We’ve all seen cheap welders for sale from the usual online sources, small inverter stick welders for a very tempting price. But are they any good? When my local supermarket had one in its offers aisle, I took the plunge and placed it in my cart alongside the usual week’s supply of Marmite. That was some time around the start of the year.

Does Your Supermarket Sell Welders?

What I’d bought from my local Aldi was a Workzone WWIW-80, an 80 A unit that had cost me somewhere just over £60 (about $75), and came with welding leads and a rather poor quality face shield. The German discount supermarket chains specialise in periodic offers on all kinds of interesting things, so a very similar unit has also been for sale with a Parkside brand from their competitor Lidl. These small inverter welders are fairly generic, so they can be found with a variety of brands and specifications at a lower price online if you don’t mind forgoing the generous Aldi 3 year guarantee. The cheapest I’ve seen was about £35, or $44, but that price included only the inverter, without welding leads.

As a working blacksmith my dad has had a high-quality inverter welder since the 1990s, so my frame of reference is based upon that. He tried one of the first tiny inverters when they originally came to market in the last decade, but it couldn’t take the demands of a professional welder and packed up. I thus didn’t have high expectations of this unit, but I needed one of my own and for the price it was worth the punt. I’ve used it for occasional general purpose heavy welding tasks, repairing bits of farm machinery and fittings, and rebuilding some steps on a narrowboat in 7 mm plate. It’s acquitted itself well in those tasks, in that I am not a skilled welder and my work isn’t the tidiest, but it’s allowed me to do a satisfactory job.

How Do These Welders Perform?

It’s now a long time since inverter welders were new, so perhaps fewer readers will be using AC stick welders than might once have been the case. For me the comparison is one of smoothness, my relative lack of welding skill reveals itself in finding the inverter less easy to strike an arc than my dad would have, but once that arc is under way it’s so much easier to draw it and control it. I can fill holes with weld much more easily with an inverter welder, and the better control of current means that I can more easily deal with lighter work where someone of my abilities would normally be better served with a MIG welder.

To demonstrate this I decided to push the limit a little, and try the Workzone welder with some offcuts of 1 mm thickness square tube from my makerspace scrap bin. These had come from an office table leg, and were the type of stock that would push the boundaries with any stick welder. Because this is a relatively small welder, I use it with 2.5 mm rods, which as you’d expect will happily blow a hole in a 1 mm tube wall at higher currents. This is why you’d normally use MIG on a task such as this, and indeed at 80 A I was rewarded with something closer to cutting than welding. Dialing back the current to 40 A, I could easily rebuild the hole, and when trying to join two pieces at a right angle I could produce a smooth weld with good integrity. To me, the ability to weld this material is nothing short of amazing, as I’ve never managed to do that on such thin metal with a stick welder. That’s almost car bodywork thickness, I’d never have imagined even an inverter could come close. It’s worth saying as an aside that maintaining an arc at only 40 A is a little more challenging.

…And What Are Their Limitations?

I’ve described my Workzone then as a capable little welder that has served me well over the jobs I’ve used it for and which has even surprised me with its capabilities. Where are the deficiencies of it and welders like it, if they’re so good, why do better welders exist?

Construction-wise, these units tend to be robust enough for serious casual users. A sturdy sheet-metal case with decent cooling apertures and a fan to stop overheating, and brass locking connections for the leads. They are nothing special if you are used to other switch-mode power supplies: the usual electronics and a toroidal transformer. The leads are substantial, and on inspection proved to have copper conductors rather than aluminium as I’d feared, and because this was sold through a European distributor everything bears the European standards markings. If you buy a similar welder from an online source it may not have these approvals, so beware appliances with lax safety standards.

Where they differ from professional grade welders is in their duty cycle, and probably also in some cases in their claimed capacities. This isn’t the welder you’d use for large-scale fabrication or to build ships, it’s the one you keep in the shop for short welding tasks, or perhaps you have as a lightweight and portable backup for jobs where your shop welder is just too big to get to. If I was to hazard a guess as to why my dad’s little inverter welder broke down, I’d put the finger on duty cycle: the demands of a blacksmith fitting a piece of work on-site were probably too much for it. So if you’re an occasional welder it’ll be fine, but if you’re using it all the time it might pay to invest a little more.

Then there are the sometimes optimistic specifications quoted on small inverter welders. The Workzone unit is comparatively modest in its capacity at 80 A, but it’s not uncommon to see similar models claiming to be capable of as much as 200 A. When something that only costs a few tens of dollars is promising capacities that seem unrealistic for its price, it’s not unreasonable to assume that exploring its limits will hasten its demise. You get what you pay for, and perhaps if your needs run to more substantial currents it would reward you to pay a little more.

Among the Hackaday readership will be people whose welding skill is far ahead of mine, as well as plenty of people with experience of similar cheap inverter welders. I hope sharing my experiences will help you decide whether or not to try one of these devices, and as always it would be great to hear your views in the comments.