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# Pyrographics from heating element wire? Answered

I wish to attach a piece of heating element wire to the two ends of a cord& plug directly into wall.  Wrapping the heating element in a pattern around a cane-stock; I will plug directly into the wall to burn the pattern into the cane.

I'm not sure of size-limits for household 110 volt current. (I dont want the wire to burn up, or not get hot enough)
Anyone have that info?  Thanks for your time.

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## Discussions

As Steve and others have said. it's dangerous, so don't go off half-cocked. I'd recommend discussing getting some hands-on help from someone educated and experienced with electricity.

When designing an electric heating element, it is usually a good idea to start with an idea of how much power (in watts) you want the element to dissipate.

The reason for this is because designing for power makes the math easy.

All I do is assume the heating element is a resistor R. Then I use the formulas for Ohm's Law and power dissipation,

P = V*I = V^2/R = I^2*R

to figure out what size R should be. Then I calculate the length of wire needed to make this resistance R, given the wire I am using has some constant resistance per unit lenght; e.g. some number of ohms per meter. The value of that constant depends on the wire, its thickness (called gauge, or AWG), and what material (e.g. NiCrome) it is made of.

The trouble is, you would probably like to start with a different quantity, like temperature. I mean you could look up in book, the temperature at which wood starts to burn, and say, "Ah ha! I want a hot wire that is exactly 200 degrees C. How do I design that?"

Unfortunately the math for modeling how heat power translates into temperature increase is tricky. I claim the temperature of the wire, greater than its surroundings, will be roughly proportional to power divided by surface area through which the heat is flowing, but really that's just me making noises and waving my hands.

So your initial guess for how much power is needed will probably be a bad guess, but I have a suggestion for an inexpensive tool you can use to compensate for bad guesses.

That tool is the humble lamp dimmer. Using a lamp dimmer you can chop up your 110 VAC waveform into something with RMS voltage variable from approximately 0 VAC to the full 110 VAC. It will give you some measure of control over how much power you're throwing into the wire.

I have another suggestion for the wire itself. My suggestion is that instead of going shopping for a spool of nichrome wire, you should sacrifice an old hair dryer, assuming it is the kind with coiled nichrome wire in it. I mean if you can unwind a complete hair dryer heating element, you know it is made to dissipate like 1500 watts or so, at 110 VAC.

Toasters have bare nichrome wire too, but for some reason the kind used in toasters is often flat, ribbon-like wire, that is somewhat fragile. Usually hair dryers have the better, sturdier nichrome wire, the kind with a circular cross-section, like most wire.

Anyway, regarding the lamp dimmer, you should be able use that gizmo to throttle that power down considerably, like to, I dunno, 50 watts? 100 watts? And just by turning the knob ( I suggest using knob style dimmer rather than slider style) you'll be able to get any amount of power between that minimum, and the maximum, i.e. V^2/R, where R is that heating element, and V= 110 vols RMS

By the way, I recommend you DO NOT TOUCH the wire with your fingers, NOR PLACE YOUR HAND CLOSE TO the wire, for to feel how hot it is, because even if the wire is thermally cold, touching live electrical wires is a very bad idea.

Don't touch live wires. It's probably advice you've heard before.

Just patiently watch the nichrome wire from a distance, to see if it is incandescently glowing, or making wood smoke, or other indicators of heat.

If it looks like nothing is happening, unplug the apparatus first before messing with it to find out why.

;-)

***Shortest comment ever***

How much time did it take you to type all that?

Is that sarcasm? I dunno how long it took. An hour maybe?

I was dreaming when I wrote this. So 'scuze me if it goes to fast.

Naaa, I was kidding, It probably would've taken me a year to type that! :)

Because life is just a party! And parties we're meant to la-aa-ast!

Don't do it. The tip will be live and your likely to kill yourself or someone else.

Low voltage, high current is what you want.

Go ahead if you want to kill yourself, otherwise stay away from mains!