Pneumatic questions, sorry!

[Max]

To fill a paintball bottle from a fire extinguisher cheaply could I take the nut from the extinguisher, turn it on a lathe to open up both sides so I can screw the paintball bottle in one side and the extinguisher on the other? Would the nut be able to cope woththe pressure? And because the nut will only be half screwed onto each bottle will it be held on enough?

I know that I should have a dump valve in-between the two bottles but i think I should be ok?

[kane]

You need to have a vent valve on the filling rig. You should be able to pick one up for £20 - £50.

[woody]

http://www.google.co.uk/search?sourceid ... 24&bih=588

and of course Ebay.

[Eventorizon]

Hi All

We are going to be taking out first steps towards building some pneumatic machines. We got hold of 2 cylinders of Jamie a while back an I have 2 machines in mind. As we only have spinners, these machines will be for the Robotwars and other events that don't have a Class 1 Arena.

1: A 2WD flipper using a small 10 Bar, 40mm Bore, 75mm Stroke cylinder. This gives approx. 300kg of force at the tip of the cylinder which will be dropped to about 30kg over the flipper arm.

2: A 4WD (2 motors, belt driven) Horizontal spike machine with a 16 Bar, 50mm Bore, 100mm stroke. This will give around 500kg of force on the end of the piston which will have a hardened spike on the tip.
We know that spike bots have not been overly successful over the years but we want to make something different, but given some of the thin armour out there on some machines (LF3, LH3 Explosion) it might be able to do some damage.

The first issue we have is what Tanks to use. We got what looked like a 16oz paintball tank and we also picked up an empty 1kg powder fire-extinguisher which we were thinking of using as buffer tank in the Flipper.

What standard tanks do people use and what valves as well. We have, what I think is, a 3-2 valve to direct the flow in double-acting cylinders.

I just want thoughts on the 2 ideas. I am going to be putting up concepts fairly soon but I cant really do it until I know what parts are going inside. We might have some fun making an Asymmetric machine but neither machine is meant to be overly competitive, just low cost and fun.

[Liftoff]

My preferred solution is a 5/2 way valve operated system with QEV, buffer tank and spring/bungee return. I use all paintball parts for the reason that they are readily available, not expensive and properly rated. Buffer tank and main tank I'd use 12oz tanks, paintball low press regs are available as well, and they connect directly to the tank so there's no hassling with adaptors. 16bar is a bit on the high side to find LP valves and push fittings rated at that pressure.
The thing you should really take care of is making sure there are no restrictions from the buffer to the ram, that will be the difference between a flipper and a lifter!

[typhoon_driver]

the thin armour on LF3 is titanium sheet. You will struggle to do any kind of damage against that kind of armour with a spike.

By all means build one, but just be aware that you will likely do sod all damage.

[psychostorm]

Maybe if you rammed it with a run up...

[Eventorizon]

What pressure are the push fittings usually rated to? The plan was to make the spike bot from MDF. We are not massively fussed about weight as its never going to be for competition. As it will all be fixed I was going to get parts you have to bolt together rather than push fit parts.

Also, thanks to Kane's talk at the Robochallenge awards we know his list of little tricks to get the most out of a pneumatic system, like making sure the flow its straight just to name one.

And I know what the armour is Gary. 1.5mm Grade 6 on the sides and back with 3mm Grade 5 on the front. I still think 250kg of force is enough to do something to it. (250kg as we will push ourselves back as we fire, halving the force)

[plargen]

250kg of force will just push the 2 bots away from each other and if your lucky make a small dent

the main issue is that they way so little and don't have a great amount of grip on the floor

[typhoon_driver]

No need to have the sarcastic response. Only trying to save you some time going down a route that won't work.