|SHOCKER SFT DESIGN & THEORY|
Put simply, this is how the marker operates. When the bolt moves forward, air passages within will become open (the ring of porting seen at the front of the bolt), which allows air to expand down the barrel and fire the ball. When the bolt is retracted backward, said air passages become closed again, and the marker will wait until fired again.
This type of design is generally referred to as a spool valve firing mechanism. This generally describes a one-piece moving part (the bolt) which also functions as the valve for the marker. This is significantly less complicated than the traditional stacked-tube design that many previous markers utilize. These involve a hammer, percussive valve, bolt, and a number of connections and housings between them. The stacked hammer design was invented in the late 80's / early 90's and is perhaps somewhat outdated in comparison (in my opinion).
The advantages to this type of design generally include decreased recoil, higher air efficiency, decreased energy used per shot, and decreased volume for the shots (meaning they're more quiet than other markers). Similar designs can be found in several other markers, including the Matrix and DM series markers, PGI Mayhem, FEP Quest, and some others. In the future we may come to see additional designs like this, since it is a very simplistic method of firing a marker with many possibilities for modification.
Firing Assembly Synopsis:
Now for some technical information and further explanation of the firing cycle. You may wish to use the first animation listed below for reference. While the solenoid rests idle, the front portion of the bolt sleeve is pressurized, which holds the bolt in the rear/open position. The fire chamber is filled with pressurized air, ready to be released. When the solenoid energizes, the sections of the bolt sleeve that are pressurized switch; the air holding the bolt open is vented and the rear section is simultaneously pressurized (see the page how solenoids work for details). With this action, the bolt is driven forward. Once it reaches the end of its forward stroke, the ring of porting at the front will cross over the tip of the bolt guide and all the air pressure within the fire chamber will be released to the inside of the bolt and out the front, firing the paintball in the chamber.
The marker's bolt will be actuated upon the venting/pressurizing caused by the solenoid. The most important factor here is the use of the dwell time, which is the time the solenoid remains energized, which translates to how long the bolt stays forward. The dwell setting must be set to allow the bolt to cycle forward and dump the air to fire the ball. This is my definition of dwell and what it is used for.
Seen above is the stock bolt assembly. Click here for a slower version. Please note that Shocker NXT markers come with the upgraded SP HE bolt as stock (animated below).
Keep in mind that dwell isn't only the amount of time the bolt remains forward, since the majority of the dwell time is actually taken up by the bolt moving to the forward position. In some markers the bolt speed is an important factor in its firing cycle, that can be adjusted in some cases. For instance, if the dwell time is 10-ms, the first 8-ms may be taken up by the bolt moving forward. This leaves another 2-ms to fire the ball. The bolt then takes another 8+ ms to retract to the open position (these numbers I've derived from my own experimentation).
This is an important factor when it comes to the type of solenoid used in the marker (of which there are two), and is discussed in the solenoid comparison section. Please refer to the Related Links.
Please note that the base model Shocker has two holes in the side of the body (within the Shocker symbol), this allows the sides of the fire chamber to be externally visible. This is relevant information for the aftermarket bolts, since some of them use o-rings to seal these holes. Some model bodies have different porting which are incompatible with some bolts. Read the information on the aftermarket bolts for details on this.
The flared section of the bolt sleeve (toward the back) isn't just for looks; it's actual purpose is to act as a small pressure reservoir to help resupply the solenoid. When the marker fires, the fire chamber tends to suck away pressure from other parts of the assembly, so the pressure held in the bolt sleeve is provided to help guard against any pressure-related dropoff problems that may occur (bolt stick, dropoff, etc). This reservior is accessed through the solenoid inserts, which are lightly explained later on, with more detailed explaniations on their own page (please refer to the Related Links section).
The design of the bolt allows it to freely move forward with an approximate force of 17 pounds. Additionally, the stationary portions of the firing assembly will absorb smaller amounts of force, which in practice serve to decrease the total moving force of the bolt by additional, albeit smaller, amounts. This special function of the Shocker makes it quite impossible for the application of an additional regulator (LPR) to drop the pneumatics pressure any further. This is because, when the pressure actuating the bolt is reduced, the force driving the bolt will see more reduction and prevent the marker from fully-cycling. It is for this reason that the Shocker doesn't readily accept an LPR. It is true that some developers have released their own LPR kits, however as said, the practical benefit of these is low.
