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No-tool 4" piston valve

A place to ask general spud cannon related questions.
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Unread postAuthor: LikimysCrotchus5 » Sun Sep 23, 2007 6:42 pm

Does your valve work? Im talking about trey's valve. What if you cant get a rubber fronco coupling. Can you put rubber on the cap and use that?
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Unread postAuthor: Trey33088 » Mon Jul 05, 2010 9:36 am

Wooooowwww its been a long time since I posted.

I did end up building the valve that spring, though in the several years since I know long have any of my notes/paint drawings/autocad models and very few pics of what was built.

However, the gun still exists, packed away either in my stepfathers workshop or riding around in his construction van. I gave it to him after enlisting and leaving home. Last I saw it, the construction crew were using to random stuff from the worksite onto neighboring unoccupied worksites (wood blocks, tyvek wads, small applejuice bottles, whatever was laying around).

As for build notes off the top of my head:

all couplers were the back to back style, not the conical style.

Coaxial, completely contained within 5' of 4" PVC
on the Front was a completely removable barrel assy that used 5 flush mounted hex head screws that went through the 4" pipe into a coupler. I can't remember how i sealed it, but i think i used a 4"-3" coupler, a short piece of 3" pipe with a rubber coupler sqeezed completely around it, then a 3" to 2" coupler on the end that had a 3' or so length of 2" pvc as the barrel. I remember it being a major b*tch to get in and out.

As for the valve:
I used a 2" to 2" rubber coupler over the end of the barrel as a seal.
A 3" endcap butted up against it amazingly snug, sealing it incredibly well.

Behind that i remember using the same trick as the front with a 3" to 1" reducer and a short piece of 3" pipe with a rubber coupler mounted so that about 1/4" stuck passed the pipe towards the front, thereby creating a lip for the piston to slam back against.

That kept it from being PVC on PVC. once again, 5 hex head screws, sunk flush into the 4" pipe, held the assy in place so it too could be removed. Also a b*tch.

On the rear side of the 3" to 1" reducer, was a 1" to 3/4" threaded reducer.

past that, a 3/4 modified sprinkler valve.

A U shape was cut out of the 4" pipe so that the top edge of the sprinkler valve as well as the blowgun could clear. on the bottom of the modded sprinkler valve was a 90degree brass fitting that lead to a tee with a pressure gauge and small ball valve, followed by a male fitting.

Hose hooked up to male fitting, ball valve opened, pressure to 115psi, valve closed,(air into bottom of sprinkler valve, rushing FORWARD, thereby pushing the piston/endcap against the sealing face, the continuing around the gap b/t the piston and 4" pipe, filling the chamber around the barrel).

Pull trigger, air rush out, vaccum behind piston sucks it backwards, opening barrel and Voila!!

MASSIVELY LOUD. Cops showed up twice, reports of gunshots fired. The second time they pulled up just as I shot a 50' plume of water with the cannon pointed straight into the air. Apart from a lecture of noise concerns and a warning of what would happen if I were to ever be caught firing actual projectiles, they let me off with a grin and asked all about how it was built.


Problems I do remember:
The pop off valve was ::I think:: 125 psi, but mounted BEHIND the piston. So it was essentially a trigger in itself, though not quite a 1" port. After building it, realized my mistake, but said screw it and kept it there. So if you over filled to 125 psi, the cannon fired... very bad juju. However, see below for 115-125 psi:

At anything over 115 psi, there was noticeable swelling that sometimes led to a very small trickle of air through the assembly seal behind the piston. Scary prospect, considering if it leaked fast enough to cause a slight vacuum, the piston would crack its seal and be forced back by air rushing through the barrel, essentially becoming its very own pressure release valve. again, Bad juju.

I think total build price came to $200, including several trial and errors resulting in new parts, and once rebuilding the whole valve over from scratch. The sprinkler valve and brass fitting cost the most.

http://viewmorepics.myspace.com/index.c ... ID=6526202

http://viewmorepics.myspace.com/index.c ... ID=6526218

http://viewmorepics.myspace.com/index.c ... ID=6526226

http://viewmorepics.myspace.com/index.c ... ID=6526240

http://viewmorepics.myspace.com/index.c ... ID=6526248

http://viewmorepics.myspace.com/index.c ... ID=6526255

http://viewmorepics.myspace.com/index.c ... ID=6526266

edit:theres are three layers on the front. after writing this, i do remember that it was a 4" pipe, with 3" to 3" perfectly smooth coupler, with another coupler on the inside of it that had a 2" section on the back side for the barrel. How i sealed it, I still am not sure.

If I get to go home anytime soon, I'll fully disassemble it and photograph it all again.

