Really Small Fuse

[Evil Dog]

Years back (like in the early 80s) I remember buying a very small diameter fuse for use with one of the CVA model cannon.  It was a brownish color and appeared to be a coated wire.  It was maybe 1/32" diameter, may have been even smaller.  Is this stuff still made?  Know where to find any?  I checked the board resource links and couldn't find it.

[Rickk]

I think it's called Jetex. I don't believe it is made any more, at least with the wire core. There apparently is a resurection of Jetex powered planes, so a fuse is available. The new fuses is not wire cored. I'm not sure how hard it is to get... you may be ordering it from England. If you search on google for "Jetex", you should get about 1600 hits... good fuse hunting :-)

[Evil Dog]

Hmm..... shipping charges from England would be a little rough.  Seems to me I remember a thread a while back about making your own fuse using string and black powder.  Just thinking about it though, maybe a little string coated with glue and then rolled in some FFFFg.... or..... the same using wire instead of string.  A whole new thing to experiment with.  The main idea is to have a really small fuse to go with one of those really small mortars.

[Rickk]

I've made it.... there was a thread way back about how.

I've made 1/8 inch... never something that small.

You mix 90% BP with 10% Dextrin (which can be made from Corn Starch). Add water to make a watery paste and soak cotton string in it. Then you pull it thru a small hole drilled in a plastic container cover and hang to let dry to make the finished product.

[Evil Dog]

Thanks Rickk... will definitely give it a try.

[Rickk]

http://www.graybeardoutdoors.com/smf/index.php/topic,95774.0.html

[GGaskill]

You might try supersaturating some small tightly wound cotton string with KNO₃.  It should work like extra fast slow match.

[Rickk]

"Grant's Stump Remover" = KNO3

[Evil Dog]

Looks like a trip to the local hardware store might be in order... will have to wait until tomorrow though.  Merry Christmas.

[Rickk]

Home Depot and Ace Hardware stores carry it, although Home Depot rarely has any on the shelf. Either they don't figure it sells, or all the local pyro's shop there and keep them out of stock. My local Ace store almost always has some in stock. It will be in the gardening section of either store.

Black Powder saturated string will burn a bit more violently than KNO3 staturated string.

Another nice feature is that black powder is, well... black, so you can see that it is on the string. KNO3 is white, so it is harder to tell. Either way, if you don't have enough on the string for it to feel crusty and stiff, it won't burn like a fuse. You want it stiff anyway so that you can insert it into the hole.

[accuratemike]

I have a few old packs of commom firecrackers laying around. I'll often scavenge a piece of fuse from them for nano projects. I was looking at it just now and thought of something. It isn't string at all, but very thin paper. Maybe if you take the BP slurry and were to coat tissue paper (maybe the stuff laying around all over the house today). You could cut thin strips and twist it into a a really thin fuse. Or maybe even thinner paper, like cigarette rolling paper (  ), and make nano fuse. Just a thought, MIKE

[Rickk]

I just made a few pieces of quickmatch. The string I use is 3-ply, so I unplied a piece and soaked just one strand to see how it works out. The single ply looks like it is maybe .062 diameter.

While the experience is fresh in my mind, here are a few tips...

When you mix the mess together, it won't dissolve right away. Give it an hour or so, shackiing every 15 minutes or so, and you will have a nice gooey mess - exactly what you want. It doesn't matter what gransulation of BP you use, it will all disolve. The bigger stuff might just take a few more minutes.

Also, when you put the sting in the goo, let is sit for about 5 minutes before drawing it out. This will allow the sting to saturate better. If you unwind the strands a bit after you make it and see bare whiite string, it will still work but not as well. It would be better to stick it back in there and let it absorb some more goo.

Swipe some clothes pins from you-know-who. Have some nails nailed into something like ceiling joists in your basement or workshop to tie one end of the string to, and use the clothespin to weight the other end down untill it dries. You will have what looks like uncooked, black spagetti when you are done. I hope this is obvious, but keep fire away from this stuff as it is drying, as once it is relatively dry it will burn very intensely.

You can't really coil this stuff, so get a long container, cut it into long lengths and store it that way. Alternatively, if you are untilmately making them for a specific application you can cut them all to the final length and store them in something smaller. I store 2 foot lengths in a waterproof PVC rocket storage tube untill I need them.

