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Unread 19-01-2006, 12:11
KenWittlief KenWittlief is offline
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Re: Cylinder Force Calculation

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Originally Posted by Arkorobotics
Say we didn't want to preload it, just have the air flow in instantly when the piston is drawn back. Then would it work?
all the testing that teams have done (over the years) says no. The air cannot flow through the little openings in the solonoid valves, fittings and tubing fast enough.

Ever see the pumpkin-chuckers, the giant air cannons that launch a 10" pumpkin about a mile away? they have huge air valves that someone pulls with a foot long handle.

we dont have those valves, so you need to get the air in the cylinder first (precharge) and then pull the mechanical pin out of the way.
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Unread 19-01-2006, 20:55
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Re: Cylinder Force Calculation

Quote:
Originally Posted by KenWittlief
all the testing that teams have done (over the years) says no. The air cannot flow through the little openings in the solonoid valves, fittings and tubing fast enough.

Ever see the pumpkin-chuckers, the giant air cannons that launch a 10" pumpkin about a mile away? they have huge air valves that someone pulls with a foot long handle.

we dont have those valves, so you need to get the air in the cylinder first (precharge) and then pull the mechanical pin out of the way.
2" bore 4" stroke and a 12V solinoid with 60PSI wont work!?
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Unread 19-01-2006, 22:30
KenWittlief KenWittlief is offline
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Re: Cylinder Force Calculation

Quote:
Originally Posted by Arkorobotics
2" bore 4" stroke and a 12V solinoid with 60PSI wont work!?
try it and see for yourself. The cylinder will not fill up fast enough.

I know a cylinder with 60psi slamming it back and forth looks fast, but not compaired to something like pulling a spring back and letting it go.

By precharging the cylinder, blocked half way, you are creating an air-spring. scroll back up and look at the drawing in post #9 in this thread.
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Unread 19-01-2006, 22:46
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Re: Cylinder Force Calculation

Quote:
Originally Posted by KenWittlief
try it and see for yourself. The cylinder will not fill up fast enough.

I know a cylinder with 60psi slamming it back and forth looks fast, but not compaired to something like pulling a spring back and letting it go.

By precharging the cylinder, blocked half way, you are creating an air-spring. scroll back up and look at the drawing in post #9 in this thread.
What if it was a springloaded piston? I have seen them on McMaster?
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Unread 19-01-2006, 22:51
KenWittlief KenWittlief is offline
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Re: Cylinder Force Calculation

you can only use pneumatic cylinders that are on the Bimba purchase list, and none of those have internal springs

you could use an external spring, and use a cylinder to retract it.
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Unread 20-01-2006, 00:55
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Re: Cylinder Force Calculation

Quote:
Originally Posted by KenWittlief
you can only use pneumatic cylinders that are on the Bimba purchase list, and none of those have internal springs

you could use an external spring, and use a cylinder to retract it.
Say if I modified the bore and stroke length? Would that make a difference? a smaller volume means it will get filled up fast right?
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Unread 20-01-2006, 08:40
KenWittlief KenWittlief is offline
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Re: Cylinder Force Calculation

you are not allowed to disassemble the cylinders or modify them in any way - but you can build them into a mechanism that alters its behavior (adding an external spring-return, or an external trigger release.

No matter what the bore and stroke of the cylinder is, the air flow is controlled (restricted) by the valves and fittings and hoses. There is nothing you can do to the cylinder to make air flow through the valves faster.

And you cannot use other valves, or modify the ones in the KOP.
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Unread 20-01-2006, 10:16
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Re: Cylinder Force Calculation

Quote:
Originally Posted by KenWittlief
you are not allowed to disassemble the cylinders or modify them in any way - but you can build them into a mechanism that alters its behavior (adding an external spring-return, or an external trigger release.

No matter what the bore and stroke of the cylinder is, the air flow is controlled (restricted) by the valves and fittings and hoses. There is nothing you can do to the cylinder to make air flow through the valves faster.

And you cannot use other valves, or modify the ones in the KOP.
By mod i meant like change sizes, I know you cant mess with the parts. I just want to make less volume to cover, to it fills up faster, but I guess that doesn't work.
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Unread 20-01-2006, 10:32
KenWittlief KenWittlief is offline
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Re: Cylinder Force Calculation

a smaller diameter cylinder will fill up faster, but it will have less force on its pushrod. The force a cylinder generates is equal to the surface area of its internal; piston plate times the pressure of the air you feed it with.

So, yes, a smaller diameter cylinder will pressurize faster, but the trade-off is less output force.

Is there some reason why you dont want to implement the release-trigger like I drew in the diagram? its probably the easiest way to make a pneumatic shooter.
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Unread 20-01-2006, 23:43
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Re: Cylinder Force Calculation

Quote:
Originally Posted by KenWittlief
a smaller diameter cylinder will fill up faster, but it will have less force on its pushrod. The force a cylinder generates is equal to the surface area of its internal; piston plate times the pressure of the air you feed it with.

So, yes, a smaller diameter cylinder will pressurize faster, but the trade-off is less output force.

Is there some reason why you dont want to implement the release-trigger like I drew in the diagram? its probably the easiest way to make a pneumatic shooter.
I think a lever would be a better idea. Where a bar has a pivot on one end, then have the piston in the middle then the other end of the bar hits the ball.
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