How I Made My Own Plasma Cutter From Junk

How to Build a Plasma Cutter

When I started assembling my cutter, I began with taking a good look at my parts list, later in this article. Once this was accomplished, I would study each the parts pictorial to get familiar with each part/component and they would be placed.

The next step was to study my schematic and create a layout diagram. My board layout diagram is the most valuable piece in the building, repairing, and modifying process of my cutter.

As I began mounting my parts, I organized my board into four sections. Those sections are Power Control, High Current DC, Low Voltage DC and High Voltage Arc Start.

Power Control
3KVA step down transformer and contactor. The transformer is mounted off board because it is big and heavy, as you can see in Section 13. The contactor became my first part on the board. I wired it so when the head trigger is pressed, it turns the contactor on and allows my DC components to come on line. Then I began with my next system, High Current DC.

High Current DC
Bridge Rectifier
Large Capacitors
Reed Switch (which I used as a current sensor), what it does is allow the high voltage arc system to fire and as soon as high current starts to travel to the head and cutting starts it shuts down the high voltage arc system while cutting since it’s not needed at this point. If you lose your fire it restarts the arc and gets you going again automatically. My next system was placed on board.

Low Voltage DC
The low voltage DC components are mixed with power switch and 120 volt terminals.
Power Switch
120-volt terminal blocks
12 volt transformer
Low voltage bridge rectifier
Auto relays
Terminal strip, 4 position is all I needed but 5 position was what I had in my toy box.

High Voltage Arc Start
Microwave capacitor or run capacitor, a household dimmer switch rated for 15 amps. A Ford or Chevy ignition coil. I used the Chevy on this cutter. As you can see, I have terminals to all parts that get an external connection outside of their system so all I have to do is run a piece of wire in-between. When wiring all my components, I used my Chevy board layout diagram to run my wires.

I checked and rechecked all wires before mounting external parts. If you go to the final wiring section, you will also find pictures of my rigging of these parts. I could have done it many different ways, but this is what I chose at this time.

It took me about 3 hours of procrastination to finally assemble it all. You know how it is on a project, once you are ready with all your parts, your mind starts giving you a million ways of doing something. And, at last, you just pick a way and go with it.

Once I got it all together, I connected my air tank hose and put the pressure setting at 28 for a safe point to start. I fired it up and BAM – that baby didn’t need any more adjusting. It was cutting!
You can imagine all the relief and pride I felt when the Plasanator started kicking ass.

Yea, I said it Kicking Ass Baby. Oops Wife just told me I need to stop, hee hee and for all you creators – ah ah ah ahhhhhh.

I hope you enjoyed riding along with me in my journey.

Take care and be safe. Remember, there are dangers in dealing with welding equipment. If you make an attempt to build this Plasma Cutter you do so at your own risk.

The Plasmaman

Parts Pictorial

Parts to Build a Plasma Cutter — Fan is optional for cooling bridg rectifier on 240 volts. I only run 120 volts so didn’t use it.

Parts List

3 metal or plastic switch boxes and covers for switches
2 house switches
1 dimmer switch 15-amp rating
1 contactor 40/50 amp rating
1 bridge rectifier, 700 volts 60 amps or higher (3 phase works great)
2 electrolytic capacitors, at least 350 volts 2500 microfarads
1 transformer 120 volts primary / 12 volt secondary rated at 2 amps
1 low-voltage bridge rectifier, 50 volts 25 amp rating
3 unversal auto 12 volt dc relays
1 automotive ignition coil, Ford or Chevy
1 microwave capacitor or any run capacitor, at least 120 volts 1 to 15 microfarads
1 squeeze clamp like jumper cable end clamp for work clamp
1 reed switch, 12 volt 1 amp rating, wrap 5 turns of 10 gauge strand around it and secure with tape or zip ties
1 air valve, 120 volt
1 air filter regulator (plumb to work on your set-up)
1 plasma head with 2 pin leads rated 30 to 80 amps
1 120 volt cooling fan like whats in a computer or microwave. Does great for cooling a large rectifier (optional)
1 5500 watt 220 volt water heater element. Use 2 in parallel for more amps or if you use 220 volt system
1 step-up/step-down transformer, 240/120 3 kva for best protection
Miscellaneous Parts
wire ties
assorted terminal ends
assorted wire nuts
electrical tape
plumbing fittings for air regular set-up. Your set up may be different than mine
about 10 feet of 16/14 gauge strand wire – 12 feet polyproelene tubing 1/4″ for tip wire cover
about 12 feet of 10 gauge strand wire
1 large paper clip for tip wire connection to plasma head tip
3/8 plastic tubing for head hose connection to isolate from electrode.