Cylinder shells

[Merlin]

I would like to try can shells. I want to make "3" inch which are actually "2.5" inch. I take it these are not meant to fit close in a 3" mortar. My question is which supplier would be best to get casings. Does anyone use plastic or are the casings made from scratch?

[Maserface]

If you use prefabricated paper or plastic halves, the shell is generally considered a "canister" shell.

 

If the casing is wet or dry rolled around a case former, spiked, and pasted, it's generally considered a "cylinder" shell.

 

In the latter case (the one true path to happiness), your case former is 2.5", and the outside diameter of the shell (after spiking and pasting), is about 2.75-2.875. The pyrotechnica articles (IX and XI) are the most comprehensive English written texts regarding cylinder shells.

 

For the prefabricated paper or plastic canisters, I won't be the person to ask about sizes or methods, but someone will surely come along with experience.

[OldMarine]

There is a recent thread here that shines a pretty negative light on pre-made two piece canister shells. I bought me a former from Mikeee and have found I can build a casing in less than 15 minutes. I've only done a few but already I'm getting faster and more precise but I'm lifting with rockets so fireproofing against the lift isn't an issue. I still pleat each sheet and glue my discs because someday I plan to lift shells from tubes as well.

[mikeee]

Quicker, Easier and Cheaper to roll your own cylinder shell casings. You can make a basic tool out of anything the correct diameter for the intended shell size.

Fulcanelli articles have all of the information needed for making proper shell casings. Virgin craft paper is preferred, but hard to find these days, other grades

of paper can be used successfully.

[Mumbles]

I've only really used casings made from scratch. I think there are some plastic casings available however. Pyrodirect has them listed, but they're out of stock. There may be other suppliers that carry them though. I'd check pyrocreations, cannonfuse, skylighter, and Precocious Pyrotechnics. I'd bet at least one has them if you're really interested. They' don't work very well in my experience though, or at least take some less orthodox methods and dialing in. They may be a loose fit as well.

2.5" is the diameter of the former. Once complete they're a comfortable fit. I guess that a 3" shell built with typical methods is probably 2.85" or so after rolling the casing, spiking, and pasting. I've never had one fit loose enough that it effected my lift at least, unlike ball shells of the same diameter. If you're concerned, you can increase the former diameter up to probably 2.625" (2 5/8") without issues. There might be a supplier or two who carries disks of that size, but it'd more than likely require hand cut disks.

There are a lot of household items that are about the right size for a former if you want to get your feet wet. Standard 12oz beverage cans are about 2.55" OD for instance. There are a plethora of other appropriately sized items around if you take a look. I would also suggest using a liner in your casing of some sort. It helps to get a flat, even fill your first few times. I prefer to use them in all of my shells, but it's a matter of preference.

[OldMarine]

Quicker, Easier and Cheaper to roll your own cylinder shell casings. You can make a basic tool out of anything the correct diameter for the intended shell size.

Fulcanelli articles have all of the information needed for making proper shell casings. Virgin craft paper is preferred, but hard to find these days, other grades

of paper can be used successfully.

Yeah, you can use anything but your former is a true tool! I somehow enjoy it more than a piece of pipe with some duct tape...

[OldMarine]

I found the thread on those pre-formed canister casings:

http://www.amateurpyro.com/forums/topic/11775-what-is-your-opinion-about-these-pre-fabricated-canister-shell-halves/?hl=canister

[Merlin]

Thanks for all the info. I suspected rolling your own from "scratch" produced the best results. I confess I have only used Lloyds method for plastic ball shells and they work well but I want to try cylinders. It appears in videos the cylinder shells offer more versatility and better results. I am going to go this route. I have a bunch of videos to study online. I suppose it's best to purchase end disks rather than cut from card board. Old Marine remarks about Mikee's formers so is there a website? One other question- is it possible to get good burst patterns without the use of flash or whistle? Thanks Edited July 6, 2016 by Merlin

[OldMarine]

I'm no expert by any means but

1) You can cut your own chipboard discs cheaper than buying.

2) Cylinder breaks aren't as round as ball shells though some items like bowtie shells work better as cylinders.

3) You should build rockets. Period.

Come to the dark side...

[Merlin]

I'm no expert by any means but

1) You can cut your own chipboard discs cheaper than buying.

2) Cylinder breaks aren't as round as ball shells though some items like bowtie shells work better as cylinders.

3) You should build rockets. Period.

Come to the dark side...

