Beyond Unboxing: Inside a Very Chinesium Mini MIG Welder

Saturday, June 15th, 2019 @ 2:58 | Beyond Unboxing

Welcome to another episode of Beyond Unboxing, where Charles buys something almost solely for satisfying his morbid curiosity. Generally, it’s something made of pure Chinesium (except last time) that I’m trying to press into service for something completely unintended, and I’m more interested in a part inside rather than the thing itself.

This time, it’s a little different. What Big Chuck’s Auto Body Center has been missing for the work I want to do in it has been a welder so I can start doing some sheet metal repair on the van fleet in earnest. I began shopping around in earnest a few weeks ago for a MIG welder, which would pretty much handle everything I would typically weld. It would have to be at least somewhat shitty, since we paid top investors’ dollar for the company welders, but just not shitty enough such that it makes me want to “borrow” them periodically.

At first I was just considering a used Miller or Lincoln unit with dual voltage input since Big Chuck’s Auto doesn’t have any 240V or 3 phase – I only have 120. Hella butts 120 (several independent 50 amp circuits fed by what looks like a 200 amp breaker) but still only 120, and most welders will power limit automatically. Buying a giant step-up transformer was, of course, one workaround which I didn’t want to consider, and buying a dual-voltage one would also be expandable for any future shops I spider-hole in. Recent vintage ones will usually go for somewhere in the upper hundreds to low thousands, and usually quickly since they’re desirable. But wait….

Hold up, trap. This is me we are talking about here. I’m the king of spending more money and putting more effort into finding a suboptimal solution than just spending money on something that works. Just ask my van fleet and all my robots! Anyways, just buying a welder which actually works has no hack value. I came to this startling realization and decided I needed to do me: Go explore the horrible Chinesium product market and see what the bazaar of the world has to offer me for very low dollar. After all, I could just borrow the company MIG welder for a day and….

So! I spent an evening reading up and studying about Shitty Chinese MIG welders. Heaven forbid I put this much effort into actually studying something that’s useful for society, right? Here’s what I learned!

The Chinesium welder market is generally split up into 3 Gaussian bands for pricing. On the very bottom shelf, you have stuff like this…

 

These things are usually not even MIG, just flux-core only with no gas handling ability. They also don’t have discretely adjustable output power like a knob or setting keys, but just have 2 big switches which rearrange taps on an internal transformer to get you 4 vaguely different voltage and current settings. I’ve used the Harbor Freight Special of this kind before, and they do work with some getting used to, but this wasn’t even worth looking at for me honestly. No, not even the cheesy handheld welding screen was worth it.

Up around the $250 range, you start to get actual adjustability and gas handling, though some are still flux-core only……… but you have to read the description to find out! The torches are still usually hardwired in (this is where I learned the difference between the various welder output connector systems like Tweco style or “Euro” style torch fittings) – guess there’s not money in that product dev budget for a nice chunk of leaded brass.

For this price and less you begin to see the “inverter” based ones – cheaper ones if you just search Inverter Welder will be stick only or a combo stick/TIG machine. These are actually pretty cool in my mind, just I don’t have a use case for them. MIG needs a wire feed system so it’s usually pricier.

And getting close to the “Please buy a used brand-name machine” price range is when you’ll see the whole feature set of inverter machines with adjustable voltage/current/wire speed, gas handling, removable torch, and the like.

I decided to play a game and find the least expensive machine which had:

  • Knob- or button-dialed variable voltage and wire speed
  • Removable torch
  • Inverter-based
  • Dual voltage advertised, or at least I suspected could be dual voltage capable.

This last part is important, because I had a sneaking suspicion that these Chinese inverter welders were stupid enough that they would run on 120V even if advertised for 240V.  A lot of inverter machines were being advertised as 220/240V only – which was weird, since the way I know these things should be working, it doesn’t matter. Perhaps the Value Engineering had really made their power supplies dedicated to one voltage or another, or perhaps they are just seeking different markets. Either way, we fast forward ….

…A few days! What? It turns out that this thing is actually Fulfilled By Amazon. Thanks, Jeff Bezos! I was expecting to continue haunting the market for another 2 weeks or so while gently regretting not just getting a usable machine off Facenet Marketplace.

So this here is a “REBOOT” branded … box of something. There’s a crude lineart of a dude welding something – or perhaps shooting his death ray at something. It says Good Quality on it. You know, much like my LED headlights say ‘DOT” on them, writing Good Quality on the box doesn’t make it necessarily true. But, optimism shall prevail!

As of this writing, you can find this thing on eBay for $237.50 with FREE! shipping, which for a box this size is a nontrivial value.

So I’m gonna scoop my own Beyond Unboxing real quick. I actually got this thing so fast that I didn’t prepare anything else, and I was already at Harbor Freight for a company run and decided to unpack it to see if I could get any accessories that fit it right away.

