Yes, you can cut steel and other metals with a plasma cutter by setting the right amperage, standoff, speed, and following strict safety steps.
New to plasma? This guide walks you from power-on to a clean, straight kerf. You’ll learn setup, safe habits, torch movement, and fixes for rough edges. The aim is simple: repeatable cuts with less grinding. Below you’ll see how to cut with a plasma cutter safely and cleanly, with steps you can use today.
Plasma Cutting Basics In Plain Terms
A plasma cutter pushes compressed air or gas through a small nozzle, adds DC power, and turns the gas into a hot, conductive jet. That jet melts metal and blows the molten pool away, leaving a narrow groove called a kerf. Handheld systems shine on sheet and plate; CNC tables add speed and patterns for repeat parts.
Setup Checklist And Starting Specs
Get your station ready before you squeeze the trigger. Tidy cables. Clear the spark landing zone. Confirm PPE, ventilation, and a watch for fires. Then dial in settings by plate thickness.
| Step | Why It Matters | Quick Check |
|---|---|---|
| Power & Ground Clamp | Completes the circuit so the arc stays stable. | Clamp on clean metal near the cut line. |
| Air Supply | Dry, steady air keeps the arc smooth and parts alive. | 90–120 psi at the machine; drain the water trap. |
| Amperage | Too low won’t pierce; too high widens kerf and eats tips. | Use plate charts; start near 40 A on 3 mm. |
| Pierce Height | Saves the tip from back-spatter during start. | About 1.5–2× cut height for hand work. |
| Cut Height (Standoff) | Right distance gives a narrow, square edge. | ≈ 1.5–2 mm with drag shield touching work. |
| Speed | Controls bevel and dross. Slow travel fattens the kerf. | Sparks should trail 10–20° behind the cut. |
| Leads & Path | Prevents snags and shaky motion. | Dry-run the line before striking an arc. |
Safety Gear And Safe Habits
Plasma arcs are bright and loud, and they throw hot sparks. Wear eye protection with the right shade, hearing protection, leather gloves, cotton sleeves, and boots. Keep a respirator ready. Use screens to shield bystanders. Vent the area or use local fume extraction. Store rags, paint, and gas far from the spark stream and under the table.
See the OSHA welding and cutting hazards for eye, burn, fume, and shock risks, plus practical controls. For machine setup and technique, Hypertherm’s tutorial on how to plasma cut gives clear starting points that match the steps below.
How To Cut With A Plasma Cutter: Setup To First Cut
1) Prepare Work And Layout
Clean the line with a flap disc. Wipe oil. Mark with a soapstone or scribe. Prop the plate so the kerf can blow through without splashing back.
2) Connect Power, Ground, And Air
Lock power off, hook the ground clamp to bright metal, then open the air valve. Confirm pressure while air is flowing. Dry air beats wet air every time.
3) Set Amps And Test On Scrap
Pick amperage for thickness. Thin sheet runs at 20–30 A. Six millimeters sits near 40–45 A. Thicker plate needs more. Do a one-inch test cut on scrap. Check the edge and dross; adjust a few amps and try again.
4) Set Standoff And Torch Angle
Drag shield resting on the plate keeps distance steady. Hold the torch close to vertical for a square edge. Tilt 10–15° away when starting a pierce to deflect splash.
5) Pierce Smart
Start off the finished line when you can. For a pierce in the middle, raise to pierce height, pull the trigger, let the arc break through, then lower to cut height before moving. Count a beat after full penetration on thicker plate to avoid blowback.
6) Move At A Steady Pace
Watch the spark stream. It should exit under the plate trailing slightly backward. If sparks shoot straight down, speed up. If they come back at you, speed is low or amps are low. Keep wrists locked and move from your shoulders for straight lines.
7) Finish The Cut
As you reach the end, keep moving and don’t pause in the corner. Overrun the line by a small step to clear the last web. Release the trigger and let post-flow cool the tip.
Close Variant: Cutting With A Plasma Cutter Safely And Cleanly
This section reinforces safety and edge quality while keeping the pace brisk. It ties to shop habits that stop dross, bevel, and tip damage.
Eye And Skin Protection
Use a shade that blocks arc glare while letting you see the line. Wear a full face shield or a welding helmet with rated lenses. Cover skin to avoid UV flash.
Respiratory And Ventilation
Plasma work makes fumes and fine dust. Use local extraction indoors. A P100 half mask helps during hand cuts, especially on galvanized or stainless.
Hearing And Housekeeping
Arcs get loud. Add ear protection. Keep hose runs neat so your feet don’t snag mid-cut.
Consumables, Duty Cycle, And Air Quality
Nozzle, electrode, swirl ring, and shield take a beating. Inspect them often. A worn or oval nozzle widens kerf and tilts the arc. Replace parts as a set when the center pit on the electrode grows deep or the orifice looks rough. Keep spare sets ready so you don’t push worn parts and wreck a clean job.
Duty cycle keeps the machine honest. If the spec says 50% at 40 A, that means five minutes cutting in a ten-minute window at that output. Work in batches and let the unit cool. Hot internals shorten part life and invite thermal trips.
Air quality matters more than most people think. Water in the line gouges tips and makes a frothy kerf. Add a dryer or desiccant tube. Bleed the tank daily. Use longer post-flow after harder cuts to chill parts.
