Help with wiring??

[RobotLizard]

Hi everyone. I have no idea if this is the right place for a question like this, but this is the only forum I use, so any help is appreciated!

I've started a project to build a hot wire foam cutter for making models out of foam board. I have a plan of how to build it but I have no idea if my plan for power will work, as I have no electrical experience. So I'll walk you through my plan, and I'd love to hear your opinion. Will this work? If not, how do I make it work?

The idea is to make the cutter frame itself based on this video: https://youtu.be/RjpeV8lsgMY
The video doesn't detail a power supply, just that nichrome wire is used as the heating element to actually cut the foam board.

The plan is then to use mains electricity to heat the wire. These rocker switches (http://goo.gl/YZGcbM) are my preferred option. They come pre-wired, but I think without a plug (I contacted the seller to find out as the photos don't show). If I wire one end to this plug (http://goo.gl/5yUstc), and the other end directly to the wire cutter (as shown in the step at roughly 10 minutes in the video above), will this allow me to heat the whole nichrome wire sufficiently to cut through foam board?

As I said, I have no electrical experience, so if you need more information about the project, please don't hesitate to ask. I just need to know if this idea will successfully power the project, without me risking electrocution or something! And a final thought; if I do use mains power, will there be any need for a transformer?

Thanks in advance,
Sam

 

[ex_bubblehead]

Absolutely you MUST use some sort of controlable power supply. DO NOT UNDER ANY CIRCUMSTANCES WIRE DIRECTLY TO THE MAINS! With no electrical experience you are walking into a potentially lethal situation here, find someone with some experience to do the actual wiring for you.

 

[Mousemonkey]

They are so cheap why risk it?

http://www.hobbycraft.co.uk/woodland-scenics-hot-wire-foam-cutter/574601-1000?gclid=CNKSksTv5swCFcFsGwod-XAEMw

 

[Rookie_MIB]

Ok - need to do some math here, and lay out some other reasonable assumptions.

1) Do not use mains power. Duh. That's 120 volts and if you make contact with that and a ground accidentally, you'll shock the crap out of yourself.
2) Use a computer PSU to change it to low voltage DC. A cheap 300w unit would be fine.
3) What are the gauge and length of the cutting wire you're going to use? The rating of nichrome wire is ohms/foot dependent on the gauge.

Here's a great reference for Nichrome wire.

http://hotwirefoamcutterinfo.com/_NiChromeData.html

Now, lets make some assumptions, according to the data on the nichrome wire, 600F is more than sufficient for cutting foam. They also recommend 26 gauge wire as a nice balance between strength and cutting currents. You'll be using a 2 foot span of wire for the cutting, and the aforementioned 300w PSU which can deliver approximately 15A of power on the 12v line. That is probably wayyyy too much, so you'll need to limit the current with some big resistors.

At that level, it's going to require about 2.2A to heat up the wire to 600F, the total wattage draw will be about 28 watts, it will have a resistance of about 5.2 ohms.

So - that's probably the best way to do it safely, and inexpensively.

 

[USAFRet]