The other benefit to this type of spool design is the energy efficient design that it utilizes. When examining the amount of energy that is wasted per shot, it is found that the placement of the dump chamber as close as possible to the breech of the marker is optimal for energy consumption, which would mean the mechanism to move the bolt can then be placed further away (bolt sleeve in this case). This makes sense from a pneumatics standpoint, and is the exact type of design used in the Shocker. Other markers, such as the Matrix, use a design where the moving mechanism is closest to the breech, and the dump chamber is located behind it. In this type of design the air firing the ball must be shunted through the middle of the moving mechanism before it reaches the ball, and energy is lost during this activity. In the Shocker, however, the path of airflow is much shorter and more pronounced, allowing for a noticeably less energy used per shot. This is, in my opinion, what makes a Shocker one of the premier spool valve operating platforms.
This is viewed during experimentation by observing the amount of time it takes pressure to release. In a Shocker this time is generally 1-2 milliseconds, whereas is 2-4 in some other markers.
The components of the bolt which accept pressurized air to operate receive said air from porting in the walls of the bolt chamber. These ports lead to special air-directing tubes called solenoid inserts which are used to direct air within the inside of the marker. Refer to the solenoid inserts page in the related links section for technical details.
In this picture of the Shocker body, three of the four total ports in the bottom of the chamber wall are visible (the fourth port is in the very front, which is shadowed out).
Aftermarket Bolt Assemblies:
· SP HE bolt, aka high-efficiency bolt, aka Turbocharger bolt: The HE bolt from Smart Parts uses a special sealed fire chamber design to gain its efficiency benefits over the stock bolt. This is an upgrade for the older SFT models, or a stock feature on the current NXT. The HE bolt uses an added o-ring located on the surface of the bolt, inside the fire chamber, to seal off the input ports on the chamber when the bolt is in the forward/firing position. This serves to prevent additional amounts of pressure from entering the chamber while the bolt is firing. The stock bolt in comparison, dumps pressure out the bolt face continuously as long as it stays forward. Even with properly-set dwell timing, there will always be a benefit to sealing off the air supply from the bolt face during the shot. The added benefit of this design is that the placement of the bolt's sealing o-ring allows it to act like a spring when in the closed position. Pressure on the other side of the o-ring pushes against it and helps to blow the bolt into the open position when it recocks. This helps to conserve energy use and optimize the firing cycle.
Pictured above is the SP HE bolt. Click here for a slower animation. This is also an animation of the NDZ v3 bolt, which functions using the same operation.
· NDZ v3 bolt: This uses the same design as the SP HE. The only functional difference is that the NDZ fire chamber is designed to hold more volume, thus allowing the NDZ bolt to use a single row of ports instead of the elongated ones that the HE bolts use. The NDZ bolt functions at a lower pressure but this isn't necessarily a performance increase, rather a different way to accomplish the same task (it's a misconception that lower pressure will give you higher efficiency).
Previous versions of the NDZ kit functioned similar to the stock bolt except with added fire chamber volume. The version-3 kit uses the same HE technology patented by SP in the HE bolt. Specifically, the Stinger v1 kit was essentially a replicated stock bolt with some modified features (angled porting, added air volume for the fire chamber) and the Stinger v2 was the same as the v1 except for the high-volume fire chamber that the v3 version utilizes.
· Evolve bolt: The Evolve bolt was the first aftermarket assembly to be released for the Shocker. It has since been redesigned to a more reliable version, but the original version functioned relatively the same. This bolt also uses a design which seals off input during firing, however the Evolve version works a little differently than the HE bolt. Instead of placing the added seal on the outside of the bolt (like the HE) the Evolve bolt places the added seal inside the fire chamber itself. The bolt is then notched to allow air around the seal when in the rear position. This notching reflls the fire chamber while it's open and seals it off when forward/closed. The benefit to this is a perfect seal on the bolt, however the design is difficult to machine correctly, and has some technical problems getting all parts to evenly seal at once. This design is patented by Evolve.
Pictured is the Evolve bolt. Click here for a slower animation.
· Evovle ULP: This is the same as the SP HE / NDZ v3 bolts, with modified features such as porting and o-ring placement.
· Freeflow bolt: The design of the freeflow bolt is a modified stock assembly. It uses a large, moving ring section to attempt blocking off the air input to the fire chamber, but it doesn't seal it completely. The design isn't as reliable as the other bolts, and isn't as beneficial when totally functional. Previous versions of the Freeflow bolts used different porting patterns but the basic design never changed. The Freeflow bolt was discontinued when Freeflow Technologies went out of business, discontinuing any and all support for the parts.