This is my prototype bb gun I just put together, it doesn't look like much, but it demonstrates the power of a drink bottle. I came up with the idea after failing many times to make a piston valve, I thought it would be simpler to have something similar but actuated mechanically.
It uses a water bottle as a chamber, the bottle top is the valve, and an aluminum barrel to fire 6mm bb's at 274 fps (thats as fast as a quality spring powered bb gun).
The drink bottle cap opens very quickly when there is pressure behind it, it just takes a little bit of force to actuate it.
I couldnt find a good way to attach the end of the bottle cap to a barrel so i put the barrel in a fixed position through the wood. When I fire it, I hold the drink bottle behind the barrel (about 5mm away from barrel) and then open the cap, when the cap is fully open it connects up to the barrel so most of the air is directed down it. Some air escapes through the side but that doesn't matter because it is just a prototype.
At 10psi it will perform better than a $2 shop bb gun which fires at 48fps
At 20psi it performs better than my other crappy bb gun I made
At 30psi i recorded it at 63.1m/s (207 fps)
At 40psi i recorded it at 83.6m/s (274 fps)
I don't want to take it above 40psi because it is just a water bottle, not really made to hold pressure.
When i get the chance I will make a proper version, I hope to get over 500fps by:
Making a replica of the drink bottle top out of brass using a lathe
A smaller chamber at higher pressure
A built in mini shock pump
Creating a proper seal around the barrel
And making some kind of semi auto setup.
So tell me what you think about my design.
my proto bb gun
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shud_b_rite
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- Location: Auckland, New Zealand
- Attachments
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- I know, it looks poor
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- Close up while the valve is open
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- This diagram is a bit messed up. The top picture shows the valve open. The lower picture shows valve closed
- diagram.JPG (15.03 KiB) Viewed 4321 times
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- Damage. It will go through a cd and through a milk bottle but its not quite powerful enough to go through a can.
Last edited by shud_b_rite on Fri May 11, 2007 11:07 pm, edited 2 times in total.
Airbeds... so many different uses
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super spuder
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nice. . you should use a pop bottle. they will hold 120 psi
trying to decide on a new project, probably something small.
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shud_b_rite
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Because the needle on it wont go below 30psi anymore for some reason. I use a different tire pressure guage checker thing to check the pressure of my cannons.
Airbeds... so many different uses
Cool but i still don't get how yall are using pop bottles. I mean to get the valve in why not use a gatarode bottle. It's twice as thick and stronger to but if it gets to cold it will shatter under the psi. I think those can go to 145 PSI but don't quote me. So please tell and others how the gatorade bottles work , they work well for combustion cannons as said by one poster on this site. Also the large poweraid bottles might work to but the walls are thinner than the gators but thicker than pop bottles. 
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spudthug
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because he needs a pop thingy on the front..it is the valve..
4" piston valved cannon-half done..( i spilt my cement...)
Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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shud_b_rite
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- Joined: Tue Jan 30, 2007 7:10 pm
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When I make my proper one (when I find time) I will use an empty 12gram co2 cartridge as the primary chamber. This will be filled by a secondary chamber (an old paint ball tank) filled to about 200psi with air. The hardest part is trying to make a valve similar to these drink bottles, I am not good at making valves.
Airbeds... so many different uses
i have an idea. You can ge a bit of slingshot tubing and put it over the end where the bb goes, then glue that to the bottle. hyave about a cm hanging off the end, and join it to the bottle top. Will act as a sealer,and if you poke the bb into it when it shoots it will have more power
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shud_b_rite
- Specialist 2
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- Joined: Tue Jan 30, 2007 7:10 pm
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???not such a good idea there russel
Yea that will work. But im not going to spend anymore time on it. I just need to figure out a way to make a valve similair to this that is made out of metal. Flow isnt that important, opening time is.
Airbeds... so many different uses
Someone else spotted the sports caps too?
I was messing about with those caps last month. I've found one type which has the exact diameter of 15mm copper pipe and I've been fiddling with it to secure it in a copper fitting as a kind of exhaust valve for a little piston
I was messing about with those caps last month. I've found one type which has the exact diameter of 15mm copper pipe and I've been fiddling with it to secure it in a copper fitting as a kind of exhaust valve for a little piston