Torch Motion For Straight, Curves, And Holes
Straight Cuts
Use a guide. A scrap angle or clamp-on ruler works fine. Keep the shield lightly touching and glide along the guide in one smooth pass.
Inside Corners
Ease into the corner with a tiny arc. Roll the wrist, then swing out cleanly. Pauses pile dross, so keep the torch moving.
Curves And Circles
Plant your elbow and pivot. For repeat circles, use a circle guide kit. For one-offs, scribe and follow the line in a single sweep.
Holes And Slots
Pierce high, lower to cut height, then move in a small circle until through. Add a lead-in to avoid a divot on the finished edge.
Reading The Cut: What Good Looks Like
A good cut shows a narrow kerf, even drag lines, and a near-square edge. The top has a small rounded edge, not a ragged lip. The bottom drops flakes or a light beard that snaps off with a tap.
Symptoms And Tweaks
- Low speed: Big bevel and globs on the bottom. Increase travel speed.
- High speed: Kerf narrows and arc lags. Slow a touch or add amps.
- Too low amps: Arc dances and won’t pierce cleanly. Bump amps.
- Too high amps: Wide kerf and quick wear. Roll amperage back.
- Standoff too high: Tapered edge. Drop the torch closer.
- Wet air: Spatter and a pitted tip. Dry the line and swap filters.
Starter Settings By Thickness
These ballpark settings help you land close on common jobs. Always test on scrap and refine.
- 1–2 mm sheet: 20–25 A, drag shield on the plate, brisk speed. Keep arcs short to avoid warping.
- 3–4 mm plate: 30–35 A, steady pace. Watch for a slight trail on sparks and even drag lines.
- 6 mm plate: 40–45 A, small tilt at pierce, then upright. Overrun the edge to finish clean.
- 8–10 mm plate: 50–60 A (if rated), slower travel. Add more post-flow and let the torch cool between runs.
Material-Specific Notes
Mild Steel
The easiest start. Cuts clean with shop air. If edges show heavy oxide, grind light scale along the line for a sharper start.
Stainless Steel
Edges stay bright but can drag dross when speed is low. Use a touch more travel speed. Vent well and wear a P100 on hand jobs.
Aluminum
Thermal conductivity pulls heat fast. Use the upper end of the amperage range and keep the torch moving. Expect a wider kerf than steel.
Common Mistakes And How To Avoid Them
Most bad cuts trace back to rush and guesswork. Slow down setup. Test on scrap. Keep spare consumables in reach. Plan the path so you never backtrack across fresh sparks. When the job matters, clamp a guide so the line stays straight end to end.
| Fault | Likely Cause | Fast Fix |
|---|---|---|
| Heavy Dross | Low speed or low amps. | Increase speed or amperage; hold cut height steady. |
| Top Spatter | Piercing at cut height. | Pierce high, then drop to cut height before moving. |
| Beveled Edge | High standoff or worn nozzle. | Lower standoff; change consumables. |
| Arc Out | Poor ground or wet air. | Clean the clamp spot; dry air and check pressure. |
| Wide Kerf | Amps too high. | Reduce amperage until drag lines look even. |
| Ragged Pierce | Moved before through-pierce. | Wait for full blow-through, then move. |
| Short Tip Life | Dirty air or long arcs. | Filter air; keep the shield in light contact. |
Cutting Thick Plate With Small Machines
Many 120-V units rate out near 6–10 mm for clean cuts. You can sever thicker stock, but the edge will be rough and slow. Pre-heat with a torch for a tough start, then let the plasma finish the line. Keep expectations grounded; pick a shop service for big jobs or deep bevels.
Bevels, Beads, And Edge Prep
Need a bevel for welding prep? Tilt the torch slightly and make a pass along the line, or switch to a guide that holds a fixed angle. Leave a small land for the root. A second pass can tune the angle once the first pass opens the edge.
Fixtures And Simple Guides
Magnets, clamps, and straightedges kill wobble. A circle guide makes round cuts repeatable. A plywood sled lets the torch glide over rough plate without bumping. For long lines, tack a thin strip as a fence and run the shield along it.
Edge Clean-Up And Post-Processing
Chip light dross with a chisel or snap it off with pliers. Use a flap disc to break the top edge. If paint is coming, wipe with solvent and scuff the face with a quick pass so the coating bites. For a tight fit-up on welds, dress the edge square and leave a small gap for penetration.
Straightness Tricks That Work
- Stand so your eyes track the line. Move your feet, not just your hands.
- Keep elbows close to your sides for steadier motion.
- Use two hands on the torch body when space allows.
- Practice short runs on scrap until the spark trail looks right.
Storage, Transport, And Care
Coil torch leads in wide loops. Keep the clamp jaws clean. Store nozzles and electrodes in small labeled bins. Drain the compressor daily and crack the filter bowl to dump water. Dust off the machine vents and keep the intake clear.
Checklist Before You Power Down
- Swap worn consumables so the next start is smooth.
- Bleed water from the filter and tank.
- Roll up leads and clear the floor.
- Log amps, speed, and standoff that gave the cleanest edge today.
Bringing It All Together
Now you know how to cut with a plasma cutter from setup to finish. Use clean, dry air, the right standoff, and steady speed. Check the spark trail, read the edge, and tweak in small steps. With a guide and fresh parts, you’ll get crisp pieces with less cleanup and more pride in the work.