Here is a long post for ya.

I obviously needed to clean out the entire pneumatic system so I decided to just pull it all out of the robot. While it was out I thought I might take some detailed picks of it to explain it all to you.



The 20oz paintball CO2 tank on the right holds the liquid CO2 to supply the system. The tank is aluminum and weighs 29oz empty (822g) and another 15 - 20oz heavier when full (425g - 567g). The amount of gas I can get into the bottle when filling is dependent on the temperatures of the donor bottle and the recipient bottle.
The gas is then siphoned off the top of this bottle and pipped into the 12oz CO2 tank on the left which acts as an accumulator.
When I trigger the solenoid valve that is attached to the side of the 120z tank the gas is dumped sraight into the bottom of the custom made ram in the center. When the valve is closed the gas in the ram escapes through a small hole in the top and the piston is returned by a spring.



This a close up of the fitting on top of the 20oz supply bottle. All the fittings in the robot are designed for use on paintball guns and have therefor been design to safely handle all pressures that may be expected.
This bottle has a on/off valve built into it but most have a pin valve arrangement that is opened when the bottle is screwed into the duckbill mount. A separate ball valve is used as a main shutoff valve when using a pin valve type bottle.
While you can't see it in this photo a 1300psi burst disk is mounted on the back off the bottle that is designed to rupture if the pressure in the bottle gets too high, such as if the temperature gets too high or the bottle is over filled.



Next is the top of the 12oz buffer. It is fairly simple. A 1200psi gauge to read the pressure and a manual dump valve to empty the buffer after a match. The buffer is also fitted with a 1300psi burst disk.



This is the Burkert 2/2 solenoid valve that is used to control the system with a Team Delta solid state RC switch attached to it. I just spent a few hours pulling it apart to clean a load of aluminum swarf out of it as well as the buffer and ram.



This the custom made ram for the robot. It has a 70mm bore and a 50mm stroke. A steel case and end plate, aluminum shaft and piston with UHMW polyethylene bits. Very nice.



Detail of the piston showing the 1mm hole to vent the gas after firing. There was swarf in here as well.

I hope you found all that interesting. I did.
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Secretary of the Queensland Robotics Sports Club inc.

Very Nice

If its still apart, can you show me a side view of the piston? Cheers.
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Secretary of the Queensland Robotics Sports Club inc.

Does it have any dampener stopper, on the can?
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Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

It ends up polyethylene on polyethylene.
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Secretary of the Queensland Robotics Sports Club inc.

I am getting fed up with this marine grade aluminum.
After much building, testing, breaking then re-designing, hammering, testing and breaking again I have finally got a return strap that almost works. But all the testing has shown several weak points in the ali chassis, mostly in the hinge. After bending several 1/4" hardened steel pins there are now several cracked welds and the "ears" on top of the chassis are bent out of shape. This chassis has been about modified to death over the years and needs to be rebuilt from scratch.
For now I plan to cut the hinge assembly off the top of the chassis, weld up a new one out of steel and bolt it on.
After Melbourne I will make a whole new chassis with a welded steel sub-frame to support the weapon.
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Secretary of the Queensland Robotics Sports Club inc.

Some photos of the cracked parts of the hinge on Devastator





And how Andrew fixed it

Theres some ugly pics there Are you going to put a steel pivot point in there now? Keep up the good work guys, a reliable Devastator will be a fantastic foe to face in the arena and a lot of FUN!
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Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

So those cracks are from the force of its own flips?
That's pretty impressive...
Just wondering, the frame is 5083 isn't it? Perhaps in future there's some better grade to use, although aluminium is notorious for having brittle welds.
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quote:

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Just wondering, the frame is 5083 isn't it? Perhaps in future there's some better grade to use, although aluminium is notorious for having brittle welds.

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This is a good page on the various grades of aluminium and their weldability

http://www.azom.com/details.asp?ArticleID=310
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The ram, thanks to the Gravity system it was build too, doesn't need space and weight wasting dampers.

The idea is simple. Mass* acceleration= force. By dividing up the moving masses the piston doesn't have to stop the moving mass of the arm. Only itself.

And the piston is HDPE, with a large ali washer, the rod solid ali. So the "moving mass" is low. So the forces acting on it are low too.


About the swarf; Only 1 place it can come from. The side hole in the buffertank.

I normaly flush the difficult to flush buffertanks with brake cleaner and a few shots of gas CO2 at FP.

I have already flushed the buffer so that is no longer a problem. I have also welded up some steel brackets for the new hinge which will get attached tomorrow. And yes, it is the force of the arm alone that deformed the old hinge assembly. I just need to work out how to make a lighter arm.
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Secretary of the Queensland Robotics Sports Club inc.

F=MA as you say. The problem is hitting an end stop means stopping the whole thing over the length of flexing you have in the end of the ram. so A becomes astronomical. We had the same problem with Plan-C's weapon. When we fired it last time it punched its way out of the cylinder by breaking a 60mm diameter weld, twasnt pretty, every doubling of stopping distance halves the force required to do the stopping.
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Mechanical engineers build weapons, civil engineers build targets