Double break canister shell

[Pretty green flame]

This tutorial shows the construction of a double break canister shell.

 

First off all to even attempt a multi break you should be fully aware of single break canister shell construction. Many of the factors there, also apply here.

 

So let's get started

 

1. Prepare 2 shell casses. For this you will need a 50cm long by 9cm wide strip of craft paper. Roll it up on your former, i used a 56mm OD former. Leave the shell on the former and slide it down so about 2cm are overlapping. Insert a pre punched end disk and fold the laps down, seucre them with some diluted wood glue. NOTE: Here it is important that all discs are punched in the same spot so the shells will stack together properly.

 

2. 2 spolettes are prepared and "nosed" with a couple of pieces of black match. The first or "initial" spolette has a delay of 2.5s, the second has a delay of 1s. Now remember, multi breaks are built from the bottom up. so the last break is the first to be built. So now glue the second (1s) spolette into one of the casings, use plenty of glue so you have a fireproof seal

 

http://i15.photobucket.com/albums/a374/AVP2/Nosedspolette.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Cases.jpg

 

3a. Let's begin constructing the last break The shell is placed upside down on a stand so the spolette is at the bottom . The "canulle" (This will form the powder core) is inserted and powder is poured in to the desired height. Stars are put in the space between the canulle and the shell wall. The canulle is removed from the shell leaving behing a powder core.

NOTE, here i'm using a chipboard liner as a height fill gauge and and a strenghtener for the shell wall.

 

http://i15.photobucket.com/albums/a374/AVP2/Canulle.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/starsandbreakcharge.jpg

 

3b. After the shell has been filled it's time to seal it. Put a cardboard disc in it and foled the overlapping paper down, secure with some diluted wood glue. I glue another disc over the flaps just to hold them down untill the glue dries.

 

http://i15.photobucket.com/albums/a374/AVP2/Flapsdown.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Lastbreakclosed.jpg

 

3c. Final step in the construction of the last break is spiking. Now multi breaks require offcenter spiking, this is crucial or the shells won't stack nicely. Now with smaller shells you might get away with normal spiking but larger ones will build a lump of string around the spolette and this ain't good. So if you're using normal spiking try to keep a low profile. After the spiking is done you're finished with the first break.

 

http://i15.photobucket.com/albums/a374/AVP2/lastbreakspiked.jpg

 

4a. Building the second break is similar but first you must place the first break onto the already built one so the spolette gets through the punched end disc. Done, OK. Proceed by filling the case with stars and break charge.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellfilling2ndbreak.jpg

 

4b. When filled you should have a prefused end disc handy, the initial spolette prepared eariler should be glued into a punched end disc with plently of glue to make an air tight seal. Now hloding the disk by the spolette gently wiggle it in the powder core untill it's flush with the chip board liner. Done? Ok, now fold the flaps down and secure with diluted wood glue You can glue a punched end disc if the flaps are giving you problems.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellclosed2ndbreak.jpg

 

4c. Now for the spiking. You will now be spiking 2 shells at one, yes, the second shell is going to get another spiking treatment. Just do as you normally would but at the joint where the two shells are connected you should give it a few more turns (Horizontal turns ofcourse) of string to secure everything in place.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellspiked.jpg

 

 

http://i15.photobucket.com/albums/a374/AVP2/Shellextrastring.jpg

 

4d. Final step is pasting, prepare some wheat paste as per pudidk's instructions and impregnate a sheet of craft with it. The craft should be sufficiently long to go 2-3 turns around the shell and wide enough to overlap the shells diameter by a little over half a diameter. Anyway, roll it up and fold the overlapping paper down.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellpreptoroll.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Shellpasted-1.jpg

 

Now leave it to dry for atleast 24 hours.

 

Second part will follow tomorow when the shell's dry

 

My comments: OK, i admitt, the spiking job was not my best, but what the hell, it'll break open in anyway

[pudidotdk]

Great tutorial and nice pictures!

Looking forward to see the result!

[gods knight]

very professional

[Xtreme Pyro]

Awesome tutorial Pretty green flame, ive been looking for a tutorial on how ro construct a multi - break shell i plan on trying this, thanks btw can't wait to see the results!

