Re: T-shirt Launcher
 

Unfortunately, if you can't afford to do it with the proper materials, it's probably not worth the possibility of serious injury in the end.

Re: T-shirt Launcher
 

In order to get much range at low pressure, you'll need to have large pipes and valves. On our air cannon, we use a 3/4" solenoid as the smallest point in the line. This means that we cannot use a tank designed for tools; the flow is not enough. We have a large (probably 8 gal) cast iron accumulator with about a 2" fitting at one end. We usually charge to about 40-50 psi, and have thrown t-shirts over the top of our press box with it at 60. Also, a large-bore relatively short barrel gets more of the energy to the shirt than long and narrow. We're currently using a 3" barrel about 20" long. The 3" barrel also works well with small foam rubber footballs.

We figured out a very simple way to prepare the shirts for the launcher that does not require any tie wraps or string or tape:

1. Lay the shirt flat on a horizontal surface
2. Lift the bottom hem a few inches, and raise (relative to the shirt orientation) until the fold is at the armpit.
3. Lower the hem until the next fold is at the shoulder
4. Repeat the two previous steps until you're out of shirt
5. Fold one sleeve over the shirt body
6. Roll from that sleeve, across to the other shoulder
7. flip the other sleeve inside out and wrap around the cylinder, like folding socks.

This fits a large short-sleeve shirt in our 3" barrel nicely. A small shirt may require making the cylinder a little shorter, and an XL a little longer.

Ok so what do you recommend in particular.

I've heard copper pipe is ok but what about conduit. That stuff is still decently cheap.

Also how thick and how much do we need.

Lastly what do you reccomend as a valve is a sprinkler valve ok.

Well we can't afford 5k that's for sure. We also don't need or want anything fancy looking we just want to shoot one shirt decently safely and move around

Re: T-shirt Launcher
 

Copper pipe is good.
Conduit may or may not be good. If it is plastic (especially PVC), do not use it. If it's metal conduit, that should work.

Copper 1/16" wall is enough for the ~60PSI shock that the barrel should see max.

The biggest thing with the valve is safety and leakage. Make sure the valve is GAS rated for the max pressure it will see. The gas rating is important because most other valves will leak as well as possibly burst.

The most important thing here is safety. Remember that this will be in the public eye. Any failure, especially one that results in unexpected release of pressurized air, is very bad.

If you cannot afford to ensure it is completely safe at all times then don't build it. That being said, with some leftover KOP/FirstChoice parts you should be able to build a decent safe single shooter for a few hundred dollars.

What valve do you recommend.

Re: T-shirt Launcher
 

Something like This would probably work. It's designed for use with Air and is safety rated to 72PSI.

It's flow may be too restricted though ... I haven't done the calculations.

It also has BSP threads so connecting to it is ... fun.

Re: T-shirt Launcher
 

so we would need to buy
1.that solenoid
2.harbor freight 5 gallon air tank
3.3 or 2 inch wide metal conduit

and we would also need to use(that we have)
1.compressor
2.normal tubing
3.chassis

and some fittings.

is there any weird adaptors or entire components im missing.

Re: T-shirt Launcher
 

You'd want a dump (ball) valve, an overpressure (Poppit) valve, and a pressure switch to shut off your compressor at a safe pressure.

Other than that, it looks like you have a good list.

Re: T-shirt Launcher
 

We're using one that looks just like this (I think it's the same one). We're switching it with a relay module, though a spike would also work. We have two barrels, and one of these on each. We often fire them about a tenth of a second offset from each other; 50ms for each to be open is more than enough.

We currently have all steel, brass, and rubber up to the final nozzle, and PVC barrels. Based on what I've read here, we'll be making some mods before next football season.

BTW, we did not use a 'RIO for our air cannon - an arduino on the robot with an xBee comms module, and a remote with just an xBee module and a 9V battery and some buttons/joysticks to dive, shoot, and someday aim in azimuth. Our accumulator is filled manually from a scuba tank; the accumulator holds enough for about 40 good shots before losing pressure.

Re: T-shirt Launcher
 

We had the same discussion a few years back and opted to go a different route. We made a giant nerf gun which shoots 1' sections of pool noodles. At top speed it will now shoot a "nerf bullet" about 70' which can then be traded in for a t-shirt or whatever you choose. It also allows for good demonstrations with younger kids and has little chance of injury. The pneumatics only feed each noodle into the spinning wheels which work like a baseball pitching machine.
here is a picture location

http://www.chiefdelphi.com/forums/sh...099#post776099

Re: T-shirt Launcher
 

I share everyone's rightful concern for safety, and I certainly lack credentials on PVC and air pressure vs. water pressure. At the same time, I have to question whether PVC knows what's inside it (water or air). Pressure, it seems, is pressure.

The documented examples I have seen of PVC failure have occurred at low temperatures, where I will agree, PVC gets brittle and dangerous. If inside a warm building at 1/2 rated pressure, I would tend toward not worrying excessively.

Re: T-shirt Launcher
 

We'd never get permission to put our tires on the gym floor. The main place we use our air cannon is outdoors during football season. Even in the deep south, I'm getting a bit queasy.

Re: T-shirt Launcher
 

You are incorrect that pressure is pressure. Liquid (which PVC is rated for) is incompressible where gasses (That PVC is not rated for) are compressible.

The issue with PVC is the failure mode. When PVC fails with liquid in it the internal pressure relieved immediately (due to liquid being incompressible) thus there is little time to accelerate the shards that are generated during a failure. Gasses, though, relieve pressure only as fast as the gas can escape, thus giving the force plenty of time to accelerate the PVC shards.

Hope this helps to explain the difference.

Re: T-shirt Launcher
 

Have you had any issues with the pvc barrel. We are in ny which is cold. We would probally use ours most at football and lacrosse games which are both cold.