Hi all, Can you help me with Pneumatics? sorry

[helihurley]

Hi all. I hope this forum is as friendly as it seems from the outside :wink: .

Im completly new to robotics but i do like trying to make stuff out of anything that looks like it might, with a little bit of imagination be a perfectly usefull (or fun) something else. I find i have a nack of crafting stuff together and enjoy doing it. With that in mind I have been eager to give myself a project to do for some time to stave of the temptation to stare at the telly box (boring!!). I have decided to try and build a big robot. (A heavy weight I suppose.) I€™m not looking to make anything over night but spend as long as it takes to complete.

I decided on a flipper type design and as such have been doing the research to try and figure out how it all works. With the help of reading through countless posts on this forum and following the suggested links I feel i have come along a great deal in understanding how the system works but as always i am still left looking for answers. Hence this really rather long drawn out post. (sorry!)

I have drawn a little diagram of what i think the Pnuematic system will be like PLEASE help me in the right direction if im going the wrong way this really is completly new and mindboggling stuff to me.



Im extra stuck on the following and any info would be greatly appreciated.
1) Is this diagram correct as a start?
2) What type of hose can i use on FP and where can i get it from can only find stuff rated 25bar im after ½ inch sizing all round and also need all the various fittings?
3) Is the two buffer tanks big enough i read something about it needing to be 3 time volume of ram? How do i find volume of the tanks out?
4) What fitting could i use to fit on paintball/buffer tanks so its open/ not regulated could i just drill the centre of the PB regs?
5) What is the best way do the exhaust? I read about adding a QEV how would this operate ie no when to open/close?
6) With the 5404 burket valves what one (2) should i get.

I would just like to add I am completly aware of the dangers of high pressure Co2 and will make sure i have a full understanding of operating them safely and taking all precautions i can to handle as safely as possible.

Thanks in advance fo any help that you can give me.

[maddox10]

Hi all. I hope this forum is as friendly as it seems from the outside :wink: .

Im extra stuck on the following and any info would be greatly appreciated.
1) Is this diagram correct as a start?

It is correct, but you lack 2 parts. Dump valve and Pressure relief device (safety valve)

2) What type of hose can i use on FP and where can i get it from can only find stuff rated 25bar im after ½ inch sizing all round and also need all the various fittings?

I normaly use hydralic polymer , aramide reinforced hose. It's pressure rating is a lot over what we need, and it is light and can accept narrow bends. In other parts I use rigid steel piping (standpiping?) or even milled and turned collectors. Lighter and more purpose build (and therefor smaller) than use all steel hydraulic connectors and T pieces.
I'm lucky in that part that I worked in a hose manufactoring firm, and have good contacts there.

3) Is the two buffer tanks big enough i read something about it needing to be 3 time volume of ram? How do i find volume of the tanks out?

A CO2 tank has 1.5 times volume compared to rated weight. 20oz=600grams= 900 cc.
The 140mm bore 120mm stroke ram has a volume of 1.85L, so your 2 20oz tanks are on the small side.

4) What fitting could i use to fit on paintball/buffer tanks so its open/ not regulated could i just drill the centre of the PB regs?

Remove the valve, that's obvious, as the valves have a let trough of next to nothing.
If you can find connectors, you can fit those directly in the buffertanks. Other option is to rethread the neck with 3/8bsp or drill it out ,and rethread it with 1/2 bsp, and have then recertified.

5) What is the best way do the exhaust? I read about adding a QEV how would this operate ie no when to open/close?

Never seen a FP QEV, and it operates like a piloted 3/2 valve. Meaning you need a FP capable QEV and small 2/2 valve to use it. Best bet is to use a third Burkert.

6) With the 5404 burket valves what one (2) should i get

.
Normaly closed 1/2 bsp, brass body.

[helihurley]

Thanks maddox10, great info!

I assume the pressure release valve will go in, or just after the main tank? Could this be just a burst disc or would it need to be a mechnical type valve?

How about the dump valve I guess that goes after the safty valve (main tank) and is that for releasing the pressure in the system on command (without firing the ram)?

So is my maths right in thinking I need a minimum of 5.55L, so lets say 6L. So two 1kg buffer tanks would be on the money at 6 litres. If thats the case is my 2kg main tank going to give me enough gas lets say 10 shots as an ideal.

If i were to get 5 port burketts would it be possible to route the exhaust to the unused side of the inlet valves to save on buying a third. If a third burket is required would it be a case of the inlet and exhaust working in oposites. i.e as one opens the other closes.

Thanks again for any info.

[Anttazz]

There was a picture posted just a few days ago about this actually, its for a low pressure system but its basically the same (obviously not components wise though) slightly different to your system, but from that you can see where the required safety valves go in the system .

EDIT: Forgot to post the link, Oops

viewtopic.php?f=111&t=4390

[helihurley]

Thanks, so it goes dump valve then prv. Also that means a burst disc wouldnt do as a safty valve then. Does a fire exstinquisher have a safty release valve (useable to my needs) on it any where i assume it must have some means of protection.

Just thinking out load here but what is the purpose of having a safety release valve in the line of the system when the system is running full pressure. Full pressure systems are obviously aimed at giving you the most pressure available from the tank meaning (in my head at least) that over pressure would be unfeasable (spelling?).

[helihurley]

Is this looking like it would work main thing im unsure of is will it exhaust quickly enough (or at all)

[terry]

no that wont work burkerts are 2 port only, on or off. You will have to use one for exaust aswell, another £100 :shock:

[jonny]

Hi, welcome to the forum! And yes. By the way did you get that ram off eBay ? Now I'm on holiday at the moment which unfortunately I cannot draw you any diagrams, also I'm only able to get on the forum once or twice a day but I'll do my best to answer your questions. When I get back back on the 20th i can draw diagrams, give you links, monkeys etc etc.

Fire extinguishers unfortunately don't have a prv in them, the burst disk will blow way before any other part of the fire extinguisher. A prv is very important as burst disks generally blow at 190 bar, burkerts are rated for 70 bar.
I see on your drawing your ram has 3 ports, I'd recommend using 3 Burkert valves, 2 inlet 1 exhaust. This is the easiest way. A well filled 2kg co2 bottle will give you 6 fires of that monster, if you want to acheive 10 flips you'll need to double it up with another 2kg bottle or use a larger bottle such as a 5kg. Other sizes of co2 bottle between 2kg and 5kg are hard to find. I know there was some 4.5kg scuba tanks adapted for robot use floating about a while back but they might have been sold by now.

Sorry for any typos, im tired and writing this on an iPhone

[robotic_ants]

Cannot wait to see what design you come up with for the actual bot, I was making some offers on the ram and got down to about £175 but got unlucky when someone paid full price. Guess this is the ram lol. Should make a good machine but as just mentioned above you may need a bigger supply bottle or be really good at driving. When fighting other good flippers you'll use half of those flips self-righting.

[jonny]

Ahh, so now I know who mr rants is

A good trick is to pulse your valves when self righting so that you use less gas/don't hit the roof!