3 position pneumatic cylinder question

I have heard they exist but cannot find much information about them. we are looking for a pneumatic cylinder that will stop in three different positions. does anyone have any experience with them or know how they work or know how the positions are determined. Thank you

We have needed 3 positions cylinders and have made them in the past by bolting two cylinders together. We used cylinders from Mcmaster that have bases that lend themselves to bolting together:

In this case, you can get the appropriate sized aluminum tube and thread it, then screw the ends of the cylinders into your aluminum tube to make a single assembly.

Bimba sells 3 position pneumatic cylinders here: https://www.bimba.com/Products-and-Cad/Actuators/Inch/Round-Line/Non-Repairable/Original-Line-Three-Position

I believe you also got a bimba voucher in the virtual kit of parts.

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We designed one on the Bimba site that would work but can’t figure out how it works. It looks like they put 2 cylinders together end to end somehow but I can’t find anything. Has anyone used one of these?

The Bimba voucher is usually for a specific set of cylinders, all double acting single stroke.

If you’re looking for the third position being right in the middle, you can use two double end mounting cylinders and two “mending plates” to bolt them together in opposite directions. You can do similar things with unequal lengths, but that one is really easy.

We have used three position cylinders before. You will need 2 solenoids to control the piston, or at least that is how we did it. The first input and middle input works as if it is a normal piston. IE you can extend retract and it will hold its position using a double solenoid. The third position works as if it is a single solenoid that is attached to a normal position. Meaning that it needs to be fed air in order to extend to the last position. You have to be careful on what you want your starting state to be in. After using them for one season we probably wont go back to them unless we had a super unique reason to. Last year we had place where we could have put them but opted to put two cylinders back to back with a custom threaded coupler, that sounds more complicated than it is… All you need is some round stock. drill out a whole and tap it so both ends of the pneumatic can screw into it.

Hopefully that helps. Good luck

One way you can achieve 3 positions is to mount the cylinders opposite of each other. We did it for our Stronghold robot
position 1- was up and within frame perimeter Position 2- was our shooting angle position 3 was down on ground and used to collect balls etc.

This video shows some of our early testing with the set up- we plan on doing something similar again this year

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If you don’t need a lot of stroke the Dart 12" actuator kit offered by Andymark might work. It has infinite positions but only 12" stroke. They are currently out of stock but expected by Jan 22.

We looked at it but there were a lot of complaints about it’s build quality and pot breaking in CD. I couldn’t find anything recent. Have you had success with it?
THanks

We have not tried it as it has not become available.

We’ve done similar work, but packaged the cylinders a little differently.

That’s how we packaged two pairs of cylinders to get a 3-position wrist. Two straps of aluminum with nose- and tail-nut sized holes to bolt the cylinders together.

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That is a very elegant solution. I love it.