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#1
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pic: T Shirt Shooting Robot
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#2
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Re: pic: T Shirt Shooting Robot
Any chance we will get to see this in action at the TNT event this year, or will we have to wait till the 2010 Florida regional?
Last edited by techtiger1 : 13-07-2009 at 12:47. Reason: I am asking a question, therfore it should have a question mark lol. |
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#3
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Re: pic: T Shirt Shooting Robot
I am going to quote artdutra04 from another thread on the reasons to not use PVC
Quote:
Last edited by jason701802 : 13-07-2009 at 18:01. |
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#4
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Re: pic: T Shirt Shooting Robot
Well we're hoping its ready for football season. So... I'm positive you'll see this beast at TNT.
And we understand the hazards of PVC. But we glued everything and made sure that there are no leaks. The PVC is very heavy and was brand new when we glued it. So as of right now there is NO chance of it breaking. These cannons have been through a lot, and I know that a lot of PVC cannons have bursted... but because this is brand new PVC there shouldn't be any chances of it shattering... just an end cap or reducer popping off. But we made sure that the glue was perfect and its definitely covered. Thank you for your concern. As of right now we're looking for nice metal tubes in our closet for our 3rd Gen tanks. |
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#5
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Re: pic: T Shirt Shooting Robot
Quote:
New vs. old PVC -- Makes very little difference. PVC can fail on the 1st or on the 1000th shot, with no (or very little) warning. Glueing PVC makes it stronger -- Depending on the type of glue (or cement) this will (more than likely) weaken the PVC as it breaks up the polymer chains within the PVC. Typically bonding plastics to plastics weakens the strength due to the bonding process at the molecular level. "there is NO chance of it breaking" -- Never assume nothing can go wrong or something cannot break. Things can always break with enough force applied in the wrong (or right) directions. Instead plan on worst case and make it safe. Especially if it will be near the public. I am very happy to hear that you are looking into metal tubes for your next generation t-shirt launcher. Sorry to be so negative ... but pressurized PVC and the public always brings out the 'safety police' in me. |
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#6
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Re: pic: T Shirt Shooting Robot
I would set this aside as a proof of concept, and not fire it until the PVC has been replaced with a safer material.
The cost is really worth it, it shouldn't be much work to replace them, and it could potentially save someone's life (assuming extreme failure), prevent decent injury and/or making your team look very amateur. |
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#7
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Re: pic: T Shirt Shooting Robot
We had it working with these cannons last year, but there were a couple design flaws including the cannons that we are going to fix now.
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#8
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Re: pic: T Shirt Shooting Robot
Yeah the PVC is not a good idea. The only way to make them PVC and not risk them shattering is if you fiberglass coat the PVC. Which is really cool if you've ever seen it done before, doesn't come cheap though.
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#9
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Re: pic: T Shirt Shooting Robot
To all of you out there who detest PVC it is meant for this. You are all underestimating the streingth of PVC. It is put in sewers and all over houses unless you are using paper thin piping or PVC that is not made to hold pressure it is actually better than metal ![]() |
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#10
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Re: pic: T Shirt Shooting Robot
The only thing I'm going to say to that is: You don't know what you're talking about, and you're comparing apples to oranges.
PVC is NOT used within houses. It's commonly used outside, underground, for irrigation systems. Note that irrigation systems are never used with air, unless they are being drained (and, in that case, they are left open at at least one point to release pressure). Also note that the ground will contain most catastrophic failures of reasonably sized PVC pipe. Within the house is always metal, often copper. And no, PVC isn't used for sewers, either. I would guess that either that's ABS or it's a specialized pipe plastic. Again, note that sewers are underground and are often not pressurized (at all). Note: in all of the cases you cited, the PVC is underground and used for liquids, not gasses. A T-shirt cannon is above ground and used for compressed gasses, which is a completely different case. If you're going to use parallel examples, then please use examples that are truly parallel. |
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#11
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Re: pic: T Shirt Shooting Robot
To be fair I've seen quite a bit of PVC pipe used underground but in houses. Probably not what's supposed to be used but it's there. Regardless, a pressurized liquid and a pressurized gas are completely different forces (especially because gas firing tends to shock load), and PVC should never ever be used to hold any kind of pressurized air for any period of time.
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#12
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Re: pic: T Shirt Shooting Robot
We built a launcher last summer out of spare parts and various scraps, and we managed to blow a 200 lb solid steel door open 90 degrees at about 110 psi. We found that the t-shirts work best when either taped or zip-tied (if you are going for distance). If you aren't going for distance, then there is a way to fold the shirt so it opens when you launch it, making it much less dangerous. We have used it at a couple of tractor pulls, and we are planning to mount it on our robot from the 2006 season (the robot's name is Tank, so we are planning on making the launcher rotate). To help with safety concerns, we found that it is best to keep the launcher and air storage tanks in separate locations, along with the hoses (if there are any). Hope the build goes well!
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