pic: T-Shirt Launcher, still needs a chasis
 

Re: pic: T-Shirt Launcher, still needs a chasis
 

Nice revolver! That's something we wanted to add to our t-shirt cannon but never got around to doing. We were worried about air leaks where the revolver seals on the barrel... do you notice any issues like that with your set up? I like the use of 3 compressors too, how long is the shot to shot recharge time?

Very cool project, hope you get it mounted on a base soon and start shooting some engineering-enthusiasm into crowds.


EDIT: oh yeah, pvc and exploding and all that... someone's bound to go into more detail later in this thread

Re: pic: T-Shirt Launcher, still needs a chasis
 

:eek:

Re: pic: T-Shirt Launcher, still needs a chasis
 

sweet!! how did you guys get revolvers' chamber to rotate? or is it manual?

Re: pic: T-Shirt Launcher, still needs a chasis
 

Thats awesome...good work!
Hopet that you can have some fun with that later in the season, good choice of an offseason project!

Re: pic: T-Shirt Launcher, still needs a chasis
 

forget a chassis!!!!! i want that thing shoulder-mounted!!!

Re: pic: T-Shirt Launcher, still needs a chasis
 

Man that's cool! Nice revolver design also. How does loading work?

Re: pic: T-Shirt Launcher, still needs a chasis
 

I see so much WIN in this picture... I want to cry.

Re: pic: T-Shirt Launcher, still needs a chasis
 

got to do something with all that old equipment laying around.

An yes that is amazing.

Re: pic: T-Shirt Launcher, still needs a chasis
 

alright i'll try to answer the questions in the order they arrived:

1.The revolver hasnt caused any leaking, the chambers are slightly smaller than the barrel itself and are mounted to a single piece of acrylic. Also, the parts were all CNCed so they fit together extremely well. Theres a switch at the bottom of the revolver that will stops it each time a new chamber is lined up. Since the chambers are cylindrical, the switch will only trigger at the absolute lowest point on the chamber (which also happens to be the center).

2. We used all pressure rated PVC and never let it get above 60 psi, no matter how much we want to :). I know where you're coming from tho, using PVC gave me the jitters at first

3. I havent really timed how long it takes to fill with air... im guessing around 20 seconds? i'll see if i can get you a more proper estimate.

4. There are 3 motors on the cannon, one to rotate the base for aiming, one on a worm gear to change the launch angle, and finally one to rotate the revolver.

5.You can load tshirts in any chamber thats not in the barrel. You just shove the tshirt in any of the rotating chambers that you can get to. Normally the revolver spins only when the cannon is shot, but we also put a loading button on the joystick so we can cycle through the chambers to load them all. When we're firing, i mentioned the switch below the revolver earlier. After each shot, the revolver spins until the bottom of the chamber triggers the switch. If anyone's interested i can post the code

at the moment we have two chasis for consideration. We are either going to build a new chasis with tank treads or possible 6 wheel tank drive, or steal the chasis and crab drive from our lunacy bot (with much bigger off road tires of course) I for one am voting for the tank treads

Re: pic: T-Shirt Launcher, still needs a chasis
 

Rule #1 when making air cannons is do not use PVC.

Rule #2 is DO NOT USE PVC.

There are huge safety concerns with PVC, because PVC IS NOT DESIGNED TO HOLD ANY KIND OF COMPRESSED GAS, AND HAS BEEN BANNED BY OSHA FOR USE WITH PRESSURIZED GAS IN INDUSTRY. PVC has the awful tendency to spontaneously explode when pressurized with any kind of gas, even if that pressure is below the maximum pressure stamped on the pipe. (The max pressure rating for PVC is ONLY for liquids, such as water).

On a personal note, one of my friends had a PVC air cannon explode while holding it a few weeks ago. He wasn't even moving, and the air cannon didn't hit anything. He was just standing there, holding the pressurized air cannon, when it spontaneously exploded between his arm and his body. He was very lucky in that the way the shrapnel flew out, nearly all of it missed him. His jacket on that side of his body was not so lucky, and literally was torn to shreds.

Since this air cannon is being shown as for "marketing", it seems like it would most likely be used at public appearances. In order to protect any innocent bystanders from possible exploding PVC shrapnel, I would seriously urge your team to avoid using PVC on the air cannon at all costs.

I don't want to sound negative here, but at the same time I don't want to see people put themselves in dangerous situations.

Re: pic: T-Shirt Launcher, still needs a chasis
 

I agree with the concerns about the PVC, but, is there an alternative that would be anywhere light enough?(not metal)

I've seen 400PSI rated ABS blow a hole in the ground at 60PSI when a cannon of mine fired, not a pretty site...

overall, the only solution i have found is to wrap the whole thing in Molecular Bonding Tape (adheres to itself on a molecular level giving a shock strength of 1500PSI) then again in duct tape for appearance (and cachage of schrapnel that gets through the molecular tape)

after that, i've gone to metal for most of my cannons... since it'll bend, not shatter if it has to...

Do you by any chance have Inventor drawings of this???

I've been working on a similar project,but haven't gotten the revolving part down quite yet...

video? Please?

thanks,

-Z

Re: pic: T-Shirt Launcher, still needs a chasis
 

so are there any drawings of this thing out there that you would be willing to share with other teams. I would love to look closer at it.

i totally agree about upgrading to metal though. the last tater cannon we built was air powered and we actually had a remote firing system on it so that we could be in the barn watching it incase it blew up.

Re: pic: T-Shirt Launcher, still needs a chasis
 

Since you have access to a CNC I recommend Using a Geneva Drive to index the chambers. We have some experience with one and it works well if manufactured to close tolerances and well lubed.

Re: pic: T-Shirt Launcher, still needs a chasis
 

i'll talk to one of the mechanical guys and see if we can get some drawings out on the internet (they lock me in a dark closet and make me write code all day). As for the exploding part, the only part of the cannon that holds pressure is the air tank on the bottom of the barrel, i'll see if we can get that replaced with a safer material, all other valves, pipes, ect. are metal.

Video: http://www.youtube.com/watch?v=0cHf3iY4h9k

sorry the video isnt that great, we finished the cannon right before build season. the website isnt quite up to date either.