homemade bowling ball cannon

[pitmaster]

I have a oxygen tank homemade cannon. I shoot reduced diameter bowling balls. Great fun, however I would like to have a non projectile, spark flying , noise making night shoot. Any suggestions?

[BurritoBandito]

...this sounds like an accident waiting to happen. I hope I'm misunderstanding you.

[dwheadstone]

Trying to blow up a bowling ball mortar: http://youtu.be/vtmlDGosDsI

[dagabu]

...this sounds like an accident waiting to happen. I hope I'm misunderstanding you.

 

Actually, be-headed O2 and Co2 tanks are used for 7" mortars, my old club had several. The steel is high burst and tends to fold back rather than become shrapnel when burst. Most gas places (Airgass etc) sell tanks that don't pass inspection for close to scrap prices.

 

You have to bury them and barricade them like any steel gun but they do work well. As far as a night shot, mixing Ti into the BP and wadding it well will probably be the safest and loudest you can do with the mortar but remember to bury it, they will split and burst eventually, the breach is way to thin for mounting on a carriage.

[Arthur]

Most of the problem is that unconfined BP is not particularly loud -it just fountalns with much smoke. Some wadding felt, or cotton waste, or a toilet roll (if one fits) can make enough back pressure to make some noise. But the wadding has to go somewhere.

[dagabu]

Vermiculite wrapped in parchment works for the reinactors around here. Whetted enough to 'stick' together and wrapped up in a ball and tied off.

 

Careful! These "canons" can be dangerous.

[nater]

Pitmaster PMed me on the subject, and I encouraged him to start this thread to get some better advice.

 

He is wanting a NON-PROJECTILE effect to fire in his cannon at night. I have posted in the past that we have made night time effects by firing primed stars out of cannons in the evening after a Civil War reenactment. This is essentially making a mine and replacing the mortar with the cannon.

 

I don't know anything about cannons and my only experience with them has been the above and setting up close prox pyro effects during the same reenactments. I don't have one of my own and have never fired one myself.

[BurritoBandito]

I could see burying it, as suggested by Dagabu, as being a "safe" method (and I use the term safe very loosely). I have no experience whatsoever with cannons, nor do I have any factual knowledge of the wall thickness or grade of metal used in oxygen tanks. With that being said, I would personally not feel comfortable anywhere near this thing when it is fired. Perhaps this is a case of me being overly cautious, but I feel that it is within reason to state that sometimes you're just playing the odds. You may fire that cannon 100 times without issue, and then on shot 101 KABOOM!!! I can only imagine the effects of explosively rupturing an oxygen tank to be deleterious at best.

 

Pitmaster, please understand that I mean no offense, but this just seems dubious to me in terms of safety. I definitely don't want you, or anyone else getting hurt. Would you mind posting some pictures of your cannon, and perhaps describing your firing process? There are plenty of people here with more knowledge and experience than myself, and I would like to afford them the opportunity to guide you to safety. Thank you.

[pitmaster]

Yes, I am a newbie to pyros and my first blog. My computer crashed yesterday. I may need a pyro computer expert. I do shoot bowling balls in my homemade oxygen tank cannon.

The tank is not rifled and has a constriction in the middle. I use six tablespoon of cannon black powder in a ziplock bag with a wick fuse. The base is nautical design with pneumatic wheels on the front. A lot of the pressure is taken up in the recoil. When I have computer help, I will send pictures and video. Cannon is not accurate and good for fun only.

I am very interested in persons have experience with this type of cannon. I accept opinions well.

I am interested in a non projectile shoot similiar to the tampa bay bud lite commerical. I wouldl like to do something with a crowd in city limits at a bbq contest.

Let It rip!

[BurritoBandito]

I'm probably going to end up showing my ignorance here, but would hate to see this thread die without you getting an ok or no way from a more experienced member. Maybe this bump will provoke a response.

 

What's up with your computer? I'm no expert, but may be able to help.

