Pneumatic

I have built a robot on Rexs Robot Challenge and am looking to update the machine to pneumatics. I am on a budget and need to know what i need to start as i have no experience in this area
Can anyone help?

Heres a great place to start:

http://www.technobots.co.uk/Technical/Guidance/A%20Guide%20to%20the%20Design%20and%20Use%20of%20L ow%20Pressure%20Pneumatics%20On%20Fighting%20Robot s.htmhttp://www.technobots.co.uk/Technica...e%20Design%20a nd%20Use%20of%20Low%20Pressure%20Pneumatics%20On%2 0Fighting%20Robots.htm

It covers heavyweight pneumatics but featherweight pneumatics are exactly the same really

Youll be looking at quite a large price tag for a conversion to pneumatics Im afraid though

How can i get hold of Co2 ? If i use air what sort of cylinder is best ? and where can i purchase one ?

Co2 is available at 99.9% of Robot Events so you can just refill your bottles. Use the link I gave you so that you can calculate how big a stroke and bore ram you want. Technobots sell some cheap low pressure rams, but check the for sale section in the forum where a few can be found.

If it is still for Rex Robots challange then I would surgest a bicycle pump with a compresser set up. They are quite cheep. Will give more info later when I find it on my other computer.
Regards
Ian

Tom - John Reid from Terrorhurtz has a good pneumatics how to on his website. Again its aimed at heavyweights but could be of some use.

http://www.johnhmreid.dsl.pipex.com/killerhurtz/howto/pneumatics.htmhttp://www.johnhmreid.dsl.pipex.com/...pneumatics.htm

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

http://www.teamdavinci.com/understanding_pneumatics.htmhttp://www.teamdavinci.com/understanding_pneumatics.htm

If it is for Rexs challenge- I wouldnt suggest bike pumps...because there crap, You can pick up cheap rams of ebay, Or im sure if you place a wanted add on the forum you will be able to pick one up- Also I looked into it exstensivly and my old feather Turbine 3 would of been classed as illegal for using a compressor.

If its not for RRC you can buy bottles from Jackson+keay, a valve, fittings and pipe from technobots and you could probably pick up a small regulator of someone on the forum- or get a welding reg moded.

Jackson & Keay Ltd
Private Road Number 7
Colwick Industrial Estate,
Nottingham,
NG4 2JW
01159617113

Hope this helps.

Does anyone who how to control a solenoid 5 port valve by radio control ?

The normal way is to use a RC switch:

http://www.technobots.co.uk/en-gb/dept_78.htmlhttp://www.technobots.co.uk/en-gb/dept_78.html

or you can just have a servo hitting a microswitch.

I am looking for a M5 solenoid 5 or 4 port valve but am struggling to find one. Anyone know where i can get one ?

Tom

1/8 bsp is more common. M5 is realy small.

I have started a featherweight flipper project with a friend of mine. I have the whole system picked out but the valve and cylinder. I know I will use something in the 38mm x 160mm range for the cylinder. But as far as the valve I have not had much luck finding many good ones. I need a double acting valve with the best possible flow and PSI ratings. Anybody have something that they would recommend? Thanks!

~Chad

Hi Chad ,
What is your gas ... CO2 or Air?
How much will your regulator flow ........if its flow rating is low youll need a buffer tank.
Port size of your 38mm x 160mm ( 1.5 x 6 ) ram ?
Can you add extra ports or increase their size yourself?

Woody

Hey Woody, thanks for the post! You have helped alot of US builders, I was kinda hoping that you would reply.

This system is going to use Co2 for power.
I have been looking at this regulator to use. http://www.palmer-pursuit.com/online-catalog/stabilizer-female.htmhttp://www.palmer-pursuit.com/online...zer-female.htm

Some people around here have used it and I have not herd any bad things. Any super secret UK regs that you think might be better? I was kind of planning of a buffer tank regardless to try to keep freezing from going on.

