Tutorial: Crossettes

[pyrokid]

The discussion of flash powder in crossettes isn't an issue. It is the k3wls that get on peoples' nerves.

 

I think you would have trouble using strictly BP to break crossettes. Flash is used to provide a bit of "snap."

 

One of the more experienced members here should be able to give you some proportions. Experimentation never hurts though.

[Mumbles]

The tooling you made for yourself is confusing me a little. As I understand it, the comet outer diameter is 1.25", and the cruciform shape of the cavity is .75" wide? The cavity is fairly large if that is so, but should be able to work. I don't know what sort of dimensions the chinese tools use, but they might be around those proportions.

 

For large comets, I've heard reports that you can get away with just BP. These would be several inches in diameter though. The smaller the crossette, the harder it is to get to work properly, or at least dial in the break. There are many ways to break crossettes. If you'd prefer to avoid flash powders all together, you might want to look into granulated whistle mix, or some combination of whistle and BP.

[dynomike1]

Thanks everyone. I will get me a pump now that i understand probably a .75".

[Scott2Fisher]

Whistle mix eh? Im not too familiar with its characteristics; but im fairly sure i cant ram it. do i just pour it into the cavity and close it off?

[mathiasxx94]

Scott2Fisher: Yes I would recommend whistle mix since your cavity is rather big. Granulating as Mumbles said would be a good idea though to increase burn speed (note that small granules will burn faster than big, granulating is just to allow better heat transfer and increase burning area). Whistle mix made with salicylates for example sodium salicylate instead of K/Na benzoate tend to produce a hotter mix (more burst strenght). And as you said never ram whistle mix. Yes just pour the mix into the cavity and close it off, don't forget to "tack" it, thank Mumbles for new vocabulary Note that whistle mix is also quite friction and static discharge sensitive.

 

Dynomike: it was not so clear, but here's my method same as Mumbles said:

 

1. Fill cavity

2. Cap the cavity

3. Cover sides with paper, but let the paper rise a few millimeters over the cap so you can lay it down afterwards.

Edited February 4, 2013 by mathiasxx94

[Scott2Fisher]

OK GREAT! last question (for now), Mathias said to granulate the whistle, but small granules burn better. Is there an optimum grain size ( is there a thread devoted to this i should know about) for burst charges as compared to whistle mix rockets as compared to whistle lift charges?

Thanks so much everyone

[mathiasxx94]

I don't know of a thread, but I will try to answer as good as I can: (When I say that powdered whistle mix burns slowly, it's not literally meant, it is just to demonstrate the effects of granulation)

 

Let us think of a small pile of whistle mix. If the pile is ignited the flame would propagate "slowly" through the powder just burning at the exposed end of the powder, in the same manner as a star.

 

Now imagine making grains out of the powdered whistle mix, the grains are shaped such that there become air gaps between them, this allows the hot gasses to rapidly propagate between all particles almost instantly. As I said in the last post the burn rate does increase as the grain size is reduced, but as the grains become even smaller the gaps between them will also get smaller thus creating a barrier for the hot gases.

 

This means that if the grains become too small the surface area will not ignite simultaneously, this will result in a slower burning composition. Although I can't give you an optimum grain size for the fastest burning comp, I would say that making the powder smaller than 50 mesh would not give you any better results rather poorer. The use of a normal kitchen sieve (i think they are about 30 mesh) would be the best solution for your use, I think.

[dynomike1]

All he has to do is burn some BP comp and some granulated BP he will see it. What had me confused i thought the crossete was slotted all the way out, that's why i couldn't see how to hold the powder in with out putting the paper around it first. Also would a .75" pump would work for 4" shells? Edited February 4, 2013 by dynomike1

[Scott2Fisher]

Im aware of how BP changes if its granulated or not, but have never ventured into anything more advanced than BP and Tiger tail (real simple and inexpensive things to start learning with) and just wanted to make sure before i went ramming ungranulated whistle mix into a tube. but hearing that the optimum grain size for whistle is that of the sieve i already own is great as im a starving student and all.

