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I discovered a problem.

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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I discovered a problem.

Unread postAuthor: boyntonstu » Wed Dec 16, 2009 5:18 pm

I built a second gun with the same 3/4 > 1/2 fitting reducer as the seal surface.

After a week of trying to get it to seal, I discovered a misalignment that prevented the flat washer from completely sealing.

Probable solution, add a tiny length of 1/2 tubing that extends about 1/8 beyond the 3/4 > 1/2 fitting reducer.

I am anxious to get the breech loader going. "Trom-Boyn" design.

I received "Just For Copper' glue and I will try it on my next gun.

I will attempt to design a 3" 10d nail dart that will take 550 psi without blowing out.

My goal is 900 fps.



Here it is:

The new piston and the new seat worked the very first time.

I have the recipe if anyone would care to try to make one.

In this new gun, the barrel fits directly into the valve T.

It goes in a little over 0.6" and therefore I can load a dart with just a 3/4" bolt throw.

I can use the chamber end cap as a slide stop.
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Unread postAuthor: Brian the brain » Mon Dec 21, 2009 3:40 pm

Nicely made!!
Does it need a spring to keep the barrel in place when shooting?
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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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Unread postAuthor: boyntonstu » Mon Dec 21, 2009 11:01 pm

Brian the brain wrote:Nicely made!!
Does it need a spring to keep the barrel in place when shooting?


I have shot it at 300 psi and the 0.6" fitting insertion depth plus the dual T's have enough friction to hold the barrel in place.

Surprising.

What it means is that you can do away with a bolt if you design your gun along these lines.


I have been shooting 110 grains at 500+ fps.

A 3" 10d nail goes through a thick telephone book and the 5/8" plywood it is attached to.

Very powerful!
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Unread postAuthor: Crna Legija » Tue Dec 22, 2009 12:44 am

but i think if you get a tight fit or jam in the barrel it could blow out the barrel
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Unread postAuthor: Brian the brain » Tue Dec 22, 2009 5:10 am

Wich could be used as a safety.Better have the barrel blow out than explode...

Maybe you could add a rubber band to pull it in.

Either way I love this design!
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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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Unread postAuthor: boyntonstu » Tue Dec 22, 2009 8:00 am

Another possibility is to 'play' the Trom-Boyn as you shoot, placing back force on the barrel.

So far unnecessary.

Darts are easily loaded and it shoots very well.

Onr additional benefit to the slide load is that you can look down the barrel to check for fouling.

My sequence is:

Slide open the barrel to the side.

Inspect the barrel.

Load a dart.

Pressurize the chamber.

Insert the barrel.

Shoot.

A bonus of the slip T design is that barrel can be removed and the 'plumbing supplies' can be carried in 2 pieces.


Gun? What gun?
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