Oxy-LPG Cutting Set, Angle Grinder or Welding Machine: Which Steel-Cutting Tool to Rent in Bangkok

For steel thicker than 10 mm, rent the oxy-LPG gas cutting set: it cuts through in a single pass and needs no site power at all. Below 6 mm, an angle grinder finishes faster and costs half as much. And to be clear from the first line, a welding machine is not a cutting tool. It joins steel together, which is the opposite job.

The three rates are not equal. The oxy-LPG cutting set rents at 1,000 THB per day or 6,000 THB per week, while both the angle grinder and the welding machine rent at 500 THB per day or 3,000 THB per week. On those numbers the grinder looks half the price, but the comparison is not finished, because grinders and welders both need electricity.

The variable that wrecks most budgets is site power. If the site has no supply connected, neither the grinder nor the welder will run until you add a generator, which is another 500 THB per day. Once that is added the daily cost matches the gas cutting set exactly, even though the gas set cuts thick steel considerably faster.

The sections below take each tool in turn: what actually arrives when you rent it, the thickness each one handles, the site-power question, then a worked three-day job and the break-even point where a weekly rate beats a daily one.

Gas cutting separates steel with heat and a chemical reaction rather than by grinding it away. A mixed oxygen and LPG flame preheats the surface to roughly 850-900 degrees Celsius until it glows, then a high-pressure oxygen jet is released onto that spot. The oxygen reacts with the superheated steel and blows the resulting slag clear, opening a cut.

The oxygen and LPG cutting set comes with an oxygen cylinder, an LPG cylinder, a cutting torch with its nozzle, pressure gauges on both cylinders, and the twin red and green hoses running from the cylinders to the torch. Nothing in the set plugs in. That makes it the only one of these three tools that works on a site with no electricity connected.

One limit matters before you book: gas cutting only works on carbon steel. Structural sections, rebar, angle iron, box section, H-beam and I-beam all cut fine, but stainless steel and aluminium do not, because the oxides of those two metals melt at a higher temperature than the metal beneath them, so the reaction stops. Stainless work needs an angle grinder with the correct disc instead.

The thickness range where gas cutting performs well starts at roughly 6 mm and runs to 100 mm or beyond depending on the nozzle fitted. The advantage grows with thickness, because cutting time rises only modestly even as the section gets several times thicker. Below 6 mm it is the wrong choice, since the heat warps thin plate and leaves a ragged edge.

An angle grinder cuts by abrasion. The disc spins at high speed and wears the steel away progressively until the section parts. Far less heat builds up in the workpiece than with gas, so the material does not warp and the cut edge is noticeably cleaner. AR stocks two sizes, the 4-inch angle grinder and the 7-inch angle grinder, both at 500 THB per day.

The grinder's limit is cutting depth, set directly by the disc diameter. A 4-inch disc reaches roughly 25-30 mm, a 7-inch disc roughly 50-55 mm. Those figures are per side. Thicker material means flipping the work and cutting from the other face, which is possible but slow, and the two cut lines rarely meet perfectly.

The welding machine rents at 500 THB per day, the same as a grinder, but its job is to melt two pieces of steel together using an electrode, not to separate them. A skilled operator can gouge through steel with an electrode, but the resulting kerf is wide, rough, covered in slag, and burns through electrodes quickly. A job intended as cutting should not start with a welder.

The simple way to remember it: gas sets and grinders take steel apart, welders put steel together. Most steel strip-out work needs both sides of that, cutting the old structure out and joining the new one in, so renting a cutting tool and a welder on the same ticket is normal rather than redundant.

Thickness is the fastest deciding factor. For steel below 6 mm, such as thin-wall box section, sheet, or small angle iron, use the 4-inch grinder: the edge is clean, there is no preheat wait, and the workpiece will not warp. At that thickness the gas set is clearly the weaker choice.

Between 6 mm and 25 mm both tools are viable and other factors decide. With only a handful of cuts and mains power already on site, the 7-inch grinder gets it done for less. With several dozen cuts, the gas set is far quicker and avoids stopping repeatedly to change worn discs.

Above 25 mm, on H-beams, structural columns or heavy plate, choose the gas cutting set and nothing else. That thickness exceeds what a 7-inch disc reaches even cutting from both faces, and forcing a grinder through it wastes both time and a stack of discs.

The other criterion people forget is the metal itself. For stainless or aluminium the gas set will not work at any thickness, so an angle grinder with a disc matched to the material is the only option. When you call to book, give both the thickness and the metal type together so the team can send the right tool the first time.

Grinders and welders are both electric. If the site has no supply, neither runs. That situation is more common than people expect: strip-out jobs where power has already been disconnected, empty plots still waiting on a meter, and outdoor work too far from the nearest supply point for an extension run to reach.

The fix is adding a 5,000 VA generator at 500 THB per day. Five thousand VA is enough for one grinder, or one smaller welding machine, at a time. If you intend to run a grinder and a welder simultaneously, call the team first to check the load rather than assuming it will cope on site.

Once the generator is in the total, the numbers flip. A grinder at 500 THB plus a generator at 500 THB is 1,000 THB per day, matching the gas cutting set exactly. The difference is that the gas set needs no petrol top-ups, no cable runs, and gets through thick steel faster.

