Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 59 users online :: 3 registered, 0 hidden and 56 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Coin Gun?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Coin Gun?

Unread postAuthor: Mitchza89 » Thu Sep 27, 2007 6:59 am

G'day guys,

I've had the idea for a long long time of making a coin gun. I'd love to shoot some sharpened 5 or 10c peices like frizbies at a few hundred feet per second but just have no idea on what the hell I'm gonna do for a barrel. Does anyone have any idea's?
  • 0

User avatar
Mitchza89
Brigadier General
Brigadier General
 
Posts: 1056
Joined: Tue Jan 09, 2007 12:05 am
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Thu Sep 27, 2007 7:12 am

Apparently not the most efficient ammo in the world, have a look here - though you probably were thinking of launching them sideways...
  • 0

Last edited by jackssmirkingrevenge on Thu Sep 27, 2007 7:16 am, edited 1 time in total.
User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Mitchza89 » Thu Sep 27, 2007 7:16 am

Well I was hoping to fire them like disks....but for that, I would need to some how make it spin so it stays level and that will definatly be the hard part. Some sort of rifling that spins it could be an option
  • 0

User avatar
Mitchza89
Brigadier General
Brigadier General
 
Posts: 1056
Joined: Tue Jan 09, 2007 12:05 am
Reputation: 0

Unread postAuthor: goose_man » Thu Sep 27, 2007 8:02 am

If you want them to spin like a frisbee, first you'd need a rectangular barrel of the perfect size. If you could get this, just polish one side of the inside of the barrel for a few inches (a short side), and use some tape to put on the opposing side. If the tape has enough friction the coin will rotate as if rolling on the tape and sliding against the polished side.

All in all, you need a very well machined barrel.

-goose_man
  • 0

User avatar
goose_man
Sergeant First Class
Sergeant First Class
 
Posts: 134
Joined: Sun Apr 08, 2007 6:37 am
Reputation: 0

Unread postAuthor: Mitchza89 » Thu Sep 27, 2007 8:04 am

Cheers mate. Thanks alot but all in all.........this idea sounds like more trouble and money then its worth. Would be cool though.
  • 0

User avatar
Mitchza89
Brigadier General
Brigadier General
 
Posts: 1056
Joined: Tue Jan 09, 2007 12:05 am
Reputation: 0

Unread postAuthor: psycix » Thu Sep 27, 2007 8:09 am

Maybe if you let it roll on the side inside ur barrel, firering the coin vertically aligned and having a frontspin.
BTW your barrel should have a weird shape wouldnt it?
  • 0

User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Thu Sep 27, 2007 8:20 am

The problem is one of surface area when it comes to firing them on their side. Say a coin is 20mm in diameter and 1.5mm and weighs about 3.5 grams.

A typical steel BB weighs 0.35 grams and has a surface area of 0.159 square cm.

The coin will have almost double the area, but weighs ten times more. This means that velocity will be severely limited, even if using shock pump pressures. Ideally you'd have your air pressure driving a large diameter piston that then pushes the coin out between guide rods (or just make a 1" cannon and load them sideways in a sabot ;) )
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Sponsored

Sponsor
 


Unread postAuthor: fred » Thu Sep 27, 2007 8:41 am

I do have an idea for that. I could make up a drawing using my disks.
  • 0


fred
Corporal
Corporal
 
Posts: 62
Joined: Wed Jul 25, 2007 3:18 am
Location: USA
Reputation: 0

Unread postAuthor: williamfeldmann » Thu Sep 27, 2007 8:58 am

psycix wrote:Maybe if you let it roll on the side inside your(sic) barrel, firing(sp) the coin vertically aligned and having a frontspin....


Yes, this firing alignment would give you spin, but the coin would exit the barrel in a nose dive, The front spin would make the coin rapidly ark forward, and thus down.

A coin fired on its side with any spin would also ark, but to the side. Assuming a left spin the coin would ark left, a right spin the coin would ark right. It is possible to grind the coin to make a more frisbee or aerodynamic profile for flight which would provide some range, but accuracy would be zilch.

The Navy is said to be messing with disk ammo in its rail guns, but there is actually no contact between the disk and the gun. It is levitating due to magnetism.

