Pnemautics help

We have built a pnemautic catapult using two cylinders one single acting and one double.) we are using single acting positions however and a single solenoid. Our problem is that the new double acting cylinder is leaking air… Any ideas?

Don’t worry the problem is solved

One suggestion is to put blue lock-tight on all of the threaded connections. (On the pistons and solenoids) Also make sure the ends of all of your tubing is straight. We had a very leaky pneumatic and this made it leak free!!

I would be careful with using lock-tight for the pneumatic connections. The reason is lock-tight does not dry and stay one piece after a certain point it becomes powdery and the powder could get into the pistons. There is a product that is liquid sealant tape that I use to seal threads on pneumatics which is made to seal air connections.

Can anyone help me with programming the pneumatics? I ordered the double acting ones, but have no idea what to do programming wise

You just need to set the digital output port the solenoid is plugged into to 1 (extend) or 0 (retract). In EasyC this would be SetDigitalOutput(port) or use the joystick digital to digital output block.

Just a warning, I was testing with one vs. two solenoids last week and found you lose air flow and therefore catapult power by using just one solenoid.

What about good old Teflon tape? It’s even specifically referenced in the manual that you are allowed Teflon tape to seal connections.

If you are using easyc I can give you a program for double acting.:slight_smile:

I am, so that would be a huge help, thanks

Would you please send me your programming?

In this thread:

I broke down every single step you need to program your pneumatics in EasyC. The program has one button that fires the pneumatics and then has another button that makes the pneumatics fall back down. Good luck. Let me know if you have any problems.

Hey all, were speculating purchasing pneumatics, and we can’t grasp the mindset that is the difference between double and single acting pneumatic, and their varying ways of control. Thanks for the help.

Even though the programming still isn’t clear for me, I can answer that. Single acting retracts automatically, and double acting stays extended until told to retract

A double acting piston has air push and air return. To achieve this there are fittings on two ends of the pistons, and when connected normally to a double acting solenoid, the solenoid will either allow pressure in one end to extend the piston or the other end to contract the piston.

A single acting piston has air push and spring return. Because of this, the single acting solenoids either allow pressure (extending the piston) or block the pressure (allowing a spring to retract the piston). Because the single acting piston only has a spring pulling it back it will not have much force on the return, and because the spring is counteracting the air extending, the air does not provide as much power either. The advantage to single acting is that they do not use as much air.

This year most teams are using double acting pistons, but only powering the extension, because gravity will naturally lower the catapult after the shot without needing to reduce the power with a spring return or waste air on the return stroke. This can be achieved by either using single acting solenoids on the pistons or blocking the release tube.

I noticed you would be willing to share a sample program for running double acting pneumatic cylinders. My team just received the single acting kit and will be receiving a double acting kit shortly and are completely lost in how to program either and have had trouble finding good tutorials anywhere online. Any assistance would be greatly appreciated. Thanks again,
Anthony Milanes
Valley Academy of Arts and Sciences, Granada Hills, CA

If you are using Easyc then I can send you the pnuematics program that we used this year.

If you are using robotc, then in motors and sensors setup set the digital port the solenoid is plugged into as Digital Out. Then set SensorValue[port solenoid is plugged into] to 1 to activate the solenoid, and set it to 0 to deactivate.