Introduction: Plasma Cutter From an Arc Lighter
I recently purchased a few cheap arc lighters on ebay with various projects in mind for them. I hadn't thought of a plasma cutter until I had one in my own hands and saw how it could bore a hole through thin materials that get in the way of the arc. There's an issue with trying to cut things with an arc in exposed air as the material will typically burst into flame. In this project I'll show how to integrate the arc lighter with a cutting head that acts as both a shield against air flow as well as a heat sink to prevent the arc from heating materials to their carbonation point beyond the edges of the cut. In case the embedded video above does not work for you here is a direct link to the full tutorial and a video demonstration of this project.
- Arc Lighter
- Extra Wire
- Insulating Shrink Tube
- 4" x 4" Sheet Glass
- Steel Screw (~1/8" in diameter, trim to length)
- Conductive Work Surface (steel sheet, metal baking pan, etc.)
- Wood Drawer Handle (optional)
- Wire Cutters
- Hot Glue Gun
- Soldering Iron
- Screw Driver
- Flux Core Solder
- Scratch Awl
- Sand Paper
- 1/8" Spear Tip Glass Bit
- Mason Jar Ring
Step 1: Preparing the Glass
I went to my local hardware store and asked to have a stack of glass squares cut from the scraps they had on the shelves. I choose 4" x 4" squares as I figured that would be an appropriate size for this miniaturized project while still being manageable. I had multiples cut as I knew I would have some experimenting to get everything right with this project, especially in terms of drilling through glass which I had not done before. I also had the squares cut from the thickest scraps of glass they had available for durability reasons.
First thing I did with these squares is to blunt the edges with some sand paper. I did this slowly so not much dust was kicked up, but ideally glass should be sanded wet. You really do not want to be inhaling glass particles.
I will be mounting the output electrode for this plasma cutter into the center of the glass and as such a hole needs to be drilled to accommodate it. For the sake of longevity of the drill bit as well as to prevent the glass from cracking due to heat, glass should always be drilled under water. A trick for this is to temporarily glue a ring around where the hole is to be located. The ring is then filled with water and drilling can commence. I used a 1/8" Bosh spear tipped glass and tile bit which worked very well. It's best to drill glass with high speed and very light pressure. Once the bit penetrates the far side but hasn't quite made it all the way through the sheet should be flipped over to complete the hole. Doing so will prevent the glass from chipping.
Once the hole has been made the ring can be detached from the glass, if necessary using rubbing alcohol to loosen the hot glue. Wet a paper towel in alcohol and press it against the glue joint for a few minutes and it will cause hot glue to come free of just about anything.
Step 2: Disassembling the Lighter
Fortunately arc lighters are of fairly simple design. Most should pull free of the outside casing with the removal of a single screw inserted through the bottom. For this project the top shroud will have to be removed which is held in place with a series of pins that become accessible once the electronics are free from the case. I used a scratch awl to press the pins from one side, then pull them out the rest of the way from the other side with some side cutters.
With the top shroud removed it should expose the piece of ceramic that house the output wires to keep them from burning themselves up when an arc is struck. The wires should only be loosely set in this ceramic and it should otherwise fall out of the body freely. As soon as the shroud was initially removed you may have noticed a few springs fall out - it's nothing to worry about. These were likely part of the mechanism and flips an off switch when the lid of the lighter is closed. We won't be wanting that feature enabled for this project anyway.
Step 3: Lighter Modifications
At this point the electronics can be pressed back into the case and reinstalled with the single screw at the bottom. The two output wires should now be free and accessible, extending above the top. These need to be lengthened and so a small section of the ends should be stripped and soldered to some spare wire. What length is used is dependent on how far of a reach you would like the cutting head to have from the lighter body. I wouldn't recommend more than a couple feet of extra length. Once the soldering is finished the connections should be covered with some shrink wrap tube or another insulator to prevent an ark from jumping between the joints.
For cosmetic purposes I decided to reinstall the lid of the lighter, first drilling two holes in the top so the output wires could pass through. I then glued the lid in place since there isn't much of a reason for it to open anymore.
Step 4: Connecting the Pieces
At the end of one of the two output wires we need to attach an electrode. This can be anything from a piece of graphite to a conductive screw as I use here. The electrode must be a small enough diameter to fit into the hole made in the glass, but short enough that it doesn't poke through the other side. It doesn't particularly matter which output wire this electrode is attached to.
The electrode is placed into the hole on the glass sheet and glued in place. I attempted to use hot glue for this purpose but found the electrode got too hot and would re-melt the glue. Epoxy is a better choice here.
Last of all I decided to attach a small wooden handle to the corner of the glass sheet to help guide the cut.
Step 5: The Work Surface
With the cutting head complete the final ingredient needed is a conductive work surface to act as the electrode opposite the one mounted in the glass. I used a small scrap of steel but any flat metal object should work fine. The free electrode coming from the lighter should be placed such that it makes good electrical contact with the work surface.
That's it, the plasma cutter is ready to use!
Step 6: Using the Cutter
The material you would like to cut should be placed on the work surface and the cutting head set above. Some lighters may not function properly if they ground out on the work surface to they may need to be held in hand. To obtain a clean cut you must make very smooth movements, and the arc will be most accurate if there is already a small hole in the work for it to pass through at the start.
I've received some feedback that this is not a plasma cutter as some believe a true plasma cutter requires gas injection. While most industrial plasma cutters do use gas injection to direct the arc and blow away slag, that injection is not a required component of plasma production. Any time electricity passes through a gas in the form of a visible arc that luminescence and resultant heat is due to the production of plasma. With the design presented here air flow to the work piece is limited but enough remains to make the transition to plasma and facilitate an arc.