pneumatic question

[team_orr]

hi

does anyone have any idea what a reasonable pneumatic system would cost me and where i could find some bits for it or anyone could offer their services...

cheers

jack

Team Orr

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anyone seen my hammer???

[team_orr]

Re: pneumatic question

any advice at all...

[leorcc]

Re: pneumatic question

Hi Jack,

What kind of pneumatic system are you looking for? Full pressure, low pressure, single-acting, double acting? Is it for an axe, a flipper, a crusher?

[team_orr]

Re: pneumatic question

its for a flipper, i dont really care about low or high pressure just want to be able to oota!!!
i know i need a ram, a tank and something called a buffer tank?
apart from that i have NO pneumatic knowledge
jack

[woody]

Re: pneumatic question

Read this...
http://www.teamdavinci.com/understanding_pneumatics.htm

[woody]

Re: pneumatic question

You could also download this utilitiy that I knocked up ...It's a bit of a mish mash of odds and ends... but could be helpful.

http://www.teamonslaught.fsnet.co.uk/Max.xls

[team_orr]

Re: pneumatic question

*blows away cobwebs*

wow, its been a while, decided to make a pneumatic system again XD got a bit more knowledge now and im a bit older lol

thinking of using an ikea, £7, powder fire extinguisher for my buffer tank, and a big co2 fire extinguisher as my main tank. not sure on my ram tbh, want it to be full pressure and, even tho its a bit of a change that my previous design, an axe for the weapon, so the ram would have to be double acting

any advice?

and also, can anyone recamend a cheap valve? and any other bits that go inbetween XD

TA

jack

[Metal Demons]

Re: pneumatic question

Full pressure - good luck, it's expensive! You'll need a custom made ram or modified hydraulic cylinder and to properly build and pressure test your system - off the shelf components won't do for a lot of it. Terrorhurtz doesn't use full pressure and I'm sure you know just how powerful that is, so you really don't need full pressure to make a powerful axe

Also, just a heads up - a powder fire extinguisher is pressure tested to like 20-30 bar, working pressure is more like 10 bar... not the kind of thing you want for a full pressure buffer tank! You really don't want to scrimp on pneumatic components, 150psi is scary enough when things go wrong... 750 would be positively terrifying.

I'd advise sticking with a low pressure system - you can get rams, valves and such like far easier, from surplus suppliers and ebay if necessary. It's also slightly safer, especially when you have little experience with pneumatic systems - though that's a relative term, these things can (and have) killed people... I'd STRONGLY advise you to get some help with setting everything up from someone with pneumatics experience.

As for what you'll need: CO2 tank (fire extinguisher will do it), CO2 bottle valve (comes with the fire extinguisher - you can modify the valve on it by drilling a hole through the handles so you can stick the pin through to lock them in place with the valve open), regulator or regulators (you may want 2 in parallel for higher flow rates and better tolerance of icing up) to drop the 750psi down to ~150, buffer tank or tanks, pressure relief valve set to ~165psi for a 150psi system, dump valve (to let the gas stored downstream of the regulator out when shutting down the robot after closing the main CO2 bottle valve) 5/2 solenoid valve, probably a high flow solenoid valve in parallel with the extend half of the 5/2 to increase your flow rate while extending the cylinder (means your weapon will move faster), quick exhaust valve on the rod end of the cylinder (exhausts gas from the other side of the piston faster when the piston is extending - again, quicker weapon activation).

That's just about an effective system, but you'll also need the axe mechanism - I'd suggest a rack and pinion setup similar to what Terrorhurtz uses (you can see a diagram on their website) as it's small, light, reliable, and tough - you will need to get some parts at least made in a machine shop.

[team_orr]

Re: pneumatic question

eek, il go low pressure then XD
found i diagram on team terrorhurtz's website showing me a pneumatic system, looks fairly easy, but i know its a lot harder than it looks

havnt found that diagram for rack and pinion tho

got the powder fire extinguisher, how would i convert this into my buffer tank?

and, does anyone have a spair ram they are willing to sell bone cheap?

ta

jack

[Metal Demons]

Re: pneumatic question

http://news.terrorhurtz.com/axe/default.htm has a good overview of how a rack and pinion axe setup works - it's probably the simplest way to do it.

Converting the fire extinguisher into a buffer tank: set it off, make sure all the pressure is gone, take the extinguisher valve off so you're just left with the bottle, then screw a fitting (adaptor to 1/2 inch BSP ideally) onto the bottle which you can connect to your setup.

Ebay's a good place for affordable rams.

[widow_twanky]

Re: pneumatic question

Rack and pinion might be a bit more on the expensive side than you'd like. It tends to be much easier and cheaper to make a shunt style axe like Hydra has. All works very well with standard rams with 300-400mm throw.

[team_orr]

Re: pneumatic question

cool, how does that work?

[daliad100]

Re: pneumatic question

It's a sort of four bar linkage which can be seen in this video (sorry aout the quality though) http://www.youtube.com/watch?v=g9lmE...eature=related.

I have also made the linkage here (the lengths are all aproximate so have a play when designing your axe)
http://incredibots2.com/?robotID=dal...cff49.17217602

You could also try a chain based rack and pinion like the judge shown here:
http://members.toast.net/joerger/AskAaron/weapon.html
just Ctrl-F and paste this into the find box How were the chains attached to the weapon sprockets on 'The Judge' (without the speech marks).

[widow_twanky]

Re: pneumatic question

cool, how does that work?

As Daliad100 says it's a four bar linkage. which is designed to accelerate the speed of the arm to more than that of the ram. Probably the simplest way is to have a look at hydra and copy that. I'd suggest a bit of a bigger ram (80/100mm) and definitely at least a 1/2 port valve. When we changed to half inch valves (and finally got it working) it made a massive difference.

Flow in a 1/4 valve is about 1000l/s for a 1/2 valve it's about 4000l/s so it suddenly throws the whole arm at a much faster speed.

Andy