High Voltage Turns Welder Into Plasma Cutter | Hackaday

For doing basic steel welding, most of us will reach for a MIG welder. It might not be the best tool for every welding job, but it’s definitely the most accessible since they tend to use only basic parts, easy-to-find gas, and can run from a standard electrical outlet. A plasma cutter isn’t as common, and while they’re certainly useful, [Rulof] wanted to forgo the expense of buying one off the shelf. Instead, he used parts of an old welder and a few other odds and ends to build his own plasma cutter.

The welder he’s working from in this project uses low-voltage alternating current to drive the welding process, but since a plasma cutter ionizes gas it needs high-voltage direct current. A 200 A bridge rectifier with some heat sinks from a Mac and an old stereo get this job done, but that’s not the only step in the process. A driver board and flyback transformer is used to generate the high voltage needed for the cutting head. There are some DIY circuit protection and safety features built in as well, including a spark gap using two nails, galvanic isolation from a transformer built from copper pipe, and some filtering coils made from old copper wire and iron bars. Argon For Tig Welding

High Voltage Turns Welder Into Plasma Cutter | Hackaday

With everything connected to the old welding machine and some pressurized air inside to push out the plasma, [Rulof] has a functional plasma cutter that can make short work out of a variety of metals at a fraction of the cost of a commercial tool. With the cutting tool finished, we’d recommend mounting it to a home-built CNC machine next.

Thanks to [Adjustinthings] for the tip!

Am I the only one that gets a nasty sunburn from electric welders? Seeing a bare hand holding the torch makes my skin itch.

No. Anyone using an electric welder or plasma cutter should have some sort of protection from the intense ultraviolet radiation that comes off of these tools while being used. The U.V. protection should cover up any part of your body exposed to this U.V. light including your skin and especially your eyes. Keep in mind U.V. light can be reflected off of all kinds of surfaces. Check me on this, but i believe for arc welding you need up to shade 5 optical glass protection and for plasma cutting up to shade 8 protection.

Believe you may have it backwards there, because I weld with a shade 11 and cut with a 5.

welding needs a 9 or higher. same for plasma. brazing(soldering) is done with 3 to 5

I have no idea what the proper shade is, but this whole thread is a wonderful example of why you shouldn’t take safety advice from random people, and why you shouldn’t gut corners and ignore protocol and do stuff without understanding the procedures…

which is exactly why i said “Check me on this”

I had to do some quick welds (stick welder) and decided to not wear long sleeves since it was warm and this was going to be tops 15 minutes of intermitent welding.

Long story short I ended up with a bad sunburn on my left arm, because of the position I had to take when welding I was shading my other arm. This was with less than 15 minutes of exposure to an arc, and, let me tell you something, I’m hispanic so I don’t usually get sunburn from the sun.

This was a nasty burn that lasted for about a week and hurt for about two days.

Yea, welding arcs generate full spectrum UV, including UVC which doesn’t care about skin pigment. Someone mistakenly used UVC fixtures instead of UVA ‘blacklights’ for an event in Hong Kong in 2017 I think and hundreds of people suffered from severe burns and eye damage. Nasty stuff.

Same experience here. Unbuttoned shirt, nice V-shaped sunburn in the middle of winter. Stick, and some pretty long weld (which made the tube warp, and made the part useless, to add insult to the injury).

Conversely, short welds of few inches total without gloves were universally without any ill effect.

It’s the dose that matters. Protect eyes always, and skin when the dose is meaningful.

Seems like if UVC is involved, whether the affects is noticable doesn’t matter. I wouldn’t want to be exposed for even a few seconds unnecessarily, who knows what that stuff does long term.

Made that same mistake when i started to try learning welding😆

Good advice for so many situations…

Has anybody made any sense of the electric circuit despicted here? Have you ever seen this circuit elswere ? I just dont understand how the high voltage part works

if your skin is very pale you should be wraring fire retardant sleeves. that much uv exposure can lead to melanoma

The spray arc MIG process used when welding aluminium throws off insane levels of UV. I found out the hard way. I once did 15 seconds of test weld and had a UV burn like I was in the sun for an entire day.

Only made that mistake once….

Welding suntan is very real, most of the processes throw a lot of UV out – the higher the current the higher the dose.

And yes you can give yourself a painful burn in only a few minutes if you’re not careful.

I have a pair of flame retardant cotton sleeves that I use unless I’m doing heavy welding. Easy on and off and just covers from the glove to the shirt sleeve.

They are cheap and readily available.

Diy Hobbyist here, 1st time i used my machine w/c took me some time to get the hang out off, any exposed skin will get to that sunburned feeling😁 now i know why some welders here in the Philippines are well covered from head to foot.

Agree with Adrian . I guess I am a hobby welder. , used to get burned on the inside of my thighs. Found sunscreen effective.

Given that we’re in a post-scarcity society and even discount supermarkets like Aldi or Lidl will sell you a real plasma cutter for like $99 from time to time I question the safety & sanity of this.

I’m impressed he made it work, I’ll say that much.

“…and can run from a standard electrical outlet.”

Has me jealous of our European friends with their fancy 220V outlets. Sure, my Harbor Freight special plugs into the 120 line but it also tends to pop the breaker.

So use the 240V circuit in your garage or basement. You do have a 240V circuit for clothes dryers, water heaters, kitchen stove, AC, or “general garage mayhem”; right?

Is this just a “my family hasn’t cared about electric codes” issue?

Seeing how many people here are concerned about the UV radiation, how about the fumes?

I don’t think the plasma creates any fumes on it’s own, but the item being cut certainly will. Like I said in my other post, half face respirator that fits under your welding hood is pretty cheap.

On another note, I paid way more for my plasma cutter than they cost now. They are incredibly useful especially to cut odd shapes from sheet metal. I’ve even cut and notched some thin steel beams that would have taken a long time to cut with a blade. I would not recommend one that runs on 100VAC though.

The air itself only makes a bit; plasma cutters using compressed air will make ozone or nitrogen oxides or whatever. Much less of a problem than e.g. zinc vapor on galvanized stuff. Generally for this sort of thing you want to have a fan bringing in fresh air, it helps keep you cool near the hot things anyway.

thanks for suggesting this youtube channel – it’s a very entertaining personality, and it’s refreshing how he just slaps things together with seemingly practical skill.

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High Voltage Turns Welder Into Plasma Cutter | Hackaday

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