[Pretty green flame]

Here's the second part

 

Finishing the shell - Lift and leader

 

First you have to know that multi breaks, even small one are all top fused, this mean that the initial spolette is on top of the shell, this prevents a possible blow through and flower pot of the shell.

 

1. For a start we begin by rolling a bucket tube, the bucket slides over the spolette, this is where the shell leader, spolette and passfire pipe meet. This part is very important to get right. This tube is rolled from a lenght of paper suffieciently long to go 2 turns around the former. Only a light pasting of glue on the sides of the paper strip is used. The lenght should be around 3-4", the ID depends on you OD of the spolette, it should have such an ID so it easily slides in place with a couple of milimeters of space for the passfire, in this example i've made a 14mm ID tube.

 

2a. If you have made a bucket tube proceed by cutting some quickmatch. Now the quickmatch has to be long enough to go the full lenght of the shell up to the spolette + a couple of inches should extend to the part where the lift will be. This is out passfire pipe, now the quickmatch here has to be seriously good. So 3 strands of GOOD black match should be used in the pipe. (I was lucky enough to obtain some commercial QM so this is what i'm using here). Also trim the edges of the QM so an inch or so of the black match within is exposed to the flames.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellpassfire-1.jpg

 

2b. Ok, now run the passfire (quickmatch) vertically across the surface of the shell. All the way it should be touching the surface. Now lightly tie it to the spolette, also apply a little glue so it'll stay put.

 

http://i15.photobucket.com/albums/a374/AVP2/Connection.jpg

 

3. Now take a strip of paper wide enough to overlapp the shell on one side by 1.5 shell diameters and long enough to go 2 turns around the shell (I'm using a strip that is 17cm wide and 50cm long). The paper is now pasted in a special manner. Only paste it so much as the shell is long. In my case i paste a 10cm wide strip that is moved to the side. The other 7cm that remains is where the lift will be contained, the last few cm's of the strip are pasted all the way. Now roll it up. Leave it to dry. The paste will shrink and tightly bond the paper to the shell wall. This prevents the powder from migrating in between the lift wrap and shell.

 

http://i15.photobucket.com/albums/a374/AVP2/Shellprepforliftwrap.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Shellliftwrap.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Shellliftcup.jpg

 

4. Apply a lil bit of wood glue to the spolette and slide the bucket tube over it. Now tie it, but not too tightly or the possibility exist of choking the passfire (if this happens say bye-bye to your mortar).

 

http://i15.photobucket.com/albums/a374/AVP2/Shellbucketon.jpg

 

5. Measure out the lift powder required to lift the shell. Now i want to put this baby up as high as i can so i'm going to overlift it a bit. It weighs 207.50g and will be lifted with 25g of 10-20mesh willow lift. Put the lifting charge into the cup formed by the lift wrap. Now gather the paper up and tie it and apply a little glue to the knot.

 

http://i15.photobucket.com/albums/a374/AVP2/Lift.jpg

 

http://i15.photobucket.com/albums/a374/AVP2/Tiedlift.jpg

 

6. Final step it attaching the shell leader. get a piece of quickmatch and put it in the bucket, again an inch or so of black match should be looking out of the pipe so it passes fire properly. Now tie the leader into the bucket on two places. And again be carefull not to tie it too tightly or you will choke the quickmatch.

 

http://i15.photobucket.com/albums/a374/AVP2/Leaderconnection.jpg

 

 

http://i15.photobucket.com/albums/a374/AVP2/Finalproduct.jpg

 

Load this baby in a mortar, light fuse, get away. And enjoy the show

 

Cheers

[gods knight]

it looks just like one of the shells ive fired for last years display.

 

 

 

very professional!!!

 

i hope to see a video

[pudidotdk]

So when do we get to see the video?

[Tyneman]

Verry nice tut PGF!

 

Still a bit too big a project for me. But verry interesting to see up close.

Gr33tZ

[Pretty green flame]

So when do we get to see the video?

Saturday eveing i will fire it so the vid should be up by sunday morning

[yellowcard]

Very, very nice tutorial. I'm impressed. I can't wait to see the shell going to the sky.

