Irresponsible and dangerous: need help to set knives on fire

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Token
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Irresponsible and dangerous: need help to set knives on fire

Postby Token » Tue Jul 20, 2010 9:23 pm UTC

Hello, science forum. Here's the story: my friend's 21st birthday is coming up, and I'm currently weighing up the idea of getting her some kind of flammable knife or knives (it's an in-joke). Problem is, I'm not sure what would be the most awesome way to realise such an idea. So I turn to you, ingenious people that you are, to advise me on potential ways to go about it. Obviously, I'm restricted to materials that can be purchased through civilian channels - no chemicals that can only be purchased by military researchers, etc. Any ideas?
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Re: Irresponsible and dangerous: need help to set knives on

Postby BlackSails » Tue Jul 20, 2010 9:34 pm UTC

Is an electrified taser-knife good enough?

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Josephine
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Re: Irresponsible and dangerous: need help to set knives on

Postby Josephine » Tue Jul 20, 2010 9:36 pm UTC

If it doesn't need to burn long, simple paraffin wax would work.
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Re: Irresponsible and dangerous: need help to set knives on

Postby Omegaton » Tue Jul 20, 2010 10:02 pm UTC


Token
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Re: Irresponsible and dangerous: need help to set knives on

Postby Token » Tue Jul 20, 2010 10:17 pm UTC

Omegaton wrote:Something like this?

http://en.wikipedia.org/wiki/Fire_Knife

Not really, thanks - wrapping a knife in flamabble fabrics doesn't really have the indefinable awesomeness factor that I'm looking for. I might see how paraffin wax does, though.
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Charlie!
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Re: Irresponsible and dangerous: need help to set knives on

Postby Charlie! » Tue Jul 20, 2010 10:56 pm UTC

It would be possible to attach fuel-soaked cloth to a knife while still leaving the edge exposed - maybe by drilling a few small holes along the edge and using wire to hold on the cloth.

Or you could carve him one out of fatwood, maybe color it appropriately using food-safe stuff.

Or find a novelty foam knife and soak it in kerosene - If the kerosene doesn't dissolve the foam, that one should be handled with asbestos gloves or a long pole when lit.
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Josephine
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Re: Irresponsible and dangerous: need help to set knives on

Postby Josephine » Tue Jul 20, 2010 11:15 pm UTC

Charlie! wrote:Or find a novelty foam knife and soak it in kerosene - If the kerosene doesn't dissolve the foam, that one should be handled with asbestos gloves or a long pole when lit.

Doesn't that make napalm?
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Re: Irresponsible and dangerous: need help to set knives on

Postby Mr_Rose » Wed Jul 21, 2010 12:17 am UTC

How much work are you prepared to put into this?
If you have access to machine tools, you could carve some 1mm wide grooves into the back of the blade, or just below the back on the faces, then lay some fine brass tube, with a series of holes drilled along its length, into those. Hook up a disposable gas lighter and you'd have a decent fuel source and potential ignition source too.
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Re: Irresponsible and dangerous: need help to set knives on

Postby Charlie! » Wed Jul 21, 2010 12:49 am UTC

nbonaparte wrote:
Charlie! wrote:Or find a novelty foam knife and soak it in kerosene - If the kerosene doesn't dissolve the foam, that one should be handled with asbestos gloves or a long pole when lit.

Doesn't that make napalm?

Hmm, so I guess polyurethane will dissolve. Maybe soak it in concentrated alcohol then?
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Vyn
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Re: Irresponsible and dangerous: need help to set knives on

Postby Vyn » Wed Jul 21, 2010 3:36 pm UTC

I'm curious if making a knife blade out of magnesium would work. I know it'd burn nicely, but I'm not sure how easy it would be to get it to look like a knife/get an edge on it before you decide to light it on fire.
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Re: Irresponsible and dangerous: need help to set knives on

Postby Mr_Rose » Wed Jul 21, 2010 4:50 pm UTC

Vyn wrote:I'm curious if making a knife blade out of magnesium would work. I know it'd burn nicely, but I'm not sure how easy it would be to get it to look like a knife/get an edge on it before you decide to light it on fire.

Actually...
Turns out that large blocks of solid magnesium just don't heat up fast enough to get past the surface oxidisation and actually burn without serious encouragement. OTOH, making a knife blade out f the stuff should be relatively simple, assuming you can get a hold of a block large enough and some oil-cooled machine tools.
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Re: Irresponsible and dangerous: need help to set knives on

Postby EricH » Wed Jul 21, 2010 4:51 pm UTC

Vyn wrote:I'm curious if making a knife blade out of magnesium would work. I know it'd burn nicely, but I'm not sure how easy it would be to get it to look like a knife/get an edge on it before you decide to light it on fire.

Solid magnesium is hard to ignite; shavings or powder are hard to put out.
My suggestion would be some kind of flammable gel spread over your knife blade; Sterno comes to mind.
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Re: Irresponsible and dangerous: need help to set knives on

Postby Telchar » Wed Jul 21, 2010 5:53 pm UTC

Sterno gel is readily available, easy to put out, and easy to apply. Probably your best option. Any place that sells hardware to restraunts will have them.
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Re: Irresponsible and dangerous: need help to set knives on

Postby mmmcannibalism » Wed Jul 21, 2010 6:07 pm UTC

coat the knife in tar or corn oil?
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Re: Irresponsible and dangerous: need help to set knives on

Postby fooliam » Wed Jul 21, 2010 9:13 pm UTC

Mr_Rose wrote:How much work are you prepared to put into this?
If you have access to machine tools, you could carve some 1mm wide grooves into the back of the blade, or just below the back on the faces, then lay some fine brass tube, with a series of holes drilled along its length, into those. Hook up a disposable gas lighter and you'd have a decent fuel source and potential ignition source too.


