Robotic T-Shirt Cannon

[robself705]

This is our cannon.

http://www.youtube.com/watch?v=xKCwbomY82c

We have 4 compressors, 3 batteries, 4 cim motors, we are using a 3/4 in gate valve modified with a pneumatic piston to release the air. The video is of a shot at 20 psi. We have shot up to 200 feet before and can shoot 10 shirts in one load.

[Stephen of REX]

That robot fires compressed win! How many shots from one tank, how long to recharge? I love the treads and overall clean white design.

Also, how exactly is your gate valve seated? My team uses a 1" gate valve with a cylinder, like yours. But It keeps jamming closed due to the pressure closing it.

Unfortunately I cannot approve of the PVC air tank.

[reversed_rocker]

we just finished it so we didnt have time to work out the details. How many shots on each tank depends on how quickly the pneumatic valve opens and closes, thats a simple thing to change in the code but we havent had time to find the perfect value. So far it looks like we can get about 2 shots per charge, but it starts filling air as soon as it fires and it only takes about 3-6 seconds to go from fully empty to fully charged.

note: the shot in the video was taken at 20 psi with a leaky pbc joint. before we had the turret mounted to the tank treads we were shooting at 60 psi. the video of the turret is on cheif delphi/youtube somewhere...

[robself705]

I know there is a lot of debate on PVC for pressure fittings but we have done the research, read all of the hazards and found tests that approve the schedule 40 pvc 3in that we are using has a SAFE working pressure of 200 psi. We rarely go above 60psi. In addition the burst pressure in tests shows that the pvc wont burst until 700 psi. I understand all of the concerns but a lot of the horror stories come from tanks that have been beat around, dropped, improperly glued, etc. Ours is securely mounted and cant be dropped or hit easily. We have considered building a copper tank but for the time and money required we will stick with the pvc. If we note anything unusual about it we will definitely switch. We have had much discussion about this issue. I will be doing a more in depth review of our robot when time permits.

[squirrel]

The pressure ratings for liquid probably should not be used for air, though.

I suggest you change the tank material...even if the risk is low, you're gonna get lots of flak from concerned people here, and some of them have hair raising horror stories....

[Bruceb]

If you put a restrictor valve on the close side of the piston valve you can make the valve close slow enough so it does not jam.
Bruce