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Choosing a mobile plasma cutter
A plasma cutter can save time on a repair truck when the job means cutting dirty, painted or rusted steel that would be awkward to saw or grind. The trade-off is that a cutter needs a suitable power source, compressed air and consumables. Before buying, check the truck’s generator capacity, the cutter’s input requirements and the thickness you actually cut—not just the advertised maximum.
For general mobile repair, a 30–45 amp machine is often a useful range. It can handle many sheet-metal and equipment repairs without the size and power demands of a larger cutter. If your work regularly involves thick plate, look at 50–60 amp units, but confirm that the generator can supply the required input current at the correct voltage. A cutter that trips the generator or struggles to maintain an arc is no bargain on site.
Match the cutter to the power supply
Many portable cutters run on 120 volts, 240 volts or both. A dual-voltage unit gives more flexibility: use a regular outlet for lighter work, then connect to 240 volts when more cutting capacity is needed. But “dual voltage” does not mean a small generator can run the machine at full output. Check the manual’s input amperage and generator recommendation, and allow headroom for starting loads and other equipment running at the same time.
If the truck has only a modest 120-volt generator, a smaller cutter may be the sensible choice. It may cut more slowly and need a lower duty cycle, but it is better than carrying a high-output unit that cannot reach its rated performance. On a 240-volt setup, verify the plug, breaker and extension-cord requirements; an undersized or overly long cord can cause voltage drop and poor arc performance.
Air supply and duty cycle
Most air plasma cutters need clean, dry compressed air. Compare the cutter’s required pressure and air consumption with the compressor’s delivered airflow (CFM) at the specified pressure. Tank size alone is not enough: a small compressor may start the job, then fall behind during repeated cuts. Moisture and oil can shorten consumable life, cause an unstable arc or produce rough cuts. Use the filtration and water separation the manufacturer calls for, and drain the tank regularly.
Duty cycle tells you how long a cutter can operate within a 10-minute period at a stated output. For example, a 40% duty cycle at a given amperage means about four minutes of arc-on time followed by six minutes of cooling under the stated test conditions. Repair work often has natural pauses for measuring and repositioning, so a lower duty cycle can be acceptable. Continuous production cutting is different: prioritize a higher duty cycle at the amperage you will actually use.
Mobile cutter comparison
| Type | Best fit | Main compromise |
|---|---|---|
| Compact 120V, roughly 20–30A | Light repairs, thin sheet and occasional cuts | Slower on thicker material; limited output on a small supply |
| Dual-voltage, roughly 30–45A | Mixed repair work with access to 120V and 240V | Full output may require a substantial generator or 240V circuit |
| Higher-output, roughly 50–60A | Frequent cuts in thicker steel and heavier field work | Greater power, air and consumable demands; more to carry |
These are broad categories, not guaranteed cut ratings. Manufacturers may list a maximum severance thickness that is possible only at a slow pace with a rough edge. For cleaner work, use the machine’s recommended cutting thickness and test on the same material and power setup you expect in the field.
Features that help on a truck
Look for a clear amperage control, a torch and work lead long enough to reach around equipment, and consumables that are easy to find locally. A pilot arc can help start cuts on expanded metal or surfaces that are not perfectly clean; it does not eliminate the need for proper grounding or good technique. Some torches require contact with the work to start, which can be less convenient on coated or uneven surfaces.
Weight and case shape matter when the cutter must be lifted out of a truck repeatedly. Check whether the package includes a regulator, air filter, torch consumables and the correct power cord; bundle contents vary. Keep spare electrodes and nozzles in a clean container. A worn nozzle can widen the kerf, make the arc wander and leave a bevel, while a damaged electrode can cause unreliable starts.
For a general-purpose truck setup, compare dual-voltage plasma cutters around 30 amps. If the truck is limited to ordinary outlets, portable 120V plasma cutters may be the more practical fit, provided their output matches your material.
Cut quality and field safety
Plasma cutting leaves a kerf and can produce dross, especially if you move too slowly, use too much amperage for thin stock or cut with a worn consumable. Moving too fast can break the arc or leave an incomplete cut. Make a test cut, adjust travel speed and stand-off according to the torch instructions, and clamp the work securely. A plasma cutter is not a substitute for a saw when a square, repeatable edge is critical.
On a repair truck, sparks can reach fuel, hydraulic hoses, wiring, tires or dry vegetation. Move the work where possible, shield nearby materials and keep a suitable fire extinguisher close. Wear the specified eye protection, gloves and flame-resistant clothing; plasma cutting also creates fumes, so provide ventilation and use respiratory protection when the material or conditions require it. Never cut a tank or closed container unless it has been properly cleaned and made safe.
A smaller, less expensive cutter is fine for occasional thin-metal work if its power and air needs suit the truck. Pay more for output and duty cycle only when repeated cuts or thicker stock justify them. Before ordering, confirm the generator, compressor, voltage, cord and consumable supply as a complete system—not as separate specifications on a product page.