 

I have one question.

The tube used for the spoilette, is it hand-rolled or a commercial bought tube ?

 

Nice work.

[Pretty green flame]

Very, very nice tutorial. I'm impressed. I can't wait to see the shell going to the sky.

 

I have one question.

The tube used for the spoilette, is it hand-rolled or a commercial bought tube ?

 

Nice work.

The spolette tubes are bought ones from http://www.pyrotubes4europe.com/

[Pretty green flame]

Sorry guys. Only one break ignited. Don't know what happened.

 

http://www.youtube.com/watch?v=bkXgMqBn5fU

 

Cheers

[yellowcard]

Kinda sucks...

But it's a nice break you have there voor an cilinder.

[gods knight]

That was a very powerful shell,it sounded like it was raining, probably that was the cause,(highly unlikely) ,or the fuse,(spolette) wasn't coated it black powder,I've gotten a chance to open a 4 inch triple break,dud before and the second and third break were smothered with black powder to ensure ignition.

 

 

 

 

But those are just wild guesses(correct me if i'm wrong)

[Pretty green flame]

That was a very powerful shell,it sounded like it was raining, probably that was the cause,(highly unlikely) ,or the fuse,(spolette) wasn't coated it black powder,I've gotten a chance to open a 4 inch triple break,dud before and the second and third break were smothered with black powder to ensure ignition.

 

 

 

 

But those are just wild guesses(correct me if i'm wrong)

The spolette was not primed yes, probably the most likely cause of malfunction. And yes, it was raining, was dry the whole day, then the skies opened up and it started raining

[gods knight]

One question: Did you happen to recover the malfunctioned shell ?

[Pretty green flame]

One question: Did you happen to recover the malfunctioned shell ?

Unfortunately no, but my friend went to the shoot site today to clean up the remains and he said he hasn't found it. From a safety perpective it should be ok as it was raining and the ground was soaking wet so the water should have taken care of the dud. Would have been nice ti find it though, perhaps it would shed some light on the reason why it malfunctioned.

[pudidotdk]

I made a 2" multibreak, it worked:

http://www.pudi.dk/video/2chrmulti.wmv

[FrankRizzo]

Watching the video frame-by-frame, it looks like the time fuse of the second break never lit. You want to tie a strand of two of bare match across the face of the spoolette, and bend the both ends up like rabbit ears into the break charge from the first break.

[Pretty green flame]

Good work pudi, that was a nice shell.

 

Frank, thanks for the advice, i'll remember that when making another multi break.

 

 

Cheers

[Mumbles]

Another hint is to roll the can completely over the first break. Actually use a piece of paper and cover the 1st shell as if you were pasting it in (sorta).

 

Just a few notes:

Prime the spolette like FrankRizzo suggested.

You don't need to horizontally spike the second break twice.

You don't mention if they were the same stars, but is it possible the 2nd spolette blew through and they both went off, or did you hear it hit the ground?

 

My personal preference is to build the shells completely independantly, and just stick the spolettes into the bottom of the next shell. I think it gives more consistent breaks, and makes transitioning over from single to multibreak shells very easy.

[Pretty green flame]

Some good suggestions there mumbles, thanks.

 

Indeed the shells might have gone off at the same time (Stars were the same in both) as i didn't hear it hit the ground and the dud was not recovered so i guess thats the most likely thing that happened apart from the second spolette not taking fire and out inability to recover the shell.

 

Cheers

[Pretty green flame]

Watching the video frame-by-frame, it looks like the time fuse of the second break never lit. You want to tie a strand of two of bare match across the face of the spoolette, and bend the both ends up like rabbit ears into the break charge from the first break.

 

Yup, I've made some multi breaks and insert shells using this method from then on and they've all worked, 100% of the inerts and breaks lit.

[50AE]

....

I fear this topic will become into a mess.

(Ontopic) Stupid of me I see this topic for the first time and it's 3 years old. Very good job PGF, but I was almost sure the second shell wouldn't burst because you didn't prime the spolette. It's very important to do.

I also like the crown near the spolette.