Help with Pneumatics

[chompalot]

Hi,

Im very new to the whole bot scene, I have had plans to build a bot for a year or 2 now and am about to start building, I have no problem with electronics or building, just pneumatics. My plans currently have electric motors driving cutting weapons, but I would rather have something a bit more powerful ;-)

I know ( kinda ) how pneumatics work but the fine details such as size of buffer tanks and exhausting pressure from the ram and such like still elude me.

could anyone share some Genius with me??
Whats the simplest way to build a pneumatic system?

[Guest]

Help with Pneumatics

Take a look at the Technobots guide notes - http://www.technobots.co.uk/en-gb/pg_19.htmlhttp://www.technobots.co.uk/en-gb/pg_19.html theres two very good articles about LP and HP pneumatics.

However, it has to be said, people who dont know what theyre doing shouldnt play with compressed gas (dont think Im being condescending, I include myself in that statement!). Pnaumatics have the capacity to do a lot of damage to humans, so I, personally, avoid them at all costs. If youre not comfortable with pneumatics, theres plenty of weapons you can build without them.

[chompalot]

Help with Pneumatics

Thanks Steve,

Ive had a good read through the articles, and Im not feeling to inclined to build a pneumatic weapon. Will wait until I find a new team member with skills in pneumatics.

May just have a pneumatic weapon on the next design....After this bot has been thoroughly pounded in battle.

[defyer]

Help with Pneumatics

Anthony I have Canadas number 1 Heavyweight, its a 4 wheel drive flipper running at 1000 psi and can be run up to 2000 psi.

My system uses High Pressure Air,my system is as basic as it can get, I have 1/2 lines on the high pressure side, I have two 3 inch rams that are feed by a 1/2 ball valve which is attached to a pneumatic actuator the rams are double action which the exhaust ports left open, on the main feed line I t off to another 1/2 ball valve which exhausts the line so the flipper comes down as fast as it goes up, no need to feed air into the exhaust side or bungee cords, the feed and vent are instant, with neither valve being able to be open at the same time.

The valves are feed by a low pressure line feedding from the high pressure, via a smaller regulator, in all the system is extremely powerful, both valves are rated for 2000 psi not that i will ever use that much power, but 1000 psi system is what I was aiming for and managed to build it on the 4 th attempt.
I also dont use a buffer tank.

Think long and hard before you go the pneumatic route, it can be a pain in the arse.

[jamesb]

Help with Pneumatics

hi martin,
welcome to the forum. that sounds like a great robot mate, and thanks for the description.
im sure, if anthony is still on the forum, hed find that as interesting as i did, but he posted last on this subject about 2 and a half years ago, so maybe he wont get your reply.

seriously though, i found it very interesting, any pics?

[jamesb]

Help with Pneumatics

scrap that request, just visited your website and found pics.
cool, and so is the site.

[woody]

Help with Pneumatics

http://www.buildersdb.com/botpics/4133.jpghttp://www.buildersdb.com/botpics/4133.jpg

[defyer]

Help with Pneumatics

The pic you see on the builders database was a quick mock up, the bot has had a total frame rebuild, to shave 25lb off, as it came in at 220 lb, the valves we use to give us the 1000 psi and upwards each weigh 9.5 lb, I will be posting a new pic in the next couple of days as for my site, well that needs a major update.

[woody]

Help with Pneumatics

Hi Martin.

I made a visit to your site a while back ..September last year I believe.

Tescom and Goreg are popular high pressure / high flow air regulators .... whose make and model/specs do you use?
You say that your using 2 off ball valves , couldnt you have used a T or L ported ball valve?
How fast can you open the ball valves? ..... etc.
Cheers Woody

[defyer]

Help with Pneumatics

Hi Woody
I tried a tescom high pressure high flow solenoid, operating pressure was 3000 psi, however I didnt get the force it was more of a lifter, we have a Valtorc 1/2 full port stainless steel ball valve operated by a pneumatic spring return actuator with a nema 4 24vdc direct mount solenoid. the nema 4 gives us the following torque on the ball valve of 30lb*in at 40 psi upto 37,903lbs*in at 120 psi, the valve was only one way normally closed, the web site is http://www.valtorc.com/pneumatic.htmhttp://www.valtorc.com/pneumatic.htm

I didnt think of trying a 3 way ball valve, its just clicked now I will be contacting them monday may just change to that. it would save buying another valve.

Not sure what the speed the valve is but it gives us the desired effect, we tested it out on a dishwasher weighted to 150lb and gained 14 foot of air at 1000 psi.

The rest of the parts are : 2 x mag 400s 2x Victor 885s, drive system is 4 wheel drive double sprocketed down, runs about 25 mph. 4 battlepack Nicad 3600 ma 24 Vdc batteries in relay, and a double electric switch solenoid for the valve.
The regulator is a Victor SR4 inlet 4000psi outlet 2000 psi high flow.

Armour includes 12 x 12 Hardox 3/8ths (AR400) plate on the front of the flipper, 3.1/2 inch 3/8ths Hardox plates down the sides.

cheers Martin

[woody]

Help with Pneumatics

Excellent specs Martin.

Its difficult to build an effective flipper 1st time....... you look around and then buy an expensive high pressure high flow solenoid only to find that its opening time and flow is nowhere near good enough for the application of robot throwing .......

An OPEN full port ball valve has the best flow rate possible.... the quicker you open it the sooner you reach maximum flow.

Your set up sounds v.good.......but have you tried WITHOUT a weight to flip?
The biggest problems H.P. flippers have found is stopping the arm without it either bending or the inertia taking the robot right over......Oh! whats the self righting like?

Woody

[defyer]

Help with Pneumatics

We have tried the flipper without weight, the first couple of times we managed to rip out the rams from the frame, after a few modifications we are now solid. As for flipping over we only jump the front by about 4 to 6 inches, we have kept most of the weight in the front 12 inches of the flipper, the whole flipper weighs in at 25lb, while on the back of the bot we have a scuba tank that weighs in at 21 lb, so the bot is well balanced.The self right test gave us a perfect self right and the only time we bent the frame was when i drove it into and through a 4 ft high brick wall..at full speed, left a nice gap in the wall....ooops
Now that we have built the new frame, (pics will be posted in the next day or so, I will post the link here) we have decided to keep the old frame and move it upto a super heavyweight, with some hardex plating, and the same flipper setup.

Mart

[woody]

Help with Pneumatics

Look forward to seeing it.

[glen]

Help with Pneumatics

i hear that the defyers cylinders exploded at WBX

[woody]

Help with Pneumatics

Shame....but not surprised.
There are some horrendous forces involved in stopping the flipper arm and the rams LOOKED like low pressure but really its impossible to tell from just pictures.
Hopefully Martin will post a report.