilot-arc cutters and verify their input and air requirements before buying.
How to cut expanded metal cleanly
First secure the sheet flat and support it close to the cut. Expanded metal flexes and vibrates; movement can pull the torch off line or make the strands snag. Keep the work lead connected to clean bare metal on the piece, not to paint, rust, or a loose fixture. Wear a suitable welding helmet with a plasma-cutting shade, gloves, and protective clothing. Sparks can travel through the openings, so clear combustibles below and behind the work.
Use the manufacturer’s recommended settings for the material thickness and torch. Hold the torch at the specified height, or rest the drag shield on the work if the torch is designed for drag cutting. Move at a steady pace: too slow makes a wide, rough cut and can increase dross; too fast leaves uncut bridges or causes the arc to lag behind the torch. On expanded metal, steady travel is more reliable than stopping at each strand.
Make a short test cut on a scrap piece of the same material. Adjust travel speed and amperage within the cutter’s guidance, then check the underside for consistent separation and excess dross. If the arc stops at every opening, confirm that pilot arc is enabled and that the torch is suitable for expanded metal. Also inspect the electrode and nozzle for wear, check air pressure while flowing, and clean the work lead connection.
Common problems and the cheaper-option question
A pilot arc that starts but will not transfer often points to a poor work connection, a bad consumable, or a torch held too far from the metal. A cut that sputters can indicate wet or contaminated air, low pressure under load, or a worn nozzle. If the machine trips a breaker, check its input-voltage and current requirements against the circuit; an extension cord that is too long or too light can also cause voltage drop.
You do not need pilot arc just because the material is expanded. If you cut a small amount of thin mesh once in a while, a non-pilot-arc cutter can be the sensible budget choice when you can start on an edge and make short, controlled cuts. But for repeated cuts across open sections, pilot arc reduces interruptions and makes the work less frustrating. Spend extra on a higher-amperage machine only if material thickness, cut length, or workload justifies it; buying more output will not fix poor air or an unsuitable electrical circuit.