Multi Break Ball Shells

[wizard7611]

Is it safe to make a multi break ball shell over 4 inches? Would the time fuse or spolette break while the shell reaches its height?

[PyroJoeNEPA]

Not sure what you mean by a "multi break ball shell". I assume you are referring to a peanut--two or three balls stacked on top of each other? Or a "shell of shells" which is a large ball shell containing many smaller ball shells?

[wizard7611]

Peanut shell, not a shell of shells.

[Chris H]

They're fine in any caliber. I've seen 12" peanut shells, and possibly even a 16". Like with most shells, you need to be more careful as you go larger. Sloppy techniques will be more likely to lead to failures, and the failures are more dangerous. If you want to try to build some, I'd suggest a thin slice of a hardwalled tube between the two to help lend some support and help both shells make it out of the gun intact. If you look toward less than reputable pyro info sources, like youtube, you'll see all sorts of ways of doing it. These will range from just adding a few loose individual shells to the tube (aka double bubbling or piggy backing), to using a big puddle of hot glue. These half-assed methods will start to get dangerous or ineffective with larger shells.

Also keep shell weight in consideration, and choose your mortar type and support (buried vs. racked, etc) appropriately. Firing heavy shells from HDPE can cause the bottom plug to crack, move, or get blown out. There is some concern about fiberglass as well, but can handle a little more weight by virtue of being a single piece. Probably nothing to worry about unless you start to get into the 10lb+ region.

[wizard7611]

Do you think a 6 inch HDPE tube can withstand the weight of at most a triple break shell?

[Northern Sky]

Why do I picture people doing this kind of stuff in their garages sipping a beer?

May I suggest a club membership and some well informed tutoring. A little place like PGI comes to mind. There are plenty of clubs that have regular gathering and open shoots to get your manufacturing fix on.

There are no second chances or oops when you get to this level.

Gotta toss that out there.

[Chris H]

To be honest, a three-break 6" shell would make me sort of nervous out of a 6" HDPE gun. The weight of that shell will probably come in between 7.5 and 9lbs. This probably is in the grey area. I wouldn't personally fire a shell of that weight out of a 5" HDPE gun, but a 6" gun is somewhat stronger. I'd prefer to look for fiberglass if available. If you go with HDPE, make sure it's buried and well supported on the bottom with a railroad tie or other substantial support.

I have to agree with Northern Sky. It might be helpful to find a local club and members to bounce ideas off of. They will also provide safe places to shoot. Midlands Pyrotechnic Association is probably in your neck of the woods.

[wizard7611]

To be honest, a three-break 6" shell would make me sort of nervous out of a 6" HDPE gun. If Italians can do it, why can't we?

[Chris H]

You can do whatever you want. You asked for advice, and I gave my personal opinion. You'll be the one dodging shells and stars, not me.

I haven't seen too many 3 break shells from Italy fired from HDPE for what it's worth. Generally steel is used.

[wizard7611]

I haven't seen too many 3 break shells from Italy fired from HDPE for what it's worth. Generally steel is used.
Is the plug made of steel too? I've seen them use fiberglass mortars for their large report ring shells. Do you think 90 degree corner braces on the bottom of my tubes would help?