LP pneumatics - ram exhaust hole size

[Danjr1]

I'm working through the thought process of how a LP pneumatic flipper could work if the return was based upon a bungee cord (i.e. like a FP system). The bit im stuck on is the position and size of the hole that would need to be drilled into the bottom of the ram. As its low pressure, I'm thinking 0.5mm on the opposite side to the port so the gas has further to travel before exiting the ram. Obviously, I only have one shot at drilling this hole so any advice would be great. FYI, the ram is 50mm stroke and 80mm bore.

Cheers

Dan

[maddox10]

If you want pure speed, the exhaust hole should as big as possible.

If you want adjustable speed, the exhaust hole should be adjustable in surface/diameter.

[Danjr1]

Maybe start at 0.5mm on opposite side to the port then enlarge if required? I need to make sure that get all the power out of the ram due to the short stroke.

[Max]

I think there is some confusion going on here, I think Mario is talking about the exhaust hole on the non-powered side (ie the side where you don't put in the compressed gas). Dan is talking about a vent hole in the pressurised side.
For an LP system you don't need a vent hole as LP 3/2 valves are so common and cheap that you can just use one of those to vent the gas.

[Danjr1]

But flow is awful through common 3/2 valves (I'm planning to use a larger 2/2 NC valve) and I'm trying to keep the whole thing as simple/ compact as possible. It would literally be a FP set-up using LP components @ 10 bar.

[maddox10]

http://www.teamonslaught.fsnet.co.uk/pneumatics.htm

[Gabe01]

Assuming your competent with pnuematics then I wouldn't bother with low pressure. Keep it simple and go high.

[Gabe01]

Do yourself a favour, if Flow is yours, build her a new chassis and bodywork, she's tired

[Danjr1]

This would be my first venture into pneumatics and going FP would require me to outsource manufacture of the system which isn't something I'm keen on as I want to learn more about how to put these things together.

Ermmmm........ I dont own flow lol.

[Gabe01]

So pop up a list of parts you have, then we can go through them before you drill any holes

[Gabe01]

And flow isn't awful through 3/2 valves when she works, she works well. Jarvis just needs to learn a bit more about pnematics

[Danjr1]

In regards to Flow, I wouldn't know enough about it to comment and a little confused as to why it was mentioned in the first place?! lol

Anyway, the only part I have at the moment is a SMC CDQ2B80-40D double acting cylinder (80mm bore, 40mm stoke). Bought it from ebay a couple of years ago for £20. Could have sworn it was 50mm stroke but its nice, compact and should give a decent kick.

The valve would be a simple 12v valve along these lines (http://www.aliexpress.com/item/Free-...986222776.html). Cheap and heavy but should do the job with a decent straight-through flow.

Two 12oz paintball tanks with one as the buffer and a paintball regulator. Assembly would involve attaching the valve directly to the cylinder using a simple "T" shape plumbing arrangement to attach the tanks. Then a small ball valve as a dump and PRV. Return would be via a bungee and the aforementioned drilled hole.

This is purely theoretical at the moment but my aim is a for cheap, simple, compact and reliable flipper that has plenty of shots.

[RogueTwoRobots]

But flow is awful through common 3/2 valves

Time to sort out the confusion. Gabe, I believe he was referring to the flowrate of the gas rather than Flow the robot

[Gabe01]

Haha! Now I've got you!

[Gabe01]

"But flow is awful through common 3/2 valves (I'm planning to use a larger 2/2 NC valve) "

he forgot the word 'the" .....But the flow