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Safety of HDPE Golf Ball Cannon


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#1 bjc4073

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Posted 05 August 2015 - 12:29 PM

I made a howitzer looking cannon out of 1.91 mortar tube. It takes about a dixie cup and a half of homemade bp and a golf ball wrapped in paper towel. I eventually blew the plug out (which was only stapled) at about 2.5 cups of powder. At all times I was behind a windshield at a safe distance. So is it safe? 

 

 

BTW the plug blows at 0.55 and the barrel moving was my fault. The dowel that I brought broke on the first shot so I resorted to twigs.


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#2 TYRONEEZEKIEL

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Posted 05 August 2015 - 01:52 PM

Why do you allow so much backlash in the barrel hinge? It seems like its robbing your shot. 


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#3 otto

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Posted 05 August 2015 - 06:55 PM

I'd say anything burning out of the gun after the ball leaves is wasted BP.....



#4 Arthur

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Posted 06 August 2015 - 11:19 AM

Firstly "an unknown person on the internet" isn't the best when asking about your safety!

 

secondly you've pointed out some failings which need designing out before you do further tests.

 

Remember that BP imparts heat to the barrel when it fires, the barrel will warm and will start to perform differently when it gets too hot.



#5 bjc4073

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Posted 06 August 2015 - 08:06 PM

Why do you allow so much backlash in the barrel hinge? It seems like its robbing your shot. 

I only brought one dowel which broke. I was using some twigs but I have since bought some metal rods. No doubt it was taking some power out.



#6 Sparx88

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Posted 25 August 2015 - 04:15 PM

Nice video. I would also say that you may have too much powder in there. Not that the tube is in terrible danger at the pressures you are doing, it's just a waste of powder with all that fire after the shot. And that extra fire is extra heat. Hdpe will just split and deform if you go to far with it. try it with 1.25 cup and pack in over the golfball with some bread about 2". Other than that, nice job on putting it together.


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Finding solace and comfort on my path of pyrotechnic illumination and enlightenment. Painting the sky with strokes of vibrant anticipation and freedom. From spark to spark, the chain reaction of beauty and power that ignite the imaginations and inspirations of young and old alike.        -my pyro sparxs- 

#7 dynomike1

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Posted 28 August 2015 - 05:59 AM

Dam i only use 4oz. and that will shoot a 2lb. lead ball 1000yds. Spaarx you are giving bad advice, i have heard of people putting a wet paper towel in them and busting the barrel. there is no need putting anything in front or that ball. Both of you need to go here and read.

http://www.go2gbo.co...oast-artillery/


There are very few problems that cant be solved with explosives.

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#8 Sparx88

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Posted 28 August 2015 - 12:01 PM

I did say he was using too much. But your right about the packing thing. I was considering how lightweight golf balls are compared to a 2 pound lead ball. I have loaded powder in excess of that back in the day with small hdpe golf ball cannons to find the point of fail and never did until it was packed to the muzzle with 2 Oz.

But yah forget the whole thing about packing anything in there. No need to be wild and crazy like me doing dumb stuff like that. Dynomike knows his stuff about cannons.

Edited by Sparx88, 28 August 2015 - 12:05 PM.

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Finding solace and comfort on my path of pyrotechnic illumination and enlightenment. Painting the sky with strokes of vibrant anticipation and freedom. From spark to spark, the chain reaction of beauty and power that ignite the imaginations and inspirations of young and old alike.        -my pyro sparxs- 

#9 dynomike1

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Posted 30 August 2015 - 06:59 AM

Maybe this will help. Just trying to keep everyone safe.

SwitlikLoadsOne.jpg


Edited by dynomike1, 30 August 2015 - 07:03 AM.

There are very few problems that cant be solved with explosives.

                             Explosives are a bang up job.


#10 RTT

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Posted 20 December 2015 - 05:11 AM

I made a howitzer looking cannon out of 1.91 mortar tube. It takes about a dixie cup and a half of homemade bp and a golf ball wrapped in paper towel. I eventually blew the plug out (which was only stapled) at about 2.5 cups of powder. At all times I was behind a windshield at a safe distance. So is it safe? 

 

 

BTW the plug blows at 0.55 and the barrel moving was my fault. The dowel that I brought broke on the first shot so I resorted to twigs.

