tshirt cannon

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
kb18951452
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Thu Jul 26, 2012 8:33 am

technician said that a 2.5-3" barrel was ideas for a tshirt. Wadded tight, and tassel attached (to reduce tumbling in flight)
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jackssmirkingrevenge
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Thu Jul 26, 2012 8:54 am

kb18951452 wrote:technician said that a 2.5-3" barrel was ideas for a tshirt. Wadded tight, and tassel attached (to reduce tumbling in flight)
Sounds about right, remember that cross section increases exponentially with diameter so a 3/4" only has around 56% of the flow of a 1" valve - but you're firing T-shirts, so that's fine :) you can use a regulator to tune the power by altering the pressure.
hectmarr wrote:You have to make many weapons, because this field is long and short life
kb18951452
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Thu Jul 26, 2012 10:21 am

That's what I was thinking.

What are CO2 Bottles usually pressured at? Any suggestions on the size of the chamber i would want to work with? Concerning fitting these all together. I'm guessing the Pilot Port on the QEV can be small since its only usd for filling, and the 3 way aswell, its the 2 "other" ports on the QEV that i need to worry about being 3/4 or 1" (but it seems i read it will be tricky to find one that size)
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jackssmirkingrevenge
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Thu Jul 26, 2012 3:18 pm

kb18951452 wrote: What are CO2 Bottles usually pressured at?
800-900 psi at normal temperatures.
Any suggestions on the size of the chamber i would want to work with? Concerning fitting these all together. I'm guessing the Pilot Port on the QEV can be small since its only usd for filling, and the 3 way aswell, its the 2 "other" ports on the QEV that i need to worry about being 3/4 or 1"
Typically, a QEV will have all ports the same size, so not really an issue.

In order to figure out what sort of chamber size and barrel length you should be looking at, I suggest downloading this excellent virtual launcher modelling program:

http://thehalls-in-bfe.com/GGDT/

Play with the parameters to have a good idea of how you should build it to get the performance you want.
hectmarr wrote:You have to make many weapons, because this field is long and short life
kb18951452
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Thu Jul 26, 2012 7:33 pm

http://www.ebay.com/itm/Pneumatic-QE-04 ... 3f19db3d49

This what i am looking for in a QEV?

I can't read Gasses/Liquid schematics (yet ) :)
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mattyzip77
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Thu Jul 26, 2012 7:45 pm

Cannot see the link when I click on it so I am assuming you got it??
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kb18951452
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Thu Jul 26, 2012 7:58 pm

Pneumatic QE-04 3/4" Inlet Port Air Quick Exhaust Valve

The link works for me. ITs one of those actions with more than 10 available.
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Mr.Tallahassee
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Thu Jul 26, 2012 8:10 pm

I'm not too sure about the sizing of the gold port. There isn't any indication on which port it is. If it's the P port then sure but if it's r, that's where the air would flow into the barrel. That gold port is only 5/8'' versus the rest being 3/4''.
EDIT: I found a valve for double the cost that is 3/4'' porting on all three ports. long url $20 dollars and I've seen this exact one used a few times on the forums.
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Petitlu wrote:My balls are made of lead and weigh 22g but I can make heavier or lighter ...
kb18951452
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Thu Jul 26, 2012 9:54 pm

Awesome.

Thanks for the link. I'm still pretty unfamiliar with CO2 bottles. What kind of hoops will i be jumping thru to get the to mate with whatever 3 way solenoid i get?, and for that matter, If i want more control over shape than pipe might provide, can i use some other (shapable) pipe system for the air supply and 3way to QEV connections to provide better configurability. Thinking maybe copper tubing (Can be bent), or some kind of industrial hose?
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Thu Jul 26, 2012 10:13 pm

kb18951452 wrote:Awesome.

Thanks for the link. I'm still pretty unfamiliar with CO2 bottles. What kind of hoops will i be jumping thru to get the to mate with whatever 3 way solenoid i get?, and for that matter, If i want more control over shape than pipe might provide, can i use some other (shapable) pipe system for the air supply and 3way to QEV connections to provide better configurability. Thinking maybe copper tubing (Can be bent), or some kind of industrial hose?

Of course you can choose some type of bent configuration it your cannon but then your looking at really high money costs


Also depending on what size copper you use and how much, your spending costs are going to jump, but again your spending limit it pretty high. If i were you would just stick with pvc
kb18951452
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Thu Jul 26, 2012 10:17 pm

Thanks,
there are 2 primary goals. 1. Make a tshirt cannon
2. Make it looks like a flintlock pistol.

I have friends who can help me make bent pipes. Its more of a question, what materials might i use if i'm going for high pressure/small chamber setup? If i use paintball bottle w/ HPA, I might want to go with 300psi in a smaller chamber (If i need a smaller chamber)
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Mr.Tallahassee
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Thu Jul 26, 2012 11:04 pm

All I can tell you for the mating of the two is find the right threads in steel pipe or fittings. I read somewhere that almost all paintball tanks today use 5/8'' 18 UNF threads, I don't know for sure what the regulator threads would be though. But do not use pvc for HPA. PVC is not meant for 300PSI.
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Thu Jul 26, 2012 11:44 pm

Mr.Tallahassee wrote:EDIT: I found a valve for double the cost that is 3/4'' porting on all three ports. long url $20 dollars and I've seen this exact one used a few times on the forums.
Be aware that this is probably BSP threaded, not NPT - since you have a decent budget, you might want to be looking at stateside sources for your fittings.
I have friends who can help me make bent pipes. Its more of a question, what materials might i use if i'm going for high pressure/small chamber setup? If i use paintball bottle w/ HPA, I might want to go with 300psi in a smaller chamber (If i need a smaller chamber)
Technically all the low pressure fittings will hook up together, the only tubing you will need will be between the regulator and the three way valve.

Since this is "low" pressure as well (assuming you're regging it down to 300-400 psi), copper tubing should be fine assuming it's not bearing any load, ie the actual tank is otherwise supported and not hanging off it.

If you're going with the three way valve setup, a large "main" and smaller "firing" chamber are essential.

I would go for HPA over CO<sub>2</sub> if you have the choice.
hectmarr wrote:You have to make many weapons, because this field is long and short life
kb18951452
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Fri Jul 27, 2012 12:45 am

like fastenal, grainger, etc?
QEV
http://www.fastenal.com/web/products/de ... ku=0443031
NPTF


3-way solenoid:
http://www.grainger.com/Grainger/INGERS ... Pid=search
NPT

Mixinf NPT and NPTF won't be a problem if teflon tape is used will it?
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Crna Legija
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Fri Jul 27, 2012 1:08 am

kb18951452 wrote:Mixinf NPT and NPTF won't be a problem if teflon tape is used will it?
nope NPTF is for fuel and just made with a better tolerance other then they are the same.
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