So the first question to settle is not price, it is whether the site has power yet. With no supply and a pure cutting job, the gas set is the more direct answer. With mains already available, the grinder genuinely is the cheaper option at 500 THB per day.

Rates are taken from the AR Rental Tools site as at the publication date. The oxygen and LPG cutting set is 1,000 THB per day or 6,000 THB per week. Angle grinders in both 4-inch and 7-inch sizes are 500 THB per day or 3,000 THB per week. Welding machines in both large and small sizes are 500 THB per day or 3,000 THB per week. The 5,000 VA generator is 500 THB per day or 3,000 THB per week. None of these include delivery.

Take a real job. A factory roof structure strip-out, H-beam at 9 mm, 40 cuts required, three days scheduled, and power already disconnected at the site. Choosing the gas cutting set gives 1,000 multiplied by 3, which is 3,000 THB, and that is the whole figure because no electricity is needed.

Choosing the 7-inch grinder for the same job gives 500 multiplied by 3, or 1,500 THB for the tool, plus a generator at 500 multiplied by 3, another 1,500 THB, for exactly the same 3,000 THB total. Yet 40 cuts through 9 mm steel with a grinder takes longer and burns through several discs. The example shows how comparing daily rates alone, without the power question, leads straight to the wrong call.

The daily versus weekly break-even is simple, because every weekly rate here is exactly six times the daily one. For the gas set, 6,000 divided by 1,000 is 6 days. For grinders and welders, 3,000 divided by 500 is also 6 days. So any job running beyond 6 days should move to the weekly rate immediately, since day seven onward is effectively free. Compare every rate side by side on the equipment and pricing page.

The gas set carries the highest risk of the three, involving pressurised cylinders and an open flame. The operator needs gas cutting goggles with a shade 5 or darker lens, leather gloves, a leather apron, and boots covering the ankle. Cylinders must stand upright and stay secured against falling, never laid on their side or placed near a heat source.

The point that cannot be skipped on gas work is spatter. Molten slag travels several metres and always falls below the cut line, so everything flammable underneath has to be cleared first, including timber offcuts, cloth, fuel containers and foam. Keep an extinguisher within arm's reach, and watch the area for a while after finishing, because a smouldering spot can flare up later.

Grinders carry a different risk. The main hazard is a disc shattering at speed, and fragments leaving it can cause serious injury, so the guard must never be removed for any reason. Check every disc for cracks or chips before fitting it, hold the tool firmly with both hands, and stand out of the plane of the disc in case it breaks.

Welding machines bring arc flash, which inflames the eyes, so a welding mask is mandatory, plus a shock risk when working in damp conditions. On skill level, the grinder is the easiest and a first-timer can pick it up straight away, while the gas set really needs someone who has set regulator pressures and adjusted a flame before. If nobody on the crew has done that, the grinder is the safer choice.

The first is booking a welding machine in order to cut steel, which happens often because people assume a welder handles every steel task. The tool arrives, will not do the job, and half a day goes on waiting for another delivery. Telling the team up front whether you are cutting or joining avoids it entirely.

The second is forgetting site power. A grinder or welder gets booked, the crew arrives to find no supply, and someone has to call back for a generator while the morning disappears. Simply answering whether the site has power at booking time prevents the whole situation.

The third is underestimating thickness, then booking a 4-inch grinder for 20 mm steel. A 4-inch disc does reach roughly 25-30 mm on paper, but once the guard and the real working angle are accounted for it usually falls short. The result is several worn discs and no progress. Measuring the actual thickness before calling takes under a minute.

The last is taking a daily rate on a job already known to run past a week. An eight-day job on the gas set at the daily rate is 1,000 multiplied by 8, or 8,000 THB. Taking the weekly rate plus one extra day is 6,000 plus 1,000, or 7,000 THB, saving 1,000 THB purely by changing how the rate is counted.

In short: steel below 6 mm, or stainless, use the 4-inch grinder at 500 THB per day. Steel from 6 mm to 25 mm with power on site and only a few cuts, use the 7-inch grinder at 500 THB per day, but with several dozen cuts use the gas cutting set at 1,000 THB per day. Steel above 25 mm, or any site without power, use the gas cutting set only. And if the job is joining steel rather than cutting it, use a welding machine at 500 THB per day.

AR Rental Tools has branches in Bang Kho Laem and Bang Khen. You can collect from either branch or have the equipment delivered to site across Bangkok and the surrounding provinces. The gas cutting set includes two pressurised cylinders that must be secured against tipping in transit, so team delivery is both easier and safer than moving it yourself. Delivery is confirmed by the team based on distance and piece count.

Booking takes a few steps. Call 089-690-9876 or message LINE @ar.tools and give three things: the type and thickness of the metal being cut, roughly how many cuts, and whether the site has power yet. Add your start and return dates, and the team will confirm the right tool, the net price, delivery cost, and the truck slot.

On handover, check the pressure gauges and gas hoses for cracks or leaks before signing. For a grinder, check the guard and run the tool briefly under no load. Report anything unusual straight away so it can be swapped before work starts. Full equipment and rates are on the equipment and pricing page, or reach the team through the contact page.