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[DeTrevni]

No, not a pneumatic assist, but just pneumatic! Okay, so I've got an Osiris kit, and I'm trying to justify building an Osiris or a Sniper, and then I thought, "Why not both?" We all know how easy it is to switch from a mech (or even electro) 'cocker to a Sniper, but because of the Osiris's internal ram, it wouldn't be that simple.

For those that don't know, the Osiris is a 'cocker conversion (or an entire marker) offered by PGI that replaces a 'cocker's stock hammer/spring/cocking rod system with an internal pneumatic FASOR ram and dual LPR's. The bottom LPR controls the internal ram and the top controls the 2-way ram that actuates the back block. Because of this, you can get the marker to cycle at insane speeds, and drop the cycling pressure so low you'll only pinch. I think there's a vid of an Osiris doing 15 BPS with no eyes and a gravity hopper. Obviously, it was blanking a few shots, but it didn't chop!

Anyway, here was my idea. When running the Osiris, whoopty-doo. There ya go. But when you want to run pump, you'd have to replace the old springs and hammers, which really wouldn't be all that convenient. So what I thought of doing, was using a FABCO MSV-2 3-way valve behind the trigger to actuate the internal ram, and a pump kit to cycle the block. This way, you'd get an insanely light trigger pull (the MSV is what's used in the walkable pneumag kits), and an almost sinfully light pump stroke. Picture an MQ Sniper, minus the batteries! A mech frame of your choice could be modded to mount the MSV, and an LPR could easily be attached. I'm sure it could easily be hidden within the frame as well. The only problem with switching form the Osiris kit to the pneumatic pump kit would be swapping the internal ram's microline, as pulling it off a barb usually weakens that end to where it can't be used reliably again. However, I found some fittings that are very similar to macroline fittings, just in microline sizes, and you can switch microlines without weakening the line itself!

The only problem I can really see would be "dwell." As long as the MSV is held open (i.e. trigger is depressed), the ram will be pressed into the valve, spiking velocities and such. Any ideas on how to remedy this?

[HP_Lovecraft]

Originally Posted by DeTrevni

The only problem I can really see would be "dwell." As long as the MSV is held open (i.e. trigger is depressed), the ram will be pressed into the valve, spiking velocities and such. Any ideas on how to remedy this?

I had a similar idea last year for converting a cocker to fully pneumatic by simply swapping the hoses, removing the sear, and fixing the block to the rod. So that it "throws" the hammer to the poppet.

I had originally thought that it would solve the above problem of controlling dwell since the poppet itself would push back the hammer, and thus close the valve naturally.

However, when I tried it out, I quickly ran into a problem. It worked when I pulled the trigger normally, but if I pulled the trigger slowely, it didn't work at all. Clearly the speed in which I pulled the trigger effected how fast the ram moved, and thus how hard the hammer hit the valve.

My solution, which I have not tried yet, is to have the 3-way actuate a PILOT VALVE, instead of the ram directly. Then the pilot valve will actuate the ram is a much more consistent manor.

nick

[DeTrevni]

Hm. Is there a way to simplify that? I see where you are going, but it seems a bit excessive. Also, it may need a different setup with the internal FASOR ram as opposed to the standard 2-way ram.

What about an exhaust port in the ram, just before the complete cycle? That way, there won't be air pressure holding the valve open after the striker hits the valve. I'm just kinda hesitant to drill into an Osiris ram...

Edit: Clever idea with the pneucocker.

[y0da900]

You could try modifying an off the shelf pneumatic pulse valve to control dwell. It's described in this patent:

http://haveblue.org/tech/patents/US006343599.pdf

There are several things in the description of how it is laid out in the patent that I think could be done better, but the idea is great.

[Contour]

While reading this I think I figured out a way for a mechanical mq. Basically run a hose down to a msv-2 or what ever 3/4 way that you want. Basically just vent the air with the 3way instead of the solenoid. Only problem with this is the dwell, but you may be able to cause some deflection in the trigger so the msv'2 can reset. Or maybe the air could be used to for the trigger to return, although I'm not sure how you would rig that one up.

[applesauce]

not to jack the thread but where do u get the osiris kit?

[DeTrevni]

You look VERY hard, as they have been discontinued for a few years now. They won't be cheap.

[HP_Lovecraft]

Other option is for a AT85 style rig to control dwell. I considered this as a solution to my Pneucocker project, but the complexity kept me from going any further

To make your Osiris control dwell like the AT85, you would do this:

First, rig up the MSV-2 to control ONLY the bolt-ram. Pulling the trigger will close the bolt (if doing it openbolt style). Releasing will open the bolt.

The bolt-ram is also connected to its own MSV-3 valve. When the bolt closes, it actuates the valve, which sends pressure to the HAMMER-ram, which strikes the poppet.

At this point, the HAMMER-ram will retrip the MSV-2 to reset itself putting it back in the "cocked" position.

This would work, though might be more complicated then its worth. Hard to tell if this would be harder to do then my piloted MSV-2 variation above.

Granted, the easiest solution we are ignoring. At least for a cocker, you can just run the bolt "open bolt", have have the sear actuated by an autotrigger. But that solution would not work for you, since you have both a pneumatic bolt AND pneumatic hammer.