You read my mind.

You could also creat a groove down the spine of the blade and put some sterno in there...might give the effect you're looking for.
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Telchar
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Re: Irresponsible and dangerous: need help to set knives on

Postby Telchar » Wed Jul 21, 2010 10:28 pm UTC

The Sterno I've worked with is jelly consistency and is probably do-able w/o grooves. It really depends on whether or not you want to actually cut anything with it, and whether you want to eat what you cut, in which case Sterno is a bad ida.
Zamfir wrote:Yeah, that's a good point. Everyone is all about presumption of innocence in rape threads. But when Mexican drug lords build APCs to carry their henchmen around, we immediately jump to criminal conclusions without hard evidence.

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Re: Irresponsible and dangerous: need help to set knives on

Postby fooliam » Wed Jul 21, 2010 11:06 pm UTC

Telchar wrote:The Sterno I've worked with is jelly consistency and is probably do-able w/o grooves. It really depends on whether or not you want to actually cut anything with it, and whether you want to eat what you cut, in which case Sterno is a bad ida.


I was just thinking about making it as much like an ordinary knife as possible. A lot of jelly on a knife might be pretty obvious. A little bit in a semi-concealed groove may be less so. Smearing the whole blade in sterno and lighting it on fire would certainly work though.
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Re: Irresponsible and dangerous: need help to set knives on

Postby tuseroni » Thu Jul 22, 2010 12:22 am UTC

soak Styrofoam in gasoline(i hear white gasoline is the best, you can get that at walmart) til it wont absorb anymore and becomes a thick gel consistency, then coat the knife in that and light it. should stick to the blade, if you dont coat too thick it shouldnt come flying off when you swing it, probably wont go out either when you swing it but in case im wrong and the idea of sending burning napalm flying everywhere is unpalatable....probably don't swing it too hard...
grooves would be good too...and look cool...
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Re: Irresponsible and dangerous: need help to set knives on

Postby TaintedDeity » Thu Jul 22, 2010 1:04 am UTC

If that burning gel touches your skin it will burn and you will not be able to wipe it off. I would recommend against it.
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Re: Irresponsible and dangerous: need help to set knives on

Postby tuseroni » Thu Jul 22, 2010 2:36 am UTC

this is why you do not swing it around.
also you can dunk it in water to put out the fire and cool the gel...
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Re: Irresponsible and dangerous: need help to set knives on

Postby Aelfyre » Thu Jul 22, 2010 11:19 am UTC

Mr_Rose wrote:How much work are you prepared to put into this?
If you have access to machine tools, you could carve some 1mm wide grooves into the back of the blade, or just below the back on the faces, then lay some fine brass tube, with a series of holes drilled along its length, into those. Hook up a disposable gas lighter and you'd have a decent fuel source and potential ignition source too.


oooh.. have you ever seen anything like that done? I myself have always wondered how I could go about getting a "flaming sword" together.. just so I could go into [redacted] then who'd be laughing?

no but seriously I may have to start googling now and give this some more thought.. do you perhaps have a link to a diagram of what you are talking about? cuz that'd be +2 awesome :) (+4 vs Undead)
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Re: Irresponsible and dangerous: need help to set knives on

Postby Velifer » Thu Jul 22, 2010 1:47 pm UTC

Aelfyre wrote:just so I could go into [redacted] then who'd be laughing?

Even carrying a flaming sword, we're all gonna laugh at you for sitting in a lit crit class.

Make the blade out of plasma.
http://www.ncbi.nlm.nih.gov/pubmed/7109809
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Re: Irresponsible and dangerous: need help to set knives on

Postby Argency » Thu Jul 22, 2010 10:22 pm UTC

I say kevlar wicks, dipped in citronella oil, kerosene or FireSol, and bound to the blades with wire. Safest, most practical way to do it - that's how firetwirlers do it.
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Re: Irresponsible and dangerous: need help to set knives on

Postby fooliam » Thu Jul 22, 2010 11:24 pm UTC

Argency wrote:I say kevlar wicks, dipped in citronella oil, kerosene or FireSol, and bound to the blades with wire. Safest, most practical way to do it - that's how firetwirlers do it.



He wins. By far the best idea. Well, provided we define best as "makes a flaming knife with the lowest likelihood of setting yourself/your house/your friends on fire"
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Re: Irresponsible and dangerous: need help to set knives on

Postby Telchar » Fri Jul 23, 2010 12:05 am UTC

Velifer wrote: lit crit class.


Way better meaning in the context of this thread.
Zamfir wrote:Yeah, that's a good point. Everyone is all about presumption of innocence in rape threads. But when Mexican drug lords build APCs to carry their henchmen around, we immediately jump to criminal conclusions without hard evidence.

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Re: Irresponsible and dangerous: need help to set knives on

Postby tuseroni » Fri Jul 23, 2010 12:26 am UTC

Velifer wrote:
Aelfyre wrote:just so I could go into [redacted] then who'd be laughing?

Even carrying a flaming sword, we're all gonna laugh at you for sitting in a lit crit class.

Make the blade out of plasma.
http://www.ncbi.nlm.nih.gov/pubmed/7109809

are you the one the OP is talking about (i had an hypothesis when i seen an avatar you had with flaming swords...)
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