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some pics of threading
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http://i57.tinypic.com/2mzab6s.jpg
http://i59.tinypic.com/vcyzpi.jpg
some pics of threading
Bought a proper co2 cylinder now! currently setting up the regulator on it..
What cylinder did u use in your bot? dosnt look branded , is it self made?
I just bought a scuba diving cylinder weighing 1.5kg, I have used a pneumatic regulator like this https://encrypted-tbn1.gstatic.com/i...s_ys8EoijQsv0A
The problem is , I think the regulator freezes inside when i turn the gas flow on. what is the solution to this?
Thanks
QEV Question... I have been watching some videos and is the function of a QEV entirely dependant on pressure so it functions automatically?
Also, its this suitable as a dump valve? http://www.ebay.co.uk/itm/1-4-PT-Mal...item2c7ab4335a
I am guessing if you are putting the dump valve between the buffer and main tanks you only need one as both can vent via the same port?
For this to work you need two ports on the same side of the ram do you not? This isn't possible without adding a splitter to the port on the ram. Why would you bother?Quote:
Originally Posted by Liftoff
was that question for me?
other than that, is it possible to use the small co2 cartridge refills (40g)-50g as buffer tank?
The dump should be on the buffer. On the paint ball bottle I'm using as a buffer the dump valve can be connected on the bottle fitting where the burst disk is. (Have a look at the first photos on this thread at pg1)
Liftoff, can you tell me where I could find full pressure valve and cylinder?
What does the burst disc look like? I can identify most of the parts but not the burst disc.Quote:
Originally Posted by Liftoff
it looks like a small copper circle sheet which fits inside this https://encrypted-tbn2.gstatic.com/i...1OA8jpcfFgo-9C
I know what a burst disc is. I think I have spotted where its mounted now in the pictures on the first page. The base of the ram is propped up against it which is what was confusing me.Quote:
Originally Posted by Rahulvyas
Chris, where did you get your Burst Disc units from? Ebay and Google are only showing units that blow at a minimum of 1800psi, I need around 200-260psi for a low pressure system.
You don't need a burst disk for the low pressure side of the system, you only need a pressure relief valve.
I believe what Chris is suggesting is you can remove the burst disk from the valve (presumably with the centres drilled out to increase flow) and replace it with an ordinary ball valve to act as your dump valve.
Yeah, I reached the same conclusion about 20 minutes ago :-P
Yep thats right, spot on Max. I used the pin valve which came with the tank, drilled the centre away and took the burst disk off. That way there will be no restrictions from buffervto qev.
@Rahul, I don't do any FP systems, better someone with hands on experience to give you an answer
Ok, another thing what is the bore and stroke of the cylinder that you are using in your bot?
63mm bore 75mm stroke
Using Chris' parts list and advice from many of you guys, I've finally got a pneumatic system that works :D Now to design a robot around it...
https://www.youtube.com/watch?v=C2_3...VQ237jdg-dJ2Iw
single acting, cool.
What are the specs of your pneumatic cylinder?
It look like a 40 Bore 75 Stroke. Nothing amazing but it can put a robot out of our arena if attached to the right robot.
It's this one from eBay, 50mm bore 45 mm stroke. Modified like Chris suggests by drilling port holes bigger and had to drill and tap an exhaust port at the bottom to vent it after it's fired.
http://m.ebay.co.uk/itm?itemId=190837115480
Why not use a QEV? (Quick Exhaust Valve)Quote:
Originally Posted by ChrisKazoo
I have a QEV on the inlet and have pondered whether having a QEV on the exhaust would be worthwhile but I would still have to drill and tap a port for it as it's a double acting ram so normally would be vented by putting gas in the top port and exhausting through the bottom port back through the solenoid valve. Without a new port drilled the ram fires and then the gas has nowhere to go to vent.Quote:
Originally Posted by Eventorizon
is QEV necessary? I am using mine without it, no trouble till now
Not necessary no, but very helpful to increase the flowrate and thus the power
okay thanks
Chris, what I would do is to drill some holes at the top end cap, say six 6mm holes - that will eliminate back pressure when you fire the ram ( the air on the top side of the piston is creating a restriction as its being forced out of the top port)
QEV on the exhaust is not such an issue as long as you have strong enough bungees to retract the ram. Have a look at the ram on my build, it has two ports at the bottom, one connected to the QEV/buffer (inlet) and a small one as exhaust.
Something like this, top end drilled (1st photo)
Bottem end two ports (2nd photo)
Mine is a custom ram, but you can modify yours in similar way.
Attachment 4827Attachment 4828
I'm surprised that circlip can take the forces exerted on it- I would have expected it to pop out
Nah it won't....as long as its not operated at fp! Those are the same circlips from the original manufacturer ram. It's not the circlip which could fail but the ram itself if there's not enough recess for the clip to rest on....
Attachment 4829
I had a chat about back pressure at the champs. It seems it is actually better to leave it as is. The air in that side of the cylinder will easily compress and will also prevent the piston slamming into the end of the ram, improving reliability. The actual improvement in terms of force and speed is negligible. Got no data to back this up but I agree with the reliability option and think that is better than a minute increase in speed as you have more than enough power anyway.Quote:
Originally Posted by Liftoff
You got a point there, to counter this some rams incorporate cushions in the endcap...on mine I placed a rubber disc on the piston so the impact will be dampened
http://m.machinedesign.com/pneumatic...atic-cylinders
I have drilled 4mm holes in the top of the ram since I made that video. Where can I get my hands on these rubber cushions Chris?
I doubt you'll find any off the shelf for your ram, there are kits you can buy, but only for branded parts eg festo, parker, smc etc. On mine I used a piece of rubber, punched it into a disk and glued it to the piston. You could do the same, take the circlip off and remove the top cap, put a piece of rubber say 5mm thick and you're good to go.
Is my 8mm pipe fine? Or do I need bigger?
I bought a 50mmx50mm stroke and bore cylinder which didnt have smooth action. :( Can it be fixed?
When I supply co2 into it, the piston doesnt have a sudden action like all the videos I have watched of you guys.
Also, where do I connect the QEV in double acting cylinder? Will that help me in anyway?
Rahu your 8mm pipe should be ok :lol:
What's the port size of the cylinder you bought, and at what pressure are you operating?
I am operating at about 100-110psi
I am not using buffer tank.
Port size I am not sure, its about 6mm I guess
Then you got your answer... not using a buffer means you're relying on the regulator for flow, the regulator orifice is very small and flow is low, you got yourself a lifter not a flipper.
You need a buffer tank to achieve anything close to what you see on videos you've seen.
A better idea would be to enlarge the port orifice on the cylinder and install a QEV on the inlet...all this has been discussed at length on various threads...and I believe on this thread as well...on the first pages there's a schematic
Okay I will see that Thanks,
The schematic was for single acting, so I was a bit confused with the connection of QEV
Your issue is indeed flow. You need enough of a reserve of pressurized gas to be able to get the ram filled quickly. The best way to achieve this is with a buffertank between the regulator and the valve. Rule of thumb, the volume of the buffertank should be at least 3 times the volume of the ram. But even if it is smaller, it all helps.
I am planning to use a co2 catridge 30g-50g ( quite small) , should do the work as we are not storing 50 bar pressure into it directly, its just a small co2 collector, right?