2" Can shell case former

[DaMounty]

Morning,

 

I am wondering what the ideal case former OD would be for a 2" shell?

 

I am thinking that using the typical 1/2" smaller than the gun in this case would not work.

 

Thanks,

 

DaM

[Maxim]

I use 36 mm inner diameter for the 2" shells!

[mikeee]

The "2" shells vary depending on the wall thickness needed for the type of shell.

You might want to work your way backwards on these, determine the mortar/gun ID you are going to use.

Determine how large and heavy a shell you intend to build and the strength of the lift charge you need to

attain the altitude needed for the shell being made. Some of the Chinese 2" shells are broke very hard and

have a large diameter pattern for the size of shell, which requires a fair amount of lift to get them in the air. I

have seen some of these shells break low and scatter stars on the ground, which can be a hazard when it is

dry outside. If you are making single break shells you should not have a problem. Allow for the diameter of the

fuse and another 1/8" of play for the shell to easily drop into the gun.

 

If you have an an 1-1/2 OD case former or anything close you can wrap additional layers of craft paper around the

diameter to build it up to any diameter you need for "2" shells and the mortar/gun you have on hand.

[Mumbles]

I use a 1.75" former for a true 2" mortar. 1.75" former does not leave a lot of room for error however. 1.625" might be better suited and more forgiving. I agree with Mikeee, to work backwards from your mortar size. Your string thickness will be the biggest factor. I use 2 turns of posterboard liner and two turns 70lb for the casing, spike with 1mm hemp twine, and paste in my shells with 3 layers of 30lb paper. Like I said, there's not a lot of extra room after this. I need to use flat quickmatch to fire them.

 

Keep in mind that commercial mortars are smaller than 2" ID, even though often sold nominally as 2". They're usually 1.91" or 1.81" if HDPE, and presumably close to the same sizes if fiberglass or cardboard. If you have one of these, then 1.5" formers work well.

[DaMounty]

My mortar is a true 2" fibreglass. I borrowed it from one of the racks at the last show I fired.

 

I found a 1.670" (according to the calipers) abs pipe. I went with 2 liner wraps (manila file folder), going to add 2 wraps of 70 lbs, and spike with 1mm hemp twine.

As for the end disks I used a cereal box??? 4 in all.

 

Once spiked I was going to check the diam. and decide from there for either two or three turns of 30 lb pasted.

 

pics to follow shortly.

 

DaM

[MadMat]

As funny as it may sound, I have been using empty toilet paper roll tubes for my 2" shells. The tube from a roll of paper towel works as well. There are differences in the diameter of the tube with different brands of toilet paper some are a little too large. I made a shell with one of the larger diameter tubes once and fixed the problem of it being oversize by using dental floss (unwaxed) for spiking. It worked quite well.

Edited November 28, 2015 by MadMat

[DaMounty]

I made two shells prior to this one using TP rolls as well. Now all 3 are waiting to be paste wrapped. I figured I'm going to have to learn how to roll em from scratch one day.

 

Has anyone else found pleating to be a pain in the ass? It was a test in patience for me, in the end I wound up cutting it and folding in. It must be easier on larger dia. shells.

 

As for the end disks I bought this gizmo for the drill press, works so so, but I had to cut more than 4 because the singles seemed a little flimsy to me used a total of 8.

 

DaM

Edited November 28, 2015 by DaMounty

[Mumbles]

DaMounty, it sounds like you're pretty well setup already. I'd suggest laminating two or three sheets of cereal box together for the disks though. I tried single layers a few times and never had very good luck. This was pretty early on in my pyro career though. You can probably find thicker chipboard (1/16" or so) that would work as well.

 

I've made a lot of shells from toilet paper tubes. My biggest problem was the lack of commercially available end disks. Not an issue if you have an arch punch, Allpax gasket cutter, or cut your own of course.