 

As for the cannon itself... 6 tablespoons of "cannon black powder", is this just a course 75:15:10 BP? Is your powder corned or riced? Are you using any wadding? When you say "a lot of the pressure is taken up in the recoil" you are aware that prior to the pressure escaping the cannon, it is all built up inside, trapped behind the bowling ball. Without proper knowledge of the pressure generated, or how much the oxygen tank can handle, I'll reserve my judgements about potential rupture, but doubt the recoil does little to prevent that.

 

Hopefully, someone more knowledgable will chime in here, but I personally still wouldn't feel safe firing that cannon. Like I said before, sometimes you can get away with doing something hundreds of times before the inevitable accident occurs. I speak from first hand experience (sorry, bad pun). I got away with my unsafe milling method for a long time. It made me complacent, and I paid the price for it. I would hate for you to have to learn the hard way. 6 tablespoons doesn't sound like a lot of powder, but under proper circumstances could have devastating effects. I don't know if it's enough to rupture your oxygen tank, but I don't know that it's not either. Take everything I say with a grain of salt. It would probably be best to wait for someone more experienced to reply. How far does this thing fire? Just curious.

 

I don't want to make assumptions of what you do or do not know, but have you ever seen a cremora? They aren't terribly loud, but are pretty cool, and you may enjoy the effect.

[Wiley]

I've seen some safely constructed bowling ball mortars, all of which had a breech piece welded to the tapered end of the oxygen tank. The breech piece is 6" OD with a 2" bore and is what holds the powder. The breech piece is the real cannon; the oxygen tank is just there to guide the bowling ball in a straightish direction. I've heard that the ones made the way you are describing are referred to as "Darwin mortars."

[BurritoBandito]

Well then.... I suppose I'll just shut the hell up now...

[nater]

Unfortunately, it will be difficult for you to fire any special effects in front of a crowd at a competition. To do so legally, you will need to operate under the NFPA 1126 code for proximate pyrotechnic effects. This means being a licensed display operator in the State of the event with the proper licenses for close prox effects and a permit from the local AHJ for the event. This is not impossible at all, and is done all the time at concerts, sporting events, theater and other similar events. Without having the experience behind you, you will not be able to convince an AHJ that you can do this safely in front of an audience. The best way to get this experience, is to start performing pyro on a crew with an established display operator. In your case, you will want to express interest in proximate pyro as well so you can learn to set everything up safely.

 

BB - There is commercial "Cannon grade BP" available as a sporting grade powder, it is equivalent to 2FA in size.

Edited October 26, 2014 by nater

[pitmaster]

Burrito Bandito You were right about several things. The pressure in the tank is independent of the frame. I don't know if the black powder iscorned or rice. I am using Gorex cannon powder which is a very coarse grain. The label doesn't say anything.

 

The tank does have a constriction in the middle. When the bowling ball gets past that, it is not a tight fit. I don't use any wadding because of the mess and I am on someone farm. To Improve the fit, I have lately been putting duct tape around the ball with the middle beaded up to increase diameter. The tape comes off when shooting. Been getting 450-550 yards on six teaspoon. More shakes the carriage too much.

 

I am concerned about the tank blowing up also. After 25 times, I used a camera snake and inspected for cracks. I am past due to inspect again.

 

Cremora was a great idea. Will let you know how it works.

 

Pictures next time

 

Pitmaster

[MrB]

The ball goes past the constriction? It's bound to cause it to rattle around in the tube on the way out. That alone would make me shy away.

B!

[Wiley]

Assuming that I'm understanding you correctly, the middle of the tank is narrower than the rest of it. If that's the case, shooting this or any firearm that has a bore obstruction is a really, really bad idea. If you want to keep using it, you could always just cut the barrel shorter to get rid of that constriction. Though, I'd still be worried about repeatedly launching a 15 pound projectile from a gun that only has .25" walls. Eventually, those walls will fail.

[calebkessinger]

Hey Guys,

Lets look at this Mortor just as it is.

If you are wanting a cannon just forget that idea with a thin walled barrel and funny restriction that needs cut out.