[Merlin]

What tool do you use to cut disks? Idon't have punches that large. As for rockets.. Last year I rammed some BPs. This year I got a hydraulic press set up and pressed several end burners. I have a variety of 8 oz tooling but I don't yet have confidence to put a shell on them. I have whistle tooling but yet to work up the courage to press such a powerful comp to such pressures. I do love rockets but need lots more experience to arm them . A Cato with a shell is a fearful thing!

Thanks for the links they were informative.

Edited July 6, 2016 by Merlin

[BengalFlair]

I have got some nice round break of my 4'' can shell !! Here is an example...

 

[Mumbles]

Buying them is usually easiest. I feel this way at least for sizes I make regularly.

 

The tool of choice for cutting end disks tends to be an allpax gasket cutter. They're pricey brand new, but ebay has them regularly. There are other cheaper brands out there and other designs that should also work. For smaller shells, though 3" can be done, arch punches are usually used for speed. Some even go as far as to use arch punches with their handles ground down to fit in a drill press. Grinding down a hole saw is another cheap route if you feel like making your own. It sounds like this might be the best route if you decide to make your own.

 

If you're just making a couple, scissors will work in a pinch if you're using thinner chipboard. You may need to laminate a 4 or 5 layers together with the stuff from cereal boxes, pallets, or soda cases.

[Zumber]

I have got some nice round break of my 4'' can shell !! Here is an example...

 

wow..!!

really nice shell.

[dagabu]

I did a tutorial some years back using soda cans as the former:

 

https://sites.google.com/site/spamento/

 

Making the disks:

 

https://www.youtube.com/watch?v=ZkY8GMtdInc

[Merlin]

I have got some nice round break of my 4'' can shell !! Here is an example...

 

https://www.youtube.com/watch?v=YpF3tt-UQoQ

[Merlin]

I would be proud of that break regardless the shell type!

[Merlin]

I did a tutorial some years back using soda cans as the former:

 

https://sites.google.com/site/spamento/

 

Making the disks:

 

https://www.youtube.com/watch?v=ZkY8GMtdInc

[Merlin]

Thanks. I have the tutorial saved as pdf. That disk cutter is a precision machine. In my case I will not need a large number of disks. I will use use Mumbles suggestion to make them or if the size I need is commonly available buy them. If I made a large number of shells your machine would be the way to go.

[schroedinger]

Merlin a cheap 3" case former that is good for a start can be bough of ikea as a rolling pin.

End disk easiest is to buy them if possible, else take the covers of old books or ram board. If you don't have an alpax or punch, take a compass and draw the circle. Thenncut out with scissors. (You will swap for one of the other methods after some time).

For punching holes for TF a .22 works, else buy a hole punch set. They are cheap 3-10 mm are needed anyway every couple tasks.

[Merlin]

Merlin a cheap 3" case former that is good for a start can be bough of ikea as a rolling pin.

End disk easiest is to buy them if possible, else take the covers of old books or ram board. If you don't have an alpax or punch, take a compass and draw the circle. Thenncut out with scissors. (You will swap for one of the other methods after some time).

For punching holes for TF a .22 works, else buy a hole punch set. They are cheap 3-10 mm are needed anyway every couple tasks.

[Merlin]

I can punch holes all day with .22 but might be a little off center! Seriously I do have a question. Let's say I purchase chip board end discs. They are all a specific diameter. How do you know your case former will produce cases the correct diameter to match available commercial end disc diameters?

[OldMarine]

There are standard sizes but I've read an article where Ned wrapped a piece of manila folder around his former to accommodate some slightly oversized discs.

[mikeee]

Patrick,

 

That is one of the easiest ways to make a custom sized case former or turn a 3" into a 4" and so on.

Regular craft paper can be taped onto the undersized case former and roll enough layers to attain the size you need.

The craft paper provides for a smooth flat surface that will allow the paper casing to slide off the up-sized former.

You can always remove the craft paper and reuse for your shell casings.

This really works nice for custom sized rocket headers when you need a slightly larger casing to hold your specific number of inserts

depending on the finished diameter of your manufactured inserts and the number you need in a ring.

Going from a 3-1/2" to a 3-5/8" diameter casing provides a good amount of area when you calculate the circumference.

And it really sucks try to force that last insert into a ring when the casing is a little small for the number of inserts in the ring.

Several layers of craft paper on the case former will gain you the needed space for those tight fitting designs.

Making uniform sized inserts is part of the solution when making the "TR" style headings.

I added a couple of free insert formers to the package I am sending you today.

[mikeee]

Dave,

 

This is the barrel stave design case former I have been using for the larger tools. This is an 8" tools 7-1/4" OD made of pine.