 

Im home in my shop, for the first time this year, this weekend so im very eager to get things going with this whole whistle thing.

thanks everyone.

[dynomike1]

Well i am not much further than you, i am still in Charcoal streamers to. I would try Whistle on top of BP before you do all that work. Some says Whistle works some says it don't, i don't know i haven't tried a ccrossettes yet.You could put 10% Sulfur in Whistle that would lower the ignition temperature. The main thing at this point is try something first then go from there.

[Jordan123]

Realy good tutorial, because me, my crossette is break after pump ...

I must just add 2% on my composition ?

 

(Sorry for my very bad english, i'm french)

[Jordan123]

You granulated the whistle mix ?!

[dynomike1]

Got to be careful with it while it's wet, Over pack it then take a knife and cut off excess before you take it out of the pump.

[Operator]

 

Tutorial: Crossettes

Hello! Where can I find the tool for making drawings of these stars?

 

[WindowLicka]

Ok another idea i have an aluminium foundry can i make a wooden prototype and cast it?

Better yet make it out of foam and do the replacement casting by burying the foam prototype in greensand, then pour the aluminum, brass, ect, and you have an exact casting. From foam to metal...easy peezy.

[OldMarine]

Just reviving this so I can find it again!

[RiderX]

Just reviving this so I can find it again!

good revive , replying to subscribe to thread

[PeteyPyro]

Im subscribing to this thread too so that I don't lose it either. I'm posting this crossette snippette from way back in 06/06/06. It was helpful for me, as 10 years ago I didn't know how to properly break a crossette with either a 'tied shot' or filling the cavity with a break charge. There are a couple of ways to skin a cat, or break a crossette. I found this on a google forum regarding pyro crossettes.

From a Google Pyro forum chat.... post was by John Reilly!:

 

"The method described in Fulcanelli part II is the traditional Italian

method and is the best in my opinion. The stringing of the hole shots as described is an art. The dried shots are cut apart and the string ears overlap the cavity end of the crossette star and are held in place by the pasted paper crown when finishing the loaded star. The string keeps the shot from falling through the burned open cavity as the comet is spinning through the air. I cheat a little and use 3" gummed paper tape to roll the shots using a 4 point crimp to close one end before

punching and fusing.

For the 1-1/4" comet shots I take a 5/16" diameter piece of wooden

dowel (mandrel) which is about 4 to 5" long and waxed by rubbing with a

candle stub to avoid the paper's sticking to it. One end of this

mandrel is bored dead center with an 1/8" hole about 3/8" deep. The 3" gummed kraft paper tape (std. 60# weight) is cut into 3" lengths to give three turns around the mandrel. (One 3" strip gives 5 finished "hole shots". A piece of this paper is placed gum side up with the mandrel squared and centered on the edge nearest you. With thumbs and forefingers the first turn of paper is laid on the mandrel and held tightly against the rolling board with the fingers of the left hand (if you're right handed) grabbing the damped sponge and wiping the remaining pasted side of paper to activate the glue. The thin casing is formed with a push of the palm of the hand and rolled firmly back and forth the round and tighten the 3" long tube. The damp tube is slipped up about 1/8" to 3/16" past the drilled end and with a thin awl, a 4 point crimp is started on the overlapping paper. (12:00, 3:00, 6:00 and 9:00 o'clock positions. The mandrel with the overlap crimp end is smashed smartly down on the rolling table which folds the 4 point crimp down on the end of the mandrel. While the mandrel (crimped

tube end) is held tightly against the table the mallet is taken and the mandrel is give two or three quick raps to "set" the crimp closed. The awl is taken and a hole punched in the center of the crimp to allow for the insertion of the fuse later. The case is slipped up on the mandrel again and with sharp scissors is snipped off (into a small box) so you have a shot tube with one end open, one end crimped closed, and with a fuse hole in the center of the

