Interesting can shell remains

[MeowMix]

I was using some plastic can shells to test some break powder, PVC glued lid, wrapped in three turns of 75lb, pleated, and spiked using off center. I happened to find one of the left over pieces, and it seems that the lid ripped off all the spiking, wrap, and pasting off in one piece. If anyone knows how to fix, it would be appreciated, but I personally don't really mind if I fix it. It's just interesting to me.

 

Images

 

https://imgur.com/a/HGY3ju8

[NeighborJ]

I would imagine a bit more booster would fix that issue if extra spiking won't fit in the mortar. The breaks are probably looking like half a bowtie if the cans aren't breaking.

[Arthur]

Do you LIKE the effect? As well as ball shells there are horsetails and bow ties that look good -maybe other shapes. The brisance of the burst and the evenness of the pasting and stringing make a lot of differences.

[MeowMix]

The effect was nice, and I'll use it for other shells, but it wasn't the effect I was looking for. I'll try double spiking and adding booster to my next tests. I'll also make sure to keep my break separate from my stars as well, would tissue paper work for that?

[Mumbles]

What kind of materials are you using? Things like string, casing material, paper source, etc. Those don't look like typical plastic shells I'm used to seeing, but it could just be a little beat up after firing and breaking. Maybe it's just the extra paper, but the bottom disk almost looks like cardboard.

 

Breaking plastic shells is also generally a different game than breaking paper shells. You're probably looking more at flash bags than a traditional cannule. If you want to try a cannule, 2-3 turns tissue paper works great to keep things separated.

[MeowMix]

[MeowMix]

What kind of materials are you using? Things like string, casing material, paper source, etc. Those don't look like typical plastic shells I'm used to seeing, but it could just be a little beat up after firing and breaking. Maybe it's just the extra paper, but the bottom disk almost looks like cardboard.

 

Breaking plastic shells is also generally a different game than breaking paper shells. You're probably looking more at flash bags than a traditional cannule. If you want to try a cannule, 2-3 turns tissue paper works great to keep things separated.

They're 3" cans from cannonfuse, I used cotton string because it's what I had, I have some hemp twine coming, Uline for my kraft, I used Elmers to pleat and gum tape for pasting. The bottom is a cardboard disc I used to reduce impact on shell during lift, and to mark spiking. I'm currently a little spooked about flash, no real reason, just a gut feeling. I'll try your cannule idea, and if that doesn't work I might look into flash bags.

[MadMat]

Were you using MCRH in a 3" shell? That is too small of a shell for that. I would switch to granulated BP with a little flash for a boost. I have been getting great breaks from my 4 and even 5" cans with granulated BP. I don't bother keeping the burst separate either. I make my cannules out of a few turns of pasted paper to make hard, reusable tubes. After filling the shell, I pull the cannule out. A little tip if you try this; fill the stars and polverone first, then add the burst. Do it in this order before pulling out the cannule or else the whole mess likes to pull out! In my 4" and 5" shells I don't even add any booster, but then again, my BP is pretty hot.

Edited April 28, 2018 by MadMat

[MeowMix]

Were you using MCRH in a 3" shell? That is too small of a shell for that. I would switch to granulated BP with a little flash for a boost. I have been getting great breaks from my 4 and even 5" cans with granulated BP. I don't bother keeping the burst separate either. I make my cannules out of a few turns of pasted paper to make hard, reusable tubes. After filling the shell, I pull the cannule out. A little tip if you try this; fill the stars and polverone first, then add the burst. Do it in this order before pulling out the cannule or else the whole mess likes to pull out! In my 4" and 5" shells I don't even add any booster, but then again, my BP is pretty hot.

I've been using my MCRH in my 3" with great results for a while (Ball shells, w/ booster).I can try to granulate my bp instead of putting it on rice hulls. Do you have a recommended method of granulation?

[MadMat]

I granulate my BP by pressing lightly moistened mill dust into pucks, breaking them up and sizing the grains with screens. I made my press out of a small bottle jack, two pieces of 6" channel iron from a scrap yard and 3/4" threaded rod. I know it's ugly, but it works. I then made my pressing form out of a piece of 2" pvc pipe (reinforced with a few pipe clamps). For the pistons, I simply coated the inside of the pvc pipe with some petroleum jelly, put in some pieces of chopped fiberglass cloth and poured in polyester resin. On my first attempt, I skipped the fiberglass cloth and cast the pistons out of solid resin. They didn't last too long before cracking ( a lesson learned). My present pistons have pressed a LOT of bp pucks and are holding up just fine. I moisten my mill dust with 70/30 water/alcohol and use very little. I used to measure the liquid out to get a certain percentage, but after doing it a bunch of times I just go by "feel" and haven't had a problem.

[Baldor]

Do you have a picture of your press, MadMat? I tried this with M24 DIN 10.9 grade threaded rod, and had problems with rigidity.

[Richtee]

Man that’s a heavy looking can... almost looks like a chunk of HDPE mortar tube!

[NeighborJ]

What guy doesn't like big heavy cans? It makes some exciting fireworks.

[MeowMix]

Man thats a heavy looking can... almost looks like a chunk of HDPE mortar tube!

I'm not quite sure what they're made of, but they are quite strong. Very thick wall at the bottom as well.

[NeighborJ]

ABS plastic.

[Mumbles]

That's interesting to know. Most of the ball shell casings I've gotten are high impact polystyrene I believe. I think I have a couple biodegradable ones around too before they stopped making them. I sort of assume they're poly lactic acid.

 

Good luck on the cylinder shell casings. I never really got them to work for anything but horsetails. I will back the idea of using granular BP. Cylinders don't have as much room for burst, and you want to pack as much explosive material as possible in there.

[Wiley]

You'll need a flash bag to get a nice burst with those cans. Shouldn't need spiking or additional paper, either.