1569 replies to this topic

[1145climber]

I use regular 75:15:10 home-made black powder. it is a mix of fine powder and some larger grains. my stars are basic white and gold pumped stars made also according to the instructions on the 'pyroteknix' site. they arent primed. the stars on the top look kind of ugly, because i ran out of my pumped stars, so i had to use old ones. and yeah, i strongly glued the ends as well as spiking the shell with cotton string. heres a pic before i wrapped it in tape to prepare it for using it:



so, do you think my stars will ignite, or will they maybe get scattered across the sky unlit?

finally, another question: what height do you think would be good for this small 2 inch paper towel tube cylinder shell? i did a test fire with a similar weighing shell with nothing in it. it went 110 feet up, which i assume is not high enough. i was thinking 300-400 feet maybe?

[sasman]

Please post a video of it going off!!...

thanks

[rooster]

I see many of those type of shells. I think you are using too thick string. Is that 8-ply cotton?

I would split it to 1 strand, and rather make more vertical and horizontal lines. Also, pasting paper outside the spiking will help the break alot. The maltese use flax twine, but My friend at Lija fireworks factory told me that 8-ply cotton should only be used on 6" shells and up, or else the break will suffer.

This can be one of the things to try if it doesnt work out. Best of luck though, looking forward to seeing the vid!

[1145climber]

oh sweet... ill use single ply string instead with more wraps. thanks for that tip. and ill make sure to get you all a video of it.

[1145climber]

might be a little before i can try out my shell, but anyway, heres a pic of the new string-spiking:



no longer a thick 8-something-play cotton string, now its only 3-ply, but the threads are really thin. hope it will work better.

[adamw]

Please note that to get a good break and good symmetry the spiking needs to be regular and parallel with the other strings.

[alany]

Your average 2.5" shell is lifted to only 80-90 metres, such a small shell should be just fine lifted to << 100 metres, probably closer to 50.

Edit: typo

Edited by alany, 29 April 2005 - 09:29 AM.

[1145climber]

Please note that to get a good break and good symmetry the spiking needs to be regular and parallel with the other strings.

aww damnit. maybe i should fix that.

[Yugen-biki]

I would say 50m for a 2" shell. To high and the effect will be to far away.

This picture is taken from svenskakemi.nu :


That's how the spiking should look ;-)

I don't think there will be any problems will star ignition.

Edited by Yugen-biki, 24 April 2005 - 04:41 PM.

[1145climber]

This picture is taken from svenskakemi.nu :


That's how the spiking should look ;-)

my god, thats impossible! i gotta say, props to whoever made that. it is harder to do with smaller shells though, but ill try.

[Lil_Guppy]

My 2in shells come out looking like that after spiking. Not so many verticals and horizontals though. Usually I use 8 to 10 verts with anywhere from 5 to 10 horizontals, depending on what the shell contains.

[rooster]

Now I am back in the military, so I can't get any pictures for ya, sorry.

I made 2 3" shells this weekend. One was a RAP shell. I dipped it in methylkene chloride, but just in case, I made some strips and pasted on one layer, so that Im sure the shell won't break on the seam.

The other 3" I made was a cynindrical one. I started out with a 15-20cm wide sheet of thin cardboard, and wrapped it around a case former. Put on some tape and folded in the bottom. Then I put in a canulle and filled it with granulated BP(~2FG). Then I added my TT stars around the canulle. The top was folded in around the fuse, so that both ends were now closed.

Then I soaked medium weight kraft paper in paste. The paper was wrapped 3 times around the shell. After this, the air bubbles beneath the surface of the pasted paper were pushed out but hand force, so the the pasted kraft was tight onto the shell. Then the shell was left to dry in the sun.

The next day, 3 ply string was used to spike the shell. I spiked it very tight, so that the string made dents into the dried pasted paper shell surface. I used 12 verticals, and probably around 20 or so horizontals, since the shell was so long. Then the whole shell was coated in paste, so that the string would soak up. This is because it makes the string more brittle, improving the break. Unpasted cotton string may reduce the quality of the break because its more elastic than the pasted type.

Then two more wraps of pasted kraft paper was added on the outside of the spiking string. Here it is especially important to push out the air bubbles from the beneath the surface, so that the shell doesn't look smooth. The shell should look like a checkerboard when done, the squares from the spiking string clearly visible through the pasted paper. Then the shell was dried in the sun, and is ready to be fired.

Some of the techniques presented here, I learned in Malta last summer. I will show you pictures next weekend, also of the shell breaking.

Sorry for the long rant, hope at least some of you find it useful

[paul]

Very useful indeed. Because it?s a bit hard to get information directly from persons who "learned it"...

So, old books describe it but knowing how they do it today in factorys - from people who were there - is much more worth I think.

Good post. I?m looking forward to see the pictures you promised....

greets,

paul from sunny germany

[rooster]

Hell, I'll just make a tutorial on it. I'll host it on chaz' site if its okay for him. I'll make a new shell, take a lot of pictures during the making process, and get a video of the break, where I add the best still to the tutorial. Look forward to next weekend then!

[rooster]

I didn't really need to double post, but wanted it to show up as a new post.

Here is my 3" shell, spiked with 3-ply cotton thread, and pasted over that again. The spiking job isn't very symmetrical, but it is good enough to get an even break.