13 replies to this topic

[pyrotrev]

Does anyone know what kind of machine is used to make this please?. For those who haven't seen it, it seems to consist of kraft paper tightly wrapped around a powder core with some threads wrapped around the outside in the opposite direction to stop it unravelling.

Edited by pyrotrev, 20 December 2006 - 01:29 PM.

[Frozentech]

Does anyone know what kind of machine is used to make this please?. For those who haven't seen it, it seems to consist of kraft paper tightly wrapped around a powder core with some threads wrapped around the outside in the opposite direction to stop it unravelling.

http://tinyurl.com/y3t3am

[T-sec]

The flat kraft paper coated fuse used for shells is called "Quickmatch". The core is made of blackpowder coated cotton strings which normally burn slow, but wrapped in paper burn extreme fast.

You can make it you self in simple steps; as an expample:

1. Cut 4 cotton strings of 4 meter, you can use cotton like your granny uses to make your sweater.

2. Take a plasic coffee cup, punch a small hole in the middle of the cup's bottom, a bit bigger than the cotton's diameter.

3. Make a mix of 90% black powder, 10% Dextrin and add some 50/50 water/alcohol fluidmix to it until it's thick as porridge.

4. Take one string, put the beginning trough the hole in the coffee cup and fill the cup for 50% with the black powder porridge. Pull the complete string through the cup so that the complete string gets coated with the mix. Empy the cup and repeat the action with all the strings.

5. Hang the black powder coated stings somewere so that they can dry without touching anything. And let them dry in normal condition for 24 hours.

6. Take a piece of kraft paper; 400cm x 3cm and fold it up over the length 3 times; 1cm folds. Open the paper again, put some paperglue on the first fold and put the 4 strings next to each other on the paper. Now fold the paper up again, beginning with the not-glued part, folding it over the strings. Then fold it up again, towards the glued part and close the kraft paper tube well by pressing it with your hands.

7. Let the arised quickmatch dry again for 24 hours, and you've got your self 4 meters of quickmatch.

More info can easaly be found with Google, like http://www.angelfire...cboom/fuse.html

[Creepin_pyro]

T-sec, he's referring to Chinese/Japanese time fuse, as shown here.

So, it looks like it's closely related to a visco machine.... you thinking about constructing one Trev?

[RegimentalPyro]

I know chinese time fuse also has a layer of tar surrounding the core. I've no idea of how it's made though....

[T-sec]

Jep, after reading it more closely I understand that it's concerning the time fuse part and not the quickmatch.

Making time fuse is a hard job. For me it's better to buy than to make it your self, cheap and good. The 1st reply of Frozentech looks like a simple machine to make time fuse your self.

[karlfoxman]

To make the real stuff I think it would be very difficult, your best of trying to buy it. Dont forget the timefuse were talking about hae a layer of tar inside to stop side spitting and this also makes it resistant to moisture (from the sides) I guess you could 'get rid' of the tar and just use finely milled high quality powder very very tightly wrapped inside gummed tape and finaly tighly covered in string. Good luck if you do make one!

[pyrotrev]

Thanks for that link Frozentech. My question was more out of curiosity than wanting to make a machine (too many other things to do!!) - though it would be nice to be able to have this style of fuse with alternative core compositions!

[Mumbles]

A possibility for a similar product would be to take your visco machine and run a length of premade visco through it and wrap on tar coated string. Tar coated string is actually a fairly common item in pyro. It is used where waxed string is. Connecting drivers to frames is particularly common.

Wrapping in aluminum foil, or foil tape also works to prevent burn through. Not really sure how one would make a machine for it though. Dipping in wax may be adequate for short lengths.

[cooperman435]

Ive made very sucsessfull time fuse by simply buying some 100mm X 100mm gummed squares, cutting strips from them (diferent widths for diferent delays) and wrapping them round visco tightly. The I prime the end in slurry and dip it in granulated bp.


