48 replies to this topic

[cooperman435]

Ok I think Ive perfected (or at least satisfied myself with) a good pyrogen. Ive been trying to balance the violence of the ignition, flame production, ease (speed) of ignition and that a lot of my comps seem to pop and extinguish themselves after the initial ignition resulting in little or no actual flare.

Its nothing new or revalutionary I have to admit but rather a modification of alany 's bridgeless ematch composition found on here and his website. Ive removed the lampblack due to it being unnececcery now as there bridged and replaced it with some extra Antimony trisulphide and some K Benz as an aid to flame production. It now stands at:

65 K Chlorate
11 K Benz
21 Antimony Trisulphide
3 NC POWDER

all are ground seperately but for the NC Powder and mixed WET to a syrup like smooth paste and the ematch head (tutorial to follow) is dipped.

They dry hard though Im going to do some more testing with higher amounts of NC powder as you can still damage the head with rough handling. This is likely to make the head pop when ignited though so I will see.

They give a small ping pong ball sized globe of white flame when ignited with a lot of heat and ignite as good as instantly though I still think I will be better off with thinner nichrome than the 40swg I curently have as on auto fire my remote firer only sends current for a small space of time and some just dont fire when using it. Not had any failures at all yet as any that didnt fire on the auto feature fired after when I used the single fire system.

AAAAAAGGGGHHHHHH!!!!!!! had a look at the composition this evening and found it to have turned to a jelly! even with more acetone it doesnt seem willing to re emulsify so another set of experiments to come. Im guessing its some rection involving the K benz as no one has mentioned anything before re the antimony tri or K chlorate doing this in an NC laquer before.

Edited by cooperman435, 06 January 2008 - 05:48 PM.

[BrightStar]

I'm still using the same three layers for my #50 guage PCB chip type match heads:

Primer: 50/50 Potassium Chlorate with Antimony Trisulfide, each passing 200-mesh (important), mixed wet with a little 5% NC ping pong laquer in acetone, adding extra acetone to thin if needed. Stir frequently for consistency. This should cover the tip of the match only.

Pyrogen: BP (fine willow meal, easy) or fine H4 (70/30 perc/charcoal, better - no sulfur) in minimal lacquer. This covers the body of the match and can be fairly thick.

Coating: One single dip in 5% laquer, covering the body of the match and the first few mm of lead wire. If this layer is too thick, the match may shatter rather than burn.

Each layer must be allowed to dry before adding the next.

The matches have a resistance of about 1.5ohms and pop instantly on 0.5 to 1A of current, making them directly compatible with commercial matches. I'm on my 5th batch and so far, they have been 100% reliable. Some have been stored for 6 months and still work fine.

Edited by BrightStar, 12 January 2008 - 11:29 AM.

[icarus]

try a tiny batch with no nc, add water for stiff slurry then jell it with a bit of wall paper paste. It sticks well but drys quite brittle when dry dip in nitrocellulose laquer stored in stoppered bottle nc in acetone drys in minutes one dip flares well 2 dips tend to go bang and wreck rocket motors I used this method for bridgless ignitersi

[cooperman435]

Right well thanks go to Brightstar, Ive used his 50:50 antimony trisulphide and chlorate setup with NC to make 48.5 : 48.5 : 3 respectively and it seems to do the trick though Im not second dipping in bp or nc laquer yet. Ignites well and fast with a decent flame and has ignited quickmatch very well with very little pyrogen at all due to its reactive nature its just not needed.

now just working on perfecting the nichrome wire thicknes. Mines still 40swg (88 ohm)and I need to make the bridge wire very very short (1mm) to get very quick ignition from my remote firing box. Ive some 42swg (137 ohm) on the way to test so Im hoping it will be a little easier to make the heads as the gap wont have to be so tiny with this new wire. Im still trying to obtain 41, 43, 44, 46 and 47swg to test too if anyone has a meter I can have?

[Draco_Americanus]

my nichrome wire is thick stuff i think it's about 20-24 awg and has a resistance of about 16.4 ohms per foot, back in the day i used it for ematch with no pyrogen, just an inch or so coiled up and stuffed into estes C class rocket engines. I have had this wire for about 15 years now so it's time to put it to use.
When you guys refer to "ping pong ball NC" is that literaly ping pong balls desolved in solvent?

[BrightStar]

When you guys refer to "ping pong ball NC" is that literaly ping pong balls desolved in solvent?

Yup, just cut 'em into strips and dissolve in acetone or MEK. About 5g ping pong to 50ml solvent gives a starting point for 10% lacquer. It's certainly not pure NC - probably quite a bit of cellulose acetate, filler, colour and plasticiser but it works as an excellent binder nonetheless. The trick is to use as little as possible in the match compositions - just enough to make a thick paste and then thin with extra acetone as you go along. Too much and the matches may crack instead of burn.

You can make e-matches using the chlorate/trisulfide primer alone, but the stuff is VERY sensitive to friction, impact, heat or sparks. That's why it's best just to dip the tip of the match a couple of mm in it then coat over with something less reactive. I would never want to have to push an uncoated match into a live shell leader

Edited by BrightStar, 07 January 2008 - 11:46 AM.

