valve impact consistencies among rams/hammers

[QUINCYMASSGUY]

OK folks, here is a new one for you. It actually stems from a discussion Jack and Coke opened up in PBTalk but I wanted to expand on the science side of things and Deep Blue is definitely the place to do that. Basically it revolves around the different methods for firing a paintball. Three categories exist:

1.) Cockers and Spyders utilize a spring to hold back the bolt until the trigger is pulled. So it is the spring pushing the hammer and the bolt which is connected to it forward until it hits the poppet valve. Issues that could affect consistency: 1.) Variation in the push the spring provides (shot to shot, not between springs) 2.) Friction due to lack of lubing, especially if running at low cycling pressures.

2.) The Mag works in a somewhat similar fashion, with air pressure instead of spring pressure being stored up behind the hammer/bolt (in the mags case, the bolt serves both functions) and when the sear drops a metered amount of air pushes against a spring. If the spring doesn't allow it to stay open enough, dropoff happens. Issues that could affect consistency: 1.) Variation in the resistance the spring provides. If it pushes alot one time, and less the next, velocity will be affected if the 2nd shot prevents all the air from being released in time. Friction can also have a similar effect.

3.) The Viking does not utilize a spring at all to give the hammer and bolt momentum, it utilizes air to supply energy and unlike the others, applies it at the time of movement instead of storing it behind a sear beforehand. Issues that could affect consistency: FSDO is a direct result of the hammer not getting the momentum it needs to fire right, so friction is a huge one. Not charging quickly enough is another. Frankly, I could see this being even more inconsistent than a spring.

So does anyone have any solid data regarding the consistencies of these methods? Thoughts to add? Ways to improve on each?

[SLICEnDICE]

I am seeing two different test to come up with the data you are looking for. One would be mounting a sensor to measure the position of the hammer when it has travled all the way foward on each cycle. This could tell you how well the gun repeats from shot to shot, in turn telling you how far the valve opens durning every cycle and what in what time frame. Both of which could be used to measure how consistant the gun could be.
Another possible test could use a force sensor to see how hard the hammer or bolt is comming foward on every cycle. This would be a good one for the air driven rams. Then you could compare the difference between well lubed, dirty, and no lube. I also bring up the second test because what if the guns with the hammer design are designed to bottom out on the valve every time? Thus possibly elimating the chance of the valve not fully opening. Look at the angel hammer design, it has a cut out in it. It looks like that is the way it was designed, to bottom out. This last part is just a idea I have thought about in the past, I have no data to back it up.

[AzrealDarkmoonZ]

Perhaps the best method would be to get those nifty practice balls, ensure that they are reasonable the same. Shoot a few thousand shots through the chrono for each marker, record the results and pop them in Excel to get your findings.

Some problems: Quality, you would have to find a high quality blowback, I haven't seen any expensive one's ala the Viper to know the quality, the best I could hope for that I have seen is a PMI Piranha. Optimum setup for each marker, ie some experimentation beforehand with each marker to achieve optimum setup.

Az

[QUINCYMASSGUY]

idea

Excellent idea, wish I could test it, I don't have a.) Vballs, but that's easily remedied B.) a reliable chrono... well don't have one at all actually or C.) a place to fire where I won't tick off a roommate or invoke a call from the cops (city life).

What I'd probably do is cock the hammer, make sure the appropriate pressure has filled the exhaust chamber, then fire. Taking my time should prevent the issues that arise with spyders (slow recharge, etc.) due to crappy craftmanship.

[athomas]

Well, I'll wade in.

1) poppet type:

Any gun that requires a sping activated hammer to hit a poppet type valve is subject issues with momentum. In order to open the poppet it becomes a (bolt kinetic energy) vs (poppet potential energy) situation. The bolt kinetic energy is a result of spring pressure and the mass of the bolt/hammer. A stiffer spring accelerates the bolt/hammer more quickly and results in higher bolt velocity. The faster an object moves, the more energy it contains. The heavier an object is, the more energy it contains at a given velocity, so a heavier bolt/hammer will also have more energy. It is a catch 22 situation though. A heavier bolt will require a heavier spring to accelerate it. When the poppet releases air and either blows back the bolt/hammer (blowback design) or a ram is used to recock, it also requires more energy to reset the heavier spring and/or heavier bolt. The trade/off can be consistency. A heavier spring and heavier bolt will overcome minor sticking problems that any associated o-rings may have. A lighter spring and/or hammer can be used as well but the pressure containe by the valve must also be reduced (low pressure operation). This can work if done correctly, but the movement of the hammer can be more hampered by outside interference such as sticking o-rings or debris. Any sticking will be a greater percent of the force when using a low pressure design than when using a high presure design, and therefore will result in greater fluctuations. It is more critical for low pressure designs to have good internals.

2)mags:

All the air used in the bolt action actually contributes to the acceleration of the ball. This makes the mag a very efficient design. It could be much better than it is. The inherent flaw is the extra air that escapes after the ball has left the barrel. This is due to the slow escape of air after the ball has moved away from the bolt. Initially, the burst of air is high due the mag having a higher pressure chamber. Then it tapers off and the remaining air weeps out the front of the bolt which acts more like a restrictor. The good part of this design is the consistency. The air in the preset chamber size is always the same pressure as long as the regulator is funtioning. There is no real friction issues with the bolt. It operates at a fairly high pressure so o-rings and other frictional forces are nearly nonexistent. The level 10 has some stickinon and lower pressure but the second stage of the bolt acceleration more than makes up for any slow starting of the bolt.

3)Ram operated guns have their own pros and cons. The theory behind the design can't be beat. The bolt goes forward and opens a huge air passage from the supply to the ball. This gives very good bolt efficiency and the forward time is precisely controlled by an electronic timer. The fault of this design lies in the low pressure operation of the ram. The low pressure is required to protect the small electronic solenoids and to regulate the forward force at which the bolt contacts the ball. The problem with low pressure is that sticking o-rings and debris can alter the actual forward time of the entire bolt system. If an o-ring sticks, it could cause a few less microseconds of time to allow air to flow. Since the air passage is so open, the forward time of the bolt is very critical. Any loss of that time due to sticking anywhere can have detrimental effects which will be seen as dropoff. This usually manifests itself more when a gun sits for a while and the o-rings bond to the surfaces as many manufacturers have found out having FSDO issues. A good o-ring size and good lubrication can help.

[lamby]

athomas:

There is one thing that needs to be addressed in your other wise great comment about poppet valves..

If you look at a cocker, there is no tie between the bolt/cocking side of the marker and fireing the marker. The poppet valve is hit by a hammer that is held back by a sear pin and has spring energy stored behind it. AFTER the marker fires there is an adjustable amount of delay that happens before the recocking proceedure starts. The back block moves back moving the bolt and hammer back. The hammer then is caught by the sear pin. The ram pressure is reversed and the bolt is closed (hammer remains cocked)

So the LPR system has 0 effect on consistancy, unless you do not have enough flow from your main reg/ tank to support the LPR and HP sides efficently in high speed shooting (which is something I have never seen in a cocker.

There is nothing that can affect the consistancy of a cocker other than the: main reg, valve, valve spring, cup seal, hammer, hammer spring, and sear catch. out of all these, the only things that I see could be a problem is the main reg, and the two springs. Unless you shoot faster than your main air system can recharge after the low pressure side is done pushing the bolt forward, that would cause your main pressure to be lower than the previous shot.

[athomas]

Lamby, you are correct. I was just stating a more generic type of operation.