I know I haven't been on in a while but i was shopping at my local Lowe's Hardware for a non-spudgun project and while in the pipe isle I saw this sitting nonchalantly in the 4" pipe section. I have no idea what caused some customer to leave it there, possibly they were caught buying such a ...

Well based on your drawing i assumed that you are using one of the conical reducers, not a reducing bushing, and that it would slip over the section of 3/4" pipe that would extend slightly out of the tee. In that case an o-ring would not be necessary, but if it is a bushing that is pushed into the ...

not yet, i'll add them soon along with pics of the internals

btw your user name is hilarious

Okay, so it is finally finished! (Sorry to bring back this thread) I took everything i've read here and technicians advice, some math, etc.. to finally design what i think is my best barrel sealer. It is ridiculously loud with that QEV piloting it, and totally lived up to my performance expectations ...

If by hold it you mean hold pressure, then yes teflon tape works great for that. Just make sure you drill a hole small enough that the threads dig into the pvc and leave grooves, it should take some effort to thread in the first time. I would suggest a threaded schrader valve like this one:

http ...

Floating designs offer a number of advantages, including greatly reduced breakout friction and longer seal life. Floating pneumatic piston seals are suited for applications in which the air pressure does not exceed 200 psi (or in hydraulic designs where a small amount of leakage is permissible ...

Alright two more questions. Will removing material around the center of the piston with a lathe to save weight affect performance? And could two rubber washers attached to the pilot end of the piston serve as a good bumper?(essentially another sealing face setup)

Thank you very much for all that information Technician, i think i'm ready to begin now, i'll post it as soon as i finish

It's going into a tee, i have a cut down reducing bushing as an end cap and pilot that is sealed with an o-ring and extends 3/4" into the tee. How far out can a 2" diameter piston extend past its track before it begins to lose its centering?

Actually i'm still using all the parts you made for me, i just have to build a new piston and make sure i've got all the spacing in order. I took a looong break from building this cannon to work on a project for a national engineering competition, but i'm ready to finish it now :D I really can't ...

It's the top view of a tee, and i threw it together just so people would get the idea.

So if the barrel is on the midline, what should the gap between it and the 2" pipe carrying the piston be?

I haven't been on spudfiles in a while, but i've got a question for everyone. I'm looking to use my experience to build a really nice piston valve, starting with the design and just building it straight through with no compromises or major changes. So i need to figure out the optimum measurements ...

What specs should I use for my valve, it would help a lot in the future.
1" green orbit watermaster, modded with 1/4" blowgun

It went 50 ft. at what pressure?

But is it at least possible with a relatively low pressure (under 50 psi)? I just dont want to have to rebuild it.

Im pretty sure the valve seals around 8-10 psi