My new 30mm 250 shot Cake

[AdmiralDonSnider]

It really depends on the design and type. For consumer bombettes of the chinese type the clay bulkhead is standard. Larger or more sophisticated units may use other designs, employing techniques similar to canister shell construction (with spolette type delay or time fuse, using multiple disks to plug both the bottom and the top).

 

Still other techniques roll them from kraft with a chip liner or from manila. Here the ends are often closed with a tongue fold.

 

There are many designs; I likely don´t know many of them.

[Col]

Thanks for that, Admiral.

The clay route seemed like the easiest method but after pressing one i`m not so sure. The bulkhead weighs in at almost 17g, total bombette weight somewhere around 55g.

[dagabu]

That's cool, 1g would be almost silent, wouldn't it?

[AdmiralDonSnider]

Thanks for that, Admiral.

The clay route seemed like the easiest method but after pressing one i`m not so sure. The bulkhead weighs in at almost 17g, total bombette weight somewhere around 55g.

 

The clay does add weight, yes. Mine came out at about 13 grams IIRC (just the casing with the clay bulkhead). The final weight depends a lot on the lenght, filling (type of stars..) and top plugging. 55g definately is on the heavy side.

 

 

That's cool, 1g would be almost silent, wouldn't it?

 

You do hear it when the two disks are pushed out (another one is added on top of the bombettes after loading). It´s not really silent, but usually doesn´t scare neighbours.

[Col]

The clay does add weight, yes. Mine came out at about 13 grams IIRC (just the casing with the clay bulkhead). The final weight depends a lot on the lenght, filling (type of stars..) and top plugging. 55g definately is on the heavy side

 

13g seems reasonable, maybe i`m overdoing the bulkhead thickness with 17mm + 6mm for tail comp? The case/bulkhead come in a shade under 28g, the case size is 28mm id, 32mm od and 80mm long, so maybe it isn`t that bad.

[AdmiralDonSnider]

13g seems reasonable, maybe i`m overdoing the bulkhead thickness with 17mm + 6mm for tail comp? The case/bulkhead come in a shade under 28g, the case size is 28mm id, 32mm od and 80mm long, so maybe it isn`t that bad.

 

No I think they´re alright. They are larger than mine (which are 28mm final OD to be shot from 30mm, 60mm in lenght). It also depends on how hard you press the clay. Make a few trials, that isn´t rocket science. Weight can be compensated by adding lift. Many case designs are possible as long as the break used harmonizes.

[Col]

Its good to know i`m somewhere in the ballpark with the bulkhead depth. I get fairly consistant clay thickness using a homebrew hydraulic press. The tubes are handrolled using kraft and pva glue..finding the right size/wall thickness off the shelf is next to impossible. Do you press your tail comp in before the bulkhead or plaster it on afterwards?

[AdmiralDonSnider]

Do you press your tail comp in before the bulkhead or plaster it on afterwards?

 

In my few trials I plastered it on (pressing may be better!). I must say the ascending tail isn´t that easy to realize. Your 6mm tracer cavity could make things easier, but with my 4mm thick squat tail stars I had troubles to get good adhesion, prevent fragmenting during the rise etc. Much depends on the comp - it shouldn´t be too fast burning, nor too slow. There is a thread of mine about these bombette tails here at APC. Give it a search.

 

If you ask me I wouldn´t go into tails as long as the units themselves leave room for optimization.

Edited October 4, 2010 by AdmiralDonSnider

[myartmehndi]

wow

[Col]

Hi Guys

I went for the pressed tail option and will let you know what happens.

 

http://i770.photobucket.com/albums/xx341/colinspyro/bombetteswithtailcomp.jpg

 

The bombettes are all primed now and ready to fill, i`m still debating whether to just throw the stars/slow flash in haphazard or arrange it so the flash is in the middle.

I was wondering how thick of a lift disc you use Admiral, cereal box card ~1mm thick or something heavier perhaps?

[AdmiralDonSnider]

 

The bombettes are all primed now and ready to fill, i`m still debating whether to just throw the stars/slow flash in haphazard or arrange it so the flash is in the middle.

I was wondering how thick of a lift disc you use Admiral, cereal box card ~1mm thick or something heavier perhaps?

 

I can´t believe that a cored charge would present any improvement in such small calibers. May be wrong however.

 

About 1mm strawboard disks are what you find in class C cakes. In absence of strawboard I just punch them out of about 1,5mm brown cardboard. As long as the thickness is sufficient to prevent the gases to escape by bending the disk in one point, it´s fine. Choose a chipboard that is slightly flexible, makes inserting the disks easier. Just don´t use chip where the layers of the material tend to separate easily - when this happens while you push them down in the tubes, it sometimes plugs the central hole and causes a misfire.

[Col]

Hi Admiral

I promised i`d let you know how it went and I had no trouble with the pressed D1 glitter tails, lift or breaks. Bombettes are truely amazing for such a small package

two 32mm bombettes

Edited November 6, 2010 by Col

[ExplosiveCoek]

Nice, looked good to me. What did you use for breakcharge?

[Col]

Thanks ExplosiveCoek

It was 2g of slow flash (Kno3=5, S=3, german dark=2) seemed to do the trick.

[Updup]

Thanks ExplosiveCoek

It was 2g of slow flash (Kno3=5, S=3, german dark=2) seemed to do the trick.

 

Do you think whistle mix would make a good break for somthing like this?

[Col]

Hi Updup

I don`t use whistle mix so i cant really say for sure but if it`s as energetic as slow flash, i cant see any reason why not.

[ExplosiveCoek]

Thanks ExplosiveCoek

It was 2g of slow flash (Kno3=5, S=3, german dark=2) seemed to do the trick.

 

Ah I see, normally I would use flake -325 mesh Al for slowflash.. But then I only got a small 'pop' when they broke, seems the GD does the trick. Might give it a try once I'm going to build a cake. Thanks.

[Col]

If it helps I used Eckhart 5413 H Super, the GD slow flash seems to deliver quite a decent report from the break.

[Trippiej!]

That thing is awesome. That was a lot of effort. I'm building right now so i was curious, how did you prime your stars? Just mealdusting? Edited December 8, 2011 by Trippiej!

[Eaglefireworks]

Great job Man..!!

[Dylan]

Looked great, good job.

[AdmiralDonSnider]

Your tailing technique (last video) seemed to work very well. Nice job.

[Mraliksr]

thanking you making such a great cake