spring powered potato gun

[blowemupspudguy]

i have been thinking about how powerfull you could make a spring powered potato gun. it would be built like a large scale airsoft gun, there would be a large spring behind a syringe like piece of rubber, like a piston, only it would be completely airtight, so that when it moved it would push air out of the barrel even if there was somthing (a potato) in the way. the spring would be thingyed back with a lever, it would have to be a realy strong spring so that it would have enough force to push the syringe forward as fast as possible. this would be a realy usefull potato gun because you wouldn't have to fill it with air for each shot. it would also be cool because it would be able to be a pump action gun that would be able to hold and fire as much ammo as you could carry on your back. it would also save the expence of a valve, although the spring and syringe like thing would prolly cost just as much, and you would need to oil it every once and a while.

[darthtator]

I think that there are a lot of problems with this. To get somewhere close to the power you can get out of a pneumatic or combustion launcher, you would need a VERY powerful spring. Then you would have to figure out a way to thingy back the spring. So that kinda eliminates the portable part. Also, are you planning on making the spring action piston push the potato out of the barrel or the air pressure from the pushing of the piston? I think this could possibly be something you could work out, but it would take a lot of time, designing, and probobly a good amount of money too.

On the spring powered subject, I have a friend that made a crossbow ( more like a ballista), he used a leaf spring out of a truck for the part that propels the bolt ( arrow). It took a floor-jack (like one to lift a car) to thingy the beast. He used a T-post for an arrow and shot it through a concrete wall, then it travelled about 75-100 yards after that. It made for a pretty amazing display, dangerous, never the less, but amazing.

[blowemupspudguy]

the air pressure from the piston would push it out, a potato would be a bit much, maybe a paintball. it would be alot weaker than a typical pneumatic or combustion, but i think i could get one to fire a golf ball 100 yards or so, with a big spring and a lever to pull it back. the trigger would be hard to assemble. im still working on that. in order to get what im saying you realy need to have disassembled an airsoft gun.

[darthtator]

Well I actually have an airsoft gun in front of me. I don't use it too much, so I'm considering taking it apart. LOL, I use it to disipline one of my cats. I have one cat that beats the crap out of all the others, so when he goes on his rampage I tag him from across the living room. He's got a lot of fur so I don't think he feels it much. Well If you end up making one, or want to talk about designing send me a personal message and I'll get back to you A.S.A.P.

I don't think a trigger would be too hard to assemble. Have a typical gun trigger with a little hook on the end, when each coil in the spring passes the hook it will grab it. When the spring is all the way thingyed the last coil on the spring would be held by the hook. Pull the trigger ( making the hook turn forward and down) and it should release the spring. Depending on how much force the spring is holding would determine how hard the trigger would be to pull. Well write back with anything else that you might have come up with so we can kinda brainstorm and try to make this work. I think this could potentially be a very cool and efficient project.

Nick

[spudkillah]

Well it would be cool but i dont think it would work. I like the idea though.

[Lukas]

I think that the single-pump pellet rifles use a big spring, or maybe some of them do. You'd be best of using a very small barrel and projectile, something in the range of a pellet, if you have to use a spring.

The problem with any trigger is that as it releases the spring, it will tend to wear down the surface.

[darthtator]

I think for a spring, you would want to have it be long and not too thick (so the compression is a little lower but you still get a longer run through the chamber). You are right about the trigger though. Eventually you would have to replace it. So keep in mind that when you find something that could meet the trigger requirements, it is also fairly easy to find. I was also thinking about the sealing meathod. To push the air in the direction you want there will have to be a seal. The seal will wear out though, from rubbing on the walls of the chamber. Would it be best to use something like rings on a piston like on a regular combustion engine uses. something cheap that is meant to wear out so nothing else wears out, ya know? Well write back with more ideas, guys!!! I think were starting to get somewhere in this process.

Nick

[blowemupspudguy]

hey iv been gone for the past week and the forum is swamped! it's gonna take me hours to respond to all the new stuff!
anyway...i think your right about the trigger and piston wearing out, alot of grease should make it last longer and get a much better seal. if the chamber was divided with a male and female adapter it would make it much easier to replace stuff. keep throwin me ideas, im gonna try to make this when i get some more $$$

[darthtator]

I think I have said everything that I think would be neccesary to look at. Now someone has to build it. Because naturaly we are going to run into snags. Then after someone makes it we will find the problems and trouble-shoot them. But until then I'm kinda out of ideas, I think we covered all the basics don't you?

[blowemupspudguy]

yeah that's true, like i said it's gonna be my next project

[sgort87]

Well this will not work unless you are incredibly strong dude. Think of it this way: An airsoft pellet has a diameter of about 1/4" which gives it a volume of approximately .0082 cubic inches. The average volume of a potato slug is about 9 cubic inches. So the volume of a potato is approximately 1100 times that of an airsoft pellet. And now remember that a potato is much more dense than those plastic pellets. So basically it will be about 2000 times the mass. Now go take one of those airsoft springs out of the gun... decently hard to compress right? Well try multiplying the spring constant on that by 2000 and try moving it. Usually it takes quite a bit of force to c0ck an airsoft gun right?(You can't say the word "c0ck" on this site without misspelling it, it changes it to "thingy") Well now try multiplying that by 2000. I bet the strongest man Alive couldn't do that. And I don't think you could get your hands on any of those materials needed anyways to withstand such a great spring force. This gun is not possible. Don't even bother attempting. It's a waste of time and money.

[sgort87]

Also, this thread does not belong in the pneumatic gun section...

[Lukas]

That's sort of my thinking, best to keep it as small as possible. I think it does belong here, though, b/c it uses air and is technically pneumatic then.

[blowemupspudguy]

im not building a full scale potato gun, im making it a 1/2" barrel. it will prolly be about 20 or 30 times harder than an airsoft gun to pull the spring back, that's not much when you get a lever on it.

[darthtator]

There's many different ways to make this work! smaller would be easier, but even to make a full scale one would be possible. Finding the materials might be a chanllenge but everything worth making should be hard, it gives you something to be proud of.