This is the more conceptualized section of the website, devoted to how and why markers are designed the way they are, and what they'd be if they were this instead of this.
It wouldn't be a stretch to describe this section of the website as the most advanced technical discussion I've scribed to date. It very literally doesn't get any more in-depth than this.
This page is organized in such a way that the most broad characteristics are first, and the more specialized ones are last. Things naturally end up this way when you start to think about which parts of a marker are common to all, and which can only be applied to some. I've put considerable thought into this process and believe this to be the most effective lineage. As you read you will understand why I chose the order that I did. For instance, all markers using one specific feature such as a bolt end up using specific other features due to how the parts interact wth each other. I try to express this as best I could.
1. Basic Firing Assembly:
For practical purposes there are two sections to a paintball marker, the frame the body (which traditionally houses the firing assembly). The frame is used to hold the marker, and is needed because of the gun-like action, however the frame isn't involved with the actual firing of the marker and how the internals are laid out. yes, the frame does hold the trigger mechanism in most guns, but the firing of the gun is carried out by other means. This page is about the firing assemble and not so much about the "support features" like frames and triggers and foregrips. From a design standpoint, the functional parts of the gun come first, and the support features second.
With that said, these are the items that are needed in a functional firing assembly.
1. Air chamber (aka dump chamber). This is a section of the marker where pressurized air is stored, usually about one cubic inch in volume in LP guns, and half inch or less with HP guns. When the marker fires, pressure stored in the air chamber is used to propel the ball waiting in the marker's breech.
Please note that the air chamber is the one true design factor that ALL paintball markers have without exception. It's imply a hollow spot in the gun that is filled with air source. The goal of a paintball marker is to shoot a paintball; the air chamber is what does this. Everything else is built around the air chamber's function.
2. Bolt or other chambering mechanism. All markers have a chamber or breech to hold paint about to be fired (if they didn't then we'd have to load the balls through the barrel like a musket). Located next to the breech is a way to load another ball after the current one is fired; this is generally the feedneck or other feeding attachment. When the marker fires, there will be a burst of pressure behind the ball which causes it to accellerate out the barrel. Because of this, there has to be a way to seal off the unloaded paintballs from the air burst (the ones not in the breech...which is all of them). Traditionally this is done using the bolt, a moving part with the same diameter as the breech, which seals off the paint waiting to be loaded. There are a few other methods as well, described later.
3. Valve that can be actuated. This is the most broad "characteristic" and I'm really using the terms loosely here. This describes the other functional parts of the firing assembly, which are used to control the release of the air chamber. The valve has two states: an idle/resting state and a firing state. During the idle state the air chamber is sealed off from the breech. During the firing state, the valve allows the release of pressure in the air chamber and the ball is fired. The valve is then de-actuated and the release of air is switched off.
2. Basic Valve Action:
All markers use a valve of some sort to seal off the air chamber from firing. In paintball markers, there are two types of valve designs: the poppet valve and the spool valve. The exact definitions of "poppet" and "spool" will vary depending on who you ask (this is occasionally debated in the technical online forums) however for the purposes of this website I am describing the most widley accepted definitions that the vast majority of developers seem to use when describing their parts.
- Poppet valve: These use multiple moving parts due to how they work, so they tend to be a little more complicated in terms of number of parts and how they interact. The original mechanical paintball markers were poppet based, and any marker with a hammer is essentially poppet based. These markers work by sealing off the air chamber with a poppet, which is a part of the assembly that seals the pressure but doesn't interact with any other components. In other words the poppet doesn't close the marker's breech. Due to this definition, all marker designs that use a poppet have to use something else to close the breech, either a bolt or some other device.
- Spool valve: These are more basic in design, however they weren't widley introduced until relatively recently (year 2000+). Spool valves involve a one-piece moving firing assembly that performs the same action of releasing pressure while at the same time sealing the breech.
We(me) call them "spool" valves because they carry out all the functions of the firing assembly in one fell swoop, whereas "poppet" valves only perform one function (seal off the air chamber) then they use a separate device to close the breech. For all intensive purposes, poppet = air chamber seal design only. This is the part that is debated in the tech forums.
