copperheat
I am not from an electrical background and this might sound silly.
What I am trying to do is create a hot wire cutter to cut thermocol(Styrofoam). The sugestions from internet is to use Nichrome but I cannot find one.
I have bunch of copper wire though. Can I heat the wire good enough to cut Styrofoam by shorting with 3 AA batteries ?
Try using a PT78ST106V-ND Through hole SIP-3 Module it's a 1" x 1" three terminal integrated switching regulator (ISR) which has internal short circuit and over-temperature protection as well as good line and load regulation.
http://www.digikey.com/product-detail/en/PT78ST106V/PT78ST106V-ND/323539
Number of Outputs 1
Voltage - Input (Min) 10V
Voltage - Input (Max) 38V
Voltage - Output 1 6V
Voltage - Output 2 -
Voltage - Output 3 -
Current - Output (Max) 1.5A
Here's the PDF http://www.ti.com/lit/ds/slts059a/slts059a.pdf
First, as Spehro points out in the comment below, you should make sure your coil matches the inductance of the original cooktop coil. This will minimize losses in the coil itself, some of which radiates as heat.
Then you should be using copper tubing for your coil, which you run coolant (often water) through. The currents going through the coil are high frequency anyway, so most of the current is in the outside of the conductor, which is fine for a tube. You'll have to make sure to properly isolate the coolant from the user, ground, and other metal and circuit parts as it will carry a small current from the coil.
There are a number of diy induction heater examples that use this technique. If you need an example, try a search for them. The image below shows more than you need. The transformer and huge capacitor in the upper left are already taken care of by your induction cooktop circuitry. The interesting part will be the copper tubing, which is connected to the plastic tubing on the lower left which then leads to a pump and a bucket or radiator.
Best Answer
Not really, it does not self heat very well and when hot it anneals and gets soft.
Nichrome is good, steel or stainless steel should also work ok and may be preferred if you need less heat and more strength. Sources of resisting wire would include fishing leaders (or other fine wire rope), piano wire, guitar strings (music wire), salvaged heating element wires (brittle if previously heated), florists wire, and pretty much anything except copper and aluminium.
Using 3 AA cells to heat wire will be disappointing. They made some gimmick bag sealers that heated a short 10mm length of nichrome wire with 2 AA cells but I doubt it would have got hot enough to cut Styrofoam cleanly.
If you should find some very fine filament that will get hot enough to melt Styrofoam with the 3 cells you may find that it will cool down in air and on contact that your cutting speed will be measured in frustration. Transformers supplying 6 to 24V are often suggested for the wire heating and this for lengths of about 300mm (12 inches). The current may be a few amps so would drain small cells fast. Note that you need an isolating transformer for your scenario - using an autotransformer may have dire consequences (including electrocution).