Balanced Spool Valve

[Forum Admin]

O rings give me a terrible time, hard to get a perfect seal using common tools. I've figured out a way to make a parachute seal out of a faucet washer and so far, they work remarkably well. I used it on the pilot side of my new piston for my t valve. Air goes in easily, but when it tries to go the opposite way, the edge of the seal flares out, making a perfect seal. On a 250 psi fill, a 10 gauge wad flew over 700 fps. I'll try to get some pics and possibly a video up later. Been having too much fun shooting.

Ultimately, I'm trying to make a balanced spool valve (QDV) using these as the seal instead of the troublesome o rings. This type of valve will give me a full bore valve seat, should yield greater power (.785 vs .625 diameter). It also offers mechanical actuation and no pilot air losses.

[BoyntonStu]

Sounds great!

I gotta see it to see how you designed it.

[josephlys]

Man you are by far the most creative person I've come across.

[Forum Admin]

I'll try to post pics tomorrow afternoon when i get off work.

[Forum Admin]

Still working too much. I'm suppossed to get off at noon tomorrow so hopefully i can share this trick

[Forum Admin]

Charging the camera batteries right now. Chronograph results are very nice - 536 fps with a 140 grain plastic slug. 89 fpe out of a 250 psi fill aint too bad. Need to get another compressor for higher pressure, but 250 is good enough for now. Stay tuned for pics and video. 

[Forum Admin]

Finally got the kids to be quiet long enough to make a video  Here it is: http://www.youtube.com/watch?v=v36yZlFUQHU

[BoyntonStu]

Great video!

I posted a branding iron idea.

Next, I thought of using hole saws to cut the grooves.

My final concept is the mount the cutting edge in a vice clamped to the drill press table and feed the washer to the tooth.

Move the tooth and cut the next groove.

Or, make several teeth and cut them all at the same time.

Use several sharpened nails poking though a board.  Done!

Great work!

[Forum Admin]

Good ideas, cutting in one process would be much easier and less prone for error. I'll see what I can come up with. On another note, it is time to test this in a QDV. If it works, my original porting design will work beautifully as there are no o rings to blow off at high pressure. http://www.airgununiverse.net/community/index.php/topic,301.0.html I'm going to increase the porting on my new valve to full .785", this should yield a decent increase (around 15%) in power over my t piston valve with .625" porting. The barrel will form part of the valve body, leaving no dead space between the ammo and the valve. This, of course, will mean muzzleloading, or moving the valve spool rearwards and loading through the trigger slot using the spool as a bolt... 

[BoyntonStu]

Wouldn't this design allow breech loading?

Copper Air Rifle Components and Assembly
http://www.youtube.com/watch?v=qku0i8LqZws

The parachute seal would require a mechanical stop to prevent the piston from traveling through the barrel when pressurizing the chamber.

I would place the stop at the rear of the piston at atmospheric pressure.

[Forum Admin]

I'm currently breech loading on my T valve, similar to what you are doing in that video. The new valve I am currently constructing will require a different type of breech loading than the one you demonstrate as the barrel itself is part of the valve body. No mechanical stop is necessary because the valve is perfectly pressure balanced on both sides. It is loosely based on this valve: http://www.youtube.com/watch?v=No3nI07mlQo. I'm simply adapting it to a more firearm like mechanism and getting rid of the floating o rings. This allows me to use one large port instead of a couple smaller ones. It will also not be coaxial, it will feed from a air chamber directly below the one valve port. By using a T fitting at the bottom of the valve, I can attach two air chambers, each with a full port ball valve to give two shots before needing a recharge. This will give me a follow up shot, not something I normally use, but you never know. Both valves could be open, giving one super powerful shot as well. I'll get some build pictures and post them as I'm constructing the valve. My idea of breech loading will be to use the piston as a bolt for reloading, we'll see how that works. If the clearances aren't there, I'll just muzzleload to keep dead space to a bare minimum.

[Forum Admin]

Here's some pictures to illustrate the new valve I'm building. The first is the parts of the valve body:

The second is the valve body assembled:

I still have to grind out the trigger port and get some allthread to build the piston.

[Forum Admin]

Here's another pic to show how the piston relates to the valve:

Note that this is not the finished piston. The gun is filled from the chamber, as there is no pilot. Because the pressure is balanced on either side of the piston, you only have to apply enough force to overcome friction to get the valve opened. Air pressure does the rest. How that is done will be shown at a later time.
Here is a picture demonstrating the piston seals:

These are the ones the video in this thread show how to make.

[BoyntonStu]

Magnetic trigger?

[Forum Admin]

A strong magnet might do the trick  It'd certainly be the easiest method and reasonably fast. If not, I'll probably use a small extension spring to open it. I've got a design that will work nicely and have a good safety built in.