Hi everyone!
I just have a technical question about the use of pneumatics.
Can we activate a piston to stay within 18 x 18 x 18 for inspection and before the match starts? For example, if we have a claw that retracts into the robot by means of an activated piston, is that VEX legal? In other words, can the starting dimensions be achieved by using an activated piston?
Thank you in advance for the feedback! 
Yes.
Please refer to the game manual for questions about rulings. In this case, your question should be answered by the rule <SG2>.
You can’t activate a piston to stay within the 18 in cube because all activations of the pistons are blocked by vex net while the match is in standby.
But you can activate a piston to push you claw out to the 18 in cube during auton or driving.
This is not true. Verify by running an example code to actuate a piston during pre-auton.
Keep in mind that in order to participate at all, your robot has to fit in 18x18x18 during inspection.
If you are using double-acting cylinders, you can change whether the piston is retracted or extended when the robot is ‘off’ simply by switching the hoses at either the cylinder or at the solenoid…
I don’t see any reason this idea wouldn’t work.
I second this.
but that’s how vex net works
I don’t think they’re the same thing…
VEXnet doesn’t disable pneumatics quite the same way it does motors.
Motors are disabled and set to coast (free spin).
3-wire outputs (pneumatics) are locked into whatever state they were in when the robot was disabled. With a double-acting cylinder, this could be either retracted or extended (with air pressure holding it in the position it is in).
The only way to make double-acting pneumatics ‘float’ without resistance would be to physically turn off the air-valve (the shut-off valve).
Not really, motors are disabled and the controller is ignored, but 3wire ports can still be activated. To be honest it is a bit of an oversight on my part, pneumatics were far less popular in the early years of V5 due to the motor penalty and they were just not considered too much, I think it may be time to address that in the next vexos update.
I was talking about single acting because that’s all my team has
Based on what James replied, you could set it to extend before the match began and things would work fine.
Every programmer does triage…
I would definitely make sure that the pneumatics can be in either state when disabled (but can’t change state).
With single acting air cylinders, your best solution would be to design a release mechanism which allows expansion (releases or unlatches) when you actuate the air cylinder. The natural state of a single acting air cylinder is retracted, which is how it will be at inspection and the start of the match
I didn’t post the problem but thanks for the tip.
Most people were confused to why I thought vex net blocked all pistons during standby
No worries 