Awesome



#11 AAF

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Posted 02 January 2016 - 05:50 PM

ruff numbers for you  to make your own call-
using a moded version on this spread sheet  http://closefocusresearch.com/calculating-barrel-pressure-and-projectile-velocity-gun-systems 

golf ball rounded up to 46 grams

1 gram of  sporting bp creats 270cm3 of gas

usable barrel of 10.5"  asumeing "standard" 12" firework mortar with 1.5" plug is 491.75CM3

a 5 gram charge would  fill the barrel  volume to 27 psi  giving 120 fps on the golfball , should give you  plenty of range,some were better then 600', likely a good bit better at a 25-30 angle

dissection of a "sky tiger" 1.75" ball shell was overall weight of the shell [casing, fuse, etc] was 63 grams.  lift charge 6 grams

DR11 HDPE  is rated to 160psi

powder burn speed and comp will effect the PSI, this is effected by the quality, grain size and confinement (such as a sub call powder chamber on a BP mortar) 




 


Edited by AAF, 02 January 2016 - 06:02 PM.


#12 dynomike1

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Posted 19 February 2016 - 06:28 PM

Thats pretty impressive.


There are very few problems that cant be solved with explosives.

                             Explosives are a bang up job.


#13 lloyd

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Posted 19 February 2016 - 07:26 PM

How far does the ball go, if you shoot the thing straight up, Mike?

 

Good powder should result in HUGE flights with just a few grams of powder.  A standard US baseball (about 150 grams) will go 300 feet high off about 15 grams of decent powder, with 1/8" clearance between the mortar and the ball.

 

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#14 dynomike1

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Posted 25 February 2016 - 07:23 AM

Don't know.


There are very few problems that cant be solved with explosives.

                             Explosives are a bang up job.


#15 dynomike1

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Posted 11 March 2016 - 08:27 AM

My guess would be 2000-3000yds.


There are very few problems that cant be solved with explosives.

                             Explosives are a bang up job.


#16 Merlin

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Posted 10 September 2016 - 07:09 PM

Never been here before :mellow:   Last week I made a nice little cannon from a 3" HDPE tube just for fun.  But what is the talk about a dixie cup of powder?  I find 25 grams of MCRH to be sufficient for launching baseballs!  A dixie cup in a 1.91?   I had a friend to show up one day with a cannon he had purchased in an antique store.  It was pieced together with industrial valve wheels but the barrel appeared to be machined.  It too was approx 1.9 bore and appeared sound- but I have heard of a couple people pushing homemade cannons to far and getting killed by shrapnel.  15 g BP in his cannon sent a golf ball out of sight-somewhere in the pastures.  Since there is really no way of knowing the strength of metal barrels aquired from parts unknown I elected to make my cannon simply a horizontal version of a hdpe mortar.  I bought the nice little wheels on amazon and the only other things were a couple 1/2 bolts and U-clamps and couple cans of spray paint.  Everything else is wood. 2x4 shaped for the barrel platform and used 4x4 and 2x4 for breech blocks (to prevent the plug blowing out).  I looked around for real cannons but I not wealthy.  Mine cost about $30. 

It is just as safe -more so- no flowerpots as a typical fireworks mortar.  But really, how much powder is a dixie cup?


Edited by Merlin, 10 September 2016 - 07:10 PM.


#17 lloyd

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Posted 10 September 2016 - 07:17 PM

Merlin,

Most golf ball guns typically use 3g-9g of BP (depending upon the type and method of manufacture of the powder).

 

We USED to use 9g all the time, but amateur powders have gotten better...

 

Lloyd


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#18 Merlin

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Posted 10 September 2016 - 09:18 PM

Hey Lloyd good to hear from you. Seems like a lull on the forum. Yeah 9 grams seems reasonable. One of the posts here a guy claims to use a Dixie cup and more. A 3 oz Dixie will hold around 50 grams of mcrh. That means he was using 10 times more powder than he should. Maybe I missed something.
Correction in the first post he says 2.5 Dixie cups so he must have been using really weak BP!
I test my powder with 25 grams in a 3 inch with a baseball for altitude. Way more than required for a 3inch ball shell! I only use 35 for a four inch and they are high to avoid fallout.

Edited by Merlin, 10 September 2016 - 09:28 PM.


#19 Merlin

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Posted 10 September 2016 - 09:33 PM

Dam i only use 4oz. and that will shoot a 2lb. lead ball 1000yds. Spaarx you are giving bad advice, i have heard of people putting a wet paper towel in them and busting the barrel. there is no need putting anything in front or that ball. Both of you need to go here and read.
http://www.go2gbo.co...oast-artillery/

Your right. I knew of a couple deaths from overloading homade cannon but that liist is staggering. Seems home made metal cannons cause more death and injury than all of pyrotechics. Wonder they haven't been outlawed.

#20 sitas

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Posted 02 December 2016 - 12:03 PM

Merlin; you don't have to be so up tight about the cannon thing. You could fall out of bed and break a neck too. I think there are enough things outlawed now. Better to start teaching about common sense instead of relying  on forums and U tube , and  the like. Everyone now days seems to think that someone else is responsible for them.That sucks.






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