This thing is… deceptively small. The company welders are all pretty beefy, and before that, the machines I’d have access to were not inverter units – they were older transformer ones. It’s in fact so small it can only take the 1kg wire spool size. It’s a very easy one hand lift. Definitely color me surprised and somewhat dubious it contained anything of value.

Alright, and we are on the operating table. This is the contents of the box. The unit itself, a ground clamp, a stick electrode holder, a length of PVC gas hose, and a 1kg spool of mystery meat flux-core wire to get you started. They really know their audience! Free consumable since you probably designed the thing to last as long as the spool does for the guy who buys this and welds 1 thing.

Let’s begin shucking this clam. First and foremost, let’s get this out of the way: Every cable on this – ground wire, torch output, and power cord – is copper coated aluminum wire.

I’m sure it was invented with the best of intentions. It’s light weight, it’s softer and easier to work, and it makes better use of copper conductors at high frequencies because of the skin effect.

Oh, and it’s cheaper. Did I mention it’s cheaper?

For the same gauge, make sure you realize you’re only getting 2/3rds the conductivity. When buying any questionable pedigree wire product, always take a cross section sample and ensure it isn’t bright silver colored, and strip a section and scrape the top few strands with a knife facing backwards. If it also feels too light to be made of metal, it’s probably CCA.

Basically every car audio product you buy on Amazon will use CCA wire to mimic the same gauge copper. This is just fine and dandy if you buy things by nameplate power and never, ever actually need all of the rated amps of a copper wire of the same size.  Listen to the man whose company product dynamometer results were thrown off 30% because we just threw the 4AWG audio cable we wired robots up with at the damn thing and actually tried to push 250 amps through it.

Anyways, I’m sure it works fine for the limited duty cycles and shorter runs (because these included cables and torch parts are NOT the whole 10-12 feet you’d get otherwise!). This is the rant of someone that is very butthurt and traumatized by one specific issue. I literally just finished yelling at a vendor recently for using car audio cable on some custom battery packs I commissioned because they came through silver – fortunately, after a lot more examination, they were just tinned well. I like my wire brown.

 

The drive mechanism is pretty generic, with fiber-filled plastic everywhere. I was hoping for a stamped metal or at least cast unobtanium drive system, but even low end brand name units have plastic wire feeds now.

What peeved me more was that this torch was hard-wired after all. The huge strain relief grommet made it LOOK like it had a Euro style connector on the output; but alas, it was just hiding the truth.

We’re off to such a good start with this one! Oh boy, this means it will be amazing.

I do have some good news – the Harbor Freight Vulcan series of MIG welder parts, such as contact tips and gas nozzles, do fit this torch. I figured the Law of Chinese Product Packaging Inertia would make this the case.

On the left is what it came with, and on the right are the Vulcan parts.

The gas hose is an 8mm push fitting; no 1/4 NPT here!

I took apart the drive mechanism to see if it would be plausible to convert the thing to a connector (so I can eventually attach an aluminum-dispensing spool gun on it) – not really, all of the cables and gas hose actually just disappear into the bowels. The cable sleeve is pretty much just a bike brake cable sheath.

My goal with taking the lid off was to investigate if there was any plausible reason why it couldn’t run on 120V. It woke up when I plugged it in, but I didn’t install any wire or try to weld anything. Besides, I was curious of what kind of Value Engineering had gone into the other parts. The case removal is easy – just undo all of the sheet metal screws.

There’s two more hidden under the handle too.

And here’s one side of the goods! The drive unit is a little speed-400 type motor, but higher voltage, feeding into a spur gearbox. This thing looked to be an OEM part of some sort you could buy – it’s genericized on eBay and other places as “24V wire feed motor”. The controls are up top, and the big money power is on the bottom.

All of the boards had this name written on them. Arcsonic seems to be the actual brand name/OEM of this unit, along with many others that look like it. I’m glad it was this straightforward!

This smaller board is the rectifier assembly. Just a bridge and some capacitors here, no fancy power factor correction.

The back side of the board – the relay is the gate for AC power to enter the rectifier and DC bus.

The part of this thing that can be called the “Inverter”, I suppose. Most of the time when welders say “inverter based” they mean this kind of buck converter architecture .  In this thing, the rectified AC mains power enters on the left side. It then gets chopped by the IGBTs under the left hand heat sinks to yield a lower voltage. It’s the same topology as almost every motor controller. The large donut on the right is an output inductor to smooth the current ripple.

Actually, looking at the backside of this thing, it’s more properly called a half-bridge forward converter. There is an isolation transformer in the middle between the input and output to step the voltage down in lieu of modulating the duty cycle across a wide range. The exact mechanics of what a half-bridge converter is are beyond scope here, just accept that it made me go “oh, neat” and can be highly efficient.