crimp. This is repeated 4 more times and the another 3" paper strip is rolled and so on till you have 100 "shots" or however many you need. This sounds like it is time consuming but I could have rolled ten shots in the time it took me to type this. I use either specially made thin fast match or chinese firecracker (tissue) fuse which is cut ahead of time into 3/4" lengths: the fuse is

inserted through the hole in the crimp of the shot leaving about 1/4" projecting outside the crimped end. The shots are all fused first and then loaded. A number of 1-1/4" pcs of thin cotton or flax string are cut (one per shot). First, a shot is taken and a piece of the cut string dropped into the open end of the shot tube with the tag end hanging out. A scoop of dark report comp. (50/50 mix of KClO3 and Antimony Sulfide)

is added to the open end of the shot. A pinch of fairly coarse sawdust is added on top lightly pressing in with the forefinger (string still hanging out.) Lastly a good smear of white glue (PVA) is run across the sawdust (keeping the string end out of the way). Set them aside to dry. When the shots are loaded into the star cavity the string lays across the comet end. The comets get a 1-1/4" very thin chipboard disc on the end (holding the string) before the kraft pastewrap is pleated down over the shot end. (The chipboard disc helps keep the paste from

soaking into the star). There are many method and tricks to cracking

crossettes and this is just one way I find convenient and workable for

me. There is no "correct" technique except the one you find reliable and feel comfortable with. Flash powder (70/30 KClO4 to blackhead or similar fine flake aluminum) will work fine with these shots too. I only use the black antimony and chlorate to avoid the bright flash. --John Reilly--- "

 

-

John Reilly has some good info from Fulcanelli part II here. I was relieved to be able to get my crossettes to break as I wanted to by dialing in a non-chlorate comp. <phew!> Potassium Chlorate and Antimony trisulfide are a very sensitive dark break mix.

Edited October 18, 2017 by PeteyPyro

[greenlight]

Sorry if it has already been asked, but can you use whistle instead of flash to burst the crosettes?

[OldMarine]

I tried Sali whistle to break my ½" crossettes and it worked most of the time. I think I need a finer granulation for consistency. I haven't tried benzoate whistle yet. Lloyd suggested cutting flash with Cab-O-Sil so I plan to try that next.

[Mumbles]

You can use whistle to break crossettes. I've typically used it granuated, and with a burn rate catalyst like iron oxide or copper oxychloride. It all depends on the size of the crossette of course. Smaller crossettes typically need a strong burst, and large crossettes typically require something with less strength.

[greenlight]

Thanks for the replies,I was asking cause I have benzoate whistle with iron oxide catalyst and only spherical aluminium so no fast flash unless I use flake Mg. Edited October 18, 2017 by greenlight

[OldMarine]

I've been working on ½" crossettes and maybe that tiny cavity doesn't hold enough whistle to break them properly. I'll try it again with some ¾" ones this weekend since I got my new pump set.

[Nordicfireworks]

Hi

I just wonder is there any type of flash powder without perclorate/clorate that is enough powerful to break small crossete stars (16mm).

Is KNO3 + Mg powerfull enough?

[Yus]

Hi! I have some questions about crossettes (20 mm dia) to the experienced peoples:

1) Could you tell me a couple of colored compositiom (pumped by using water and/or alcohol-based solvent) that work well in crosssets (with good capabilitity to the ignitiong by flash powder)?

2) Which flash powder is good for 20 mm crosssets? Your option?

3) Is the lenght of 4.5 mm of thin cavity sufficient fur such crossettes?

4) Is it necessary to fill thin cavity with small grains of BP or better insert a fast perchlorate fuse? Apropriate composition for fast fuse in this case?

5) Have anyone made color changing crossetter? Is it necessary to prime internal body of the crossettes?

Thank very much!