Hope this all makes sense!!
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Unread postAuthor: Trey33088 » Mon Jul 05, 2010 9:36 am

Wooooowwww its been a long time since I posted.

I did end up building the valve that spring, though in the several years since I know long have any of my notes/paint drawings/autocad models and very few pics of what was built.

However, the gun still exists, packed away either in my stepfathers workshop or riding around in his construction van. I gave it to him after enlisting and leaving home. Last I saw it, the construction crew were using to random stuff from the worksite onto neighboring unoccupied worksites (wood blocks, tyvek wads, small applejuice bottles, whatever was laying around).

As for build notes off the top of my head:

all couplers were the back to back style, not the conical style.

Coaxial, completely contained within 5' of 4" PVC
on the Front was a completely removable barrel assy that used 5 flush mounted hex head screws that went through the 4" pipe into a coupler. I can't remember how i sealed it, but i think i used a 4"-3" coupler, a short piece of 3" pipe with a rubber coupler sqeezed completely around it, then a 3" to 2" coupler on the end that had a 3' or so length of 2" pvc as the barrel. I remember it being a major b*tch to get in and out.

As for the valve:
I used a 2" to 2" rubber coupler over the end of the barrel as a seal.
A 3" endcap butted up against it amazingly snug, sealing it incredibly well.

Behind that i remember using the same trick as the front with a 3" to 1" reducer and a short piece of 3" pipe with a rubber coupler mounted so that about 1/4" stuck passed the pipe towards the front, thereby creating a lip for the piston to slam back against.

That kept it from being PVC on PVC. once again, 5 hex head screws, sunk flush into the 4" pipe, held the assy in place so it too could be removed. Also a b*tch.

On the rear side of the 3" to 1" reducer, was a 1" to 3/4" threaded reducer.

past that, a 3/4 modified sprinkler valve.

A U shape was cut out of the 4" pipe so that the top edge of the sprinkler valve as well as the blowgun could clear. on the bottom of the modded sprinkler valve was a 90degree brass fitting that lead to a tee with a pressure gauge and small ball valve, followed by a male fitting.

Hose hooked up to male fitting, ball valve opened, pressure to 115psi, valve closed,(air into bottom of sprinkler valve, rushing FORWARD, thereby pushing the piston/endcap against the sealing face, the continuing around the gap b/t the piston and 4" pipe, filling the chamber around the barrel).

Pull trigger, air rush out, vaccum behind piston sucks it backwards, opening barrel and Voila!!

MASSIVELY LOUD. Cops showed up twice, reports of gunshots fired. The second time they pulled up just as I shot a 50' plume of water with the cannon pointed straight into the air. Apart from a lecture of noise concerns and a warning of what would happen if I were to ever be caught firing actual projectiles, they let me off with a grin and asked all about how it was built.


Problems I do remember:
The pop off valve was ::I think:: 125 psi, but mounted BEHIND the piston. So it was essentially a trigger in itself, though not quite a 1" port. After building it, realized my mistake, but said screw it and kept it there. So if you over filled to 125 psi, the cannon fired... very bad juju. However, see below for 115-125 psi:

At anything over 115 psi, there was noticeable swelling that sometimes led to a very small trickle of air through the assembly seal behind the piston. Scary prospect, considering if it leaked fast enough to cause a slight vacuum, the piston would crack its seal and be forced back by air rushing through the barrel, essentially becoming its very own pressure release valve. again, Bad juju.

I think total build price came to $200, including several trial and errors resulting in new parts, and once rebuilding the whole valve over from scratch. The sprinkler valve and brass fitting cost the most.

http://viewmorepics.myspace.com/index.c ... ID=6526202

http://viewmorepics.myspace.com/index.c ... ID=6526218

http://viewmorepics.myspace.com/index.c ... ID=6526226

http://viewmorepics.myspace.com/index.c ... ID=6526240

http://viewmorepics.myspace.com/index.c ... ID=6526248

http://viewmorepics.myspace.com/index.c ... ID=6526255

http://viewmorepics.myspace.com/index.c ... ID=6526266

edit:theres are three layers on the front. after writing this, i do remember that it was a 4" pipe, with 3" to 3" perfectly smooth coupler, with another coupler on the inside of it that had a 2" section on the back side for the barrel. How i sealed it, I still am not sure.

If I get to go home anytime soon, I'll fully disassemble it and photograph it all again.

Hope this all makes sense!!
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Unread postAuthor: spudtyrrant » Mon Jul 05, 2010 9:46 am

well i guess this counts as something important to add, since you did finish the gun that the post was about, i would start a new topic tho, and instead of myspace, you could use this site to upload your photos, since many people may not have accounts to log into :wink:
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