[icarus]

i used a few grammes of gm3 nitro cellulose re loading powder in acetone it swells up and forms a full bottle of really thick sticky fast drying nc laquer

[cooperman435]

Ive started the tutorial now. Its still a bit incomplete lacking pictures, the video and the final process of dipping the pyrogen but it will give you the idea. Ill be putting pictures up as soon as I can and at the same time completing off the dipping part.

You can read it here just click on the "MAKING EMATCHES" picture:

http://www.freewebs....jectshidden.htm

please give me your feedback though I know its a little hard to understand without pictures I have done my best to make it as clear as possible.

Edited by cooperman435, 12 January 2008 - 06:01 AM.

[cooperman435]

OK its done pictures and all!

same link as above or just go to my website and go to "PROJECTS", "PYRO PROJECTS" and then "EMATCH MAKING"

Please let me know if you see any problems. or what you think of my method

[paul]

cooperman: that´s one good (though standard) method making matches! Nice tutorial, anyway!
Thats a good way to make small and reliable matches. I´ve found these type of matches to get higher in resistance over time. This is only when you don´t solder the nichrome to the main wires, anyway...

I´ve made a totally different attempt to create a reliable e-match, which is a bit bigger. Though I´ve created it
to be easily attached to leader match from shells for example. It´ll spit a huge but directed spread of fire when ignited.

Here´s how it looks. It can be easily produced in houndreds. A few tools need t be prepared for that, but it can be done. It looks much
more complicated that it really is.

Click me for a PDF with a few details...

Here´s a image sequence of one of the ignitors. (extracted from a 60fps video)

Flame is about 5-6cm high and very hot. Metals/Oxides can be added to get even higher thermite-like temperatures.

Edited by paul, 21 March 2008 - 11:18 AM.

[phildunford]

Hi Paul

Very nice ematches...

If you are using Nichrome wire, how do you solder it? Is the blob of solder just trapping the wire rather than actually soldering it?

[paul]

Ha! It took ages to find out how to solder it! It´s VERY easy. It´s all up to the mechanical treatment of the wire before soldering.
The wire is black and covered by an oxide layer. You have to pull it trough a folded piece of fine sandpaper (between thumb and index finger)
to get rid of that! After that it´s blank and you can solder it like plain copper wire!

I tried different expensive solders before but its really all up to the wire itself! I may post a few macro pix of the wire before/after if you lik!


Here´s the guide I promised!With a few close-ups. You can zoom in quite a bit.
I´ve used HQ pix.

Edited by paul, 21 March 2008 - 03:54 PM.

[paul]

Unfortunately the edit-function is disabled after 24hrs... So here´s another shot
of a ignitor made like cooperman makes them:



This should proove that the "swim-up" effect disappears totally, once the oxide
layer is removed...

[cooperman435]

Almost like I make them! lol

In that picture it appears though the copper wires are too large (what swg is the nichrome wire btw?) and I would suggest far more wraps on the short lead before transferring to the longer lead so the soldering isn't necessary.

Iv just worked out I've now fired over 400 of my e matches and still haven't had 1 single fault (YET) so I think that proves that the solder isn't needed? Although the picture below is not brilliant the 44swg wire is only 0.081mm in diameter and wound very tightly around both copper wires to mechanically fix them and insure a good contact. Due to the large amount of nichrome covering both copper contacts the ematch pyrogen is unlikely to ever touch the copper itself preventing any later issues with oxidisation, resulting in poor electrical contacts. Also because my pyrogen is NC laquer bound it shouldn't react with either metal anyway.

Edited by cooperman435, 24 March 2008 - 03:40 PM.

[paul]

Almost like I make them! lol

In that picture it appears though the copper wires are too large (what swg is the nichrome wire btw?) and I would suggest far more wraps on the short lead before transferring to the longer lead so the soldering isn't necessary.

Iv just worked out I've now fired over 400 of my e matches and still haven't had 1 single fault (YET) so I think that proves that the solder isn't needed? Although the picture below is not brilliant the 44swg wire is only 0.081mm in diameter and wound very tightly around both copper wires to mechanically fix them and insure a good contact. Due to the large amount of nichrome covering both copper contacts the ematch pyrogen is unlikely to ever touch the copper itself preventing any later issues with oxidisation, resulting in poor electrical contacts. Also because my pyrogen is NC laquer bound it shouldn't react with either metal anyway.

Yeah, you´re totally right there! I only posted my pic to show others that nichrome can be perfectly soldered, sause some guys always
seem to have problems with that!

The wire I use is slightly thicker than yours, it´s 0,1mm.
I´ve got thinner nichrome also, but I like to use that 0,1mm stuff
I really did not want to criticise your methods or your e-matches! I´ve used
"your" method for years as well, I just wanted to present some new ideas
on making e-matches, like a e.match with a directed flame. I´m always trying
to make up things for special purposes...



That´s by far the smallest e-match I am capable of producing... Though it´s too small
and fragile to be used in "field pyro" It has it´s uses anyway. Coated and everything
it fits through a <2mm hole. Sometimes I need such ignitors...

Anyway, for nearly everything else I´m just using the other, more durable and practical
methods! Like you...