autococker valve/other valve: time it needs to stay open to fire/changes

[Redkey]

pardon the intrusion

QEV = Quick Exhaust Valve. Little check valve like things that mount to the ports on the ram. When the air flow is to the ram is reversed, the exhaust air vents out the QEV instead of going down the hose to the three way to exhaust. The quicker the pressure opposing the new travel direction of the ram is exhausted the faster the ram can move.

[QUINCYMASSGUY]

QEVs

Thanks, I know how rams work but was always under the impression the 3-way could only do the venting needed, I didn't even know those existed. If you have a link regarding how they work exactly and who makes them I would appreciate that.

Now here is a somewhat related question: For cycling pressure, how low is too low? What is the point where inconsistency and threat of parts sticking to orings enough due to the lack of force being exerted on them are issues, like what is the lowest anyone has gotten without it being unable to acheive a respectable ROF? This can be any marker including Trixes and Vikings and assumed it is lubed every day.

In regards to the initial question, it looks like the answers are 3ms for time it has to be open and 3/16" for distance. This seems solid, but if anyone else has thoughts into this, fire away.

Electrician, your valve inside a ram idea sounds interesting, coud you elaborate? I was working on something that sounds similar however I ran into a catch where because I had the ram working in synch with the bolt, it made the autococker open bolt. So I probably goofed.

[AzrealDarkmoonZ]

Just a question, where are you getting the valve opening of 3/16" number?

Az

[QUINCYMASSGUY]

electrician

From the electricians posts regarding how he tested it. Why, do you think it may be another number?

I guess my followup is how to shorten that or incorporate the ram into the valve and even not require the ram to fire seperately but be part of the cocking process. Probably can't be or that would basically make it a Timmy.

[the electrician]

I don't know, but just make sure you don't re-invent the rainmaker! LOL just kiddin'

well the valve opening being 3/16" is just a measurement based on how far the hammer can open a stock valve. from the point where the hammer strikes the valve stem, to where it would "bottom out" and hit the retaining nut that holds the valve in. it's that simple. then I thought, what if the stem travels farther back after it's been hit? so then I made the test set-up to find out if there was an optimum "valve open distance". and basically anywhere between 1/4" and 3/16" seems to be good. any more doesn't seem to help velocity, even if you add more dwell. why? because the ball is already gone is my guess.

now I imagine that the AKA valve might be different. I don't know.

now the whole ball takin' 3 msecs to be up to speed and gone is a guess based on the fact that from other tests, reaction time tests, I've done on the MAC 44 series valves, show that it takes about 2 msec of solenoid energize time for air to start flowing through the the valve and into the ram.(at an input of 9volts and psi input of 50) now if I can shoot the ball at 280 fps when I energize the solenoid valve for 5 msec, but 6 msec doesn't add any velocity, and 4 msec takes some away, then 5-2=3. I'm thinkin' the ball is already gone and is not affected by the extra air I'm trying to throw at it by adding time. so it's just a guess.
also seems like I've read discussions in here somewhere that coincided with that.

if you would like to know anything about QEVs, let me know. I've been using them on cockers for about 4 years now. I started using them back when I made the ol' electro-cocker. now that mass produced e-frames are available for purchase everybody wants more cocking speed, so now they listen to me when I say "you should use these"

I'm still working on the springless, hammerless gun design.

[QUINCYMASSGUY]

autococker

Sounds good, I wish some real tests were available giving us the specific stats of each part but those are rare. I guess my hopes are finding a way to have a mechanical autococker that is efficient, fast, and has a short and light trigger pull. So I am playing around with stuff now and things like the valve.

[AzrealDarkmoonZ]

How are you measuring the MS? And it is a distinct possibility that it could be less than 3/16" The hammer may not be pushing the valve to the full extent...

Az

[the electrician]

the MS? you mean time? msecs? using a morlock board. it's a homemade electro-cocker.

if I use the ram to open the valve, I set it at a specific stroke. anything below the 3/16" shows velocity drop. you know maybe a hair less is okay but basically at 200 psi input on the stock valve it likes to opened 3/16" approx.

so yeah the regular cocker set-up, the hammer maybe doing all kinds of things. it could be opening the valve less, more, getting bounce, wasting air.

I'm sure AKA has done some "real tests". I just want to build another gun. so I do tsts to figure out what I am going to need to do to get what I want out of the gun.

Quincy, you make it sound like a great shooting cocker is unattainable. the right springs with the stock valve will give you decent effeciency, and also be a good start towards lowering the cocking psi. a short light pull can be had with the various hinge frames on the market, along with a good 4-way valve. the same things that make an electro-cocker shoot fast(for the most part) are what will make a mechanical cocker shoot fast. electro frames only bring out the full potential of whats already there. it starts with a good mechanical cocker.

[QUINCYMASSGUY]

ram

Electrician, my bad on how I phrased the "real test" thing. I just mean I am sure companies like AKA did what they did with solid physics tests and principles in mind which resulted in their successful product and it would be great to have their info and trial-and-error results as a reference. And cockers are good, I just mean it would be great seeing if the pull can get down close to that of an electronic marker and the best way would be to reduce the

If my idea even closely resembles a rainmaker it will be instantly dropped, I assure you.

So the MAXIMUM a WGP valve can open is 3/16, and according to The Electrician it needs all that to fire properly. It would be interesting to find out the minimum an AKA valve needs to be opened, if they are designed for Low Pressure and more open, they might work fine at 1.5/16 to 2/16. I don't know, just theorizing. I think my interest is not so much in it being shorter but being lighter during that 3/16 with still only using 1/16 momentum. The one thought I still have is a thinner valve head as it seems to be the source of so much resistance. Or maybe not.

