Arc Welding with a PC Power Supply!

Posted by Lee Garbutt | Apr 2, 2018 | Editorial | 23

Introduction

OK, call me crazy (you wouldn’t be the first) but this is something I’ve wanted to try for years, and I bet I’m not the only one. Each time a new power supply comes across the lab bench with ever increasing output capacities, I find myself thinking, “I could weld with this beast.” Well the AX1600i pushed me over the edge and I decided to give it a go; what could possibly go wrong?

133.3 Amps on the +12V outputs!

The Corsair AX1600i Digital power supply can deliver up to 133 Amps on the combined +12V rails, more than enough amperage for welding. There are dozens of PC power supplies on the market today that can deliver 100 Amps or more on the +12V output, but the AX1600i has another feature that might help make this project a success, the ability to manually set current limits on the +12V outputs. Thanks to the fact that the AX1600i is a digital power supply that allows manually setting the current limits on the +12V outputs via the Corsair Link data acquisition and control software, I might be able to add the ability to select a desired amperage to weld with. Yes!

Just because the AX1600i “can” deliver 133A doesn’t mean I want that much current available for welding. I typically only use that much power when I’m welding heavy steel pieces using ¼” rod. For this experiment I would like to be able to start out at a lot lower amperage, and I’m hoping the Corsair Link software will provide that ability.

Stick Welding with a PC Power Supply!

My first thought was to try to adapt a TIG (Tungsten Inert Gas) welder for use with the AX1600i. I figured using a TIG torch (Tungsten electrode shrouded with Argon gas instead of a flux coated rod) might give better control especially at the lower voltage and currents where I plan to start testing. TIG welders are commonly used to weld small stainless steel parts and sheet metal. But then I remembered the TIG welder power supply has a high voltage pulse built-in to initiate the plasma arc. Without that extra kick-start, it might be difficult to strike an arc without damaging the fine pointed tip of the Tungsten electrode. So I decided to just go with a conventional stick welding setup. The fact that PC power supplies put out DC voltage will be an advantage over the more common AC buzz-box arc welders for better stability and producing higher quality welds.

Modifications

Obviously, trying to convert a PC power supply into an arc welding power supply will require a few modifications. Here is a quick list of the main challenges I think we will have to overcome.

• Higher capacity fan for better cooling• Terminate all the PSU’s +12V cables into welding leads• Disable the Short Circuit protection feature• Implement selecting the desired current output• Strike and maintain a stable arc with only 12 volts

More air-flow: The AX1600i is designed for relatively quiet operation, which is not an issue when arc welding. To insure we have an excellent flow of cooling air through the power supply I pulled out a monster Delta fan that I had left over from an old water-cooling radiator test system.

This fan is a little thicker (38mm vs. 25mm) than the stock fan, so I’m going to mount it on the outside of the PSU chassis blowing in. The big Delta air-turbine spins at a constant 8,000 rpm and sounds like a hair dryer but it moves a lot of air, which will keep all the internal bits well cooled. Better to be safe than sorry.

Terminating cables: I decided to use all eight PCI-E cables and both 8-pin CPU cables to supply the +12V outputs to the welding leads. The 24-pin ATX connector will plug into a control panel with an On-Off switch to power up our PC welder and one of the 4-pin peripheral cables will be used to power the piggy-back Delta fan.

I plan to start out using straight polarity when welding, which means sending the positive output to the ground clamp and the negative output to the stinger lead. Twelve heavy-duty terminals were used to make the transition. So far, so good.

Disable SC Protection: This one caused me a bit of trouble but eventually with a little help from a Corsair insider (no names as promised) I was able to identify and very carefully disable the Safety Protection Circuit chip on the Digital Control Board.

The Digital Control Board is located at the upper left edge in the photo above. This was by far the most difficult task to accomplish; one wrong move here and we could have damaged one of the DSP (Digital Signal Processor) chips, which would have rendered the Corsair Link interface dead and the PSU useless.

Implementing Over Current Set-points: Having the ability to select Multi-rail output mode for the +12V rails and manually set over current limits via the included Corsair Link software is a huge help. I didn’t realize it at the time, but by disabling the Safety Protection Circuit, we also eliminated the problem of potentially triggering an over current shut down. Yes, that does impose some added risk, but we knew that going into this project. With Safety Protections disabled, the power supply should now just limit the current delivered to each of the +12V rails to the set points entered via Corsair Link instead of shutting down.

As you can see in the screen-shot above of the Corsair Link Home tab, Multi-Rail operation has been enabled and all ten of the +12V outputs for the PCI-E and CPU cables have been set to 6A (6A x 10 = 60A combined +12V output). This seems like a good place to start. I can always go back and try a different setting as needed.

As noted above, all ten of these +12V outputs have been routed and terminated into the two welding cables that go to the ground clamp and stinger.

By changing the over current limits on the +12V outputs I’m hoping to be able to select a useable output capacity for the PC welder. When you strike an arc it will appear as a dead short to the PSU, which is why we had to disable Short Circuit Protection. With current limiters set on each of the +12V outputs the PSU should essentially be in constant-current mode. Unfortunately, I can only change settings when the PSU is actually connected to a computer to run the Corsair Link software. But to be safe, I disconnect the computer before going into “welding mode”. I may be a little crazy but I’m not stupid!

Testing

OK, we’ve thought this through… modifications are complete… the AX1600i has been tested and it appears to still be working!

I’m going to start out using a 1/8” 6010 DC rod and see what happens.

Power On… The fan is screaming… Time to light ‘er up…

Striking an arc and keeping it stable with only 12 volts is really a challenge, even if there is plenty of amperage available. I didn’t have much luck with the current limiters set to deliver only 60A (just kept sticking the rod without establishing an arc). Normally this amperage would be fine for a small 1/8” rod but I found I needed more amperage to generate more heat to maintain a sustainable plasma arc. Not much I can do about that except work on my technique.

The main goal was to see if we could run a short bead and stick two pieces of steel plate together. It’s not pretty, but…

Bottom line, this IS crazy. You can buy a relatively inexpensive stick or MIG welder for light home use for less money than the cost of the Corsair AX1600i Digital power supply.

I hope you have enjoyed our little experiment but please don’t try this at home.

Note: No PC power supplies were permanently harmed or damaged in any way during this experiment.

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