4 inverter arc welders tested on-farm

Welding in farm workshop

©Jonathan Page

Stick welders might seem a little outdated compared with a finely tuned mig, but the modern-day arc has made big strides in the past few years.

You can now buy one that packs a serious punch – close to 200amps from something not much bigger than a school lunchbox – and pretty much everything on the market will run 4mm or hardfacing rods.

That sort of output should be ample for most farm jobs.

They are also easily carried about, remain pretty unaffected by wind and are surprisingly tolerant of contamination, so chuck one of them in the back of the pickup and you should have everything you need for an emergency weld.

See also: Six best-selling impact drivers on test

To sort the men from the boys we enlisted the help of on-farm fabricator Martin Bushnell of Yateley Plant Services in Hampshire.

We ran each welder with 3.2mm and 4mm rods. The welds weren’t always perfect because we tested them straight out of the box – with more time we could have had each one running smoother – but here’s how they shaped-up…

SIP Weldmate T183

SIP Weldmate T183

©Jonathan Page

Two-and-a-half stars

Welding output 20-180amp

Duty cycle @ 180amps 20%

60% duty cycle 104amps

100% duty cycle 80amps

Cable length and quality Power – 214cm. Positive – 189cm. Earth – 185cm. Thicker, more flexible cables than Clarke but still a long way off Kemppi’s top spot.

Clamp quality The earth clamp is reasonably strong, but the cable attaches on its tip so it can’t get into tight spaces. The electrode holder is identical to those of both the Clarke and Sealey.

Welding pitfalls

Arc too short

Arc too short – Causes irregular masses of weld to be deposited and slag contamination on an uneven surface.

Arc too long

Arc too long – Causes poor penetration and a weak weld. Telltale signs are excessive splatter around the workpiece and porosity. You will probably hear the arc make a hissing sound during the weld, too.

Electrode moved too slowly

Electrode moved too slowly – Causes a wide and heavy deposit that overlaps at the side. Moving the stick slowly will also eat through your rods at a rapid pace.

Electrode moved too fast

Electrode moved too fast – Causes poor penetration and a thin, stringy-looking weld. Slag will also be hard to chip off.

Current too low

Current too low – Causes poor penetration and the electrode will stick to the workpiece frequently. Again, slag is hard to remove.

Current too high

Current too high – Causes excessive penetration, lots of splatter and a deep creater. You may also find you burn holes in the workpiece and will eat electrodes quickly.

Build quality A smart-looking thing with metal sides and plastic ends. Far fewer louvres so it is less likely to gather crud, but that may hamper its cooling capacity long-term. A shoulder strap isn’t included.

Electrode sizes 1.6-4mm

Power for 3.2mm rod 130amp

Power for 4.0mm rod 160amp

Max metal thickness 8mm

Use with a generator Yes

Controls These are housed in a protective recess. Accuracy is an issue, though – the amp dial has only five markings and there’s no digital display.

Additional features The voltage reduction device (VRD) cuts the open-circuit voltage at the terminal to less than 20VDC when the machine is not in use.

It is designed to reduce the risk of the welding rod sparking on a grounded workpiece.

It means the welder needs more strikes of the electrode than normal to start the arc – the first should wake it up and turn the VRD circuit off, lifting the open circuit voltage to 72V.

Made in China

Price £199.98 (currently on offer)

Best online price £164.16 from Kendal Tools and Machinery

Our verdict Looks and feels good quality, but its performance was a little disappointing.

All the testers found it hard to get going and it produced the least stable arc of the four. The result was more splatter and a less tidy weld.

Sip puts the problems down to the voltage reduction device, yet the Kemppi uses a similar system and we had no such problems with it.

Sealey Power Welder MW 180A

Sealey power welder

©Jonathan Page

Three-and-a-half stars

Welding output 10-180amp

Duty cycle @ 180amps 40%

60% duty cycle 160amps

100% duty cycle 130amps

Cable length and quality Earth – 132cm. Positive – 185cm. Power – 190cm. Slightly thicker, better quality cables than Clarke and SIP, but they are inconveniently short.

Clamp quality Almost exactly the same as the Clarke.

Build quality The metal main body looks built to last, though the same can’t be said of the perspex cover over the controls. It is cruder-looking than its main rival – the SIP – with gills that expose the circuitboards inside, but it does have a plastic fold-down handle.

Electrode sizes 1.6-4mm

Power for 3.2mm rod 105amp

Power for 4.0mm rod 130amp

Max metal thickness 8mm

Use with a generator No

Controls Dial labelling is poor – it is marked with 10amps at one end 180amps at the other – but a digital readout makes up for that.

A toggle switch selects between stick or TIG work, while LEDs indicate power and overheating.

The circuit-breaker style on/off switch is a big let down and almost impossible to flick while wearing gauntlet gloves.

Additional features It is worth noting that you can’t use welding cables over 10m long with the Sealey.

Made in China

Price £229.95 (currently on offer)

Best online price £247.25 from Just Off Base

Our verdict Comfortably ran the 4mm rod and got started straight away.

It comes with some good duty cycle stats, too. Operating-wise it is level with the Clarke, but offers a better display.

Downsides to note include the pathetically short leads and the impractical on/off switch.