I think finding a way to incorporate a ram into the valve has potential. That way a spring is not needed to reset the valve, it goes back when the ram resets. It's a little less, but some.

So here's my next question: how fast do you think the bolt moves forward? Like, how fast is one half-cycle?

[athomas]

Efficiency is directly affected by the restrictions in the path of air to the ball. The ability of a gun to pinch rather than chop is directly related to the energy contained in the forward momentum/push of the bolt.

The reason high pressure guns are usually more efficient is because the restrictions have less of an effect. The trick is to make a smooth open path for the air to travel. In a poppet type valve, that would mean a larger diameter opening that opens farther. This creates a larger opening that delivers more air in less time which in turn creates more acceleration behind the ball. The quicker a ball gets up to speed, the less unusable air is left in the barrel after the ball is fired, thus giving more efficiency. The trick here is to have the hammer open the valve, deliver the air quickly, and then close quickly.

The open time and open distance of the valve in a cocker is directly related to the energy contained in the hammer and the return spring/pressure behind the valve.



The bolt force causing chopping can also be altered an is best kept low to prevent chopping. Two things can be done. Slow down a heavy bolt, or lighten a fast bolt. The energy is the same for both. A light, fast bolt is prefered to keep up the rate of fire of the gun.

Now, I'm no cocker expert, so my knowledge here is not completely up to date. Therefore, I am not going to go into any details on how to accomplish anthing here. Hopefully some of my info is good though..:)

[QUINCYMASSGUY]

contribute

AThomas, always glad to have another great mind in on this. You illustrate some really good points all of which I agree. It points out exactly why AGD can use such a small valve gap (as seen on AGDs on/off) to recharge their valve. For a marker running at 400psi, this is adequate, but for 200psi this would not work well at all due to flow restrictions. However, I would not rule out some of the physics principles behind AGD's on/off.

For example, AGDs on/off goes vertical and slices through the air flow while the cocker valve is horizontal and has to push directly against it. This could have an effect on how easy it is to open the valve. A larger version of the AGD on/off would allow proper flow for LP and with the lower pressure, shouldn't require as much as a cocker valve to open. Or maybe not, but it's an idea. And it could allow the trigger to activate the valve, reducing the pressure needed to operate the bolt as it would not have to open the bolt AND reset the ram. Just a thought. Could this work? Knowing the exact diameters for effective 160, 200, 250, 300, 350, and 400 psi operation (3ms recharge rate I guess) would be great. So would a million bucks but thats not happening either. And I have an insane theoretical idea involving this but keeping this one top secret until I evaluate it further and decide if it can be done and if it's really as good as it seems. If it works as I think it could, it would make Tom Kaye drool. Key word is theoretically. Superbolt 1 was theoretically great, but so was the Level 10, so who knows.

So here is a question you might be really helpful with AThomas: what is the EXACT pressure exerted DIRECTLY on the on/off pin of a ULT'd (or normal) Mag (meaning the exact force being applied vertically on the pin, not trigger force) in order for it to open wide enough and fast enough to shoot at 300fps and still cycle at 20-30 times a second? This would let us determine which valve setup is more effective to lower the hammer pressure needed, the Mag's or the Cockers.

[the electrician]

well how big is the on/off pin? .116" I beleive.
so use the area of a piston formula: P*R*R or pie times the radius squared.then multiply it times the psi applied to it. that's how you figure the force factor of a cylinder(ram). so that would be .01056*400 psi=4.225 in/lbs of force. that's assuming it is getting 400 psi, but I think you get the idea. no that's the pin on a standard mag on/off. is that what you were looking for?

another example:
I use an ANS mini ram on my cocker, it is a 5/16"(.3125") bore so it's force factor ends up being .0767 to extend and .064 on the retraction stroke. so at 40 psi input, it generates 3.06 lbs on the extension and 2.56 lbs on the retraction.

[QUINCYMASSGUY]

equation

OK, I understand the equation (and thank you, that's the one I needed) but where did the different force factors for the different stroke directions come from?

I'll try and figure out the ULT one soon, I am very curious about it. And it also opens up another thought I had:

What if a Mag had two ULT valves open and both chambers (before and after the on/off) were doubled, would this allow the Mag to operate at Low Pressure (half what it is now)? Just theoretically, two ult on/offs, side to side, with a double-wide sear opening both at the same time and rate so the airflow is doubled and the area for it to store to shoot (the power tube or whatever) is double, would this theoretically work and, with the pressure being halved, cut the pressure exerted on one ULT to half so the pair would still have the same weight as a single ULT valve? Not having a double-wide flow rate may be why previous LP ideas failed for Mags. Not thinking oring leaks, cost of it, or anything, just the valve function. Would it work or what am I missing?

Definitely appreciate the equation, any others you know that apply to this stuff, definitely post them, I can use them. I am good with math but weak on pneumatics, mechanical ratios, and such.

[hitech]

When calculating the force on a RT or ULT On/Off pin remember to subtract the force exerted from the underside of the pin head. The underside of the pin is pressurized from the dump chamber. Its surface area is the same as the top minus the area of the pin leg's* cross sectional area (Pie X smaller pin radius squared) . Hope that makes sense.

* - Smaller diameter long part of the pin.

P.S. Remember, when the dump chamber opens the pressure on the underside of the on/off pin changes until the on/off opens.

[QUINCYMASSGUY]

under

Hitech, I get what you are taking about but I'm puzzled. Until the on/off is sealed (right before firing) the bottom is not exposed to the pressure yet so it is not counteracting it by pushing on the underside. I am not sure if there is any point where the pressure is applying to the bottom, but I could be wrong. Feel free to elaborate.