Arm Mechanism Advice

[Timothyw0]

Thank you guys responding. I appreciate it. But mike: The arm will have to move quite frequently because it will provide our picking up ball mechanism. It won't be very heavy because it's made out of square aluminum and will have a motor attached for another mechanism. And lastly, our arm will need to stop in immediate locations.

[DonRotolo]

Originally Posted by Timothyw0

And lastly, our arm will need to stop in immediate locations.

I assume you meant to write "intermediate". If so, that's a deal-killer for pneumatics.

Why? Several reasons:
1. As the load on a pneumatic cylinder varies, its position changes. So that intermediate position will not be the same each time, as it depends on load (e.g., whether you have a ball or not)
2. Controlling air for intermediate positions is difficult. Not impossible, but difficult. There are dozens of threads on this from up to 8 years ago.
3. Pneumatic cylinders prefer either of 2 positions: Fully extended or fully retracted. For accurate end positions, you need to 'stack' cylinders, adding cost and complexity.

Bottom line: Be sure to TRY what you want to do before finalizing your design. You may find yourself agreeing with the above...

[Ether]

Originally Posted by DonRotolo

...that's a deal-killer for pneumatics

^^Yes. Watch this video