E-matches

[oldmanbeefjerky]

I have to say I agree that chlorates have received a bad rap in the past. I believe this is due to the lack of knowledge of these chems and the lack of ultra pure chems like sulfur( the older stuff used to be acidic) . It is a wonderful chem. as stated above, it has a broad range of uses that other oxidizers cant compete with. I love the fact that any person had the ability to make their own if they wish to take the challenge. Sensitivity has its uses as well. I find the dark flash (50/50) antimony/chlorate to be a great for friction igniter 's and ematches.

 

 

That reminds me, i want to start formulating an e-match mix with chlorate. Using actual match heads wrapped with super fine nichrome had become so much of a bother i stopped!

 

Thanks for the reminder Pyrojig

[Mumbles]

A gentleman on passfire recommends 7-1-1 Chlorate:Sb2S3:Conductive lampblack. With that relatively low conductive lampblack content, I bet you could use finely powdered graphite in it's place. That of course has nothing related to this thread, and we can start a new one if you want.

[oldmanbeefjerky]

Greetings.

 

As suggested by mumbles, I thought i should start this thread.

 

Currently i am starting an investigation into different E-match compounds, all of which are chlorate based, but i am open to using nitrate.

Mumbles suggested a chlorate antimony lampblack mix, but , if its all the same, ide also like to look into all the other options, rather than the obvious composition. So i am looking into other mixes.

 

Please post any suggestions and mixes that you know of or use!

I'm sure others visiting this thread in the future would also benefit from the collected information that may gather here.

[WSM]

A gentleman on passfire recommends 7-1-1 Chlorate:Sb2S3:Conductive lampblack. With that relatively low conductive lampblack content, I bet you could use finely powdered graphite in it's place. That of course has nothing related to this thread, and we can start a new one if you want.

 

This is an error. I shouldn't answer with my cell phone .

 

WSM

Edited September 30, 2011 by WSM

[WSM]

I've had good success using H-3 in NC for an e-match pyrogen. One may add a little fine metal or other additives, but the H-3 works fine as-is. A lacquer overcoat does wonders to prevent compatibility problems.

 

H-3

77 KClO3

23 airfloat charcoal

 

WSM

Edited September 30, 2011 by WSM

[Potassiumchlorate]

I use H3 as a prime with 5-10% silicon and NC-lacquer as a binder.

[pyrojig]

The 50/50 antimony/ chlorate( dark flash) seems to be the most reliable mix Ive run across. Not exactly the safest, or least static/friction prone, but 100% success rate. I like the dark flash for buttering the bridgewire and the h-3 approach for the outer protective layer. The best binder so far has been the NC . lac. I would almost suggest an additional layer of nc after that just to make a protective shell( although I never do) because I use a protective sleeve with my ematches.

Greetings.

 

As suggested by mumbles, I thought i should start this thread.

 

Currently i am starting an investigation into different E-match compounds, all of which are chlorate based, but i am open to using nitrate.

Mumbles suggested a chlorate antimony lampblack mix, but , if its all the same, ide also like to look into all the other options, rather than the obvious composition. So i am looking into other mixes.

 

Please post any suggestions and mixes that you know of or use!

I'm sure others visiting this thread in the future would also benefit from the collected information that may gather here.

[pyrojig]

I use H3 as a prime with 5-10% silicon and NC-lacquer as a binder.

 

Maybe we should move this conversation to the new thread started by oldmanbeefjerky.

What size wire is your bridgewires? I use the finer (48or 50ga) I believe ,Ill have to check. I would guess that with a larger wire you could light anything, but need a stronger source. I prefer the smaller and therefore need a sensitive comp. + I like having the ability to fire many at the same time with a smaller electric firing board.

Edited September 29, 2011 by pyrojig

[Mumbles]

Given the original post I was under the impression he was looking for bridgeless e-match compositions, which is why I gave him the one I did. For bridged e-matches it's a no-brainer to use 1:1 chlorate:antimony. It works too well to substitute. No use trying to reinvent the wheel when all you'll end up with is a square.

[pyrojig]

Given the original post I was under the impression he was looking for bridgeless e-match compositions, which is why I gave him the one I did. For bridged e-matches it's a no-brainer to use 1:1 chlorate:antimony. It works too well to substitute. No use trying to reinvent the wheel when all you'll end up with is a square.

 

Now Bridgeless is a fairly newer concept that makes a nice ematch (safety is a gained with this concept). If Im not misstaken , you need a CD sys to insure reliable ignition. Im not 100% sold on them being as reliable as a bridgewire or resistor(smd) igniters though.

Edited September 29, 2011 by pyrojig

[WSM]

Maybe we should move this conversation to the new thread started by oldmanbeefjerky.

What size wire is your bridgewires? I use the finer (48or 50ga) I believe ,Ill have to check. I would guess that with a larger wire you could light anything, but need a stronger source. I prefer the smaller and therefore need a sensitive comp. + I like having the ability to fire many at the same time with a smaller electric firing board.

