This was my first large-scale modification to the Shocker Sport firing assembly. It consists of a new firing valve with a balanced poppet operation, which uses a three-way normally-closed solenoid to fire. The goal in this project was to convert the marker to the new firing operation, with minimal modifications. However, there were still some permanent mods required to make it work. I converted the stock fill poppet assembly to have the added function of firing the gun, and the stock fire piston is only used to reset the valve. The solenoid inputs air to the rear of the redesigned poppet, which unbalances the assembly and fires the gun. At the same time the poppet shuts off air to the dump chamber (better than the stock poppet too).
The stock fire piston performs the same function except the forward end was vented to the open air and replaced with a spring to reset the valve. I cut the fire piston and its housing down to shape the new parts.
Here's a diagram of the new parts:
Here's some pictures of the modified internals. When assembled, the new fill poppet is attached to the firing piston using a threaded rod. It extends through the dump chamber so air pressure is pushing both components in either direction continuously.
This animation (.wmv) shows the movement of parts to fire. It plays twice, the second time is a little more realistic to the actual timing.
The below video shows the valve dryfiring at 20-bps (via Youtube)
When installed, the finished marker looked like this:
Theory:
The advantage to this is a MUCH more efficient firing valve. In terms of a functional redesign, the dump chamber space can be reduced by half or more, which potentially cuts a good inch and a half off the body length (when combined with a redesigned bolt). A new marker using this type of design could be pretty common-sized in comparison to other markers out there. I would gauge it to be simialr size to a classic Impulse, for instance.
The other advantage is faster cycling. I didn't get the chance to test it out very good with paint and air due to technical problems at the time, but it would have been capped at 15-16 bps due to the closed bolt action, so I wouldn't have been able to test the full cycling speed anyway.
I made this thread about the modification on the Tinkering Tech forum. The modification worked okay on paper however I came to the conclusion that its dynamics would be better used after further modification to the parts. In other words, when i was considering how to better the marker, it came to a point where the marker could no longer use any of the stock parts, no matter what I did to modify them (I would have to fabricate everything from scratch). This defeated the original intentions of the mod so I decided to call it quits and go back to the drawing board. After messing with the new parts and using some different springs and other items, I deduced the offset surface area that the solenoid created wasn't enough to be effective in this valve. It would have worked okay if the entire poppet system's diameter was enlarged, but as I said that would require new parts that I didn't want to make.
Because of this, I retired the conversion and begun working on the SpectreII project.