This will be our second year competing, and we where thinking of incorporating some pneumatics to our design for the first time. I have looked around a bit but I would like to hear what you guys have to say. Here are a few questions i have.
What are the pros and cons to the double and single acting cylinders?
What would you all buy to start out?
Is there a cheaper alternative then the VEX products, or should we just stick to VEX?
If you have any other comments to help us out along the way we would greatly appreciate it!
If you buy an entire vex pnuematic kit on another site you will save like 5 dollars or something minuscule so I would say it isn’t worth it because you have to buy each kit part by part.
Pneumatics are a fun way to increase your power without motors. My team’s been using them every year. There’s a pdf for pneumatics.
Single acting cylinders don’t need any air to retract because they have springs which pull them back to their default position. The spring’s rather weak, but it can pull a fair amount of weight back, up to a pound I think.
Double acting cylinders use air to both push and pull back in. I’m not sure if this leads to quicker air exhaustion, but if your system is well-put-together, it shouldn’t be an issue in a match.
In my own experience with swapping single and double acting pistons, the single acting ones have less power because the spring limits them a tiny bit. This shouldn’t be that big of a problem unless you’re really trying to eke out every bit of force from your pistons.
Both give the same amount of pushing distance, but double-acting cylinders are shorter by a bit.
My club had both sets 1 and 2 when we started using them, but I’d start with a Kit 2 and if you don’t quite like the double acting solenoids, get a Kit 1A so you get the solenoids and pistons.
Some posts on the forums (can’t seem to find them) have found legal non-vex alternatives for the reservoir and pistons which I think are slightly cheaper, but aren’t complete sets…So I’d suggest you buy the kits.
Make sure you don’t rip the solenoid wires from their heads when they’re connected in the solenoids - that’s a quick 15 dollars gone
Josh Wade (1103) taught me at worlds to use a wrench to make sure your pneumatic fittings on the piston and reservoir are solid. So long as you can’t unscrew it by hand, air won’t leak out a lot.
And Rick Tyler recommends dropping some soapy water on fittings and joints to see if air leaks out. If it bubbles, make sure to fix leaks.
If I were you I would just buy the vex kit to start out with, but buy from SMC for later on. That way you have the basics and you can be selective later (i.e. replacement parts or more of one type). Also go over basic principles like bell cranks and what not. Pneumatics are a great resource and can really bring your bot to the next level. Here is a link to an alternative source
* be careful, the pistons come in all kinds of variation, and it must be COMPLETELY identical in function to be considered legal.
Have fun and good luck!
You can use double acting pistons as single acting ones if you only pump air through one end of the piston and use rubberbands instead of the spring. I would recommend a double acting pneumatics kit over a single one just because it is more versatile. Also double acting pistons are slightly shorter than single acting ones so can be easier to fit on your robot.
K Thanks for your guys’s input! We will most likely be buying the pneumatics kit two in the near future.