Whisper101

You can use a homemade pump to fill the tnak. It just takes a very very long time. An alternative would be to buy a $20 compressor that runs off the jack in your car...

Maybe I have the OPV and the main tank set to different pressures. You are saying that I should not have bleeding if the main tabnk is pumped to 60 PSI and the OPV is set to 60 PSI as well?

Those were hypothetical numbers, not hard facts. The main tank is always kept at 60 PSI, and yes, I realize that the main tank really does need a way to limit pressure. WOuld a regulator, where I can pump up and then manually let air out do the trick?

You bet I did

Do you find it at all difficult to fire the tank at 60PSI? Do you think a hindered trigger pull is hurting your ranges?

Sorry? What's hindered about the trigger pull? It's extremely easy to fire at 60 PSI and even a bit higher.

@ roboman: it was actually lying on the side of the tubing before I took the picture. It's not usually all that srucnched up and kinky.

@ricochet:7/8" long, 1/4" dia., 1/32" wire dia. It's a pretty strong spring.

@Zorn: Wouldn't that make the air transfer from the main tnak to the pVAT alot slower? Maybe I'm not following...

@Kane: I think curly explained it pretty well. In fact, he's the one that brought the placement matter to my attention. I have the pSI guage there, so for me, I just don't go over 60 PSI. The OPV leaks when the button on ricochet's valve is depressed because that opens the line for air from the main tank to flow into the PVAT. Lets say there is 60 pSI of compressed air in the main tank. That tank is very large compared to the PVAT, so when you open the ricochet valve, all the air in the main tank tries to force itself into the PVAT. 60 PSI in the big tank however translates to a much higher psi in the much smaller PVAT. lets say the main tank is trying to force in what translates to 110 psi in the PVAT, but is only 60 PSI in the main tank, while the OPV is set at about 50 PSI. There is your bleed. The trick is just to hold the button down for a very short period of time and let the excess bleed out. It does so pretty quickly.

It takes between 3 and 5 pumps to fill the PVAT, depending on what pressure you want. i don't quite understand the second part. You dont have to pump after each shot. The homemade pump is only for when you've exhausted your supply of air in the main tank. Then you switch OFF the main tank selection and use the homemade pump to pressurize the PVAT directly.

OPRV Update

I added an OPRV just outside of the PVAT. It follows Venom’s OPRV writeup, but I used a nylon tube instead of PEX. The hole is about 5/32” I think. It could be larger to increase air flow out of the tank. The OPRV is fully adjustable, and can range from about a 55-85 PSI break point. It follows, then, that I can get between 2 and 5 pumps in before it kicks in. The one bad part about the OPRV is that when using the semi-auto function, pushing the button on the ricochet valve directly connects the main tank to the PVAT, which causes the OPRV to leak air from the main tank. Essentially, holding the ricochet valve’s button down for too long causes you to lose air from the main tank. To prevent this you simply have to push the button quickly, whereas without the OPRV you could hold the button down for as long as you wanted and the same amount of air would always find its way into the PVAT. Bottom line: The OPRV works great for the pump mechanism, but not quite so smoothly for the semi-auto function. Still, the gun is safer now.
PICS:




The OPRV is held onto the gun’s main body with Velcro so it can be quickly and easily removed for adjustments.

@RedRanger: I suppose you could put a check valve in the pump head. The shaft would have to be hollow to allow the air to be moved through the check valve and the pump tube would have to accomodate the OD of the checkvalve. It seems I have more work to do on the pump! I have been thinking of ways to do away wiht the Tee in favor of a coupler...The o-ring is 13/16" OD X 5/8" ID.

@venom: A venPVAT could also be used. I chose a PVAT becuase I was already building one anyway. The original also holds a bit more air, and built right, they shouldn't need to be taken apart. I can see how being able to is a valuable asset though. I also really like that quick connect fitting for the tubing input. There's no reason NOT to use a venPVAT, like i said i just had a PVAT in the works.
There's no need to eliminate the check valves. The pump works smoothly and has a logical air movement pattern. it's simpler than stock pumps in a way. It's cheap, simple and efficient, as it costs next to nothing, requires very little cutting and sanding, and fills a PVAT wiht 3-5 pumps depending on what pressure you are going for.
Yes, it does need an OPRV. That's in the works. Ideas and suggestions are welcome.

I don't feel you come off as self promoting; you're right: this si in no way perfect, and hopefully I'll get around to doing some more thinking, work, and updating on it.

Thanks for the comments everyone.