T-Shirt cannon pnuematic set ups

[Bryan Herbst]

Hey everyone,

Our team is hoping to build a t-shirt cannon this summer, but need some help.

First, to those that have built one before, or have an idea as to how to do it, could you list the pneumatic (or sprinkler) parts used, including valve/solenoid, tubing/hose, connectors, and pump? We've seen tutorials with how to do it with things like a bike pumb and manual release knob/switch, but not an electric one. If you could also link where you got it, that would be great.

Second, is there a (cheap) way to attach a digital PSI sensor to the pneumatics? We would like to adjust the PSI output from the OI, but we aren't sure if we can.

All help is appreciated.
Thanks!

[SSMike]

I'm sorry that I don't have any suggestions for pneumatics so I thought that I'd provide an alternative.

Well, I personally never built a t-shirt cannon with pneumatics but for an engineering class, I built an air cannon that could launch a nerf football through a goalpost. I felt that it was rather easier than pneumatics
imo. All I used was PVC piping, and a control valve (also PVC). We ended up launching the ball about 40 feet when the pressure was up to 30 psi, so it worked pretty well, and I'm sure would make a fine t-shirt launcher. If you decide to do this MAKE SURE YOU USE PRESSURE RATED PVC! I can not stress this point enough. If you want pictures or more detailed instuctions, just let me know.

Hope this helps.

[tdlrali]

valve/solenoid

Look into sprinkler valves, I think those are used quite often for this kind of application. If I remember correctly NItro used sprinkler valves.

Second, is there a (cheap) way to attach a digital PSI sensor to the pneumatics? We would like to adjust the PSI output from the OI, but we aren't sure if we can.

I'm sure you mean analog. If you find one, just shut the pump off at the desired pressure.

[RyanN]

Originally Posted by SSMike

I'm sorry that I don't have any suggestions for pneumatics so I thought that I'd provide an alternative.

Well, I personally never built a t-shirt cannon with pneumatics but for an engineering class, I built an air cannon that could launch a nerf football through a goalpost. I felt that it was rather easier than pneumatics
imo. All I used was PVC piping, and a control valve (also PVC). We ended up launching the ball about 40 feet when the pressure was up to 30 psi, so it worked pretty well, and I'm sure would make a fine t-shirt launcher. If you decide to do this MAKE SURE YOU USE PRESSURE RATED PVC! I can not stress this point enough. If you want pictures or more detailed instuctions, just let me know.

Hope this helps.

How about not just PVC at all!!! It has been stressed many times on different threads; PVC is not meant to hold air at any pressure above the atmosphere pressure.

We used an empty freon tank for our air tank, put two compressors to charge it, and we can safely handle up to 120PSI. We are using a 24V sprinkler valve from Lowes. These will not switch with 12V, as you probably figured out already, but what we did is hooked up a relay to a spike that switches on 3 9V batteries (27V). The 3 extra volts does not hurt the valve, especially for the duration that we use it. We used flexible hose to transfer the air... it kind of looks like a sewage line for an RV, but we also bought it from Lowes.

As for a sensor, I believe they supplied one in the kit before my time (2004 maybe?) that was manufactured by Texas Instruments.

Also, like I said before, there are other threads, not just on the safety issue of using PVC, but there are many, many threads on T-Shirt shooters. Just use the search feature.

Here is a link to ours: http://www.chiefdelphi.com/forums/sh...-shirt+shooter

As you can see, the first version had a PVC tank, and after 2 years, we deemed it unsafe and I rebuilt it last summer in our 95 degree plus summer temperatures in our garage.

I also just noticed the pictures aren't working later on in the thread. I'm about to go look into it, so hopefully I can get it working.

[s_forbes]

We built one that runs off of just the kit compressor (fills tank in 10 seconds) and fires a shirt ludicrous distances, about 40 yards or so. Instead of a sprinkler valve, we used a pneumatically actuated gate valve (see it here) that unleashes air stored in an abs reservoir into our pvc cannon. Overall it's a surprisingly simple and effective system, I'd suggest you look into it a little.

See the whole thread for our promobot here. Maybe squirrel or GUI or MattH can give you a better description of how it works if you have questions...

[RyanN]

To emphasize my point about no PVC... earlier this week, one of the kids at school was making a potato launcher and charged it to 45PSI when it exploded right in his face. Luckily he was not hurt by the explosion. It failed not in the PVC pipe, but the thick joints. This goes to show even though many think thicker is better, it is not always the case.

