Anyways, given the dangers, I think I am just going to heat it up and have it glow red and avoid arcs.

Be careful, pencil leads are polymer binders and graphite dust in modern pencils. Make sure you are working on a non flammable surface (concrete or ceramic tile). The test slips will likely come off as the pencil lead gets warm. If there is any spring tension on the wires as they want to untwist, they could flick hot material your way. Wear safety goggles.

Also, ,
Measure the resistance before you start. Then calculate the power you will have in the graphite when you add 32 volts. Power = V*V/ R

Or, for 32 volts, about 1000/R.

 

32 volts and 2 rods is way more then enough to blind you a welder has 48 volt
it's the amps that make it fire a 12 car battery can weld.
now if you wanted to jump the gap hi voltage is needed.

 

RE:""But to generate an arc, you normally require voltages much higher than the 31V you've just mentioned""
The normal arc voltage DC is between 21 and 24 Volts ONLY. Don`t believe any what speaks what he don`t know. And minimum amperage for arc MAY be not those 100 what is in often use but some 10 or even 5 in some more special cases, or even 1 (if both voltamper curves are passed). However 1 Amp arc is small indeed, like needle.
About pencil-type graphite rods - them are not made in composition what can serve at high temperature, the burn-off will happen rather near to 200 C thus the life will be rather short (many minutes) at resistive heating and less of minute in case of arc.
Therefore now mind the resistive heating: The resistance of pencil - I just measured the mild sort one - was 24 Ohms, thus the Voltage must be according the Ohms law and empirical thumb-rule of 2-50 W/cm2 of it surface. If diameter is rather 2 mm and length is ca 20 cm then area be pi()*d^2*L=3,14*0,04*0,784*20=~2 cm2 or the power must be in between 6...100 Watts in according to cooling obstacles. Or other terms, 32V/24Ohm=1,5Amp what results in 50Watts You apply - it seems rather OK.

 

The normal arc voltage DC is between 21 and 24 Volts ONLY.

From the article on Wikipedia:

A high voltage is pulsed across the lamp to "ignite" or "strike" the arc, after which the discharge can be maintained at a lower voltage.

https://en.wikipedia.org/wiki/Arc_lamp

 

That's in a lamp welding like shown you strike a arc that doesn't take a lot of voltage just some amps

A transformer-style welding power supply converts the moderate voltage and moderate current electricity from the utility mains (typically 230 or 115 VAC) into a high current and low voltage supply, typically between 17 and 45 (open-circuit) volts and 55 to 590 amperes.

He could strike a arc with 32 volts and some carbon rod how big depends on what he uses some pencils not going to work art pencils have carbon. Some cheap pencils
don't have much.

 

That's in a lamp welding like shown you strike a arc that doesn't take a lot of voltage just some amps

Yeah... I've been trying to find a table of distances vs voltage breakdown between electrodes ... Anyway, I had forgotten that air becomes ionized and partially conductive when an initial arc is generated.... thus needing a much lower voltage (like the ones you've mentioned) to maintain it.

Thanks for clarifying.

 

Safety? Who needs safety? Just look into the light like this guy:

 

I find clear acrylic plastic seems to block a decent amount of UV

 

Ok I did have 20 20 now I'm about blind and all because a bad welding hood. Got be careful

 

I have taken apart a pencil to get the graphite inside of it. My goal is to get it to glow red and be really hot. I am using a 31V 2.5A max power supply (an old printer charger). I am confident that it will work, but I am concerned about the safety. As long as there are no really bright arcs or anything, is there any danger? I head that they can emit harmful UV light. If it is not really bright but glowing red, is this a concern? Please let me know of any dangers.

Danger schmanger! I did all kinds of this sort of thing as a lad. No guts no glory. No flame, no fame!

 

Speaking of stupid human kid tricks....My dad brought home this big gyro motor from some sort of aircraft application when I was a kid. It said 36.000 RPM at 28 volts DC. I decided I'd use it to see how fast I could get a bicycle wheel spinning. So I clamped the motor in a vice and connected the motor to the axle of this wheel. After coming up to some incredible speed, the wheel started to "precess" menacingly, and then the next thing I knew there were spokes flying everywhere....embedding themselves in the ceiling and walls of the garage. It's a good thing I wasn't in the line of fire, or I would have looked like a porcupine. Don't try this at home.

 

Long time ago I used a pencil to make a light dimmer. Proved to some skeptics who said it couldn't be done. More recently I was engaged in a conversation revolving around shunt resistors. I had just changed the carbon filter elements in my RO system and wondered what kind of conductivity I could get through one of those. Some thought I'd see brilliant flashes of energetic light. But at 13.8 volts and 6.4 Ω, dead shorting this carbon element across a car battery would result in no more current flow than 2.16 amps. Certainly not going to produce any serious heat. At the most this rig in my video (yes, this is MY video) would run (if shorted across a battery) 29.76 watts. Given the size of the carbon filter I don't think that would heat up very much, if any kind of noticeable change. And no, I never did go connect this to the car's battery.

Your concern about UV is wise. But in your case, it's negligible. You won't be producing any dangerous levels of UV. And if your element (pencil) glows red then the most it can do in the way of harm is to cause nearby combustible objects to erupt in flames. Since I don't know how many watts your pencil led can handle or at what point it will start to glow red (if it will even do that much) I can't say. But for your experiment you're not going to need any special glasses.

Welding glasses ? ? ? Yes they're designed to block harmful UV from burning your eyeballs. If you've ever welded without wearing protective clothing then you also know that you can get a nasty sun-burn from arc welding. It's the UV. But you're not going to be producing any sort of sustained arcing, so - I really don't think you have anything to worry about.

Enjoy my short 2 minute 47 second video (with me narrating).