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My new 30mm 250 shot Cake


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#21 Col

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Posted 01 October 2010 - 08:08 AM

Coil mentioned the lift as being 3-4g of black alder.
I`m making similar sized bombettes (28mm id x 80mm long), if they turn out half as good as Coils i`ll be happy :)

#22 AdmiralDonSnider

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Posted 01 October 2010 - 09:18 AM

Coil mentioned the lift as being 3-4g of black alder.
I`m making similar sized bombettes (28mm id x 80mm long), if they turn out half as good as Coils i`ll be happy :)


Use a pusher disk (loaded after the lift and before the unit). This drastically reduces the amount of lift needed. 3-4g is plenty for units which Iīd say come out at about 30-40 grams each.

#23 dagabu

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Posted 01 October 2010 - 09:37 AM

Use a pusher disk (loaded after the lift and before the unit). This drastically reduces the amount of lift needed. 3-4g is plenty for units which Iīd say come out at about 30-40 grams each.


A simple single disk or a piston? That sounds easy ;)
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#24 AdmiralDonSnider

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Posted 01 October 2010 - 09:44 AM

A simple single disk or a piston? That sounds easy ;)


Just a cardboard/strawboard disk showing a small central hole and matching the tube ID in size. 1g will send the things 25 meters up.

#25 Col

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Posted 01 October 2010 - 11:17 AM

Is it common for bombettes to have fairly thick bottom bulkheads? I presume the thickness sets the delay timing (encasing the visco) and provides protection during the lift.

#26 AdmiralDonSnider

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Posted 02 October 2010 - 01:02 AM

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 donīt know many of them.

#27 Col

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Posted 02 October 2010 - 09:16 AM

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.

#28 dagabu

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Posted 02 October 2010 - 09:33 AM

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

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Posted 02 October 2010 - 10:27 AM

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). Itīs not really silent, but usually doesnīt scare neighbours.

#30 Col

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Posted 02 October 2010 - 11:25 PM

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.

#31 AdmiralDonSnider

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Posted 03 October 2010 - 01:43 AM

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 theyīre 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 isnīt rocket science. Weight can be compensated by adding lift. Many case designs are possible as long as the break used harmonizes.

#32 Col

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Posted 03 October 2010 - 12:00 PM

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?

#33 AdmiralDonSnider

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Posted 04 October 2010 - 02:02 AM

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 by AdmiralDonSnider, 04 October 2010 - 02:03 AM.


#34 myartmehndi

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Posted 31 October 2010 - 02:05 AM

wow :)



#35 Col

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Posted 02 November 2010 - 12:38 AM

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

Posted Image

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?

#36 AdmiralDonSnider

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Posted 02 November 2010 - 03:05 AM


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 canīt 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, itīs fine. Choose a chipboard that is slightly flexible, makes inserting the disks easier. Just donīt 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.

#37 Col

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Posted 06 November 2010 - 03:35 PM

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 by Col, 06 November 2010 - 03:36 PM.


#38 ExplosiveCoek

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Posted 06 November 2010 - 04:52 PM

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

#39 Col

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Posted 06 November 2010 - 06:23 PM

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

#40 Updup

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Posted 06 November 2010 - 06:27 PM

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?
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