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Home-made Scratch Igniters!

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jetra2

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Hi all,

Thought youse guys might get a kick out of this - it's so simple, easy, and fun to do that you'll never buy your own motor igniters again! (Electric matches for charges are a different story.)

OK...Here's what yer gonna do.
  1. Go to Home (rocket) Depot
  2. Buy yourself some CAT-3 Station wire. The kind that has 8 little wires inside of one big jacket.
  3. Go home.
  4. Cut yourself about a foot of the station wire off.
  5. Split the jacket open until you can grab the little wires with your teeth or pliers.
  6. Pull all the little wires out. I think they are somewhere in the range of 22-24 guage.
  7. Choose two of them, and trim them to a equal length.
  8. Now take one of the wires, and trim about a half inch off. Just cut it clean off!
  9. Strip the ends of both of the staggered pair of wires about a quarter to three-eighths of an inch. It's not rocket science, so DON'T measure it, unless you are just a perfectionist.
  10. Line the two wires up so that the solid copper wire that is exposed is staggered. If you did it right, you should be able to make the opposite end flush and have about a eighth of an inch between the end of the lower copper wire and the beginning of the higher copper wire.
  11. You OK so far? It's easy enough...
  12. Now hold the wires TIGHT between your thumb and the middle of your first finger right below the two copper wires. Hold it however you feel comfortable, but make sure your holding it tight!
  13. Now start twisting for about two-ish inches. See why we're holding it tight now? If you were holding it loose, it'll start turning itself between your fingers and you'll never get it twisted right!
  14. Ok, now that you've done that, go ahead and mover down to about 3 inches from the ends of the leads. Again, start twisting. Do it for about 1.5 inches. You want enough to keep the clips apart!
  15. Don't strip it now...do that at the field!
  16. Now smooth everything out nicely, and make sure it's mostly straight. Looks like an igniter almost, doesn't it?

That's as far as I've gotten with the one's I've been making. I am going to buy some nichrome off of eBay this week, and I'll update this thread then.

See ya'll around!

Jason
 

KermieD

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Save a little time, get some long strands (dunno--maybe 20 feet or so) of the thin wire out of the CAT-3 cable and get a partner. Chuck the pair of wires into a hand drill and have your partner hold the other ends. Voila!! Instant twisted pair.
 

Elapid

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and dip them in some conductive pyrogen, you're THERE!
they sell kits to make home-dipped igniters, but since motors come with extras, i seem to be accumulating them rather than running short.

without a pyrogen, NiCr wire will work to ignite BP motors without any pyrogen

good luck!
 

limd21

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I split surplus (aka "scrap") computer ribbon cable into pairs. Strip 1/4" from each pair for the business end, 1/2" from the hookup end. Dip into favorite conductive goo*, let dry, seal with nail polish. For BP motors, that's it. Nail polish is basically nitrocellulose which means it burns great. (Smokeless powder is just a more powerful version of the same stuff).

For conductive goo, I use graphite powder mixed with nail polish.

I'm one of those wacky low-power guys who uses homemade igniters because I usually use Quest motors. Great motors, crummy igniters - hence going homemade.
 

lalligood

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Wow. I *knew* there was a reason that I held onto several hundred feet of CAT5 cable in my garage... :D I'd love to make my own ignitors! Jason, please keep us up to date with your progress. Thanks.
Pictures too, please! :D
 

wwattles

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Originally posted by limd21
Nail polish is basically nitrocellulose which means it burns great.
Any particular brands or colors work better than others?

WW
 

limd21

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Originally posted by wwattles
Any particular brands or colors work better than others?

WW
Well, many give me compliments the on how attractive the hot-pink and sparkly purples look ;-)!

I've only used the cheapest clear polish I could find at the supermarket. I think it's "Sally Hansen" brand, and it specifically lists nitrocellulose on the ingredients list. That said, I've wondered if the metallics would make a nice flare as many pyrogens contain powdered metals...
 

edwardw

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I use the CAT-5 cable with 8 pairs inside that are twisted. I strip about 1/4" off each end, then use some 36ga nichrome for the pyrogen. I usually use about 3/16 to 1/4 length nichrome. I make the ignitors for my own sugar motors, so I just use that as my pyrogen. Never had an igniter failure.

If anyone needs any nichrome I have some that I sell. PM me and I'll give you the prices.

Edward
 

teflonrocketry1

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Instead of nichrome, you can use steel wool! Just unravel a longer strand and put it between the copper wire from the twised pairs (the fine grade works well). If you can't find nail polish that contains nitrocellulose, you can disslove ping pong balls (which are mostly nitrocellulose) in acetone or carburetor cleaner. I typically bend the end of each solid copper conductor over onto the steel wire and coat it with the nitrocellulose. I also use the ribbon cable; it makes a nice jig to hold every thing together during assembly and dipping.

Bruce S. Levison, NAR #69055
 

edwardw

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I have tried the steel wool, what is the trick with that? I could never get it to heat enough before burning out to light the pyrogen (KNCP fuel). That is the reason I switched to nichrome, cause it heated great everytime.

Edward
 

teflonrocketry1

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For steel wool I usually wad up a small piece of fine steel wool that just snugly fits into the motor nozzle so it doesn't need an ignitor plug to hold it in place. I crimp this in between the copper busses and liberally coat the ball of steel wool with pyrogen. I think the multiple strands and fine grade (00 or finishing grade) steel wool helps make the ignitor a success. Or you could try a single strand from one of the heavier grades (medium or course). I like the multiple strand approach since it's more reliable. You will have to experiment around and determine what works best for you in terms of voltage and the amount of steel wool etc. I used a 9 volt battery for the multi stranded ignitors.

Bruce S. Levison, NAR #69055
 

cdma77

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I would use nichrome wire. For one thing it is cheap and two it gets really hot and does't burn up like steel wool. It is also much easier to handle then sttel wool. Also get yourself six ping pong balls and 8 oz of acetone. Put you ping pong balls in the acetone to make nitrocelluose laquer. Check your igniter with a VOM for resistance with the nichrome wire attached. Dip your wire with the nichrome wire attached on it into the laquer mixed a a bit of bp or whatever pyrogen powder you like. Let the igniter dry. Re- dip the igniter in the laquer only(no pyrogen) to put a nice seal over it. Let it dry and re-check your resistance with a VOM. If your resistance is good (low) and should be ready to go. Remember since you aren't going to be using these for a recovery charge 100% success isn't required, however it would be nice !


Jeff
 

aksarben10

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I am a fan of the nichrome as well I use it with the wire wrap technique to make my ignitors. You can pick nichrome up cheap from McMaster-Carr, I like the 32 gauge for high current ignitors. I have used 30 gauge and found it nice but too stiff the 36 gauge was too thin and did not wrap correctly so I went inbetween with the 32 gauge and am liking it quite a bit. I collect old phone wire from the office the watch some TV and create ignitors. I wrap a bunch and then dip them later I made 30 the other night for our upcoming launch where I will give them away.

Scott
 
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