 

I made e-match bridges for years with 40 gauge (0.0031" in diameter) NiCr. I recently obtained a roll of NiCr wire that is 0.0009" in diameter which is about 51 AWG, but I haven't used it for anything yet. I have made e-matches with various gauge resistance wires up to about 28 gauge NiCr and down to 0.00065" (which was Pt wire). Any wire approaching one thousandth of an inch, looks like lint when loosely piled (if you can see it at all).

 

The 40 AWG NiCr is very fine and one pound (454g) is roughly 6 miles of wire (about 9.6 Km) if I remember correctly!!! I have no idea what it currently goes for, but twenty years ago it was about $90 a pound for new material. Fortunately, I was able to acquire several pounds on the surplus market. I think I still have one left.

 

WSM

[WSM]

Now Bridgeless is a fairly newer concept that makes a nice ematch (safety is a gained with this concept). If Im not misstaken , you need a CD sys to insure reliable ignition. Im not 100% sold on them being as reliable as a bridgewire or resistor(smd) igniters though.

 

Bridgeless is tricky without careful and exacting application of a measured amount of pyrogen to a fixed length of a known gap on the match substrate. If you don't get it exactly right every time, you have no consistency (which rules it out for commercial applications). It's easier for a one-shot device with no need for accuracy in timing.

 

I don't bother.

 

I have used an etched copper bridge with a CD system and it worked very well. Even without a pyrogen, a respectable flare of copper plasma lept off the PCB substrate. Plus a standard sheet contained roughly 3000 "match heads".

 

WSM

[pyrojig]

I've gotta ask.... where do you get your pcb boards from? That is a load of match's

Bridgeless is tricky without careful and exacting application of a measured amount of pyrogen to a fixed length of a known gap on the match substrate. If you don't get it exactly right every time, you have no consistency (which rules it out for commercial applications). It's easier for a one-shot device with no need for accuracy in timing.

 

I don't bother.

 

I have used an etched copper bridge with a CD system and it worked very well. Even without a pyrogen, a respectable flare of copper plasma lept off the PCB substrate. Plus a standard sheet contained roughly 3000 "match heads".

 

WSM

[pyrojig]

I've gotta ask.... where do you get your pcb boards from? That is a load of match's

Bridgeless is tricky without careful and exacting application of a measured amount of pyrogen to a fixed length of a known gap on the match substrate. If you don't get it exactly right every time, you have no consistency (which rules it out for commercial applications). It's easier for a one-shot device with no need for accuracy in timing.

 

I don't bother.

 

I have used an etched copper bridge with a CD system and it worked very well. Even without a pyrogen, a respectable flare of copper plasma lept off the PCB substrate. Plus a standard sheet contained roughly 3000 "match heads".

 

WSM

[WSM]

I've gotta ask.... where do you get your pcb boards from? That is a load of match's

 

They're old stock and an early incarnation of ODA matches. They were made on thin PC board material so the match heads can be cut apart with shears. The only following steps required were soldering leads on and adding a pyrogen. As I recall, the total number of chips per sheet are 2800, not ~3000. Still, that is a lot of matches. I was concerned about compatibility of the copper traces with the pyrogen, but the manufacturer assured me they were coated with a protective layer after they were etched. The best way to fire them is with a CD system. Very effective...

 

WSM

[oldmanbeefjerky]

im gonna go for just plain bridged, using 44ga nichrome.

The one problem im having though, is properly and securely attaching the nichrome to the terminals. whats the proper right way to do this?

Bridgeless sounds a bit too complicated.

 

Also, are there any good e-match compositions that are combustable and work (like with iron oxide for the oxidizing agent ), while not posing a fire hazard?

[WSM]

im gonna go for just plain bridged, using 44ga nichrome.

The one problem im having though, is properly and securely attaching the nichrome to the terminals. whats the proper right way to do this?

Bridgeless sounds a bit too complicated.

Also, are there any good e-match compositions that are combustable and work (like with iron oxide for the oxidizing agent ), while not posing a fire hazard?

 

I solder them using phosphoric acid (minimal amount, applied with a tooth pick) for the flux. Using phosphoric acid, the solder wets the nichrome.

 

WSM

[dagabu]

I have 12" x 1" x 1/16" double sided, copper plated PCB if anyone wants to make their own. Each strip will make about 500 if cut carefully.

 

-dag

[WSM]

I have 12" x 1" x 1/16" double sided, copper plated PCB if anyone wants to make their own. Each strip will make about 500 if cut carefully.

 

-dag

 

That would work but my personal preference is to use thinner PCB material to make e-matches from. If the PCB stock is cut to 3/8" (+/- 1cm) wide strips and tinned; it's very easy to solder bridgewires and leads to the chips, and cut them apart.

 

To facilitate making matches, I use hemostats with flat jaws to hold the wire and chip in place for soldering. I hold the hemostat handle in a small hobby vice for a "third hand" while soldering.

 

WSM

Edited September 30, 2011 by WSM

[WSM]

That would work but my personal preference is to use thinner PCB material to make e-matches from. If the PCB stock is cut to 3/8" (+/- 1cm) wide strips and tinned; it's very easy to solder bridgewires and leads to the chips, and cut them apart.

To facilitate making matches, I use hemostats with flat jaws to hold the wire and chip in place for soldering. I hold the hemostat handle in a small hobby vice for a "third hand" while soldering.