I have not actually picked out the cylinder yet, but I would like to get one with at least .25 (6.3mm) ports if possible.
My choice of Valve and will determine what cylinder I pick.
-I could go with a Spring return such as http://www.Mcmaster.comwww.Mcmaster.com part # 6498K548 @ 150PSI if I were to find a large valve that could really give some awesome flow.
- Or a regular aluminum double acting cylinder @ 140PSI
- Or a steel double acting @ 150PSI

Here is where I need some advice. What cylinder/regulator/valve combo would give me the best toss? I would like to have something like a 30pound Toro, little sister or any other nice flipper bot that you can think of.

~Chad

Chad, in the UK and the Netherlands several of the 12 kg (26.5lbs) featherweights use full pressure CO2 pneumatics. They are in the end not that much more expensive than low pressure and they give a lot more OEMPH for the weight used for them.

On the other side, I do have a reasonable supply of Low and High pressure rams ,valves and buffertanks. Everything between 100 and 1000 psi. Mail me for more information.

E-mail sent. If you ever get on yahoo my AIM name is wazio88

~Chad

Chad, The super secret UK regs that we use is the stabilizer as well :). Weve managed to freeze the reg even with a buffer tank but only on lower than 50psi and after 20 or so hits with the axe in a row. Other than that weve never had a problem with them. The only thing to note is they are not the reliving type so any liquid getting passed the reg will cause a greater pressure than expected so you need a good pressure relif valve.

Hi again Chad,
I suspect that Mario has already sold you F.P. setup :) or perhaps a QEV powered L.P?
If I can be of any assitance ......feel free to email via the link on my profile.

A good place for valves is RS - a bit pricey but good quality.

I have made my own regulator based on the palmer design and it gives such a good flow rate that I do not need a buffer tank, I am not sure whether a palmer reg could be modified to my spec. I dismantled a standard ram and fitted a spring inside to retract the flipper.

The main valve is of my own design but prior to that I used a 20bar 24v solenoid 2/2 valve(technobots) and a drilled hole in the ram feed to vent. This set up was capable of turning over any other machine, and if fired without a robot on top it would land me on my a**e.

I will put an image of the machine self-righting on my profile.

Feel free to e-mail me if you want to know more.

Trev ......Chad is U.S. based.

http://www.mcmaster.com/http://www.mcmaster.com/ is probably better.

(Message edited by woody on September 29, 2005)

I have been looking at the numbers from other pneu bots (in the US)...

So here they are

Judge: 60,319 lb-inches
Ziggy: 56,549 lb-in
Bounty Hunter: 84647 lb-in

So if I scale that down to a 30lb bot, That would put me in the 5000 lb-in range.

So, now I narrow my question... What do I have to do to get 5000 lb-in? (at the tip of my arm). The bot will use a 4 bar system, not the usual cylinder in the front, arm mounted at the back.

~Chad

Whats a low pressure for a feather flipper. I was thinking of 100-150psi. How long would it take to flip a 12kg robot at 100psi forward?

Or if not 5000lb (might be to high of a goal), then enough to launch a bot 8 high Or tip over a bot double its weight... Large goals, I know.

~Chad

Heres some quick calculations I just did out of interest:
5000lb-in is approximately equivalent to a ram with a swept volume of 33cubic inches at 150psi. This is approximately equivalent to a 3 bore and 5 stroke.

5000lb-in is also equivalent to a 30lb robot, 167 high (14 feet or 4.1m).
But from the crude analysis other people have done on Wheely Big Cheese, Gravity and Chaos 2, you can only get an efficiency of about 50%, so in reality if you put in 5000lb-in, the other robot will go about 7 high.
I think LP systems are typically more efficient than HP but I dont have any real experience or data to support this. Im sure a 4bar system will be less efficient than a basic rear hinged flipper.
So in actual fact your aim of 8 is more ambitious than 5000lb-in.

So two 1.5 x 6 rams may be nearly adequate.

Mario is probably the best person to advise you on this though.