This was the tank that was used on our t-shirt shooter before we converted to a real tank.

So again, please DO NOT USE PVC. People can be seriously wounded, or even killed (as evident by the hole in the roof).

Also, I was not there when it happened, so I had no control over it. What appeared to happen was a crack rapidly developed in the joint, the glue failed, and then it shot the tank off like a rocket.

[kborer22]

what seems to be popular now are what looks like modded paintball guns. They have a similar set up, with an adapted barrel to hold a rolled up t-shirt (most made out or poly carb). If you can find a painball gun with a common thread size (aka not Tippman) then you should just be able to fabricate a barrel and give it a shot! (not sure how much pressure you would need vs. what a stock paintball gun could give you or how far you plan on launching it)

http://www.tshirtgun.com/home.htm

[Bryan Herbst]

Thanks for all the info an tips.

It's giving us a good start, and well be sure to follow up on some of the stuff posted here when we start to actually build it. We haven't actually started our off-season yet, we've just been gather ideas and plans.

[Nawaid Ladak]

we did one where it was PVC piping connected to 3 cylinders, you could strap it onto your arm, and it was connected to a battery pack and compressor in a backpack. very dangrous, but very cool. it could launch t-shirts one at a time, but we mainly used it for those little stress balls, ie the NI soccer balls that they had during te deminstration in the pits during championships.

also you might want to look into what diffrent sports teams use, i was at the magic game, and they had one built into a trash can, but it launched t-shirts rolled up into bals, with rubber bands.

[artdutra04]

Look into McMaster part number 8585K21 for barrel stock.

That's the pipe I used on my muti-barrel tee shirt launcher. Although it is on the expensive side, I had to guarantee that the tee shirt launcher would be safe to operate around large numbers of people outside, and at temperatures which had a good chance of being below freezing.

There was absolutely no PVC used anywhere on my launcher for safety reasons; everything that held pressure was rated for high pressure gas use and below freezing operation.

[Martijn]

I built a t-shirt cannon this fall, and we used it for some robotics promotional stuff. Took it to a basketball pep-rally, that sorta thing.. Although PVC might not be the safest thing, you're probably ok as long you make sure that not only the pipe itself, but also the fittings are all pressure rated. The only thing that isnt pressure rated in my setup was the sprinkler valve. We've managed to hook it up to 4 compressors, and load the reservoir all the way up to around 140PSI, and we can shoot t-shirts across our school's gymnasium (two basketball courts side by side).
We had also planned to hook it up to a promo robot (similar to 1726), but we ran out of time in the fall.. Maybe the team will hook the cannon up to a kit chassis with a mechanum drive or something this fall..

[artdutra04]

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.

[Akash Rastogi]

Originally Posted by artdutra04

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.

And please make sure its UL certified no matter what you use.

(Underwriters Laboratory)

[SSMike]

Originally Posted by artdutra04

PLEASE DO NOT USE PVC FOR AIR CANNONS. PERIOD.

PVC is NOT AT ALL safe for pressurized use, as it is a very brittle material. If there ever is a leak in the material, the result will be a catastrophic explosion of PVC shrapnel. Just because it may have been used without problems does not mean that it is safe.

Please, for the sake of innocent bystanders who may be near the robot if the PVC explodes, don't do it. Spending a little more money up front on better materials is well worth it if someone is severely injured from PVC shrapnel and decides to sue.

I agree. As I read my previous post, I realized that it could be seen that I was advocating a PVC air cannon. In no way am I doing so. I was simply stating how I built an air cannon. (Just a little disclaimer)

PVC is dangerous folks, and shouldn't be used for super-atmospheric pressures

[vivek16]

Originally Posted by pyro20911d

CRT 306 has had a safely functioning t-shirt cannon for some time now..using non-pressure rated pvc is perfectly fine for the minimal pressures that you're going to be working with..120 psi=not much..hit up any of our team members for more info..aim/ pyro20911..my cell # 814-462-4904

Actually, 120 psi is a lot. There is a reason FIRST has us use only 60 psi. If you do make a pvc gun, please, please make sure that you don't use pvc for the air storage or charging.

Wrapping the tube (barrel) in duct tape a lot and putting a bigger tube around it makes it a little safer.

be safe, Vivek