How to improve power in piston shooter

[LR_connor]

We are currently using our pistons as an extra push for a pass as we are a inbound robot. Our pistons are not strong enough to shoot over the truss and i feel as though it would be a nice improvement to get working. Any help on how to get pistons to shoot higher and farther would be greatly appreciated.

[Teched3]

It would help if you would give specs on what you are currently using to launch the ball.

[Nick.kremer]

As stated, it would really depend on your current setup, but my team also went through trying to increase range w/ pneumatic and these the fixes that helped us:

1. Higher air-flow solenoids.
2. If you are using some sort of level arm, extend the arm.
3. Leaving the return side of the pistons open to vent to the air, and have the pistons return some other way (ex: surgical tubing, vacuum, ect.).
4. We had a separate air tank for each piston on our shooter, thus adding more air volume on the 60 psi side.
5. If possible, mount solenoids directly to each piston

Here are some ideas that either didn't help us or didn't apply in our situation, but may benefit you:

1. Adding more pistons.
2. Increasing piston bore.
3. Assisting the pistons (ex: surgical tubing, spring, ect)

Hope this helps,
-Nick

[Qbot2640]

Originally Posted by Nick.kremer

Here are some ideas that either didn't help us or didn't apply in our situation, but may benefit you:

1. Adding more pistons.
2. Increasing piston bore.
3. Assisting the pistons (ex: surgical tubing, spring, ect)

Hope this helps,
-Nick

Increasing the diameter of your cylinders will most likely REDUCE the "power" of your shot, because it will slow the full activation of the cylinder (bigger cylinder - more to fill). If you need a certain amount of surface area to generate enough lift, then the fastest way to activate that would be increasing the number of cylinders - each with their own solenoid - and DECREASING the size of each cylinder, so they each fill quickly.

We used three .75" diameter by 12 stroke cylinders. The solenoids we are using are from McMaster Carr, and have about three times the flow rate as the standard KOP solenoids. Our shot can cross the truss and reach the human player from the center of the white line.

Two more things...(1) if you are using the cylinders in a direct pushing action, like us - we found that it was essential to have the ball resting on the plungers of the cylinders before the shot rather than have a space between the ends of the cylinders and the ball. Apparently the impact with the ball disrupted the action enough to dissipate some of the power transfer...so "push" don't "punch". and (2) don't try to fix multiple cylinder rods together into one plunger...it is nearly impossible to gang them together without introducing some friction on at least one of the rods, thus reducing power. We made a loose gathering gasket out of bicycle tube to keep the ends of the three cylinders together.

[FrankJ]

As, if not more important than pneumatic design, is the kinematics. As much as possible, you what the line of action of the cylinder should be perpendicular to the axis of rotation.

[Oblarg]

Originally Posted by FrankJ

As, if not more important than pneumatic design, is the kinematics. As much as possible, you what the line of action of the cylinder should be perpendicular to the axis of rotation.

Not necessarily. The dynamics of these shooters is extremely complicated; quite a few designs rely on starting at a significant mechanical disadvantage to work properly.

[FrankJ]

Originally Posted by Oblarg

Not necessarily. The dynamics of these shooters is extremely complicated; quite a few designs rely on starting at a significant mechanical disadvantage to work properly.

Doesn't change the importance of the kinematics, which is probably what I should said. Even so, the more efficient the kinematics, the less air you have to use to get energy into the ball.

[LR_connor]

Originally Posted by Teched3

It would help if you would give specs on what you are currently using to launch the ball.

here is the link http://www.princessauto.com/pal/en/P...nder/8188211.p to the specs on our pneumatic cylinder

[MrForbes]

I think he wanted to see the whole launcher setup, not just the specs on the cylinder.

Do yo have a few pictures of your robot that would show us how it works?

[falconmaster]

Originally Posted by LR_connor

We are currently using our pistons as an extra push for a pass as we are a inbound robot. Our pistons are not strong enough to shoot over the truss and i feel as though it would be a nice improvement to get working. Any help on how to get pistons to shoot higher and farther would be greatly appreciated.

1. Get the highest Cv flow valves you can get. KOP ones are about .25Cv, you can find others that are higher, we found some that were .8Cv, makes a big difference.
2. Mount solenoid valves with a double male nipple directly to the piston if you have the room. No using tubing is huge as well between solenoid and piston.
3. Next create a low pressure (60) reservior (tank) right before the solenoid with no elbow fittings and use the shortest length of tubing as possible. Length is bad, avoid length.

That should help

remember the solenoid (valve) openings must be 1/8" as per rules and must be able to operate at 120psi, Cv can be high as you can get....

[pmangels17]

Make sure your operating pressure is set to 60 PSI. If you are only pushing one direction, try removing the fitting from the return end of the cylinder. That might let the air leave that section faster, potentially giving you a more powerful shot, provided the cylinder will gravity return to its original position.

[kmusa]

Originally Posted by falconmaster

... and must be able to operate at 120psi, ...

Not quite right.

Per R77-D, if the solenoid valves are rated for less than 125 psi, an additional pressure relief valve must be added to the low pressure side of your system, and set to a pressure lower than the rating of the valve.

The interesting part of this is actually setting the valve. When we cranked up our low pressure side to 100 psi (the max of the regulator, but below the rating of our solenoids), we discovered a couple of marginal fittings.

-Karlis

[LR_connor]

Originally Posted by falconmaster

1. Get the highest Cv flow valves you can get. KOP ones are about .25Cv, you can find others that are higher, we found some that were .8Cv, makes a big difference.
2. Mount solenoid valves with a double male nipple directly to the piston if you have the room. No using tubing is huge as well between solenoid and piston.
3. Next create a low pressure (60) reservior (tank) right before the solenoid with no elbow fittings and use the shortest length of tubing as possible. Length is bad, avoid length.

That should help

remember the solenoid (valve) openings must be 1/8" as per rules and must be able to operate at 120psi, Cv can be high as you can get....

Thank you for the information do you have any recommendations of where we can get some?

[Qbot2640]

Originally Posted by LR_connor

Thank you for the information do you have any recommendations of where we can get some?

McMaster Carr item 6124K511 is a great one:
http://www.mcmaster.com/#catalog/120/1007/=rc4031

[nuclearnerd]

Originally Posted by LR_connor

Thank you for the information do you have any recommendations of where we can get some?

This one has a CV of 1.0 with a 1/8 npt port, Which is 3 or 4 times larger than the SMC / Festo valves you can get from AndyMark or Vex. We haven't used them though, so don't consider this an endorsement:

http://www.mcmaster.com/#6425k11/=rc3uws