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Signing UpStep 1What You Need...
2. 1/4 X 28 nut - I had one in my parts bin
3. 1/2" Heatshrink tubing
4. 1.5v Glo-plug - Theater Effects
5. Flash cotton and flash paper.
6. JB Weld
7. Small zip ties
8. SPST Momentary Switch - Radio Shack
9. Butt splice
10. AA Battery holder and battery
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Before I had my tube I used a plastic thing that some toothpicks came in, which was closer to 3/4" on one end, though it narrowed slightly towards the back. The difference I noticed was that the wider tube creates much larger, nicer looking fireballs, but doesn't shoot them as far. On the other hand, the smaller brass tube still makes pretty nice looking fireballs, shoots them farther, and is pretty much necessary if you intend on using this for magic tricks (the bigger tube would be too visible from behind your hand).
Overall, I think 1/2" is probably a pretty good size, and I'm pretty sure it is what is used in the ones you can buy in magic shops and online:
http://ecx.images-amazon.com/images/I/41yLuil08UL._SL500_AA300_.jpg
http://www.revolutionmagic.com/images_product/flash-gun-fire-trick-pr.jpg
5/8" would probably also work pretty well. Just decide which size you need based on whether you want to be able to conceal it or not, and then based on what type of effect you'd like to produce (farther shooting or bigger fireballs).
As for the shrink wrap, that's really not necessary, it's just for looks. As you can see in the pictures above, the commercially produced ones prefer just the tube. This is probably because the brass blends with your skin better than black shrink tube, and they're normally made for magic tricks, so you want to keep them hidden.
If you want to use the shrink tubing anyways, keep this in mind: shrink tubing is normally measured at it's un-shrunk size, so you will need a piece that is larger than your tube by a fair amount, which you can then shrink down over it using a hair dryer or lighter.
It looks to me like (in the video) he happened to have a piece that was just large enough to slip snugly over his tube, and therefore didn't need to be shrunk, but it's more likely that a piece of the same diameter will not fit, and therefore you'd do better by shrinking a large one down. Keep in mind also that it will shrink slightly in length too, so cut it a little long at first.
larger = less distance, larger fireballs (and more cotton and paper needed)
smaller = shoots farther, smaller fireballs, easier to conceal.
To be specific, I used a thin walled tube, so the ID was only 1/16" smaller than the OD. However based on my experience I'd recommend using a larger tube than i used - at least 1/2" ID in my opinion.
One other fact to consider: at some point, you will get an inverse effect with a smaller tube - it will not shoot farther. This is because at some point, if the tube is too small, you can only use very little flash cotton, or else you'll just shoot the paper out without it igniting. And of course with less flash cotton, it won't shoot as far. That's the advantage of a particularly wide tube (think 5/8") - the large area lets you still use a lot of flash cotton while still igniting the paper, and using more cotton will shoot it farther, so it's generally a more optimum configuration, barring any size/concealment issues.
I noticed this effect after using a pen tube to shoot fireballs - it won't shoot as far because anything more than a teeny amount of flash cotton will just shoot the paper out un-ignited.On the other hand, a pen tube loaded with flash cotton is great for shooting other stuff out :) - it's really powerful!
Sorry about going on and on. I try to make sure I answer the question in the first line before I go on and on about other stuff I've noticed, so you can ignore the rest if you like.
(even though this is an old question, I'm posting it in case anyone still wants to know the answer now)
Just go through and add up the things you don't already have:
PARTS:
Tube - $10
Nut - $5
Glo Plug - $4-5
Switch - $4-5
Battery Holder $1
Wire Ties (you could use a lot of other things) - $5
Butt Splice (optional if you just solder it) - $4
Heat shrink (kinda optional) - $4
TOOLS:
JB Weld - $4
Soldering Iron Kit - $7
CONSUMABLES:
Flash Paper (2"x3" 20 pcs) - $4
Flash Cotton - $10
AA Battery - $2
Min Cost (if you already own the tools and consumables, skip the optionals, and find a nut laying around) - $19
Max Cost - $65
I ended up taking a piece of 1/4" plywood, drilling a hole in it, and then threading the glow plug in to make threads. I then fitted this into the end of the tube, slightly recessed, and soldered the washer that came with the glow plug onto the end, filling all the gaps with solder. I was then able to solder the negative lead right onto the end of the tube, and then thread the glow plug through the washer and solder (making contact), right into the plywood.
Sorry about the quality of the pic, though I think you can see the basic idea. You of course can't see the plywood because it's under the solder.
This is of course just what I did. If you can find a nut that would be much easier, but I got impatient and just kinda made it up.
When you buy it you want to look for N.O. (normally open), not what you have: N.C. (normally closed).
Normally open means the circuit is open until you press the switch, then it closes the circuit.
Normally closed means the circuit is closed until you press the switch, then it opens the circuit.
An open circuit is disconnected.
2. Most model rocket engines i've seen have a narrow hole that an igniter needs to be stuck into. The end is just a ceramic cap. So your glo-plug would never actually make contact with the propellant, which is what is needed for it to ignite.
You Could make something like this, but wired to a model rocket igniter instead of a glo plug, but once again, only try that if you don't care too much about having hands. Seriously.
If you are thinking of trying to get the flash paper fireball to shoot and ignite the engine, the hole in the ceramic cap is too small, so it is VERY unlikely you'd actually get a flame to contact the propellant. The engines are designed to ignite only in very specific circumstances, almost to the point where pretty much only the provided igniters would work. I actually think in most cases open flame won't even do it.
http://www.theatrefx.com/store/commerce.cgi?product=flash_paper_and_related