WSM

 

There are two schools of thought on how the bridgewire is applied to the chip;

 

1) straight across the end of the PCB material for ease and simplicity of manufacture, or

2) across an air gap so the pyrogen surrounds the bridgewire for more intimate contact and better heat transfer.

 

I've done post-mortems on many different commercial samples and have seen examples of both styles. In my own experience, if the match is well-made, either method will work. With type one, great care must be taken to be sure it is made correctly and that the pyrogen is in intimate contact with the bridgewire. This is true with both types, really. Type one tends to be fairly robust physically and the bridgewire less prone to damage by handling before application of the pyrogen. Type two offers more contact with the pyrogen for more reliable ignition but the bridgewire is more exposed to potential physical damage (by handling) before the pyrogen is applied.

 

Choose a style to suit your own preferences and skills. If made right, they all work.

 

WSM

[WSM]

There are two schools of thought on how the bridgewire is applied to the chip;

1) straight across the end of the PCB material for ease and simplicity of manufacture, or

2) across an air gap so the pyrogen surrounds the bridgewire for more intimate contact and better heat transfer.

I've done post-mortems on many different commercial samples and have seen examples of both styles. In my own experience, if the match is well-made, either method will work. With type one, great care must be taken to be sure it is made correctly and that the pyrogen is in intimate contact with the bridgewire. This is true with both types, really. Type one tends to be fairly robust physically and the bridgewire less prone to damage by handling before application of the pyrogen. Type two offers more contact with the pyrogen for more reliable ignition but the bridgewire is more exposed to potential physical damage (by handling) before the pyrogen is applied.

Choose a style to suit your own preferences and skills. If made right, they all work.

WSM

 

One of the most vexing problems facing commercial e-match makers (especially those involved in aerospace applications, particularly NASA) is failures due to poor contact of the active pyrogen materials with the bridgewire. One of the causes has been shown to be bubbles in the pyrogen slurry. Each bubble in contact with the bridgewire is an area of wasted space where little or no heat transfer occurs, and misfires can result. [Another was their choice of hightech binder and the methods of its application which would sometimes insulate the bridgewire from the pyrogen, causing a failure; but I'm not going to address this here.]

 

To avoid this problem, several things may be done. Work slowly in stirring to prevent introducing too many bubbles in the first place (avoid making a frothy mess using high speed blenders, for example) or de-gas after mixing. Degassing involves exposing the slurry to a vacuum so any trapped gasses are quickly released. Dipping the chip slowly or carefully so air is not trapped around the bridgewire. Use of thin slurries can help, if they have low surface tension but many coats may need to be applied. Avoid too much solvent in the slurry. One of my goals in making pyrogen slurries was high solids content in the slurry so there would be less shrinkage of the pyrogen bulb. Several layers or coats helped in making a good e-match that would reliably ignite a firework or rocket.

 

Use care and common sense in making your matches, especially if the application you're putting them to is critical.

 

WSM

Edited October 1, 2011 by WSM

[oldmanbeefjerky]

hmm, double sided pcb board, that does seem easier than what i am doing now which is getting some wire and taping it to some board, then soldering the nichrome to the wire.

I think i had best get some etchant, or make my own, since getting solder to stick is always a problem i have faced when getting solder to stick to copper.

[WSM]

hmm, double sided pcb board, that does seem easier than what i am doing now which is getting some wire and taping it to some board, then soldering the nichrome to the wire.

I think i had best get some etchant, or make my own, since getting solder to stick is always a problem i have faced when getting solder to stick to copper.

 

Hi OMBJ,

 

If you can get some phosphoric acid (you don't need much) it will work wonders as a soldering flux. It even helps the solder stick to the NiCr. Most other fluxes only work on the copper but this one actually wets the NiCr with solder. Also very little is required; I usually apply it with the tip of a wooden toothpick.

 

See if you can get a little phosphoric acid .

 

WSM

[dagabu]

Hi OMBJ,

 

If you can get some phosphoric acid (you don't need much) it will work wonders as a soldering flux. It even helps the solder stick to the NiCr. Most other fluxes only work on the copper but this one actually wets the NiCr with solder. Also very little is required; I usually apply it with the tip of a wooden toothpick.

 

See if you can get a little phosphoric acid .

 

WSM

 

What percentage do you need and where do you buy it? Brewing supplies stores have the 37% solution but I cannot find a higher percentage...

How about Duda? http://www.dudadiesel.com/search.php?query=phosphoric+acid

 

-dag

Edited October 3, 2011 by dagabu

[WSM]

What percentage do you need and where do you buy it? Brewing supplies stores have the 37% solution but I cannot find a higher percentage...

How about Duda? http://www.dudadiese...phosphoric+acid

-dag

 

Hi dag,

 

Those sources look like they would work. You really need only the smallest amount, a quart for example, would last a lifetime. The biodiesel supply looks like a decent source. If you have any agricultural suppliers in your area that provide farmer's fertilizer chemicals, phosphoric acid may be had where they use it to mix fertilizers to spray on crops.

 

Good luck and let us know how the search goes.

 

WSM