SpudFiles

New member here. Been commissioned to create 2 Prop Tshirt Cannons. 1 shaped like a Cannon (on a gun carriage, etc.), and another like an oversized flintlock pistol (For a "Pirate" sports team).

I started writing this as a reply to
http://www.spudfiles.com/forums/what-lo ... ter,0.html

but decided i;d probably start my own thread and not hisjack his.

I'm interested in seeing how your works. I'd like to go with durable as a very high priority. Metal parts rated for higher pressure (incase someone overfills), and longer lasting (As i assume plastic components may not be as durable).

There are a few things mentioned in this thread that i do not understand.
I don't know what kind of PSI is needed to launch a tshirt at some given density (rolled tight), in some given barrel diameter (Though i think the barrel is going to end up being 3 inches inside just a guess)

I like the idea of a solenoid pilot valve. My budget is $1500 with a majority going to fabricating the casing (The Pistol of Canon shape), but buying industrial component at $20-50 a pop isnt an issue.

Reading through the responses here, it appears there are several idea being contributed involving more industrial component.

I understand how this works, i see the plans, but i lack knowledge of the various components, what they are called, where they might be purchased, how one performs over another.

I'd like to use a CO2 bottle, And I' like the mechanism to result in, when the trigger is released, the firing tank (i don't know its common name yet), it refilled.

Fro the suggestion on winzards design, what parts would you replace, and with what part?

It seems like you would want a 3-way valve semi-auto. Use the search feature and you will find tons of information on using three way valves. They can be coupled with solenoid valves to give you a semi automatic launcher. As for a CO2 bottle, I would personally suggest buying a HPA paintball bottle and regulate it. The all metal design will handle the 300 psi from the regulator and you can have a very small chamber in relation to your barrel. Beyond that, use GGDT to find what size your chamber needs to be to get your preferred distance and velocity. I would suggest using the Engineering Toolbox website to find actual values for each nominal pipe size. The rest is up to you.

kb18951452 wrote:I'm interested in seeing how your works. I'd like to go with durable as a very high priority. Metal parts rated for higher pressure (incase someone overfills), and longer lasting (As i assume plastic components may not be as durable).

Plastic might still be a better way to go than metal. If these are to be handled by potentially untrained people and often pointed in the direction of other people then the "incase someone overfills" can not be a possibility. You absolutely have to have some type of a pressure pop-off so that it is impossible to over pressurize the gun past what gives safe muzzle velocities.

on top of the safety pop off valves, and regulated co2, wouldnt a sprinkler valve cannon be enough since he is only shooting tshirts?

See, if you tell me a sprinkler vavle setup would work, then i am all good. I mean, I'm only shooting shirts, and only 75-150 feet. Trying to avoid a bit of the blatant experimental stage. Would a sprinkler valve cannon work?

I had thought about using 2 solenoid valves, a normal closed (Sprinker) and a normal open. The idea being that when the trigger is pressed the sprinkler vavle opens and releases the air to fire the tshirt, while the other valve closes off the supply air flow. When the trigger is released, the barrel pressure drope as the solenoid valce closes, and the other opens repressurizing the firing chamber.

That's a little more complicated than it needs to be. I think you can use a modified sprinkler valve and a three way valve to get the effect you want. The image should give you an idea on what you would be looking at. You connect your air supply to the three-way spool valve and connect the valve to the pilot of the sprinkler valve. when the valve button is released the air supply will fill the pilot and chamber. When you press that button, the air supply is shut off while simultaneously opening the pilot exhaust thus opening the sprinkler valve. There's plenty of resources on how to do the modding of the sprinkler valve to work with.

like i believe 1500 bucks, is more then enough for a simple, tshirt cannon, shouldnt cost you much, just get a sprinkler valve and mod it and build you chamber

If i want to go with a smaller chamber, then higher pressure would be needed in it to achieve the same performance from a larger chamber at lower pressure.

The GGDT... I'm on a mac, and there are about 40 parameters on there i don't know how to get the data for.

I think I'd preffer to use higher pressure smaller chamber to keep everythign compact.

I was looking at what another member had done using an industrial QEV and a Slide Valve to create a kind of semi automatic action. Would a QEV offer any benefits over a sprinkler valve?

Mr.Tallahassee wrote:That's a little more complicated than it needs to be. I think you can use a modified sprinkler valve and a three way valve to get the effect you want. The image should give you an idea on what you would be looking at. You connect your air supply to the three-way spool valve and connect the valve to the pilot of the sprinkler valve. when the valve button is released the air supply will fill the pilot and chamber. When you press that button, the air supply is shut off while simultaneously opening the pilot exhaust thus opening the sprinkler valve. There's plenty of resources on how to do the modding of the sprinkler valve to work with.

I follow how the 3 way valve works. one position makes supply air go in, seond position allows pilot air out. And just so i am clear, the pilot port of the sprinkler valve would also be my filling port?

Thanks fro the replies.

One last thing.

Say i wanted to use a QEV instead (for form factor) of the Sprinkler Valve.

So, Supply Bottle -> 3-way (I'd still like a solenoid here for trigger placement)

3 has Environment port, and other port goes to QEV Pilot Port (Which is also the filling port correct?)

QEV acts just like sprinkler valve as far as number of valves and direction of airflow.

Trigger 3 way solenoid valve to vent the pilot of the QEV to the environment. The QEV opens between its chamber and the barrel.

I hope i am 1) correct in my thinking, and 2)understandable.

a qev s 100 times better than a sprinkler valve and about the same price and needs no modification. I wouuld go this route with a push button valve to keep your size small and compact. Also use the edit button so you dont double and triple post.

I guess i just thought i'd found a way to rack up the spudbux.

What diameter QEV would I be looking for?

Spudbucks are totally useless so no need to rack them up lol. A 3/4 inch or 1 inch would be fine considering you want to keep the size compact.

Ok, so i am looking for a QEV, and 3-way solenoid, and fittings for use of a CO2 Bottle.

Go for a 3/4" QEV, it should give you decent flow for the purposes of launching a T-shirt. Go for as small a diameter barrel as possible too, you lose less pressure due to expansion and, initially at least, the T-shirt "projectile" will lose velocity at a lower rate, and therefore should go further.