Kemppi Minarc Evo180

Kemppi Miniarc welder

©Jonathan Page

Four-and-a-half stars

Welding output 10-170amp (180amp TIG)

Duty cycle @ 170 amps 30%

60% duty cycle 140amps

100% duty cycle 115amps

Cable length and quality Positive and earth – 292cm. Power – 3m. Rubber cables are tough but still flexible and plenty long enough.

Clamp quality Best on test by miles. Top-notch copper connectors and a heavy spring keep the earth clamped tight.

The electrode holder also embarrasses the other three and has a protected jaw.

Electrode sizes All electrodes

Power for 3.2mm rod 100amp

Power for 4.0mm rod 130amp

Max metal thickness 8mm

Use with a generator Yes

Tig welding Optional kit available

Build quality Excellent. It has a tough, all-plastic case with a vent up one side and a built-in handle on top.

The on/off switch has a rubber gaitor and the other buttons are blisters to stop dust ingress.

Controls Dials and buttons are recessed to avoid them getting bashed. LEDs indicate power, overheating, and engagement of VRD.

Additional features Uses main power factor control (PFC) to reduce the amount of power required from the electricity supply.

It means the welder can be used with up to 100m of extension cable, which could be handy for awkward site welding.

The Minarc also has a VRD to reduce the chance of trouble while the welder is left on the workbench.

Made in Finland

Price £750

Best online price £469 from Rapid Welding Supplies

Our verdict Slightly less splatter than the others thanks to a steady current and smoother arc.

However, it was surprisingly difficult to spot any major differences in weld quality despite the price tag – it’s not until you are working on more intricate tasks that you begin to appreciate its benefits.

The fan makes a racket, too.

Clarke AT161

Clarke AT161 welder

©Jonathan Page

Three-and-a-half stars

Welding output 10-160amp

Duty cycle @ 160amps 25%

60% duty cycle 105 amps

100% duty cycle 80 amps

Cable length and quality Earth – 134cm. Positive – 188cm. Power – 2m. Inconveniently short and poor quality cables don’t flex well, and will eventually fatigue and split.

Clamp quality The earth clamp was weak and copper braiding began to fray quite quickly. It uses the same positive clamp as SIP and Sealey.

Build quality There is no denying it looks the cheapest.

The plain, all-metal box offers little protection to the fragile-looking internals and all the circuit boards and components can be seen through the tinwork.

It doesn’t come with a handle either, but you do get a shoulder strap.

Electrode sizes 1.6-4mm

Power for 3.2mm rod 110amp

Power for 4.0mm rod 130amp

Max metal thickness 3.5mm (by the book, though we had it working comfortably on 5mm mild steel)

Use with a generator Yes

Controls Current adjustments are made through a cheap-feeling dial and there is no screen to give an accurate reading. LEDs indicates power and overheating.

Additional features It comes with a wire brush and hammer tool that are hardly worth keeping.

There is no VRD, either, so the open circuit remains at 78V all the time it is switched on.

Made in China

Price £199

Best online price £156.03 from Tool Net

Our verdict The surprise package. Produced a smoother, more stable arc than the SIP.

Build design and quality were its biggest letdowns – the adjustment dial is short of markings and shielded by the metal casing.

The fan runs non-stop, but it is not as loud as the Kemppi.

How welders work

A manual metal arc (MMA) weld needs an arc to join the gap between the electrode stick and the lumps of metal you are gluing together. During this process the temperature can climb well above 5,000C.

As the arc is formed, the outer coating of the rod begins to burn. This creates a bubble to shield the molten weld pool, which helps keep the arc smooth and stable.

Droplets of the molten core wire are teased across the arc by a combination of magnetic force and surface tension – a process that adds extra metal to the joint.

The finished weld will have a thin layer of slag across the top.

This is caused by impurities from the metal floating to the surface of the liquid weld before it goes solid. Chip this off and the job should be done.

Picking an electrode

Generally speaking, you need to maintain a distance from the work piece equal to the diameter of the electrode and keep it consistent throughout the weld. The electrode should be at a 20-30deg angle.

At the end of the weld bring the tip of the electrode back to fill the crater, then quickly lift the electrode from the weld pool to extinguish the arc.

Choosing an electrode usually depends on the type of welding and thickness of the work. Make sure the core wire either matches or is compatible with the metals to be stuck together.

Also, a narrow rod will produce a smaller arc and less heat – the thicker the metal, the bigger the rod.

The table below gives a rough guide as to which electrode is suited to a particular metal thickness.

Inverter welders like the ones we tested use electronics rather than heavy transformer windings.

It makes them super-lightweight but the circuits don’t like too much voltage or random spikes that can be caused by mobile generators.

Choose the right rod for the job

Electrode size (mm)    

Material thickness (mm)        

Welding current (A)

1.6        

1.0-1.6          

25-40

2.0        

1.6-2.6                      

40-70

2.5        

2.6-4.0                      

60-100

3.25    

3.0-5.0                      

80-130

4.0        

5.0-7.0                      

130-170

Verdict

We were impressed by the range of work you can get through with one of these little inverters.

Despite their size they still have plenty of power and there’s also the convenience of plugging straight into a 13amp socket.

If we were going to buy one then it would have to be the Kemppi, but the surprise package was the Clarke.

If you’re a very occasional welder then it will do the job, and more.