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My first spring triggered pilot valve

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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My first spring triggered pilot valve

Unread postAuthor: boyntonstu » Fri Apr 23, 2010 6:58 pm

At the moment I am getting inconsistent chrono readings because of my manual opening of my pilot.

10d nail 184 gr 879 fps 600 psi
192 701
180 658
166 664
182 714

Marble 156 854
162 614
160 766
158 634
164 642

Because of these figures I decided to open the pilot with a spring.

I believe that the 156 gr/854 fps an the 184 gr/879 fps are accurate weight and speed measurements.

The lower readings were probably caused by slower manual valve opening.

I put this together in a few hours today.


Image

I made split hole wood clamps to hold the spring and the sear.

Note the ghetto wire hanger trigger.

It works surprisingly well for my first attempt at a trigger.

I am not going for max speed or efficiency, just reproducibility of opening the BV.

While thinking about the spring/trigger, I came up with a very different idea for a BV only gun.

Imagine opening a 3/4" BV in 0.003 seconds using 40-50 pounds of force.

No need for a piston valve, pilot valve, etc.

I have ordered the critical parts and I am eager to try it.

The gun will be: 3/4" copper barrel, sweat 3/4" BV, 3/4" short chamber, fill valve/quick connect.

The barrel will slip into the BV using the Trom-Boyn style design and swing bolt action.

we are going away tomorrow for about a week.

The parts should be delivered by the time we return.

The secret is what I will be using to power open the valve.

I will keep you guessing until I build it.
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Unread postAuthor: maverik94 » Fri Apr 23, 2010 7:34 pm

Ghetto, but it looks like it gets the job done. I like it!
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Unread postAuthor: Demon » Fri Apr 23, 2010 7:37 pm

May i ask you what sort of quick connect / hose you used to fill the gun?

It is very powerful! 150 gram projectile going at 900 fps ...
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Unread postAuthor: POLAND_SPUD » Fri Apr 23, 2010 7:41 pm

@demon
It is very powerful! 150 gram projectile going at 900 fps ...

it's in grains not grams... don't ask me why 'would anyone grains instead of grams ??' :D

@boyntonstu
I am just messing with you :D
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Unread postAuthor: boyntonstu » Fri Apr 23, 2010 9:33 pm

Demon wrote:May i ask you what sort of quick connect / hose you used to fill the gun?

It is very powerful! 150 gram projectile going at 900 fps ...


Yes, 150 grains.

A .22 bullet weighs about 40 grains and my projectiles are 4 to 5 times as heavy.

A .22 air rifle pellet weighs about 15 grains.

A .38 special about 160 grains.

One of my projectiles weighs the same as a .38.

158 gr (10.2 g) LRN 770 ft/s (230 m/s) 208 ft·lbf (282 J)

See how easy it is to compare and remember projectiles in grains.

I am shooting a nail dart with the speed and energy of a .38! :o

Good question about hose and quick disconnect.

I caught a bargain at Harbor Freight, 4 feet of 4,000 psi hose for $5!

I connected to a 3 foot section using quick disconnects so that when I get my Oxygen bottle fittings, I will be able to fill the bottle, switch hoses, and use the bottle away from the compressors.

The quick connects are 4 ball Commercial 1/4" type that Harbor Freight sells.

I have used them dozens of times at 600 psi without leaks.

The Females go for $3 and the Males for $1.

Be careful when buying quick disconnects.

They all look pretty much the same but you will quickly discover that you cannot fit one type into another.

My suggestion is to count the balls in the Female connector.

(That doesn't sound right).

The more balls, the more grab it has for higher pressure.

I have used 4 and 6 successfully at 600 psi.

