Me and some other members of my robotics team were passed down an independent study from a former member which was a barebones concept for a T-shirt cannon robot. Containing 3 barrels that are all fed by one larger 150psi tank, many issues arose however the largest was its limited capability as far as shots fired before the tank would need to be refilled. We could maybe get off 2 shots before we would have to refill the tank. Wanting to have a working T-shirt cannon robot, some of the people on our team took it as a side project. However we have run into some issues including a time constraint of a little over 5 weeks to have a working prototype that can be presented at our schools homecoming parade and a working
Current Plan: Our current plan is for each of the 3 barrels on the robot to have an independent air system capable of firing 3-5 shots each before a refill is required. After research we found that they don’t really sell high pressure tanks that would fit what we need outside of paintball tanks, scuba tanks being out of our price range and often too large for what we are envision. With a paintball tank and regulator designed by the same company our plan is to fill the paintball tanks to around 1000 psi & then having the regulators release a constant flow of around 145psi which we can change. Unfortunately the aperture of these regulators are 1/8 inch compared to the 1" hole that our current solenoids are. The concern here is that even at 145PSI, the 1/8" hole might not give enough force to launch the T-shirts far. We have considered adding a holding tank before the solenoid, giving us the possibility to have a holding tank with a far larger aperture to release the air, providing more force. My main question here is, is it feasible to have each regulator to go straight to the solenoid or would we have to add a holding tank halfway through to provide enough power to launch the T-shirts? I am planning on adding a CAD to this post later but would like to hear other opinions before going more in depth. However we are dead set on having 3 independent systems so we can control the range independently on each barrel and need to stay under 2000 dollars for all new components, meaning that we couldn’t look at more expensive alternatives.
Scuba tanks are definitely an easy go-to that many teams use. The regulators on those pose very similar issues as to what you describe with the paintball regulators (not a high airflow through them). Would definitely recommend a holding/intermediate tank for that. A rather simple and clean solution IMO.
Agreed that you won’t get air through that 1/8" aperture fast enough to launch a t-shirt. A holding tank with at least one large port (1", or at least 3/4") is essential.
Also agreed scuba tanks are a good way to go. That, or charge a large (multi-gallon) tank and use it to feed your holding tanks.
If you’re going to go with separate holding tanks, you’ll want to ensure that they won’t backfill into each other, either with separate solenoids to charge each holding tank, or check valves on the charging lines.
If you aren’t already, you can also greatly reduce the amount of air you use by programmatically limiting the time your large solenoid valve is open. You’ll have to work out exactly what works for you empirically, but in my experience maximum range was achieved at about 50-100ms valve open time. Anything longer is just spilling air.
And finally, a bit about safety. Be sure your solenoid valves are rated for ## psi of AIR, not just water. They aren’t necessarily more likely to rupture, but air at a given pressure has a lot more energy than water at the same pressure, and leads to more shrapnel. Air rated components are made so that they split or tear rather than break into many pieces.
I understand 3 holding tanks and firing valves to allow for firing each barrel individually. But why the need for each barrel to have it’s own unique air supply/tank?
We had looked at scuba tanks, however they were often too expensive or large. Because of this we we settled on airsoft and paintball just because they have similar pressures while being far cheaper. Additionally we can fill up the airsoft tanks with a 300 dollar compressor at our workshop, saving trips to scuba shops or buying a very expensive compressor.
Mostly so we can individually control each system, have 3 lighter weight tanks that a larger tank of comparable size, which also often then require trips to scuba shops for refills where with the paintball air tanks, we can fill them with a compressor that is affordable and can fit in our shop
If you explain how this is for an educational program, you can sometimes get your friendly neighborhood fire department to charge your scuba tank for free.
Hi, I designed and built a t-shirt cannon robot for my team last school year. Like everyone has been saying if you have the room it would be highly recommended to use a SCUBA tank. Ik they are expensive but we called a few local SCUBA shops, said what it was for, and they were able to give us an otherwise expensive tank to our team for free.
As for a holding tank (or operating tank as my team likes to call it), having one is very nice to have. If you do not use all the air in your holding tank after a single shot, it makes it a lot faster to “charge up” for another shot. If you do not have a holding tank then the wait time can be a bit annoying, especially since your output is 1/8" (although you do have 3 barrels so charge time isn’t as big of a concern)
If you could send a diagram of your current pneumatic layout that would be great. A CAD of the robot would be even better. Our layouts are super scuffed but it helped drive the “path of air” across so it was easier for other students to comprehend. One last tip DO NOT use PVC and make sure the parts you are using are rated for air PSI as well and not just water. There are a whole lot of t-shirt shooting threads you can search for that will explain more why but pretty much AFAIK when PVC pipes fail under air they will explode and shatter, ie a pipe bomb pretty much.
If you have any questions feel free to reach out to me. The t-shirt cannon robot was my first pneumatics project so I am a bit of a noob but a lot of reading old CD threads helps a lot.
3256 uses a scuba tank in their t-shirt shooter; I can’t find pix though.
If you’re pressed for time, why not get one barrel working first? You’ll have something to show, and that much more experience when you then add more barrels.
That would be great if we could reach out to you at some point, we’ve kinda taught ourselves pneumatics from this and anyone who actually has experience with tshirt cannons would be amazing to talk to.
Most of that looks good! Glad to see the relief!!!
The thing that’s going to kill your performance is the 1/4" to 1/2" adapter. You really want a bigger hole on your tank!
Another way you could improve the performance is to put a section of 1" pipe in there to act as a tiny reservoir. It won’t help a LOT, but it will help some.
