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How to use a plasma cutter for the first cut

Updated: October 2026

The carton is open, the compressor is in the corner, and there is no helmet in the box. You want the first cut on mild steel to be a line you chose. This is how to use a plasma cutter of the kind in this amazon.co.uk set: an inverter, a torch and an earth clamp, with air you supply. Air, a bare earth, a welding filter and a low current on a practice strip come before the real part. The [Stahlwerk plasma cutter comparison](/hub/cutting-tools/stahlwerk-plasma-cutter) is the model table if you have not bought yet. A qualifying purchase can earn us a commission at no extra cost to you. No shade number is printed, so none is given here.

The carton is open, the compressor is in the corner, and there is no helmet in the box. You want the first cut on mild steel to be a line you chose.

Our top picks

Reboot Reboot CUT60

Best overall

Reboot Reboot CUT60
8.3/10about £132.04
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Reboot Reboot 45 A

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Reboot Reboot 45 A
7.9/10about £103.67
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Reboot Reboot non-HF 40 A

Alternative

Reboot Reboot non-HF 40 A
6.9/10about £199.00
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On this page
  1. 1.What has to be true before the trigger
  2. 2.Air and the earth clamp
  3. 3.The first cut on mild steel
  4. 4.When the arc dies or the torch burns

What has to be true before the trigger

Three things are missing from every box in this set: a compressor, a welding filter, and any claim that the steel is ready. Unwind the extension if you are using one, and use a BS 1363 plug that is actually fitted. If the fuse has already opened, stop and read the plasma cutter 13 amp page before you try again. Do not fit a larger fuse. Stand so the sparks leave you, with arms and neck covered. The HSE page on cutting metals treats the fume as hazardous under COSHH. It has not been classed as carcinogenic. You still extract it or take the work outside. Do not cut galvanised steel in a closed garage. Zinc fume needs serious filtration, which a cracked door does not provide.

Air and the earth clamp

Set the pressure your listing prints, not a number from another brand. You may see 60 L/min at 0.4 MPa or about 90 PSI, 30–70 psi, a minimum of 6 bar, or 0.35–0.5 MPa. Drain the tank so the air is dry. Wet air eats the electrode and the nozzle. If the gauge will not hold the printed pressure, you are not ready to judge the cutter. Clamp the earth on bright metal, on the same piece, close to the cut. Paint and scale are why a touch-start arc will not establish. A SPRIGHOLLY CUT60 review says paint has to come off at the tip and at the clamp, and that a gap of about 0.5 mm is critical. If the steel is coated and you bought a touch start, clear a patch, or read the pilot arc plasma cutter page before you blame your hands. Post-flow is air after the arc, to cool the consumable. Do not copy a 2–15 second range onto a machine that does not print it.
Reboot Reboot CUT60

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Reboot Reboot CUT60
8.3/10about £132.04
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The first cut on mild steel

Start on a 2–3 mm mild-steel strip, not on the part, with the current low. One CUT60L PRO reviewer left a messy edge on 3 mm stainless at a default of 15 A and wanted more air and current. Change one setting at a time on scrap. Do not begin on 10 mm plate. 2T and 4T are trigger modes, not extra amps. 2T means you hold the trigger for the whole cut, which is the mode for learning a straight line. 4T latches until you press again. Use it only when a long cut is making your hand shake. Drag the tip only if that torch is a drag tip. Forcing a pilot tip into the plate is how nozzles die. Which model to buy is the best plasma cutter UK page, not this one.

When the arc dies or the torch burns

An arc that starts and then cuts in and out is a fault to diagnose once. Check air, then the consumable, then the earth. On the CUT60L PRO, one reviewer could not hold the pilot arc, managed 3 mm only some of the time, and could not cut 8 mm and 10 mm. A repeating dropout like that is a reason to reject the unit inside 30 days, under section 22 of the Consumer Rights Act 2015. Stop if the torch overheats, the ceramic splits, or anything burns. A SUSEMSE review reports a torch fire on 5 mm copper. A SPRIGHOLLY CUT60 review describes a ceramic that split after about half an hour. Those are failed parts, not practice. Hand structural work to a fabricator, and stop on coated metal if you have no extraction.

Common questions

How do I set up a plasma cutter?
Fit a BS 1363 plug, connect a compressor at the pressure your listing prints, clamp the earth on bright metal, put on a welding filter and cover your skin, then cut a thin practice strip at low current. None of these boxes includes a helmet or a compressor. Extract the fume before you treat the garage as optional ventilation.
What air pressure do I use?
The figure printed for your machine. In this set that may be 30–70 psi, about 90 PSI, 6 bar minimum, or 0.35–0.5 MPa, often with a flow around 60 L/min. Drain the tank first. If a small compressor falls off during a long cut, the cut will fail even though the inverter is fine.
What does 2T and 4T mean?
2T holds the arc only while your finger is on the trigger. 4T latches the arc until you press again. Neither mode adds cutting current. Learn the line in 2T. Use 4T when a long cut is making your hand tired, and you already know the travel speed.
What eye protection do I need?
A welding filter that meets a British or European standard for arc work, plus covered skin. These listings do not include a helmet, and they do not print a shade number. We will not invent one. Plasma fume is an HSE matter as well as an eye matter, so ventilate the cut.
Why did the arc start and then die?
Look at air, the nozzle and electrode, and the earth before you raise the current again. A CUT60L PRO review could not hold a pilot arc and could not cut 8 mm and 10 mm plate. If the dropout repeats on thin scrap with good air and a clean earth, stop and use the 30-day rejection route.

Related pages

Plasma cutter buying guide

Stahlwerk plasma cutter

Plasma cutter 13 amp: what the household fuse feeds

Best plasma cutter UK: the strongest UK review file

Pilot arc plasma cutter or touch start on rusty steel

Sources

Specialist sources for this comparison, checked in October 2026. Listing prices, stars and review texts come from amazon.co.uk.

  1. HSE, Cutting metals (retrieved 15.10.2026)
  2. HSE, Welding controls (retrieved 15.10.2026)
  3. GOV.UK, Electrical Equipment (Safety) Regulations 2016 (retrieved 15.10.2026)
  4. BSI, BS EN IEC 60974-1:2018+A1:2019 (retrieved 15.10.2026)
  5. Consumer Rights Act 2015, section 22 (retrieved 15.10.2026)
  6. R-Tech, how to use a plasma cutter (retrieved 15.10.2026)
  7. Stahlwerk UK, CUT 50 Pilot plasma cutter (retrieved 15.10.2026)
  8. amazon.co.uk listings for this comparison (retrieved 15.10.2026)