My maths are based on timing 10cm of visco burn and dividing it by 100 (mm) this gives a burn time for 1mm (we shall refer to this as T) simply divide the delay you want by T and this is the lenth in mm for the gummed strip to be cut.

Ie 100mm of fuse burns in 8.3 seconds

so T = .083

so if a delay of 2 seconds is wanted 2/.083=24mm paper strip

3 second delay is 3/.083=36mm strip

5 second delay 5/.083=60mm strip


Cut the paper strips and then lengths of visco roughly 25mm longer than the paper width. wrap the paper into a tube (so the tube length is the papers width) level the ends and then roll it between your fingers in one direction to make it tighten. Once the hole is nearly the size of the visco insert the fuse so it just sticks out one end about 2mm and continue to roll the tube so it tightens further round the fuse untill the fuse cannot be pulled out(it needs to be tight to not allow sparks to travel upwards). Then unwroll 25mm of the paper carefuly as to not release the whole thing and wet the gummed paper then roll it back and make sure the glue holds before letting go to do the next one. 10 minutes later I then dip the short end in the slurry and then dip it in granulated bp to make sure its ignited by the lift charge. the long peice of fuse sticking out the other end is ample to ignite the shell contents.






it should look something like this when done:



XXXXX::::::::::::::::::::::::
XXX------------------------------------------------------
XXXXX::::::::::::::::::::::::

Edited by cooperman435, 28 December 2006 - 04:29 AM.

[pyrotrev]

The great thing about the shell fuse is it has a nice big powder core = easier ignition & strong burning. Also there seems to be some stage in the production process where the paper wrapping is compressed before winding the thread around it, this gives a good solid core that doesn't shed powder (and presumably gives more consistent burning?)

[michielvv]

A fuse topic > Hope my question is here @ the right place;

I'm living in Holland and over here is quite a bit hard only to get some visco fuse. I've got them now but i want to make shells. I know to make shells i should use a time fuse to let the shell explode in the air.

I couldn't buy some time fuse sow could somebody tell me if there is sulotion for my problem, (i think i'ts a problem so i think visco isn;t good anough for this aplication)

Open for tolk

[parabolic]

Hi michielvv,

And welcome to the forum!.

If the shells are small eg 1inch up to 2.5inch then I dont think you should have any problems by using visco fuse, Infact the plastic spherical shells that you can buy already have a hole to accept fuse which can be 3/32" size, 1/8" size, or 1/4" size .

If your fuse is to slim then you can wrap the fuse in some masking tape until its a good fit. you must then glue the fuse to the shell on the inside or outside.

Just make sure that you cut the fuse at a 45 degree angle, which will expose more of the inside surface so that it catches fire easier when the lift powder burns, or dip the end in BP slurry and perhaps then dip that in granulated BP.

(on left) 2mm visco fuse taped up to 1/8" to fit hole in plastic shell , on right 1/4 time fuse on paper shell with BP slurry/powder prime.

Edited by parabolic, 05 January 2007 - 08:21 PM.

[BrightStar]

Cooperman435 has some good tips above on making a time fuse - particularly in priming. Parabolic's 45 degree cut also works well for me.

I have found that the visco takes about half a second to 'get going' when used as a time fuse. This means that I add 0.5s to the time calculated from the length x burn rate equation.

As an example, my 1/8" visco burns at 1 cm/s. My plastic 3" shell cases have a 1.2 cm length fuse moulding. When fired, they burst after 1.8 seconds (not the 1.2 that might be predicted...). I have also seen this extra half second on larger can shells timed with kraft wrapped visco.

To improve the timing for the 3" shells, I wrap a 7mm width strip of electrical insulating tape around the visco to a thickness of about 1.5mm. This is glued in place inside the plastic shell case to extend the delay, and gives a perfect 2.5s timing to burst the shell at apogee.

Hope this helps...

Edited by BrightStar, 05 January 2007 - 09:41 PM.