A trivial side note...  If you ever saw Clint Eastwood in a western (the one that he played a gun-fighter turned preacher)  where he lobbed dynamite down on the "bad guys", take a look at the fuse he used. Someone in the technical department was smart enough to realize that Ensign-Bickford had not invented safety fuse yet, so he actually was using what appeared to be this very stuff we are talking about to set off the dynamite.

One last thing... you will more than likely get black goo all over your hands. Don't be surprised if you smell a bit like BP for a day or so. You may even taste it a bit. To the best of by knowledge, there is nothing hazardous about absorbing BP, although I guess too much of anything can be an issue. If you feel better doing it, rubber gloves would help.

[Santa Dave]

I found Jetex fuse on Ebay a year ago>
It was stuff she had left over.
The new company will only sell fuse with fuel pellets!
But it's good fuse!
Dave

[Will Bison]

Jetex is/was good fuse for micro cannons but but as Santa Dave says, ya gotta buy the darn pellets too and I ain't figured out a good use for the pellets. Have you checked www.cannonfuse.com ?

[accuratemike]

. Have you checked www.cannonfuse.com ?

I just did. Their skinniest fuse is a 1.4mm (.055") paper fuse. $6.00/100' . And they have rope "match" $2.50/3' . Worth a bookmark. MIKE

[Rickk]

i've been working on my quickmatch makin' technique the last three days....

I generally only had BP on the outside of the string. It worked good, but there was variation in the ferociousness of the burn sometimes. I am atributing it to the variatio in depth of penetration of BP into the cotton string.

When the cord it cut, it is obvious that the inside is still white... no BP.

I generally only soak 5 minutes. I tried longer. At 12 hours, there was a noticable greying of the inside, but just barely noticable. I am guessing that the cotton acts like a filter, and only allows clean water inside. Once the inside is saturated with clean water, there is little motivation for anything else to go in.

I tried something different this afternoon. It is a bit messy, but does not require any soak time.

I put the cord in my BP paste bottle and shook it around a bit. Then I removed it without using the .125 in hole... I just removed the lid and took the cord out.

I then wraped the cord 1.5 times around a small metal ring, squished it a bit with my finger, and drew the entire length through the ring. This squished the string, opened up the ply a bit, and pushed BP into the cord.

I then put it back in my bottle, let it sit for about 1 minute, and drew it "normally"
 though the .125 inch sizing hole in the lid.

I let it dry for about 4 hours and tested some of it. It normally takes about 2 days to be really dry, and testing at 4 hours is generally unspectactular. Howeven, even after only 4 hours of drying it burned really nice. When I cut the test sample, I saw core pentration.

I made up two more lengths, and this time I ran them threw the "metal ring" process not once, but twice before doing a normal draw.

It is a bit messy... probably better done outside.

I suspect that it will take a couple of days to fully dry, so I'll have to wait that long to do a good test.

One thig that I had noticed about using it my "normal way" only, was that sometimes the slowmatch had a hard time lighting the quickmatch. It sometimes took a bit of fumbling to get it to go, although once it when, it went.

I am thinking that if there is more BP, and no "white" string core, that it will light easier.

So, I'll be doing a thorough test in a couple days after I am sure it is dry.

[Rickk]

I tried out my "super saturated" .125" quickmatch today.

My "normal" version burns like standard Visco fuse.

This super-saturated stuff is way better. The ball of fire around the fuse is about twice as big. When it zips thru a paper straw and gets to the end, the force blew the remaining 2 inches of fuse sticking out the unburned end about a foot, where it continued to burn in a big red ball untill it reached the end of the string.

When I cut the sample off, I still saw some white in the cores of the 3 individual strands (it is 3-ply string), but each of the three strands appears to be 100% coated. What I saw before I tried forcing it over a metal ring was that basically only the parts of the string that were completly on the outside were getting covered with BP... each ply probably only had about 50% coverage. I guess I should weigh some samples to be sure, but I am guessing that there is at least twice the BP in the string using this technique.

[hammermill]

for a little more drama as the fuse burns add in some fine al or mg to the slurry of blackpowder .
look to skylighter for some flying fish fuse for a really small diameterl

[Evil Dog]

Skylighter has some 1mm fuse listed... I have a problem with their minimum $30 order though.  Pyrocreations has 1/16" fuse.... it's not shown oh his website, but if you call and ask he has it.  Also are not limited to a minimum order.  100 ft will probably be enough to last the rest of my life.  Will be entering into the mini-micro-nano mortar fray before long.... but that's a subject for a different thread.