Now, after I wrote this I went back and tried to add some other details, rearranging the way the paragraph was laid out, etc etc until I finally decided to just put this little footnote piece down here. I added "in paintball markers" to the first sentence of this section for a reason. The difference in the poppet/spool valve boils down to whether or not the valve is linked to the bolt, or whether or not they move as one. If we we're talking about some other pneumatic device that didn't have a breech, then there wouldn't be the need for a bolt...and thus there would only be one action (a poppet action, according to the above description) and there'd be no such thing as the spool valve. So, the difference between spool and poppet, as described above, only applies to paintguns. Get what I mean?
Let me put it this way. All markers use a seal to seal off the air chamber. This is known as a poppet in the "poppet" designs and is an entirely separate component of the assemly. However, in spool designs, the part that seals off the air chamber is just a lolely o-ring that is located on the moving part of the assembly. The o-ring isn't a component in itself, it's just a sealing membrane. The spool markers don't have a dedicated air chamber sealing component. And therein lies the difference between them. Even though they both have something that seals off the air chamber, the designs end up being wildly different depending on whether it's a spool or poppet.
I keep racking my brain trying to think of ways that poppet valves are related to spool valves, but I can't come up with it, because they're simply too different from one-another. They start out with the same goals, but the single act of linking the valve with the bolt ends up making such a large change in how they're laid out. I think the bold sentence up there describes the relationship I'm trying to convey as best as I could.
3. Valve Actuation Method:
This is another of the basic principals used in the firing of a gun. As hinted to above, the valve has two "states", a resting state and a firing state. The valve will be in the resting state most of the time, but when you go to fire the gun you have to enact some sort of change to make it switch to the firing state.
Sounds simple, doesn't it? Well, it's not. This is where all the markers out there start to branch off into their own little cliques and groups. This is the design feature of the gun that will separate it from everything else out there, and boy oh boy are there a lot of them. There are many more possible designs that are combinations of things already available and have yet to be produced. There's even more further that are still yet to be invented. Although, within the confines of the traditional poppet or bolt assembly, it is true that we've pretty much plucked the design tree clean of layout ideas. (anything new from this point will most likely be more different, than not different).
Forget about spool valves for about 20 years of paintball history. The most basic pneumatic valves are poppet-based. Remeber that I said there wouldn't be such a thing as a spool valve if we didn't have to close the breech...? Well this is why I put so much stress on that, because I'm starting with the most basic valve designs, and won't even think about spoolers for a very long time.
Put basically, a marker fires its valve by applying additional force to one side of the mechanism, to physically push it out of the idle state. This creates a force differential which is the term used to describe the act of one force being larger than another. In other words, two forces act on one central object to create a differentiation, making the object move in one way (this is practical definition for the purposes here). The end result of the differential is called the derivative, and is what results in the firing of the valve.
The most basic way to accomplish this is to arrange a valve poppet to seal off the air chamber, and supply a derivative force to the other side of the poppet, used to actuate it when the time to fire arrives. You may initially think to yourself that I am describing a system where pressure is applied to the other side to fire the valve. However, that would be taking it a step ahead. For the purposes of theory and keeping in line with the design tree, take note that both these statements are true:
- You can create a functional valve action by adding force to the poppet, which overcomes the air chamber differential force, and fires the valve.
- You can create a functional valve action by removing force from the poppet, which allows the air chamber differential force to overcome it, firing the valve.
I call the first action "increasing force poppet" and the second "decreasing force poppet". There really isn't an official name to describe these, but my names make sense (at least I think so). The names describe the derivative firing state of the valve: the increasing force poppets apply force to fire the valve, whereas the decreasing force poppets supply force continuously then remove it only when firing.
That basic valve design is okay but now we have to take some other things into consideration. Namely, the other "action" of the firing assembly, which is to seal off the breech. In the first paintball markers, they were designed to be non-automatic, more commonly known as pump-action. Why? I dunno. I beleive it was an arbitrary decision based on how the guns were supposed to be used. They were designed for marketing trees and other ojects (such as cattle, although I don't konw how often they were used for that) so there wasn't a need for a semiauto gun. In other words, the activity of firing one round then taking a second to reload the next was adequate for the use. There wasn't a need to mark 6-tps (trees per second).
This is where I'm going to step out of the paintball marker timeline for a while, but you'll understand why.