Balanced Spool Valve Design

[boyntonstu]

[youtube][/youtube]

Simple, effective, cool.

Would a cross and 2 short chambers be better for flow than a T?

[Technician1002]

It looks like a cross between a toolie valve and a QDV. Shorten the gap in the middle and make a short one piece spool and it will end up as a QDV.

Are you doing anything to prevent lifting the front o ring as it comes out of the barrel into the T. An early design of mine with a gap like that instead of ports in a pipe had a bad habit of shooting the front o ring as it lifted out of the groove when fired.

I have not worked on it for quite a while. I am building a 1/2 inch coaxial copper QDV with a 1 inch chamber.

A cross would flow better than a T. Even better flow is with a coaxial chamber.

Click to see full size.

[boyntonstu]

It looks like a cross between a toolie valve and a QDV. Shorten the gap in the middle and make a short one piece spool and it will end up as a QDV.

Are you doing anything to prevent lifting the front o ring as it comes out of the barrel into the T. An early design of mine with a gap like that instead of ports in a pipe had a bad habit of shooting the front o ring as it lifted out of the groove when fired.

I have not worked on it for quite a while. I am building a 1/2 inch coaxial copper QDV with a 1 inch chamber.

A cross would flow better than a T. Even better flow is with a coaxial chamber.

Click to see full size.

It's THEAIRGUNMAN's design and not mine.

There is no groove:

http://www.airgununiverse.net/community ... 434.0.html

[Technician1002]

Nice design on the air seal. From your video it seems to work well. That would solve the problem with o rings blowing out of the groove.

[boyntonstu]

[youtube][/youtube]

[youtube][/youtube]

Test shot with spool valve.

His piston will become a bolt!

Very creative and instructive.

[POLAND_SPUD]

His piston will become a bolt!

yeah, I like that
Though it is a bit tricky as the piston/bolt stroke has to be long enough

I think I know how to build the trigger:
use a steel wire/cable (essentially just bicycle cable brakes) to open the valve... when the valve opens the piston should be forced backward by the pressure...
put a spring behind the piston that so that it can reset it

[nature-boy]

use a steel wire/cable (essentially just bicycle cable brakes) to open the valve...
...put a spring behind the piston that so that it can reset it

That's exactly what I tried last week, only thing I used strong fishing line instead of cable and a O-ringed, short and light piston out of alu pipe epoxied together. I planned on just attaching the fishing line to a simple trigger, but the problem was, that it was kind of hard to pull under pressure (like it seems in your/airgunmans videos boyntonstu), without pressure it was really easy to move the piston. I think this was because the O-rings deformed under pressure...
But the big fail of the gun, (I'm still disappointed) was the fact that I build a restriction out of a short piece of a nail, which I glued trough the pipe in front of the piston, the prevent it from going too far, when it is reseted.
Finally the restriction nail broke off, and now I have a small hole in front of the ports, what makes the gun useless. still thinking about how I can fix it because it seemed so promising and I had really nice ports...

[POLAND_SPUD]

still thinking about how I can fix it because it seemed so promising and I had really nice ports

hmmm MOAR epoxy ?

though don't forget that while epoxy is quite useful... but if something breaks, you're fu....
lol trust me I've been there

That's one of the reason why I prefer threaded fittings - you can dissemble, assemble again, service and/or modify such a gun in just a couple of minutes

that it was kind of hard to pull under pressure

you can use that effect to build a sort of compression fitting that keeps the barrel in place

you just need a T with male threads, some orings/rubber washers that fit tightly around the barrel and some fittings with female ports... the seals go between male threads of the T and the fittings.. as you tighten them the seals expand and keep the barrel locked in place

Just make sure it holds well

[Technician1002]

I have noticed that things do tighten up some as o rings hold pressure. With care, making the walls of the grooves vertical instead of on a slant helps as well as a good polish of the surfaces the rings have to slide on.

This good polish is what enables my grandson to be able to fire the Marshmallow Cannon at 100 PSI.

This tightening of the o rings is one of the reasons I am working on a 2.5 inch cannon before building the 3 or 4 inch versions. I'm going to be doing some design experiments so when I build the larger versions, they can be fired at high pressure.

Some people have some difficulty firing my 2 inch at 100 PSI due to the tightening of the o rings.

It can be seen in one of my launch videos where I tell the guy to pull hard. His first pull did not fire it.