(New)matics advice

[Ari423]

Originally Posted by euhlmann

We use mostly double solenoids. Last year, everything fit the model. Intake arm up and down, cheval/portcullis wedges up and down, shifting up and down (yes, vex 3-cim ball shift gearboxes).
So if you have something like shifting, it doesn't make sense to use two single solenoids when you can simply use a double solenoid.

I don't think you understand what "single solenoid" and "double soleniod" means. It doesn't mean that a single solenoid only has one output. It means that when you apply power to the solenoid, one of the outputs gets air and the other doesn't. When you don't apply power, a spring returns the solenoid shaft and the output switches ports. This compared to a double solenoid, where a second solenoid forces the return of the inner shaft, not a spring. For a standard double solenoid, one solenoid is on and the other is off at any given time. Otherwise either the solenoids will be fighting each other or the shaft will be free to slide around and change outputs at will. You can see whether you're using a single or double solenoid easily because a single solenoid has one pair of input wires where a double solenoid will have two pairs. In FRC (as far as I've seen), there is generally no reason to use more complicated double solenoids over single solenoids unless you are working with 3-position solenoids, in which case you can't use the manifolds posted above either.*


*That isn't to say that you can't**, just that it usually isn't necessary.
**I have a number of times because we had them in storage. They work fine and are basically the same to program. They are just a bit more complicated electrically, more places for things to fail, and more expensive.

[jnicho15]

Originally Posted by Ari423

In FRC (as far as I've seen), there is generally no reason to use more complicated double solenoids over single solenoids unless you are working with 3-position solenoids

In 2015, we used double solenoids for things like the ingestor arms so that they couldn't close into a stack when the match ends but start closed if we wanted. We also used one on the arm tilting mechanism since we had to start with the arm tilted back but don't want it to change position when the match ends.

[Wren Hensgen]

Good morning! I'm a former member of FRC 225, and still an active FTC mentor.

Through FIRST, I landed a job with a hydraulics, pneumatic, and automation company. If you have any questions on parts, terms, setups, connectors, anything, I'd be happy to work with you to get your questions answered. Please feel free to send me a PM or just talk here.

Some suggestions:

1. Buy a tubing cutter. For the fittings used in FRC (Push-to-connect), the ends of cuts have to be perfectly square to seal.

2. Buy quality tubing, and parts. Freelin-Wade, the default supplier for FIRST tubing is a really solid company. I'd also recommend Norgren for fittings.

3. Understand your terms. You have air cylinders, who's force is decided by their bore (Diameter) and the distance they work over, called the stroke. You can have a double acting cylinder that needs air to move it both ways, or a Single Acting that will retract if the air pressure is removed. You can even have a Reverse Single Acting, which will extend with air pressure removed.

4. Understand when and where to use pneumatics. It's not always the right choice. Air actuators are smaller, lighter, and faster than electric in most cases, but you only get 2 (Sometimes 3) positions. You get better granularity with electric.

5. Understand your solenoids. Use Single-Acting solenoids when you want an item to revert to a default state on power-off. Use a double acting if it's important to stay in the last state on power off.

Above all, stay safe. Air pressure can be extremely violent and dangerous if you're not expecting it, and sometimes even when you are. Loose air hoses can whip through the air, air tanks can explode if damaged, cylinders can move faster than you can see with enough force to break bones.

If you have ANY questions, please ask! There are no stupid questions.