MCB community project 1- Closed Bolt Spool Valve
Work in Progress R1_5 prints and CAD files now available
It was decided rather resoundingly in the previous thread that the most desired aspects of the first open source community project would be an efficient gun that was completely unique (not a retrofit, not a rehash of an existing commercially available gun). There was a lot of interest in the project, but not a lot of design choices put forward, let alone choices that met the decided on criteria. Based on numerous requests for it (and lack of choices), the first (of hopefully many) open source community project will be based on a closed bolt spool valve, similar to one that I have designed (and built) as an Ion retrofit.
The valve shares some similarities to the unreleased Legion Shocker (prototype closed bolt 03 Shocker) and to the Nova family of guns. The main firing valve is actuated in a manner almost exactly the opposite of those guns though. In this design (anyone want to think of some good names?), the firing plunger is held forward with pressure supplied from the output of a normally open valve, and the chamber is filled through the side with the rear of the firing piston acting as a spooling shutoff mechanism. When the chamber is pressurized, a net rearward force is created on the piston due to the rear seal being of a larger diameter than the seal in the power tube (main firing valve seal). As air of an equal pressure is supplied to the back of the piston to push it forward, the total net force is pushing the piston forward despite chamber pressure biasing it rearwards. A hole or series of holes in the power tube pushes the bolt forward to chamber the ball once chamber pressure has climbed to a point where the forces acting on the bolt bias it forwards, against the constant air pressure supplied to the front of the bolt (this gas never vents). To fire, the gas at the rear of the piston is vented, altering the bias on the piston so that the chamber pressure forces it backwards, both sealing the chamber from the air supply and opening the main firing valve. Once adequate air pressure has been vented, the air at the front of the bolt becomes the biasing driving force, and the bolt retracts allowing the next ball to fall into the breech. As air from the normally open valve is re-applied to the rear of the piston, the cycle starts over.
The only air vented (not for projectile acceleration) in this cycle is the tiny amount used to drive the piston forward. All other air is recycled in the system. That the piston creates a chamber seal on its rearward stroke allows the valve to be operated either mechanically or electronically. I tested my first prototype with a modified Cocker 4-way valve and a pair of pliers to move the shaft.
I have gotten very promising efficiency numbers from early testing with CO2. Leafy will be receiving an Ion conversion kit based on this in the near future (waiting on some back ordered tubing to come in) for beta testing, and will be doing some more testing than I have done thus far. I never got a chance to do an efficiency test after verifying velocities, but I was getting just short of 2,300 shots from a 20 ounce CO2 tank at playable velocities (as in reliably breaking paint and having a comfortable trajectory), so I have rather high hopes.
Here is the image of the gun that I posted in the previous thread.
An animation I did of the first generation prototype Ion conversion kit.
A video of some shooting of the prototype.
I have models of the design in the body shown with the rotating breech and variations that fit into a more traditional body style. I'm not sure which variation would be less expensive, or if price will even be the driving factor in our decision. The rotating breech, while having an entirely additional component, does not require boring a hole ~6 inches deep, which may be prohibitively difficult for some people to do. That's a decision that may be influenced rather strongly by the community machinists who will be working on the project. Other aspects of the design, such as the seemingly worthless change of inner diameter in the rear piece is to accommodate the other valve systems that I have designed to fit into the body trying to reuse as many of the components as possible to keep price down for future projects that use the body.
For the things we need:
Let the project begin!!
Rat's Nest (lots of paintball patents within)
So far so good, just needs a frame (which I don't know too much about)
I would suggest combining the cyan piece with the navy blue piece but I see why you didn't. It might make it time consuming to combine them.
Perhaps combining the brown(?) and navy blue pieces together and having a de-volumizing spacer hold the cyan piece in place? that would reduce waste stock and add volume adjustibility to the design.
I would like one of these, I'll see what parts I am capable of making.
Neat idea, especially based on an Ion, which are dirt cheap and readily available.... but I'm not sure I see the point, aside from a tinkering point of view. Closed bolt isn't really any better than open bolt, and I can see some issues down the road considering it's a custom gun - can you get or make parts for them available, especially considering the demise of SP? And what makes it better than a Shocker Sport?
I'm just playing the devil's advocate here - don't shoot the messenger. :)
I can mechanically design a frame, but I also have less appreciation for proper frame ergonomics than many people here do, so I'm hoping someone that maybe has actually produced a frame from one of their designs can help out in that arena. I doubt what I have is too bad considering it is sort of a combination of an Intelliframe (CAD from AGD) and an Angel LCD frame that I made a model of from one that I have, but I still lack the first hand experience.
I like volume adjustability, but if the brown piece and navy piece were combined requiring the spacer to hold the cyan piece in place, it actually requires more material than having them separate and threaded together. Having something to adjust the volume is definitely a good idea though, possibly spacers like in an Epiphany as that would be effective and cheap?
Jordan, the version we'll be making here is a completely new gun that is just based on a closed bolt Ion retrofit that I've done, it won't use any SP parts. The CAD files and prints will be publicly available allowing anybody to make or have new parts made.
You're right though, closed bolt does not have any inherent advantages to open bolt. The point is to have a unique, efficient gun that is designed and built by the community. Compared to a Shocker Sport though - that gets what, around 800 shots from a tank? This should get around a case, is significantly smaller, can be switched between electronic and mechanical with no real modifications,
Okay, I see what you mean, perhaps leave the two separate but get rid of the little lip in the navy piece and have the devolumizing insert still hold the cyan piece in place. This is so you can use thinner wall tubes for fabrication of the navy piece which means less waste.
Oh, have you asked Andy(ydna) for help with a grip frame? He seems to know what he is doing. He designed an ergonomic for the shocker nxt I think.
Shocker Sports are definitely inefficient - no doubt about that - and the opportunity to have a current closed-bolt marker would be great in my books. The versatility of the design, if you can swap between electronic and mechanical, would be a huge selling point, I think. Just look at the Phenom.
So is it just actuated by a 4 way/solenoid setup?
because obviosuly if the grips only have to hold a 4/way, the possibilities are endless..
even with a solenoid setup, the boards are endless...
actually it only needs a 3 way.
3-way, normally open. The boards are only endless if you are willing to run without eyes as it needs different eye logic than most open bolt boards support.
I'd definitely buy one (price depending)
But it does need a name I think we should use M.C.B. as the acronym for the name.
Maybe not this but something like
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