Which pneumatic solenoids/manifolds does your team use on the robot?
We used these (http://goo.gl/WDyuAw) last season, but they took up a lot of room on the robot.
Also, what tips do you have for preventing pneumatic leaks on the robot? We experienced many last season.
We used these. Festo 12V VUVG series solenoids are quite reliable and easy to mount compactly; we just stacked them together and put bolts through the mounting holes. They are pretty flat, so even if you don’t mount them together, they will almost always fit somewhere.
As for preventing leaks, we just make sure to keep tubing away from anything sharp and make nice, smooth, 90 degree cuts when cutting tubing. Utility knives work well for this; the trick is to just push down, not saw. If you start with tanks pressurized, you can catch leaks before a match.
We used the VexPro solenoids this year, two singles and a double. The manifold-based system did save a good bit of space over separate units.
In addition to using a modest amount of thread tape on fittings without washers, make sure that the tubing is cut perpendicular to the length. Beveled tubing cuts lost us a lot of air in our early years.
Are there any other manifold-based systems other than the VexPro line? I’ve seen teams using other ones, but I’m not sure what they are called or where they are buying it from.
Team 2877, the Ligerbots, We use a manifold for most of our solenoids. It saves a ton of space and makes everything easier. Also, if you are worried about space, we have found that wiring cylinders that act together up to one solenoid helps a lot. Our gearbox shifters, opening and closing our intake, and our double CDF/Portcullis wedges all used one solenoid each even though each of them used two cylinders. http://www.vexrobotics.com/solenoids-and-manifolds.html. This is the link to the solenoid and manifold that we use. In addition, this year we used a high flow cylinder for our pneumatic catapult shooter from McMaster Carr.
90 degree cuts, you say?
There is no better tool than this puppy. It’s the TC-12 pneumatic tubing cutter and you will not be disappointed by it. Every team should get one.
Actually, If you see us (AutomationDirect) at an event we are usually giving them away. In the past we have included one for free in every box of parts ordered via the AutomationDirect FIRST Voucher. I assume we’ll do it again next year …
The Festos are great - unless you need volume, say, for a ball launcher with a couple of 1.25" diameter cylinders. Then, they fail miserably compared to a valve like Automation Direct’s:
http://www.automationdirect.com/adc/Shopping/Catalog/Pneumatic_Components/Pneumatic_Valves_-a-Accessories/General_Purpose_Solenoid_Directional_Control_Air_Valves/3-port%283-way%29,_2-pos.,Body_Ported%28AVS-3_Series%29/AVS-3211-24D
The Festo VUVG has a Flow rating of 0.22 Cv (220l/min) vs. the
Automationdirect’s Cv=0.78. The numbers speak volumes (pun intended).
Further, Automationdirect charges a fair price for pneumatic components rather than what they can get away with… compared to - ahem - some other suppliers. On top of that, they give FRC teams a free voucher every year, and always offer free shipping > $49.
No, I do not have any affiliation with Automationdirect - I merely appreciate what they provide to FRC.
Other thoughts: Be sure that whenever you remove a hose from a fitting that you snip off a bit, so that the fitting barbs can get a fresh bite. Also, leave air pressure in the system after matches to insure you have no leaks - and if you do have one, use soapy water applied with a small brush to find it.
A pneumatic cylinder pushed our ball into the shooter this year, and we chose to not have an on-board compressor. Through diligence and constant monitoring, we never ran out of air on the field.
Those AutomationDirect cutters are handy. I picked one up at worlds and never had a problem with leaks from tubing. I am working on my highschool capstone project(which relies heavily on pneumatics) and the AutomationDirect’s deals were the best. Especially for our extremely limited budget. I already have solenoids and a manifold from them coming in the mail. For the project we are developing pnuematic muscles which will then be used for actuation on an exoskeleton we are making. Our first prototype for the muscles was 1/2in in diameter and lifted 70+lbs at 100psi. To lower the working pressure to make them more safe we are increasing the diameter to 3/4in which should allow us to lift 50+lbs with 50psi. All in all, Automation Direct is a huge help with their reliable products and reasonable prices.
+9001
If we need high flow rate, we use the ones from Automation direct.
If we need compact ones we use TDKs or Festos.
If we need bulk we use SMCs (see VexPro) on a manifold.
One little tip, while it may be tempting to go with single (sprung) solenoids only (to save on channels) think about what happens in an e-stop/disabling.
If you use a single acting solenoid on a large arm or mechanism, then disabling can result in that solenoid shifting back into it’s default position, and it’s arm/mechanism flying back as well. This can pose a hazard 
People expect a robot to stop moving when it’s disabled, not all the pneumatics to retract.
We do however use single solenoids on internal mechanisms that are either low risk (eg shifters), or stay in one state for the majority of the time (eg latches).