Back to a mortor. You are only launching a 16 lb. object out of a 7.7 inch mortor. If that was a shell you wouldn't think twice about lighting it. If it was a dummy shell you would stand beside the gun laughing and carring on with no worries of failure of the launch tube. In an angled mortor set up with a bowling ball out of a little short tube an ounce of powder will lob the ball a hundred yards. Just look on youtube. As for repeated wear on a steel gun shooting 16 lb projectiles. well, that depends on how hard you are hitting it. If you are throwing two pounds of powder and a huge wad in it. yeah you might get away with it not coming apart for a while, but take out the wad and it's no different than launching cylinder shells, probably lighter on it.

As for shooting around people, it just takes one oops and you are done for. but an ounce of powder and some wet rags works well, you'd be surprised how little powder you need to make a cannon (thump)

I've got my eye on a piece of steel for a real bowling ball cannon. It's 1.5 in wall and 8 feet long.

If you look at my pic here you will see I have built at least one. ok more than one and less than a dozen.

https://squareup.com/market/WoodysCreations

I know I'm new here, but i really like cannons!! You guys are gonna make me build some more!

Thanks, Caleb

Oh, jees.. what was the question.. sorry all the other posts and i missed the question completely

.

I second with firewalker. over powder it to create a larger fireball coming out the end. Just use a rag or such for the wad. I always wet mine down to give it more weight, the charge goes in a aluminum foil wrap anyway. Add some ti. or junk stars to the charge and you are good to go.

Edited November 6, 2014 by calebkessinger

[BurritoBandito]

Hi Caleb,

 

Judging by the fact that you called Dagabu Firewalker I assume you're a member of fireworking.com? Welcome to APC. one difference between this "cannon" and a mortar is that the oxygen tank is not buried, but instead is mounted to a carriage. The device may be perfectly safe. I know very little about cannons, but was concerned, and wished to have some more experienced members give their opinions.

[calebkessinger]

Hi BB,

I just always considered a cannon something that you could look straight down the barrel and aim like a gun. Throwing the projectile rather horizontal direction. 95% of the bowling ball mortors I have seen are just that. Mortors. sitting on the ground with some sort of large angle 45 degrees or the like. Sounds like you have something half way in between. which is probably fine being you aren't using fast or large amounts of powder.

No expert here. but I have shot a lot of powder through a bunch of different homemade cannons. Just nothing that big.. I am waiting to build a big one until I can afford to make it an actual cannon.

Also 90% of the time I used hardwood homemade bp that wouldn't even lift a three inch shell to 100'. I would consider something like this very safe. It doesn't spike the pressure quickly which from what i have read produces 1/2 the psi on the gun than something like sporting powder. They expand to the same amount of gas just one does it a whole lot quicker. I have used powder that was super fast also... when I load a Hot charge with a heavy projectile. I head for cover. Those are five pounders in front of the cannon on my site. That's what I would consider heavy for that little cannon. most the time we shoot 1.5 lb concrete filled pvc sleeves.

I just considered the safety of my cannons to be like everything else in life. If it feels dangerous it probably is. .we have put benzo behind chain in one before. It's awesome!!! nothing like hiding behind the engine in your car as you watch the fuse burn cause you know that's the only thing that might stop a projectile when it goes boom!! That being said. knock on wood I have never had one fail. but plenty have.

Thanks for the fun, and good to meet you, Caleb

[bota]

I recently purchased a large CO2 tank for this same purpose. These tanks are seamless and formed from a chrome moly blank. My tank has an ID of 8.5+ inches with a wall thickness of 5/16 inch. A bowling bowl can be from 8.5 to 8.59 inches. I have a stash of about 70 or 80 balls. These range from 10 pounds up to 16 pounds. The pressure build up is in the breech or neck of the tank, which is thicker than the main tank. The difference between the ball diameter and tank ID is called windage. You should have .04 inch or more of windage. There is very little wall pressure, in a properly constructed cannon, beyond the breech area. 2 to 3 ounces of BP will send a 16 pound ball several hundred yards. Just my 2 cents.

[pitmaster]

Here's a video to enjoy.

[bota]

Nice build. I like your video. You have talent. Thanks. My project is on hold until Spring.