[MadMat]

I cut my disks out of cardboard from shoe boxes, cases of coke, beer or cereal boxes. I usually glue two of them together. Haven't had a problem although it can be a pain in the ass cutting them out. I haven't tried pleating the ends. I usually cut triangles into the end, fold the points in and glue them to the end disk.

Edited November 28, 2015 by MadMat

[Mumbles]

Are you talking about pleating the TP rolls? If so, I agree it's a total pain. I made some with disks to fit inside the tube, and used a fillet of elmers glue around the edge to hold them in place. I don't think I used a second set of disks. Like I said this was really early on in my pyro career. I wasn't very well informed and used a lot of "creative" (aka bad) techniques. I cut the tube and folded/pleated the ends over on some others, but that didn't go the best.

 

I just saw your reply that you must have posted almost at the same time as my last one. It's reassuring to see that you and MadMat also came to the same conclusion that one layer isn't enough.

 

I'll be honest. Toilet paper tubes seem convenient, but are probably more trouble than they're worth. If you have a former, rolling the tubes are the easiest option, and pleat much better. Once you try it, you'll wonder why you ever tried to use TP tubes. It's a little embarassing to admit, but I still use a 4oz Renu contact solution bottle filled with sand as a 1.75" former. It's the only size I don't build upside down.

[mikeee]

Old books being discarded or 3-ring binder covers have nice thick chip board that can be recycled

into nice heavy end discs.

[Wiley]

You don't need heavy disks for these little shells. Go get yourself some "white illustration board" from Staples, and make up some kind of punch to make disks from that. I have a couple punches that will make both solid disks and disks with holes in the center. I was shooting out of 1.91" consumer tubes, and used a 1.625" former. 2 turns of 70# for the case, 20" hemp twine for spiking, and 2 turns of gummed tape or pasted paper. 4 breaks could be a bit of a squeeze if they didn't come out quite straight, but they all fit.

 

To make the former, I started with a 1" dowel, then wrapped posterboard around it until I got close to the diameter I wanted. I then held the posterboard in place with aluminum tape, and used that same tape to dial in the finished diameter to exacly 1.625". Soaked the exposed edges of the posterboard with extra thin CA to keep them from shifting around, and the former was done. I've made several this way. Takes 10 minutes to do and they last well.

Edited November 28, 2015 by Wiley

[jessoman]

For my small shells and cylinder inserts I also use cereal box end discs, a circle cutter has been sharpened and inserted to my drill press. I can cut hundreds of discs in an hour.
I have always used heavy Kraft as the casing, I spike them hard. A couple of turns of thin Kraft for fireproofing. You can dry test and wet up the final layers upon completion of tests.
I don't use a former for small casings. I cut my casings to the length which gives me 3 turns of the ID desired. Honestly materials are different. Use common sense and imagine, with your materials you are using, how much thickness will be added. Subtract from the ID to allow for a nice loose fit. I line up my outer turn with inside turn, tape it. Next casing and so on. After of have a few or a few hundred casings done. I will insert and pleat an end disc on the inside and outside of shell (same end). Ram it solid with a dowel (no glue used at all), so it stays rigid while filling. Fill shell. Throw end disc and spolette in. Pleat. Next end disc on spolette end. Spike shell, throw a few extra turns of twine around spolette to strengthen and fireproof. No glue used once again. Final layers of pasted and broken paper are added then dried. Finished shells are put in as an insert or a final wrap of dry paper with lift charge and QM is added. Very simple. I place a bit of an emphases on not using glue for pleating.etc, it isn't really needed. I have done tests with and without, no difference in performance. Good spiking does all the work here, experiment with twines being used. Give it a go
Post a video when your done.

 

edit reason: sp? errors noticed when proof read on computer (written on phone)

Edited November 28, 2015 by jessoman

[mikeee]

There are plenty of plastic molded 2" sized shell casings used for this application.

These work quite well because they provide a uniform containment.

Some of the "2" and smaller shells use very simple components quickly and easily assembled.

If the top and bottom end disc can be securely secured to the inside of the can shell you will end

up with a well patterned break. Normally the spiking of the shell helps to contain the end discs

and side walls so they break at the same time providing for a good shell pattern.