Fairly meaningless figures without a time constant.
But lets work on the assumption that you supply your 5000 lb-in effectively .......so thats 416 lb-ft .........your chucking a 30lb bot
416 divided by 30 ......thats close to 14 feet
then assume 50% efficiency ...7 feet of potential throw.

A 2 bore ram with a stroke of 8 running @ 200 psi matches your throwing requirements and would produce 628 lbs of lift ......more than satisfying your last requirement.

So its a question of matching up a decent size ram with a valve that will flow enough to fill it in a VERY short time..... i.e. tenths of a second.

I believe that a valve and pipework with a Cv of 5 or more together with the 2x8 ram would do the trick.

Seems Mark beat me to it ......... :)

(Message edited by woody on September 29, 2005)

Its nice to know we both got the same numbers independently though!

@ Mark
Yep .....a perfect match :)



(Message edited by woody on September 30, 2005)

Chad .......How much wieght can you dedicate to the pneumatic ssetup?

I would like to keep it around 10 pounds if possible, but as everybody knows... Less is better. 10 would still give me weight for a half good frame and some ok armor. Their are some 30lb spinners that are just crazy with the amount of energy they pack! But I think it would be good to see them flying about 5 in the air :)

Getting a bot up in the air is not that impressive, a bit overrated even. Its the coming down that must be spectacular. Cant throw them high enough in my opinion, because what goes waaayyy up goes mightily down.

What lasts longer? Air or Co2? I have been told air but this person could be wrong. How expensive is a 600g Co2 bottle usually?

Depends on maximum storage pressure for the same size of storagebottle.
If its 1000 psi CO2 wins hands down. If it goes over 4500 psi, air wins.
CO2 goes liquid at room temperature and increases density with a factor 10= compared to the compressed CO2 gas on that pressure.

Imagine a 3L bottle. Rules say you can fill this bottle with 2 kg of CO2, or 3L of compressed air on 1000 psi/70 bar. With air you have 3liter*7a bar =210L of gas.
With CO2 you have 2 kg=512L gas per kilo, so 1024L gas in that same bottle.

To beat this with compressed air youll have to go over 337 bar.

600grams CO2 bottles, 20oz paintball bottle with On Off valve can be bought over here around ‚45.

Are the CO2 bottles already at a certain pressure, say 1000psi? If so, how would I bring the pressure down to 150psi for the whole system?

Listen to Mario. You will find it is cheaper, lighter and simpler to go with full pressure CO2.

You could buy a paintball regulator, like the Air America Messiah, but this adds expense, weight and complexity for no benefit.

http://www.teamdavinci.com/understanding_pneumatics.htmhttp://www.teamdavinci.com/understanding_pneumatics.htm

Ok, after much talking with Woody and Mario I have made up my mind to go with a FP system. Mario is going to make me a Cylinder that has a 70mm bore and 100mm stroke. I will also use AL paintball tanks it keep the weight down. I think that I should be able to keep the whole system at about 10 pounds. I hope to get another robot to fly about 10 in the air with this large cylinder :)

Now I need to figure out how to mount it all up. What do you all believe to be the best system? By far the best flipper in the US was the Toro guys. I was thinking about a mini T-minus.

http://www.robotcombat.com/images/bbsf02/large/t_minus.jpghttp://www.robotcombat.com/images/bb...ge/t_minus.jpg

Do you all have any other advice on the type of arms and angles? And pictures of other featherweight bots so I can see what has been done before?

Thanks!

Hi Chad,

Theres a picture up on my profile now of a featherweight FP flipper tossing another featherweight into the air. This one is named little flipper, and has a rear hinged flipper with a big ram (something like 60mm bore?) and lots of gas flow. Thats the kind of thing Id be aiming for to make things fly - there hasnt been any toro style featherweight flippers in the UK though, so its very hard to compare the two flipper designs.

Chad, you had better fit a parachute for self-righting.

LoL, I will have to find weight for that somewhere ;) I figure 10lb for pneu stuff, 5lb for my kevlar/Ti armor, 1for a batt, and 4 for drive. That leaves me with 10 for a frame and whatever else. oh, and a parachute.


~Chad