Hi! Friends, Today in this tutorial, I would like to show how to make a Hot Wire Foam Cutter which is both portable and rechargeable. A hot-wire foam cutter is a tool used to cut polystyrene foam and similar materials. The device consists of a thin, taut metal wire, often made of nichrome or stainless steel, or a thicker wire preformed into a desired shape, which is heated via electrical resistance to approximately 600°F - a normal foam cutting temperature. Temperature required may vary with the type of material required to be cut. As the wire is passed through the material to be cut, the heat from the wire vaporizes the material just in advance of contact. The depth of the cut is limited only by the wire length.
The voltage required to heat the Nichrome wire to a desired temperature depends on two factor:
1) Gauge of the Nichrome wire used,
2) Length of the Nichrome wire.
So decide the length of the wire and then figure out the voltage required. For this purpose you can use the Nichrome Wire Application Calculator. Substitute,
1) Gauge of the wire,
2) Length of the wire used and
3) Required temperature
in the calculator and you will get the required voltage. If you are planning to use an AC adapter, it should have at least 1.5 A output current.If you are planning to use battery as a power source then it's recommended to use high capacity battery in-order to last long.
Caution: Hot wire cutter safety relates to the toxic fumes which can be given off when polystyrene foam (Styrofoam) is melted. Small, hand-held cutters may be used in well ventilated conditions. Large, bench-mounted types may require local exhaust ventilation: a special assessment is necessary. The ventilation required to control the toxic hazard will also control the irritant one. I recommend everyone to use a respirator to protect from inhaling harmful dusts, fumes, vapors, or gases.
If styrene fumes are inhaled remove the person to fresh air and seek medical advice.
If in eyes: If eyes water due to styrene fumes, flush with water and remove person to fresh air. If the condition persists seek medical advice.
[I'am not a native English speaker. So kindly forgive if my English is poor.]
Step 1: Tools and Materials Required
- Drill Machine
- Hot Glue Gun / PVC solvent cement.
- Screw Driver
- Soldering iron kit
- 1 x 1/2" PVC Pipe (10 cm)
- 2 x 1/2" PVC Pipe (6 cm)
- 2 x 1/2" PVC Pipe (5 cm)
- 2 x 1/2" PVC Pipe (2 cm)
- 1 x 1/2" Tee
- 2 x 1/2" 90° Elbow
- 2 x 1/2" 45° Elbow
- 3 x 1/2" End caps
- 2 x AA Battery. High capacity battery is recommended.
- Nut & Bolt
- Springs. Get them from an old battery holder.
- A metal strip that is a good conductor of electricity.
- Wire & Switch.
- Nichrome wire (28 gauge)
Step 2: Overview
In this project I am planning to make a hot wire foam cutter which is able to cut Polystyrene foam and similar materials having a thickness up to 8 cm. For that the nichrome wire should be 8 cm long. Normally, foam cutter use 24 or 28 gauge wire. Here in this project it's a 28 gauge wire. When nichrome wire gets heated, it's length increases. In order to keep the string stretched, a spring is added at one end of the nichrome wire. Now using Nichrome Wire Application Calculator, required voltage is calculated by substituting gauge and length of the wire along with the required temperature. Hence I chose 2 x 1.2 V AA battery in series to get a total voltage of 2.4 V. Finally a switch is added to the circuit. Let's see how to make it?
Step 3: Hand With the Tension Spring
First of all, we can start from the spring side. One of the hand is provided with tension spring to keep the nichrome wire stretched.
1) Make a hole at the top of an end cap.
2) Insert the nut into the spring. This spring was taken from the negative terminal of a dual battery holder.
3-4) Using a bolt from the interior, secure the spring on to the end cap.
5-9) Now take a piece of wire and attach one end of the wire on to the screw. Secure it with an another bolt. You can also solder if required.
1-2) Apply hot glue inside the end cap and attach the 2 cm PVC pipe piece.
3-4) Now attach the 45° elbow on to the other end of 2 cm PVC pipe piece.
5) Attach the 6 cm PVC pipe piece into the other end of the 45° elbow.
6-7) Attach the 90° elbow on to the other end of 6 cm PVC pipe piece.
8-9) And then attach the 5 cm PVC pipe piece in to the other end of 90° elbow.
Step 4: Room for the Switch
Now, we should make room for the switch as well as a connector for adding the other hand and the handle. So we use a Tee for this purpose.
1-2) Make hole on the Tee as shown in the image. Using a file increase the size of the hole in order to insert the switch.
3-5) Now take the wire (from the arm with tension spring) through the hole as shown in image. And then attach the Tee on to the other end of 5 cm PVC pipe piece (of arm with tension spring).
6-7) Take the wire back through the hole leaving a small portion outside the hole as shown in the image.
Step 5: The Second Arm
Now we can make the second hand. Steps are almost same discarding the spring part.
1-4) Make a hole at the top of the end cap. Insert the nut along with a bolt through the end cap hole. Now secure the nut using a bolt from the other end.
5-7) Now attach another piece of wire on to the nut and secure it with a bolt. You can also solder if required.
8-9) Apply hot glue into the end cap and attach the 2 cm PVC pipe piece.
1-2) Now attach the 45° elbow on to the other end of 2 cm PVC pipe piece.
3) Attach the 6 cm PVC pipe piece into the other end of the 45° elbow.
4-5) Attach the 90° elbow on to the other end of 6 cm PVC pipe piece.
6-7) And then attach the 5 cm PVC pipe piece in to the other end of 90° elbow.
8-9) Now take the wire from the second arm through the other side of the Tee as shown in the image. Apply glue into the Tee and attach it on to the second arm's 5 cm PVC pipe piece. Now we have both the hands connected together using Tee.
Step 6: Room for Battery
Now we need a handle as well as room for the batteries.
1) Take the 10 cm PVC pipe piece and the metal strip.
2) Place the metal strip across the cross section of one end of the pipe and then bend both ends of the strip as shown in the image.
3) Now cut the wire from the second hand as shown in the image.
4-6) Make a hole at the metal strip and solder the wire (from the second hand) in to that hole in the metal strip.
7-9) Now take the other wire (from the hand with tension spring) through the 10 cm PVC pipe piece. Then place the metal strip across the cross section of that end of the pipe and insert the same end into the Tee as shown in the image
1-2) Here comes the negative end of the wire. Cut it short and solder it on to the other spring. This spring is taken from the other end of positive terminal of a dual battery holder.
3-5) Take an end cap and apply glue as shown in the image. Now attach the spring into the end cap.
Step 7: Adding Switch and the Nichrome Wire
Now we shall add a switch to the hot wire cutter and also connect the nichrome wire.
1-2) Split the wire that project outside the switch hole. And solder both the wires on to the terminals of the switch.
3-4) Now apply hot glue on to the switch and insert it into the hole on Tee.
5-6) Connect one end of the nichrome wire on to the spring and the other end to the screw at the second hand. Keep the wire stretched and tight the screw using a screw driver.
Step 8: Hot Wire Foam Cutter
Insert 2 AA batteries into the handle so that the positive terminal of the battery goes in first. Close the end cap of the handle. Now switch ON the hot wire foam cutter and test it on a piece of polystyrene foam. In this project we use a 1000mah battery, so it will last only for 15-20 minutes. Hence use high capacity battery to make it last long. You can also use an ac adapter instead of battery. For this, simply connect both the wires to a dc jack and attach the dc jack inside the end cap on the handle. Thus it can be powered by an ac adapter also.
Kindly forgive my mistakes if any. Feel free to comment any mistakes in this tutorial and also share your opinions in improving the design.
Thanks For Your Precious Time!