pic: T-Shirt Cannon Bot Concept WIP

[MrBasse]

Originally Posted by Kyle Butzerin

So I ask my questions,
Are there valves that will release the stored air we need to propel the shirt through a 4" barrel without modification? If so, what can you suggest?

Should we go with the air storage I have in the model, or something else? Should we charge it up with a ViAir? or a better Compressor?

Are there any good ideas to lift the barrel? We are wanting to use the Lead Screw method that our 2013 team went to St. Louis, but we are open to new ideas.

Thanks!
RoboEagles FRC 4579

A bigger barrel means more air faster to propel a projectile. We use a 2.5" barrel and have been happy with that, a 3" would be nice for XL and XXL t-shirts though. There are valves that are capable and a few have been tossed around forever on CD, look to fast acting 3/4"-1" solenoids for this. We used a really cool hose from Parker Hannifin that requires no fittings and is available in those sizes with fittings being the biggest cost.

After running the FRC compressor to charge our cannon the first year of it's existence, I will never do it again. We have times at pep assemblies where we have five shirts to shoot in ten seconds, and the little viair just isn't up to the task. We use a 5# CO2 cylinder because it's cheap, we have a discount to make it cheaper, and it is a lower amount of stored energy than a SCUBA tank. The only issues we see from this is that with liquid CO2, you can freeze your system forcing you to wait a minute if you fire rapidly.

Your storage looks to be PVC, but I can't tell from the drawing exactly. Be ready to be attacked for that, and with good reason. Go find the videos of plastic tanks exploding for why. There are tons of safe high volume tanks available with large ports, you'll just have to look outside of normal FRC vendors to find them. We got ours from Home Depot with a 1" port.

For lifting the barrel, go with what you like. We change ours by hand because we have only changed it a handful of times since we built it. Ours uses a CNC Plasma cut angle gauge and wingnuts to lock it in place. We had designed a motorized version, but the only time we lower it is when it's in the trailer or if we are test firing and don't want the height.

Everyone will go over a lot of details on high pressure systems and safety and a lot more. Design safe and stay safe. We use no more than 30 PSI and typically run at 12-15 PSI for shots from our track to the top of the bleachers at our football stadium, it's around 200 feet or so. Ask yourself if you need to shoot further, then ask yourself why...

[Kyle Butzerin]

Originally Posted by MrBasse

A bigger barrel means more air faster to propel a projectile. We use a 2.5" barrel and have been happy with that, a 3" would be nice for XL and XXL t-shirts though. There are valves that are capable and a few have been tossed around forever on CD, look to fast acting 3/4"-1" solenoids for this. We used a really cool hose from Parker Hannifin that requires no fittings and is available in those sizes with fittings being the biggest cost.

We had decided on 4' because the ease of loading the way we learned to fold shirts, but 3' to me sounds more feasible, if we can load it properly. I would love a link to that hose, ABS wont cut it, too much conversion.

After running the FRC compressor to charge our cannon the first year of it's existence, I will never do it again. We have times at pep assemblies where we have five shirts to shoot in ten seconds, and the little viair just isn't up to the task. We use a 5# CO2 cylinder because it's cheap, we have a discount to make it cheaper, and it is a lower amount of stored energy than a SCUBA tank. The only issues we see from this is that with liquid CO2, you can freeze your system forcing you to wait a minute if you fire rapidly.

We could look into CO2, but the shop teacher lost a chunk of flesh on his chin to CO2 Canisters due to a careless woodshop kid, so he may not take kindly. It is a great idea and im curious to see how id work.

We work with a lot of Home Depot parts, (being near our school) so ill check that tank out, a link would be awesome. We are very careful with our tanks, we work behind protection and we dont take unneeded risks. Trying to get the new guys to do this will be an adventure, im trying to expose to everything you can use on a bot for 2016. Finally, like I said, poor school means no CNC Plasma :/ 3D Printer though!

Look on Google. We use one similar to this. If you can find one that's a bit larger (1" or 1-1/4"), even better. The most important thing is that the valve (and plumbing and tank and fittings and so forth) is rated for air, at a higher pressure than you're using. A large valve (3/4 NPT or greater) is essential to get enough air out fast enough to throw a t-shirt very far without using pressures higher than we're used to in FRC.

Like I said, we will use a 1" Valve on our bot, thanks for suggesting this valve, its a great price (which we are worried about). We need to REALLY reduce the pressures we use, being that they are many times higher than cannons ive seen (though we are using a sprinkler valve). I think our lead screw lifting idea will work, but we are considering a mortar style instead.

Thank you both for replying!
RoboEagles FRC 4579

[MrBasse]

The valve we run is a check valve run in reverse. We move the whole valve and engage it into the shell to release the valve. Clear as mud? I can try to get some pictures that will be rightside up this time to help out if not.

We had to do a little machining (i.e. sanding and filing) to make a threaded end that would fit inside our valve.

Brass with pneumatic actuation

Brass

We actually run a plastic valve that has a burst rating of 200 psi and is rated for gas to 100 psi. I don't remember where we got it from though.

Our tank is a hot water expansion tank like this. Yes it is for water and not for gas, but we are running at less than 20% of the rated pressure and it is a steel tank that has a safety vent built in.

We have had no issues and pressure tested one to 130 lbs prior to using it by filling it and draining, repeating then using some force to deform and filling and draining again. No leaks, no failures, and no worries with 10-30 psi being contained.

The benefit of how we built ours is that we use a cylinder to push the actuator to release gas. If we pressurize over 30 psi the regulator on the cylinder won't allow the cannon to fire or engage. It just hisses a little and reminds you that you are trying to do more than was designed for.

[Bruceb]

706 uses a pony scuba tank
Last about 30-40 shots.
The tank cost us something like $120 but with that we get free refills. We had to get a supplier to build a custom valve to handle the 1/8 hose. That feeds into a storage tank that holds
60psi. We usually shoot at something between 20 to 40 psi.
With this set up and how fast the scuba tank recharges the storage tank we can shoot all 10 of our stored t-shirts in something like 15-20 seconds.

[DonShaw]

Look on ebay for some 12volt air solenoid valves, I found ours rated at 215 psi and 3/4 npt threads. Fast open and close and no leaking. Cost was about $30 each.

[Kyle Butzerin]

Originally Posted by DonShaw

Look on ebay for some 12volt air solenoid valves, I found ours rated at 215 psi and 3/4 npt threads. Fast open and close and no leaking. Cost was about $30 each.

A 3/4 is good but our team really wanted a one inch. The school district is not allowing us to use CO2 Canisters of any type, they are already edgy on us making a tshirt cannon robot. I've having a lot of trouble finding a high pressure solenoid, so should we settle with a 3/4"?

Once again, thanks everyone for the feedback, but i need to identify a list of objects (Tank,Hose,Solenoid,Barrel) which could be all be strung together and put on a robot. we have 20 new members waiting on the design group to finish the model for this bot.

Thanks!

[MrBasse]

Originally Posted by Kyle Butzerin

...I would love a link to that hose...
RoboEagles FRC 4579

http://ph.parker.com/us/15551/en/push-on-hose-hpd

Magical stuff, just be sure it is the length you want before you install. Look up local industrial suppliers or use the where to buy link on Parkers site. I used to work at the Brass Products Division in Otsego, MI. They are very friendly to FIRST teams and we get donations from time to time. Might be worth a kindly written email or a phone call to the proper division.

HOSE PRODUCTS DIV

30240 LAKELAND BLVD
WICKLIFFE
OH
UNITED STATES
44092

Ph:4409435700