madmandotcom Posted March 28, 2011 Posted March 28, 2011 i have recently made a batch of electric matches using nicrome/ data cable and hooked it up to 2 9v battery's and it didn't even get warm, any ideas?
dagabu Posted March 28, 2011 Posted March 28, 2011 How thin (what gauge) was your nichrome wire? I use .003" nichrome wire.
Zeus Posted March 28, 2011 Posted March 28, 2011 Chances are your nichrome wire is too thick. Two 9 volt batteries won't make much hot at all, try 4 to 8 AAs. I've not used e-matches, I do know how much it takes to heat up wire though.
dagabu Posted March 28, 2011 Posted March 28, 2011 GULP!!! E-match nichrome wire is half the diameter of a human hair. You are using huge wire!
Arthur Posted March 28, 2011 Posted March 28, 2011 Professional e-matches use about 50 gauge nichrome wire, and it's not easy to solder so I have used the igniter chips from ODA which are ready made and available by the hundred from a USA company (ODA!) Good product and good guy to deal with. He may also sell undipped igniters with wire attached - makes life even easier.
handymanherb Posted March 28, 2011 Posted March 28, 2011 (edited) I fired the ones I ordered from harry last year with a 9 volt battery , I had every thing wired to a nail board, the negitive wired to the 9 volt and all I had to do was touch the positive to the nail and off it went, I fired 25 cakes without moving, it was nice for a change and beats the hell out of hand lighting, getting next to a cake going off, to light the next one. Is that ODA.com Edited March 28, 2011 by handymanherb
handymanherb Posted March 29, 2011 Posted March 29, 2011 http://www.oda-ent.com/default.htm Thanks Mumbles, I need to order some for the 4th, I'm not waiting till the last minute this year and wondering if I would get them on time.
Peret Posted March 29, 2011 Posted March 29, 2011 0.33 millimeters is about 28AWG. As Dag says, HUGE! It will take tens of amps to heat that, hundreds to fuse it. You could do it with a car battery perhaps. FWIW, American wire gauges (AWG) halve in area every 3 gauges, so 50AWG (0.025mm) is 1/13 the diameter and 1/170 the area of 28AWG. So to a first approximation, compared to 50AWG it takes 170 times the current to light up a 28AWG wire, and it would take in the region of 170 times longer to heat up, since it has 170 times the thermal mass as well.
Bonny Posted March 29, 2011 Posted March 29, 2011 When I made ematches a few years ago, I used ~40 gauge nichrome IIRC. I did not solder them, but just twisted tightly around the leads made from some solid cat 5 wire. They worked just fine on 50-100 ft of wire. I was firing with a 12V system.
madmandotcom Posted March 29, 2011 Author Posted March 29, 2011 yikes, my stuff is thick by comparison, think i might go back to 5 amp fuse wire, a bit more expensive, but a lot less resistive
Nessalco Posted March 29, 2011 Posted March 29, 2011 Making ematches was actually my first 'pyro' project. In high power rocketry, electronic flight computers trigger ematches to deploy parachutes, light motors, and the like. Since those flight computers must sequentially fire several ematches from a single 9v battery, sensitive matches are required. I too use the 50g ematch heads from ODA. Took a little time and some experimentation to get the process down, but at this point I'd claim 100% reliability in my results. Since I'm putting hundreds to thousands of dollars on the line with each flight, not to mention the risk to people on the ground, they had *better* work correctly. I used about 50 of my matches to fire my show last summer, and they worked perfectly. If anything, they could be said to be a bit too sensitive - A single match will fire instantly from a 1.5v button cell. From the testing I've done it seems the no-fire current is .1A, the all-fire current on the order of .35A. For rocketry this sort of sensitivity is necessary. I've tried to get them to fire from static discharge, but have not been able to do so... not saying they won't, but I haven't been able to get one to pop. A question I'd ask of the pyro experts... I use darkflash as a first-fire and H3 as the main pyrogen. As these are both chlorate based, they have to be coated with NC to be safe with BP. This sometimes has the effect of making the match 'pop' the pyrogen off without it burning fully. So long as the match is contained (for example in quickmatch tube) it's OK as the fire passes just fine, but it's not elegant. Has anyone tried perchlorate based compounds in this application? I'm assuming such a match would not need to be coated to be safe with sulfur-containing compounds, and would be less likely to shatter as the first fire caught. Thanks!! Kevin O
dagabu Posted March 29, 2011 Posted March 29, 2011 Kevin, I have another 1000 ODA chips coming and after playing with hundreds of them in various dips, i like the simple ones the best. 70:30 flash and BP meal mixed 50:50 and suspended in NC lacquer. They take longer to burn and are slow by comparison but there is no pop and the aluminum makes for a hot flame envelope.
