This is a custom-built Ion that I assembled and converted to fire without a solenoid. It's purely actuated by a mechanical trigger valve, and functions similar to the original design for the gun now known as the Matrix. In short, the gun uses a modified bolt to shut off the air inlet to the fire chamber, and a standard Autococker four-way valve is used to fire the bolt. If you want details, read on ahead.
Internals:
The marker uses a vertical regulator just like a regular Ion. Air tubing inside the frame is also similar to a regular Ion, however there are noticable differences due to the lack of solenoid. Below is a picture of the internal hoses, and the top of the trigger valve is visible...
I used a four-way valve from an Autococker, mounted in the frame behind the trigger. Air is carried to the valve using some good ole fashioned 1/8" low pressure hose. This is similar to a stock Ion, but it's where the similarities end. The "idle" output of the four-way leads to the middle air fitting (replaced with a Palmers QEV). The other output of the four-way valve is blocked off, technically making it a three-way valve instead of a four-way; this setup is designed to emulate the same function of the stock solenoid, which is a three-way normally-open valve.
What happens is this. While the marker is idle, air pushes and holds the bolt back. Then, when the trigger is pulled, this air is vented through the four-way/QEV, which allows the bolt to close and fire the ball. The difference between this and a regular Ion is that the bolt remains forward as long as the trigger is compressed (it would be as if your regular Ion had a dwell time of half a second, or however long you hold the trigger). Once the trigger is released, the front of the bolt is repressurized and it opens back up, which allows the fire chamber to refill and marker be fired again.
The four-way valve is spring-fitted on the opposite end to reset it when the trigger is released (this also provides backpressure on the trigger itself).
Air pressure is delivered to the rear of the marker through the 5/32" (4-mm) hose fitting installed in the gauge position. The hose wraps around the outside of the marker and screws into the donut at the rear. Normally I would drill the other side of the frame for another gauge, but I never got around to doing that.
Since the fire chamber will be completely emptied during firing (since it stays open for a very long time in comparison to "regular" dwell time) the velocity is controlled purely by the input pressure. I've found this to be about 150-psi to yield approx 280-fps. The marker is a little less consistent over the chronograph, due to the firing pressure being the only determining factor in the velocity. However, the inconsistencies aren't visually noticeable more than any other gun. I only noticed it when testing the setup over the chronograph.
Original Modifications:
I performed the mechion mod in June 2005. Since that time I've re-done the mod no less than three times, swapping out various parts and such. For the sake of modding parts, I'll quickly show the different versions here.
Version-1: This was my original mod from 2005. I used a low-pressure regulator attached to the bottomline ASA, so no vertical reg was used (I used a reg body from an Ion reg to serve as a foregrip). LP air was delivered from the bottomline reg to the swivel donut using macroline, as pictured. The stock air fitting hole in the bottom of the donut was then used to deliver air to the four-way valve. You can also see I was using a high-rise feedneck from a Shocker Sport, because I liked to use a Revvi loader on top.
Version-2: Different bottomline regulator, and also retapped the swivel donut (it broke).
Version-3: I rearranged the air hoses; the marker now used a standard vertical reg with a standard HP tank. The macroline visible on the outside of the marker delivered LP air from the reg to the swivel donut, where it again supplied the four-way from inside the frame. The frame's stock air fitting hole (where the "front banjo" attaches) was blocked off.
Version-4 (current version): I again rearranged the hoses. I replaced the donut with a new one and tapped it for a 4-mm hose fitting on top. I then blocked off the donut's stock air fitting hole (where the "rear banjo" attaches) and used the frame's stock air fitting hole (front banjo) to deliver air to the four-way, like a regular Ion. This is more or less the current version of the "mechion" and is actually more similar to a regular Ion in terms of design.