(3 ball types are the cheaper auto tire changer style)

My $0.02. :roll:
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Last edited by boyntonstu on Sat Apr 24, 2010 9:25 am, edited 2 times in total.
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Unread postAuthor: Mr.Sandman » Fri Apr 23, 2010 11:17 pm

Cool idea but seems a bit overkill in my opinion. The whole purpose of the piston valve was to be a step up from ball valves and sprinkler valves. Why not just pilot it with a qev piloted by a balla valve? Nonetheless great job 900 fps is a really nice fps and I think it will have a fair amount of power to it.
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Yeah, it's that important.
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Unread postAuthor: boyntonstu » Sat Apr 24, 2010 7:12 am

Mr.Sandman wrote:Cool idea but seems a bit overkill in my opinion. The whole purpose of the piston valve was to be a step up from ball valves and sprinkler valves. Why not just pilot it with a qev piloted by a balla valve? Nonetheless great job 900 fps is a really nice fps and I think it will have a fair amount of power to it.



It is currently pressurized to 600 psi.

I intend to go higher.

A trigger offers consistency and accuracy.

Anything I can make for cheap, I make instead of buying.

Being a cheapskate is a major part of my hobby.

See my $100 elevator video here:

http://www.youtube.com/watch?v=_hom61NxuaE

I feel more satisfied in making a safe elevator for under $100 than buying one for $20,000.

In use 7 years.

(No, my elevator does not meet any Building Code but it does meet mine.)
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Unread postAuthor: boyntonstu » Sat Apr 24, 2010 7:13 am

Dup, server gave an error message.
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Unread postAuthor: deathbyDWV » Sat Apr 24, 2010 7:44 am

Yep, looks ghetto but I bet it gets the job done. Good job...
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Unread postAuthor: boyntonstu » Sat Apr 24, 2010 7:52 am

deathbyDWV wrote:Yep, looks ghetto but I bet it gets the job done. Good job...


Thanks.

I have been asked about the sear:

I just threw it together before going on a trip to try it out.

Not the finished set-up.

Image

As for the sear, it is a 1" x 1" piece of scrap steel cut from a drapery rod L bracket that I found.

It had a hole in it large enough for a # 8 screw.

I cut a notch about 1/8" wide and 1/4" deep such that when the spring pulls the notch it lines up perpendicular to the line formed by the stretched spring and the screw holding the sear to the wood clamp.

The sear lines itself up and it will not move to release until it is rotated around its mounting screw.

Incidentally, I used the same screw for the wood clamp to mount the sear and at the muzzle to attach the spring.

The wood clamp at the muzzle is cut on one side and has just a single screw.

At the rear, 2 screws are needed to hold the 2 part wood clamp.

Next, I drilled a hole off to the side so that when I pulled, the sear would rotate away from the open end of the notch.

Using a fish scale, I measured 7 pounds of spring force and about 2 pounds of trigger pull.

Quite small and effective, I think.
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Unread postAuthor: Hawkeye » Sat Apr 24, 2010 1:28 pm

What is this "pounds" you speak of?
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Unread postAuthor: jackssmirkingrevenge » Sat Apr 24, 2010 1:37 pm

Hawkeye wrote:What is this "pounds" you speak of?


Oh please don't start :shock:

Have you tried without the extension on the ball valve handle? The closer you're pulling to the axis of rotation, the more the valve opens for the same spring movement (though of course the spring needs to be stronger to open at the same rate)
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Unread postAuthor: Mr.Sandman » Sat Apr 24, 2010 1:59 pm

What I have found out which many other people probably have too, when using high pressure piston valves with a ballvalve pilot, If you angle the pilot vent down 90 degrees, The air rushing out of the pilot counteracts the recoil and allows the cannon to stay straighter during firing.
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Unread postAuthor: maverik94 » Sat Apr 24, 2010 2:03 pm

Yep, looks ghetto but I bet it gets the job done.

haha. thats exactly what I said.
Ghetto, but it looks like it gets the job done.

:)
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Unread postAuthor: Brian the brain » Sat Apr 24, 2010 3:49 pm

Why not just pilot it with a qev piloted by a balla valve?

Why not eat meata-balls every day?
:D

The sprung ballvalve is very hot in France.As a main valve that is.
The idea certainly isn't new, but that's not a bad thing...it has proven itself already.
The new trigger allows you to build a stock around the gun..bullpup style..
Yeah baby!

If you angle the pilot vent down 90 degrees, The air rushing out of the pilot counteracts the recoil and allows the cannon to stay straighter during firing.

**Sawed-off by BTB thank you!!
The tromboyn has the same type of exhaust...
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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