WSM Posted April 8, 2011 Posted April 8, 2011 Professional e-matches use about 50 gauge nichrome wire, and it's not easy to solder so I have used the igniter chips from ODA which are ready made and available by the hundred from a USA company (ODA!) Good product and good guy to deal with. He may also sell undipped igniters with wire attached - makes life even easier. In answer to the soldering problem: try phosphoric acid for soldering flux. It works well and the solder wets the nichrome. WSM
WSM Posted April 8, 2011 Posted April 8, 2011 A question I'd ask of the pyro experts... I use darkflash as a first-fire and H3 as the main pyrogen. As these are both chlorate based, they have to be coated with NC to be safe with BP. This sometimes has the effect of making the match 'pop' the pyrogen off without it burning fully. So long as the match is contained (for example in quickmatch tube) it's OK as the fire passes just fine, but it's not elegant. Has anyone tried perchlorate based compounds in this application? I'm assuming such a match would not need to be coated to be safe with sulfur-containing compounds, and would be less likely to shatter as the first fire caught. Thanks!! Kevin O I've had success using perchlorate based compositions but the ones I used were very sensitive. I never made more than one gram at a time and mixed it with NC immediately (before it dried out from the wet-mixing process I used) so it was no more hazardous than a flammable liquid until dried. I dipped the match head once, dried the pyrogen and then dipped a second time. While the pyrogen was still wet I dusted it with -400 mesh titanium so it had a matte grey finish when dry. These match heads made a five inch sparkle ball when fired that would ignite almost anything. I'll post the composition preparation in the HE section, but not here. Many sensitive compositions can work, but be aware of incompatibilities that could bite you if due caution isn't practiced. WSM
dagabu Posted April 8, 2011 Posted April 8, 2011 I use ODA's composition, same as Kevin but 50:50 chlorate and Trisulfide and top with H3. They do pop but have never had one actually fail because of it. I have never been able to trigger one bt static though my son and I have tried many a time!
WSM Posted April 8, 2011 Posted April 8, 2011 I use ODA's composition, same as Kevin but 50:50 chlorate and Trisulfide and top with H3. They do pop but have never had one actually fail because of it. I have never been able to trigger one bt static though my son and I have tried many a time! The half and half chlorate/antimony sulfide mixture is basically torpedo mix, so treat it appropriately (with respect!), especially before it's mixed with NC lacquer. It works and I have no argument with it. Back in the day I had great success with nothing more than H-3 in NC. As long as the composition was in intimate contact with the bridge wire, it worked. I tried for high solids loading in the lacquer to minimize shrinkage of the composition bulb. Two dipping and drying cycles with a thinned NC overcoat afterward (to prevent incompatibilities) did the trick. Adding a few percent of hot metallic or semi-metalic components can add a lot of heat transfer ability to the match. Don't over-do the conductive ingredients or you may short out the match, electrically.!!! WSM
WSM Posted April 8, 2011 Posted April 8, 2011 ...They do pop but have never had one actually fail because of it. If the E-match pops, it's a non-issue; as long as the device you're trying to initiate ignites. If not, put the E-match in a first fire device then in contact with the item to be initiated. BUT, if the E-match IS the device; then yes, it's an issue. Things to do are: Thin the NC used as a binderExperiment with various compositionsTry layering different compositions, like a small bead of hot composition as a bridge wire butter then a milder one as the bulk of the bulbTry omitting the lacquer overcoatLowering the input voltage and current to give the bridge wire a slower, gentler heat up time If you try all these and still don't succeed, tell us and we'll suggest more options . WSM
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