Small inserts

[PyroCube]

Hi all

 

I`m planning to build small inserts for a 75mm can shell, but I`m not shure how I have to build

them so they work correctly.

I would use hand rolled paper tubes with 18mm ID and 2.5mm wall thickness. To make a nice delay effect, about 15mm

of TT composition (maybe with a little Ti) is rammed in the tube. After the delay there are some small green stars, maybe around 6mm

diameter, with Kclo4/Al flash break.

What I`m not shure about is how I should close the top of the tubes so they don`t ignite premature by the break charge?

I do also not know if a 15mm TT plug resists the bursting charge? Maybe a little dextrin with a small amount of water would help?

 

 

Greeets

[Mumbles]

The TT layer should be fine. You might also want to consider a bulkhead between the TT and the shell part. This will retain some confinement for the burst.

 

I'd probably just toss an end disk on top of the tube and paste it on. You might also want to consider a mix of BP and flash for the burst. BP can add some gas to the break and help with ignition.

 

Good luck, and keep us posted. You might want to look up some videos and posts on bombettes here. AdmiralDonSnider and/or Col are the two members that come to mind. Don't quote me on either of those, but I think they're right.

[Col]

I seal the top with a cardboard disc and hot glue. Its a good idea to test a few in a star gun and video it for an idea of the tail comp timing delay. Most charcoal star comps with dextrin should survive the break,

These used a level 7.5ml scoop of C6 pressed to 4500psi.

 

http://youtu.be/q1DUbBr2aCo

Edited March 1, 2013 by Col

[zAZO9a]

are those veline >. or rubber stars? im just starting to use these and ive come up with many uses for them. but small shells are all i can shoot without setting off car alarms. i switched from pumped because it snows in in"in"die"ana like a mother and and you cant dry anything here unless its spring or summer. pumped stars get drivin in and take forever to dry .and you have to babysit blackpowder like a chicken squattin over an egg....god i miss florida

[Col]

1/8" rubber stars (cut), burst was a teaspoon of granulated bp and 0.3g of whistle. They`re good for cakes too.

[Oinikis]

Sorry for the stupid question, but it's simply a tube, with delay, and a break with stars, and a plug? so it works pretty same as a starmine, just lit from the top?

 

Col, very beutifull inserts

Edited March 2, 2013 by Oinikis

[PyroCube]

Hmm not like a starmine, more like a bombette from a fireworks cake.

Insted of time fuse, streamer composition delay.

 

Thank your for your help, as soon as I rolled

a new batch of green composition, I`ll try to make some inserts.

 

BTW: What size of inserts do you consider as optimal for a 3" Canshell?

 

Greets

[Col]

I find 5/8" id a good minimum, i use thin walled kraft tubes to make the most of the space. I`d just go with the 18mm tubes and use as many as will fit around the perimeter

 

Cheers Oinikis,

The comet on the bottom of the insert is lit by the lift (cake) or burst (shell). When the comet burns through, it ignites the burst charge. The breaks can be a bit hit and miss but still worthwhile as you get 2 effects (tail and stars) for very little effort.

 

Here`s one that shows the tail comp end.

[Oinikis]

So, between the delay and the burst there is nothing to close it? becouse i can't imagine tube blowing up, only with one end closed. i think i would best understand drawings.

[Col]

I use a thin clay bulkhead with a hole but traditionally the comet would just have a small cavity formed in it by the tooling.

Some pics of the inserts and the tooling in this thread: http://www.amateurpy...-insert-breaks/

Edited March 2, 2013 by Col

[Oinikis]

Oh, thank you, now i understand.

[zAZO9a]

im wondering how to make strobes for small shells that wont hit the ground but will flash 2-3 tymes . but back to inserts.. i use 1/4 in. spiral wound tubes with clay plugs filled with the same 50 mgs of flash for 1- 1/2 to 2 inch shells. you can cut them shorter than normal fire crackers and they take up less room for multi-salutes .. i use the same effects fuse as everybody else. but have lately been rolling my dough in to strings..not as easy as it sounds. and rolling them with a few turns of light paper . cover with a little wood glue... next i take a needle open a hole and widen with a small awl and instead of fusing i just wet prime the holes and let them dry.miniature garnishes are not as hard as they sound. they do take some trial and error.. but at least in my opinion there better than most effects fuse.