Home made PCP airgun

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I approve of this unsupervised creative exploration/expression and your decision to tap into this online intellectual resource.
A+ for your sense of adventure and I hope you are strong enough to keep that fire burning as you enter adult hood. There will be many many people that try to put that fire out along the way as evidenced in this very thread. Surround yourself with people that stoke the creative fire. Find the real value in failures because therein lies the path to success. 
 
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"usabro"
And I did the calculation of joules for the gun. 12 cubic inches is equal to 0.197 liters. Times 16 bar X 450 is 1415.84 joules. Is that a lot of energy? I don't know.1415.8423296
So people seem to be saying that 1 gram of tnt produces 4184 joules of energy. Well then my gun contains the equivalent of 0.33839 grams of tnt when pressurized to 230 psi. An average shot I take is at 110 psi. 
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Not too much, isn't it? :) And I would stop right here for now if I were you. Its tempting to proceed further to higher pressures, bigger volumes and harder matherials, and without a sufficient knowledge of matherials and physics you innevitebly would hit a point where energy is enough to get your limbs flying accross the backyard.

It would be better to obtain inexpensive air gun from a known manufacturer, lots of good and inexpensive options were already proposed to you above. And to study how it works. To see how it was engineered, figure out what is good and why, what is not so good thought in its construction and why. There is enough freely accessible info on the internet on that subject on the for the start. My two cents, best of luck to you :)
 
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"Drunk"
"usabro"
And I did the calculation of joules for the gun. 12 cubic inches is equal to 0.197 liters. Times 16 bar X 450 is 1415.84 joules. Is that a lot of energy? I don't know.1415.8423296
So people seem to be saying that 1 gram of tnt produces 4184 joules of energy. Well then my gun contains the equivalent of 0.33839 grams of tnt when pressurized to 230 psi. An average shot I take is at 110 psi. 
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Not too much, isn't it? :) And I would stop right here for now if I were you. Its tempting to proceed further to higher pressures, bigger volumes and harder matherials, and without a sufficient knowledge of matherials and physics you innevitebly would hit a point where energy is enough to get your limbs flying accross the backyard.

It would be better to obtain inexpensive air gun from a known manufacturer, lots of good and inexpensive options were already proposed to you above. And to study how it works. To see how it was engineered, figure out what is good and why, what is not so good thought in its construction and why. There is enough freely accessible info on the internet on that subject on the for the start. My two cents, best of luck to you :)
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Well I guess the goal of this was to use parts I could find at a hardware store to make a gun. Have you seen the hundreds of kids and adults who make airguns similar to mine on Youtube. They're all amazing! Try watching this video.
 
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That can be the problem with the Internet and Youtube, it is too easy for people to make videos of dangerous and stupid acts, like the young kids who thought it funny if one of them would shoot a melon of his friends head with a 50 caliber sniper rifle at 50 yards, luckily he hit the melon, one could only think about the consequences if this young boy had missed? It can also be very difficult for youngsters to determine what is cool and what is dangerous! I agree with the other poster on here, nobody is trying to cool your enthusiasm, those of us who are knowledgeable in this area are just trying to prevent you from doing something that will end in disaster. You can be inventive in other areas without putting yourself in dire risk of serious injury. I hope you take the good advise of the members who can see the dangers involved in what you are doing. I hope your father sees sense in letting you get something made specifically for this purpose so you do not get yourself in any deeper than you already are, all the best, Neil.
 
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Have you heard of Quackenbush airguns? They are home made. At least made in a guys machine shop. And I'm pretty sure he is no areospace enginner. He just probably has had experience building them, and with mechanical engineering fundamentals.
Of course his rifles use hydraulic tubing, not brittle plastic pipe.

He says his qualitifcations are Life member NRA (National Rifle Association)
Member ASTM (American Society for Testing & Materials)
American Airgun Makers Guild
Graduate Tool & Die Institute 1974
International Association of Machinists
Tool & Die Makers Lodge #113
Journeyman Tool & Die Maker

none of which I have but still......lol

Would my gun be safe if the pipe were steel?
 
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Dennis Quackenbush has been in the game a long time and saying your fishing lure frankenstein is like one of his rifles is akin to claiming your soap box derby racer is every bit the car a Lamborghini is, because they both have four wheels and go "vroom". If the U joint fails catastrophically, then that blade thin bit of scrap you have screwed down will most likely open a hole your neck or cheek. It isn't going to protect you from anything. That said if you insist on ignoring all precautions and advice offered, using all steel parts will make it safer, not safe, and to answer your only question, no, your gun does not have as much power as a .22LR. 
 
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You just do not seem to get it, just using steel will not make the air tube safe, there are all types of steels and materials used in making high pressure vessels, they use the rating of the tubes with mathematical equations to work out what thickness to use and which materials to use for given air pressures, they do not just grab a steel tube and say that will be OK. You need to know about strengths of metals and how they react under high pressure, this is not something to just mess around with and see which is safer for you, testing can be extremely dangerous. If you want to play in this area do some homework and do some learning about how to make pressure vessels, do not just experiment yourself with various materials to see which ones will blow apart and which won't, the one that blows apart could be fatal, Neil.

PS. Look at all of the qualifications you quoted for Dennis, quite impressive, the man certainly has a lot more knowledge you and I have.
 
