DIY: Hand-held Hot Foam Cutter
Cutting Styrofoam by hand can be difficult and messy. You can build your own hot foam cutter that will cleanly and easily slice through the foam you are working with. There are several variations on do-it-yourself cutters, but the principle behind them are the same. You can add more features once you understand the basic process.
Materials
• Nichrome wire - 32 AWG (0.008" diameter), nominal resistance of 12 ohms/foot. Other gauges can be used including 26, 24, 22 and 20, depending on the amount of heat you wish to create. We can help you determine the best gauge size for your needs.
• Three pieces of one-by-two inch wood strips or PVC pipe 12 inches long. You can use L-shaped shelf brackets in addition for more support.
• Bolts and nuts for securing frame. Wood or PVC elbows. Glue for securing frame if using PVC.
• 2 metal screws, lugs or eye bolts.
• Drill with bits.
• Power source. AC power supply, Variac with an electrical cord, or battery charger and cables.
Material for Added Features
• Small spring about the size used in a ball point pen
• On/off switch
• Hinge
Wire Frame
You need to create a frame to hold the Nichrome wire. This can be done with wood or PVC pipe material. Place your wood or pipe in front of you to form a "U" shape. You need to secure the left and right vertical sides to the horizontal piece.
If you are using wood, overlap the vertical pieces onto the horizontal piece. Drill a hole through each of the overlaps, and secure the pieces with a nut and bolt.
If you are using PVC, glue an elbow on one end of each vertical section. Once the glue sets, glue each vertical piece to the ends of the horizontal section.
Wire Attachment
Screws, lugs or eyebolts will need to be installed at the end of each open vertical piece of wood or PVC to hold your wire. Eyebolts will allow you to adjust the tension of your Nichrome wire as needed. Alternatively, you can use a small spring attached to one lug or screw to hold tension.
When you install your chosen hardware, leave enough room for wrapping your cutting wire. Wind one head of your Nichrome wire around the top eyebolt, lug or screw. Pull the wire tight and wind it around the bottom piece of hardware. If you are using lugs or screws, you can attach a spring to your hardware and wrap the wire on the open end of the spring.
Adding Power
Power Supply
If you use a power supply, attach one electrical wire to the negative terminal on the supply and one to the positive. Attach the negative wire to one lug (or screw) on your cutter and the positive to the other. You can either use alligator clips or solder the wires to the cutter.
Your power supply will need to provide 1 to 2 amps and 6 to 12volts. The power supplies that are used for model railroad sets will work for this application.
Variac
Using a Variac will allow you to control the voltage to your cutting wire. If you choose this power source, you will need an electrical cord that can plug into the Variac. Cut and strip the other end of your cord and attach one end to each wire end on your cutter.
Battery charger
If you choose to use a battery charger, attach the positive cable to one screw, lug or eyebolt. Attach the negative cable to the other. Set the charger to the 6 volt - 10-amp selection. Plug the charger into a wall outlet and operate your hot foam cutter using the on/off switch for the charger. When you turn your cutter on, the wire will begin to heat up.
Alternatives to this design include making a support table for your hot foam cutter and securing the cutter to the table with shelf brackets. If you use the table method, your wire can extend from the top of the holder through the bottom of your table. With this method, a spring can be attached to the wire under the table to provide variable tension.
Adding Features
When you have finished this project, you will have a nice hand-held hot foam cutter. You can mount it to a work surface for easier use. Once you have gotten the general technique down, you can create a cutter that will cut at angles. By adding a hinge to the bottom of the cutter, you can change your cutting angle. Other guides have instructions for creating a shuttle for angle cuts.
Safety Considerations
If you use a direct AC connection, remember that the connection ends will have live power when your cutter is plugged in. You should use some form of electrical insulation on the connectors to prevent shock.
Always use proper safety equipment when cutting or drilling wood. Safety glasses are recommended.
The wire for the hot foam cutter will become very hot when the power is turned on. Use caution to prevent burns from contact with the wire. Allow your cutter to cool before you put it away.
A mask should be worn while cutting Styrofoam to prevent inhalation of fumes and debris.