A combination of a thick end disc of equal thickness to the wall of the shell casing will provide

for a consistent shell pattern when broke. The hard part is securing the end disc to the shell casing.

Some of the smaller shells use cup shaped end discs which provide a larger surface area to glue

to the interior of the shell casing. A combination of rammed clay and an end disc can also provide

for the needed containment. Cheap spiral wound cardboard tubes can be used for making smaller

can shells with modular type components that can be quickly produced. Purchase a variety of small

fireworks can shells and take them apart and you will find various methods and materials used in the

construction of these shells. A traditional paper rolled shell is fairly quick once you get used to the

process and develop techniques and tools to speed the production.

[DaMounty]

3 Amigos drying. Two in the left are TP rolls. Not the prettiest, but for my first none plastic shells I'll still fire them

 

DaM

[Ubehage]

3 Amigos drying. Two in the left are TP rolls. Not the prettiest, but for my first none plastic shells I'll still fire them

 

DaM

Looks good. Well done

 

Personally, I wouldn't leave them on a glass plate, in case something blows up.

[dynomike1]

These are 3 & 4" shells made with toilet paper tubes. When i do business with a place the first thing i do is go to the bathroom and see what kind of toilet paper rolls they use, then i get them to save them for me when they get empty. Also i watch at work when we get posters and grab those tubes. Mainly i use them for bottom shots. Three to four layers of Kraft spike them, add another layer of Kraft you're done. i just put the Al foil tape on these for looks and a little more fire proofing.

http://www.myhostedpics.com/images/dynomike1/20151129075302.jpg

[DaMounty]

Looks good. Well done

 

Personally, I wouldn't leave them on a glass plate, in case something blows up.

It does look like they are on a glass plate. I am using an elevated window screen over a tinfoil oven plate. So air can flow top and bottom.

 

DaM

[DaMounty]

Finally got out to shoot those three shells. My first two's. Proud night for me. But please honest feedback...

 

The first one I had covered the lens with my finger

 

https://www.youtube.com/watch?v=7kC68lFm7LM&feature=youtu.be

 

https://www.youtube.com/watch?v=Wfg0IoOouYM

[Carbon796]

Those turned out very nice ! Make more !

[MadMat]

I have found that Dasani water bottles work great for 3" shells. I just fill them with very cold seltzer and seal up the cap. When the seltzer comes to room temperature, the pressure makes the bottle nice and firm; perfect for rolling the shell case. The size works out great for my 3" gun, which is slightly under 3". Even if someone's gun is exactly 3" a little extra pasting would take up the slack

Edited December 30, 2015 by MadMat

[lloyd]

How do you (with temperature variations) ensure that the bottle expands to the same diameter every time? Even PETE is a little bit elastic.

 

And how do you get the casing to slide easily off a ribbed bottle (which almost all of them are, today)?

 

Lloyd

[MadMat]

I've never ran into any problem with the size varying to my knowledge (I guess cold seltzer up to room temp. expands it to just the right size.) It may also help that I do all my "paperwork" in my basement, which maintains a rather constant temperature year 'round. I picked Dasani as it has no outward "ridges" on it, it does however, have inward facing ribs that actually seem to help the paper release and pull off the bottle.

Edited December 30, 2015 by MadMat

[MadMat]

Lloyd,

You got me thinking about pressure changes due to temperature changes, so I reviewed some of my old chemistry text books (Boyle's & ideal gas law ect.) and did some calculations. The change in pressure isn't all that much unless you change the temperature considerably: p1/t1= p2/t2 (the formula for calculating pressure change due to temperature change.

Edited December 31, 2015 by MadMat

[DaMounty]

While the hunt for 70# virgin kraft paper up here in the Great White North, I came across rolls of 75#. Does anyone have any experience with this heavier weight?

 

Sourcing a supplier in Canada for this paper is proving to be quite difficult.

 

DaM