 

The control board is almost all discrete and thru-hole components. This design must date back quite aways – not being a welding historian, I can only guess it’s lifted from a 90s to 2000s era inverter welder of American or European bloodline. I wasn’t interested in diving into what it did here – pretty much just scanning what the logic power supply looked like.

At this point I was convinced that it might be stupid enough that I can just run it on 120V without issues, perhaps just taking a hit on the maximum output voltage. That’s mostly why I was staring at the power stage, since some architectures will prevent the duty cycle from changing enough to accommodate a 50% reduction in bus voltage; if not, it could be smart enough to error out of it detects a duty cycle increase above a certain limit. The design of the half-bridge forward converter is such that it’s pretty input voltage agnostic as long as your driver circuitry keeps working.

I began putting the thing back together and briefly wondered why a MIG welder would have both a volts and an amps knob – before remembering this thing can also do stick welding. In MIG mode, as I tested, the Amps knob just controls wire feed speed.

Continuing the reassembly! The torch is really, really hardwired in – if I wanted to smack a Euro fitting on it or something, I’d have to deconstruct that whole signal wiring harness to disconnect it from the control board. Not worth it, really. If you wanted expandability into the Chinesium aftermarket, this is probably not your unit – I also didn’t see any easy way to cut a spool gun into the control system. I suggest, you know, buying a real welder.

I decided to go ahead and arm up the mystery meat flux-core spool  and actually get some welding done.

So, Big Chuck’s Auto Body came with something I call “Frank, the I-beam”. It’s a 16″ tall structural beam that used to be 24 feet long. Just an entire I-beam, hanging out and squatting on the floor eating all your leftovers and smoking all your weed, the underachiever. Early on, I hoisted it onto a set of 4 car dollies so I could at least shove it into a corner. I later asked some friends to come over and have at it with torches and cutoff saws – they took most of it to make things like anvils and…. gantry cranes? I didn’t really ask too much.

Anyways, I kept 6 feet of it for… whenever I need an I-beam, or something. Right now, it’ll be welding practice. I was going to crank this thing up all the way and just deposit steel.

Well, I definitely own a steel ball spraying machine.

My history with flux-core welding has been very spotty. I’ve usually just been handed a machine in some field/competition/informal gathering and told to fix this or that, and it was filled up with flux-core wire because no gas or infrastructure to support it and no willpower to change that.

It’s always just made a mess and been horrible, and I always wrote flux-core off as a trashy third-tier welding process.

It turns out, you need to use Electrode Negative mode with it, or “straight polarity” welding. First, that’s a welding industry legacy term, because to everyone else, “straight” or “positive” polarity means something with positive voltage is touching it. Who the fuck knew!?

I sure didn’t – since I avoided the process like I avoid college town liberalism, i.e. once and never again, I never did research into it enough to find out that LITERALLY EVERYONE WHO HAS HAD ME TRY TO USE A FLUX CORE WELDER HAS BEEN WRONG.  You don’t just insert flux-core wire into a MIG welder and start firing away – well, you can, but it would make more little steel balls than weld.

This thing lets you switch the polarity of the torch and the return clamp manually. A more sophisticated machine might have a big ol’ switch on it to do so. Either way, by searching “why is my flux core welder shitty and raining steel balls everywhere” I learned a thing.

Yep, so that vertical line on the right is the first decent looking bead I’ve ever made using flux-core wire.

In my entire life.

You know, past the toxic cloud of flux vaping upwards at me, and the need to constantly wire brush and clean up your weld, it’s actually not bad! I see that, much like people fool themselves into liking India Pale Ales, people also fool themselves into liking flux-core welding. I made several more fine-ass looking beads after this, too.

So, the verdict? I had the machine cranked out to the max on both voltage and wire feed during these tests, and it handled that admirably. It’s obviously not pushing enough power on 120V input to hurt itself, nor to trip a convention 15A breaker. I deposited steel (welding implies it was usefully joining metals) for about 30 seconds straight crossing the entire I-beam width – that was a nasty looking slug by the end – and the machine didn’t throw any angry lights or stop running. In the near future I do want to drag it over to the new shop and try putting an Overhaul wedge together using 240V mains, and see if it wants to go back on vacation.

In the end, this “220V” Chinesium inverter MIG is proving itself quite handy on 120V. Luckily, it won’t be principally welding I-beams together in Big Chuck’s Auto Body. Instead…

 

IT BEGINS.

 

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    2 Responses to “Beyond Unboxing: Inside a Very Chinesium Mini MIG Welder”

    1. connor Says:

      Hey a new post! cant wait to read this after work! keep up the good work

    2. jeffrey morrison Says:

      I enjoyed your review and the snarky humor as well. I will remember the tip about reversing the polarity for flux core welding. Thank you.
      Great Work.