27 replies to this topic

[mshaner]

Hello,

I've been experimenting with different igniter formulations for rocketry over the last few months because kits like Igniterman (with Mg), etc are becoming difficult to ship and therefore difficult to find. I've found some fairly good mixtures for igniters but I would also like to find a mixture for the red glassy material found on the end of commercial ematches. I use electric matches for setting off dual deployment charges for high altitude rockets and I need something that easily ignites with a simple 9v battery. The little charge basically pops instead of a sparking and burning.

Question: can anyone enlighten me on what the composition consists of?

If you need a snapshot, let me know.

Thank you.

Shane Heilman

[mrpyromx]

I do a peice of nicrome wire about 2" long then fold it into a v and dip the end in a nice thick slurry about 5 times letting it dry for a couple hours between dips. yet to have one fail. I make my slurry with 4F BP and dextrin. to be honest, I never really messure by weight for this. I use 6tbs bp and 1tbs dextrin and add water till its the concistency I like. I make about 3 dozen from this and then whats left I scrape it into a small form and let it dry and cut it up for plain little stars.

[RegimentalPyro]

Ignitor compositions usually includes an amount of ground silicon [sand?]. The advantage with this is that small fragments of molton silicon are propelled into whatever you are trying to ignite, thereby ensuring a reliable "passfire"

MrPyromx - having made and fired your ematches, is it possible to reuse/recycle them by recoating them in slurry?

[mrpyromx]

Sometimes, it really depends on the charge of the battary. 7 times out of 10 the wire breaks. I use a fully charged 600 cca car battary and the wire I get from ladys/girls donating their dead hairdryers. I have tried using single strand of copper wire but it takes a bit to heat up fast enough.

[mshaner]

mrpyromx,

Does this mixture you use pop or propagate more like the traditional igniter?

Just curious and BTW thanks for the insight,

Shane

[Phoenix]

Ignitor compositions usually includes an amount of ground silicon [sand?].

Sand is silicon dioxide. However, you can buy polished elemental silicon from crystal shops. This shouldn't be too expensive if you're only going to make e-matches with it.

BP e-matches I have made (not very many at all) just flared up, rather than popped.

[dfk]

Bp works fine in most cases if you don't mind the small ignition delay.

Nichrome is generaly coated first with a small amount of very heat sensitive explosive prime which can then be coated with some type of BP slury to spread fire and ensure ignition.

I don't have all my comps here with me but the comp that has worked for me is a chlorate/Ant sulphide one, dangerous stuff, never mix dry.

Since I dont want to get flamed for doing so... im not going to post the comp on this forum, but I will share through PM.


Marcus

[willd]

heres a composition i found in a database im not sure how well it works as ive never tried it but if you can get the chems u can give it a go

Electric Match
Source: PML, post by Mike Carter <pyro@primenet.com
Comments: This composition does not require the use of a bridge wire. The composition itself acts as a resistor. Comments from the poster: "The matches fire just fine on 200 feet of #16 guage wire and a standard 12V battery two at a time. Sometimes there's a delay...I haven't tested these on the high power electric firing systems so I don't know how they fare."
Preparation: 1) Bind in water. Make CMC & Water into a mostly soupy mess. Add components into a container and mix well. 2) Dip freshly stripped wire with both conductors about 1mm or slightly less between them, evenly parallel. The longer the exposed metal on the wire, the less Ohmage the match will have. Allow to dry in vertical hanging position. Redip as necessary. I find that two dips is just fine. 3) Once the comp is dry, you will need to coat it with NC (Nitrocellulose) laquer. I find that two dips in the NC laquer is enough to keep the very brittle comp from cracking or splitting while manuevering the wire into your shell or mine or rocket motor. I normally will color the double-dippers with some Iron Oxide stirred into the NC Laquer so I have a visual that they're unsuitable for firing whistle motors. (Double Dipped tend to go BANG, and destroy the motor).
Potassium chlorate, Ball milled into a fine powder.....16
Conductive lampblack..............................3
Magnalium (50/50), 200 mesh.......................3
Atomized aluminum, 120 mesh.......................2
Zirconium, 200 mesh (optional)....................2
CMC Binder (carboxymethylcellulose)...............5

[mrpyromx]

mine kinda flare like a match but a bit faster.

[mshaner]

I have been told that one can clean and recoat with slurry for multiple uses, but I have yet to try it.

Shane

[mshaner]

Marcus,

Did you receive my email? Just checking to make sure I sent it correctly.

Shane Heilman

[KC Blast]

I wanted to make some e-match's much like what firefox sells. I've read the article on mbrocketry.com's web site. What I'm having troubles with is figuring out how the ruby fluid flux helps? Maybe I'm using it wrong. I'm brushing it on my copper board, both sides, then I wrap the 36ga nichrome wire around the board and apply solder. The solder isn't keeping the nichrome in place because I can lift the wire right off the board and be left with a bunch of solder. What tips or tricks can someone tell me so I can make these better. Thank you.

Eddie

[karlfoxman]

I wanted to make some e-match's much like what firefox sells. I've read the article on mbrocketry.com's web site. What I'm having troubles with is figuring out how the ruby fluid flux helps? Maybe I'm using it wrong. I'm brushing it on my copper board, both sides, then I wrap the 36ga nichrome wire around the board and apply solder. The solder isn't keeping the nichrome in place because I can lift the wire right off the board and be left with a bunch of solder. What tips or tricks can someone tell me so I can make these better. Thank you.

Eddie

Two problems can cause this. The copper on the board is not getting hot enough, solder will stick to copper that is clean and hot. The other option is that the copper is not clean, try gently cleaning the board where you wish to solder with a solvent and maybe emery paper to rough it up a bit. This should now stick, you should'nt really need the flux, it should now flow very well on its own.

Hope this helps

Karl

[Draco_Americanus]

Drat, I remember reading about a flux thats used with nichrome wire. That is assuming the solder sticks to the board, not the wire.
It's been my experance that nichrome wire has a very light coat of oil and is very difficult to solder, I just end up using as much heat as I can, but on a little copper foil/pad this can be bad.

[KC Blast]

Drat, I remember reading about a flux thats used with nichrome wire. That is assuming the solder sticks to the board, not the wire.
It's been my experance that nichrome wire has a very light coat of oil and is very difficult to solder, I just end up using as much heat as I can, but on a little copper foil/pad this can be bad.

Yeah, if I keep the soldering iron in one spot for to long, it will bubble up in that spot. It solder sticks very well to the copper board, just not to the nichrome wire. I'll try cleaning both very well and trying again. I just wanted to be sure "I" wasn't doing something wrong. Thank you both for your help on this.

Eddie Sola