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"Adam"Dennis Quackenbush has been in the game a long time and saying your fishing lure frankenstein is like one of his rifles is akin to claiming your soap box derby racer is every bit the car a Lamborghini is, because they both have four wheels and go "vroom". If the U joint fails catastrophically, then that blade thin bit of scrap you have screwed down will most likely open a hole your neck or cheek. It isn't going to protect you from anything. That said if you insist on ignoring all precautions and advice offered, using all steel parts will make it safer, not safe, and to answer your only question, no, your gun does not have as much power as a .22LR.
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Oh no I'm not comparing my gun to Quackenbush's guns, mine is more of an experiment, his is a finished, high quality rifle. By the way thanks for answering the question. Can you explain why my gun has more kick than a .22 LR though? I've been to the range many times and know what the feeling of the .22 LR kick is.

And thanks for mentioning the thing about the metal shield. I guess the only safe way to use the gun would be wear a bomb suit :) It's not a fishing lure gun though haha

I've also been considering wrapping the pvc pressure vessel in carbon fiber. I would soak the carbon fiber cloth in a special epoxy and wrap it and then let it dry, the same way people to for high pressure water rockets (75 bar).
Or possibly glass tape. That's use for water rockets, but I don't know how it would fair on a pressure vessel.

I understand that all of this is dangerous, and please don't think I'm not acknowledging that.
 
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I am trying to figure out if this is just one big troll or if you are serious. You say that you acknowledge the danger and understand how dangerous it is but you continue to do it. You add comments about all the things you do like make bombs. You say that your dad will not allow you to have a real pellet rifle but we are suppose to believe he condones you making dangerous pellet rifle alternatives and bombs over properly teaching you how to shoot and safely handle a pellet rifle? If you are not just trolling everyone and this story is all true then maybe there is a reason your dad doesnt want you to have a pellet rifle maybe he knows what you will do with it and that you are not mature enough to have those type of privileges. Maybe your dad has no idea you even do these things and if he does and allows you to make bombs then you both need some help.
 
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I think my dad let's me continue to use my airgun and not let me buy a pellet gun because he feels that I already have the home made airgun, and it's something I made, and if he buys or let's me buy something than he's allowing more. He seems to be uncomfortable about the gun I made already.


Also, I'm not a troll. You see from the pictures I am serious and I've built an airgun. And you say I continue to use it. I haven't shot the thing in the past two days. And in a previous comment I said I was considering dismantling it to keep myself from playing with it.

My dad let's me have airsoft guns but he doesn't like metal pellets flying in the back yard because he thinks it's more dangerous, and I've told him how powerful what I've made is but he seems to let me keep it cause I made it but doesn't want to promote it.

I wonder how the chance of me getting in a car accident and being seriously injured compare to the gun failing and me being seriously injured.
 
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usabro - I spent the first 20 years of my professional career as a Mechanical Engineer working with design of piping and control hardware for use with high pressure natural gas. With all my sincerity, please listen to everyone who has taken the time to post on this thread concerning your safety. You are playing with power and danger beyond your wildest comprehension. I strongly suggest you modify your homemade air gun one last time - make it non functional and then set it aside as a future conversation piece or something to show the grandchildren many years from now.
 
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Oh gosh I came to this forum asking for help and all I get is people who tell me to stop playing with this. Than tell all the kids who play with model rockets, water rockets, spud guns, dry ice bombs, etc to stop playing with them.

How is this "danger beyond my wildest comprehension"?..........It takes ten strokes of a bicycle pump. Is that really some tremendous power?

Doesn't my own body traveling 20mph on a bicycle have more energy behind that? Wouldn't I be injured far more if I hit a pot hole on my bike.

My own speed 30 fps x 30 fps x 980000 grains/450240 = 1958 foot pounds.
 
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You wanted some comments, well here they are.

Have you calculated the hoop stress on the pressurized parts and selected the material used accordingly? How about fatigue factors? Or factors of safety? And what about the polymer creep issues mention earlier? What about potential stress risers? Did you recognize and allow for them in the design? If there were a failure, are the materials involved selected and designed to minimize user exposure and risk during a possible failure?

 
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"usabro"I think my dad let's me continue to use my airgun and not let me buy a pellet gun because he feels that I already have the home made airgun, and it's something I made, and if he buys or let's me buy something than he's allowing more. He seems to be uncomfortable about the gun I made already.


Also, I'm not a troll. You see from the pictures I am serious and I've built an airgun. And you say I continue to use it. I haven't shot the thing in the past two days. And in a previous comment I said I was considering dismantling it to keep myself from playing with it.

My dad let's me have airsoft guns but he doesn't like metal pellets flying in the back yard because he thinks it's more dangerous, and I've told him how powerful what I've made is but he seems to let me keep it cause I made it but doesn't want to promote it.

I wonder how the chance of me getting in a car accident and being seriously injured compare to the gun failing and me being seriously injured.
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Again you say that you understand what people are telling you but then you argue that the airgun you made is probably less dangerous then riding in a car. Your analogies are not helping your case any and actually point to your immaturity on the subject and lack of respect for people who do know and are trying to help you and any other person unfortunate enough be close enough to be seriously injured when one of your experiments go wrong.
 
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