Alternate pull string igniters

[Apollofrost]

What you'll need:

 

One pink bendy straw

One "booby trap" party popper

shrink tubing

smoke mix

fuse of your choice

lighter

 

Procedure:

 

Stretch out the straw and cut it so the accordion section is all on the shorter side. Feed in the party popper and the fuse so the party popper ends where the accordion starts. The fuse should run the length of the straw.

 

http://i23.photobucket.com/albums/b375/apollofrost/tubestuffed.jpg

 

Twist the accordion section around the fuse and string tightly then seal with shrink tubing.

 

http://i23.photobucket.com/albums/b375/apollofrost/shrinktube.jpg

 

Fill the tube with the smoke comp. I chose smoke comp with sulfur added because it's easy to ignite and won't explode. Once you are finished slide a section of shrink tubing down into the tube to act like a plug. Heat it gently so as not to set off the smoke comp.

 

http://i23.photobucket.com/albums/b375/apollofrost/finished.jpg

 

Now you're set.

 

Words of wisdom: Do not test these by pulling the strings with your bare hands. You can get quite badly burned.

[hst45]

Very cool idea. I've been thinking of how to best make a pull-string igniter for a cannon I'm working on, and this fits the bill. OneEyeCharlie, are you listening? Cannon competitions begin this summer, when my Napoleon rolls off the workshop floor.

 

And I agree that CAREFUL with the heat gun is a good idea; we don't want to anger the silver fulminate, which I believe is the pull-string primary.

[TheSidewinder]

Now there's a neat little device. I'll have to file that one away for the future.

[birkses]

why are there two strings

[FrankRizzo]

http://www1.istockphoto.com/file_thumbview_approve/2663227/2/istockphoto_2663227_pulling_fireworks_standing_out.jpg

 

http://www.frontierfireworks.com/products/pulling.jpg

 

This a picture of the "booby trap" novelty fireworks that is used inside the straw. In normal novelty use, one string is held in each hand and they are jerked apart. Or, one string is attached to a door frame and the other is attached to the door itself. Inside the paper tube is a friction sensitive comp that ignites (bang) when the two parts of string rub together.

[Swede]

Neat idea. To ignite, obviously you pull the string. Do you hold the fuse downstream of the straw with a gloved hand, then? Or can you pull the string and have the fuse ignite without supporting the fuse with the other hand? I'd be afraid that the entire fuse assembly might get yanked out of the device you want to set off.

[Apollofrost]

There are two strings as previously stated, one which you can use to anchor the device and one to pull on.

 

If you have damaged the anchor string you can mount the device by the lower shrink wrapped section, not the fuse.

 

I suppose a section of 3/32 of primed visco could be used as both fuse and mount point if properly secured at both ends. This would streamline the device nicely but experimentation would be needed.

 

Hmm... maybe just shrink wrapping the booby trap to the primed fuse? Heat would be an issue though.

[h0lx]

The color of the straw is obviously the biggest factor in it's success, hehe. Good idea by the way!

[whitefox77]

Alternative: I'm assuming the smoke comp is meant as a primer in this to ignite the fuse. Instead I used a peice of Chinese paper fuse:

http://www.whitefoxden.net/images/gn1205.jpg

 

I cut the paper fuse so it would run the full length of my piece of straw. Then inserted it and the popper at the same time keeping the popper near one end of the straw. Then I inserted by visco from the other end making sure it was next to my paper fuse. Then I closed up the ends by twisting them, on the end with the popper I taped it (duct tape) around the twist but careful not to tape the string. On the other end I taped the twist, but also the string and the fuse. Then I pulled the string up next to the straw and taped it again to make sure it was secure. To secure the pull string igniter, just glue or tape the whole straw to what you want it to ignite.

 

In both the tests I did the visco lit without a problem.

 

There is one down side. These poppers are LOUD. If you want to make a device that uses a pull string, but wont draw undue attention your way (such as making smoke grenades for use in paint-ball), this isn't an optimal solution. Everyone within 40 feet of you will probably hear the popper go off when you pull the string.

[Swede]

I know what you mean, those poppers are surprisingly loud. I think they contain a tiny amount of either silver fulminate or the dreaded "A" mix. Not something you'd want to make in bulk.

 

There are probably a few home-brew "friction sensitive igniter compounds" that make use of potassium chlorate, antimony, sulfur, etc, that might work silently as a substitute, but with the associated dangers that come with working with such a comp.

[Miech]

For 'stealth' smoke devices I would rather take a match composition and put that on top of a spolette. On this page (lower half) there are a couple of compositions you could use if you have the chemicals for it, otherwise a 50/50 mixture of potassium chlorate and antimony trisulfide with some binder will do. Keep in mind this isn't exactly a composition to consider safe, as it is actually a quite sensitive dark flash powder. This is getting somewhat off topic however.

 

For a real pull ignition you could try to recreate an old type of aircraft distress flare igniter. This is simply a tube with the upper half of the inside coated with some kind of match composition. Inside this tube there is a stick with the lower half coated in a composition containing powdered glass or sand. Upon pulling it out of the tube, it will cause friction with the match composition and ignite it.

 

It's a bit like the igniter used on the WW II german potato masher.

Edited May 29, 2009 by Miech