I fear we are out of our pocketbook's range on this idea. It would be possible, but not practical, and a waste of good cannon money.
  • 0

User avatar
williamfeldmann
2nd Lieutenant
2nd Lieutenant
 
Posts: 216
Joined: Sun Sep 09, 2007 6:55 pm
Location: Ames. Iowa, middle of BFE
Reputation: 0

Unread postAuthor: jimmy101 » Thu Sep 27, 2007 9:43 am

A coin firing gun is probably possible though I think you need to do some "out of the box" thinking to get it to work well.

As others have posted, even if you come up with a way to fabricate a barrel the surface area of the ammo is just too small given it's mass.

So... don't think of the gun like a regular pneumatic (or combustion) where the pressurized gas acts directly on the ammo.

Outside the box... perhaps something like a baseball pitching machine. The ammo is dropped between spinning wheels. Google "Lego CD launcher" for the basic concept specifically designed to launch (with spin) a disk shaped object. Can you use compressed air to spin the launch wheels?

Or come up with a way to use compressed air to swing a launch arm like a skeet throwing machine. This method will also give you spin.

Or, use compressed air to move a large diameter (compared to the coin) piston that pushes a flat blade into the barrel that in turn pushes the coin. Use a hop-up like mechanism to give the coin the spin.

Other possibilites... ?
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3127
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: jackssmirkingrevenge » Thu Sep 27, 2007 10:20 am

Or, use compressed air to move a large diameter (compared to the coin) piston that pushes a flat blade into the barrel that in turn pushes the coin.


with a little modification, a cheapo pneumatic nailgun would be more than ideal for this application - and look, you can pick one up dirt cheap!

All you need to do is disable the safety and build a frame to launch the coin from.
  • 0

Last edited by jackssmirkingrevenge on Thu Sep 27, 2007 10:34 am, edited 1 time in total.
User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Hubb » Thu Sep 27, 2007 10:23 am

This project would be a good one for that spring air idea that's been in a few threads. Maybe even eliminating the "air" part and have a strong spring strike the coin, like in one of those little disk toys.

Edit: Another thought would be to have a system like a pitching machine. It is essentially a rubber wheel that spins with pretty fast rpm to launch baseballs using friction. This way, you could stack the coins in a tube and have a fully automatic coin gun.
  • 0

User avatar
Hubb
Major General
Major General
 
Posts: 2390
Joined: Mon May 28, 2007 8:39 am
Location: South Georgia
Reputation: 2

Unread postAuthor: psycix » Fri Sep 28, 2007 1:28 am

hubb017 wrote:This project would be a good one for that spring air idea that's been in a few threads. Maybe even eliminating the "air" part and have a strong spring strike the coin, like in one of those little disk toys.

Edit: Another thought would be to have a system like a pitching machine. It is essentially a rubber wheel that spins with pretty fast rpm to launch baseballs using friction. This way, you could stack the coins in a tube and have a fully automatic coin gun.


Then make the spinning disk more like a sawblade where coins fit in the gaps.
Coins are feeded from the side and falling in the gaps, take over the disk velocity and sweep out.
  • 0

User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: TechnoMancer » Fri Sep 28, 2007 5:44 am

williamfeldmann you are wrong about the ammo not touching the gun!!!!
in a railgun there are two metal rails (surprise surprise) and the ammo which must be metal (or at least conductive) touches both of them them a sufficiently high voltage is applied across the rails the current flows through the ammo and the lorenz force propels it down the barrel. unfortunately the high current and small contact area cause a huge amount of heat which then causes the rails to become damaged meaning that the gun can usually only be fired once and then requires servicing!!
  • 0


TechnoMancer
Corporal
Corporal
 
Posts: 64
Joined: Mon Jul 02, 2007 4:58 am
Location: Christchurch New Zealand
Reputation: 0

Unread postAuthor: psycix » Fri Sep 28, 2007 6:17 am

TechnoMancer wrote:williamfeldmann you are wrong about the ammo not touching the gun!!!!
in a railgun there are two metal rails (surprise surprise) and the ammo which must be metal (or at least conductive) touches both of them them a sufficiently high voltage is applied across the rails the current flows through the ammo and the lorenz force propels it down the barrel. unfortunately the high current and small contact area cause a huge amount of heat which then causes the rails to become damaged meaning that the gun can usually only be fired once and then requires servicing!!


He must have meant a Coil gun instead of a railgun :)
  • 0

User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'