SpudFiles

Heres my newest creation, is a coax piston valve. Its was designed to be compact but is a little bulky. It works well and can drive a nail dart into wood. Its in the discusion because its incomplete and I have a few issues with it. I want to have a smaller pilot volume, and a cool paint scheme.

Barrel-2 foot half inch
Chamber- 2 foot 1 1/2 inch
Pilot-360 turn ball valve
Fill-Schrader
Piston-Rubber stopper wrapped in tape
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Ouch that elbow is probably the weakest point in your cannon, you might want to not put your hand or any other part of your body on top of that elbow.

I was a little worried about that but many gun have schraders mounted in end caps.

I do see a faint resemblance to my 1 inch Mouse Musket. Nice job. I too think the fill makes the elbow weak. Many valves are installed in endcaps, but few have a long ball valve to provide leverage on the joint.

How are you supporting the breech of the barrel to center it?

Can you guys get the black HDPE Hansen fittings? They will thread all the way in to a PVC fitting. Replace the elbow with brass fittings and a metal ball valve. They're much easier to turn.

I did get the idea after seeing your mouse musket, the barrel support is clear vinyl tubing fill with hot glued covered in tape, MrC Ive never seen those fittings but that doesnt mean I cant get them, What pressure do you think would be safe to operate it at, this pilot setup is only until I come up with a better one, I will most likely switch to a sprinkler valve with a schrader mounted in the back of it.
Thanks for all the feedback,
Clemsonguy1125

I would say you could replace the elbow, and run it at just under the pressure rating of your weakest part.

It will handle a 120 psi compressor/ bike pump pressure just fine.... but i would be slightly concerned about that elbow.

THREADED scharader valve. u can get said valve at most any hardware store. just ask someone for it. they usually come in 1/4'' NPT threads.

Hope that helped

Thanks, right now the gun has a leak where the barrel extends into the chamber, whats the best glue to use, I was thinking JB Weld or plumbers goop. I already tried two layers of epoxy.

Some of my early designs had the same leakage problem where a barrel was shoved into a reducer from the backside.

I did not cover the fix in the showcase thread. It would have made the post too long to show reducer modification and glue procedures.

When making new guns using modified fittings such as barrels through reducers and installing the female adapter inside the chamber, I placed a bead of bathroom caulk next to the PVC glue so as the parts came together, a bead of caulk would form over the joint on the inside.

On the barrel a ring of caulk was placed on the barrel so it sealed against the reducer inside the chamber. On the breech, a ring of caulk was placed inside the chamber so when the reducer was glued in, it would hit the caulk providing the seal. This could not be added after assembly because the inner piston cylinder covered the area so it was not reachable after assembly.

Do not use caulk to glue the PVC together. Only place it to make a seal as the parts come together.

I did this on the Mouse Musket barrel and breech, and on the home made end bells on the chamber of The Dragon. Sorry you didn't learn this before the build. I had two leaky cannons prior to the Mouse Musket. We learn from our mistakes and the mistakes of others.

I'll probably start an advanced PVC tricks thread later to cover bending PVC, getting modified parts sealed, and making the Mouse Musket valve seal.

Is there anyway to fix this without rebuilding, on my tee valves plumbers goop or epoxy worked

Dude just rebuild it the right way, keep the piston though. It should only cost like 10 bucks, but anyway good job.

No, if I were to rebuild it it would be more it's just a small leak

First stick the point of the chamber in a bucket of water, find exactly where the leak is. Prime that area and then cover is with glue a few times. That should work...

I've never had luck doing that but I'll try, if that fails I'll use jb weld

If you're gonna bother with JB Weld, it may be a pain after you use PVC glue, so decided which one you want to use.