Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
The valve threads into the volume chamber at base. The air is discharged omni directionally above and routed with a manifold that slips over valve and is trapped in place by volume chamber. This is not an exhaust piston, but instead uses the surface area of the piston to shift the valve using the volume pressure.
The whole thing runs off the pressure chamber and the trigger lets some air from the chamber out to force open an oversized poppet valve which lets air from the chamber out through the multiple vents.
I sketched up an exhaustless valve a few months back which used a different system that had the poppet moving out of the chamber to vent instead of into. All too fiddly for me to actually make though
The whole valve you've got there looks pretty good.
How does the air input get sealed off when firing? I can only see a two port trigger valve there.
Coodude26 wrote:
People who laugh really hard at stuff that pisses you off/you getting hurt, who then say "I'm sorry, I can't stop" but you know they easily could.
Mr.C: That's not as easy as you think. It's like me kicking you in the balls and telling you to stop crying.
Spanerman. You are correct, the pressure used to operate the valve is tapped from the main volume chamber. I am using a secondary air source for demonstration purposes. Once the trigger is released (or volume of air depleted) the piston retracts. If there is air in the piston still, it is released through a hole in the stem of the trigger that is shown in the first picture.
Yes, I use CNC machines. I did build one out of PVC in a night once. Unfortunately I destroyed it scrounging parts from the assembly since it was glued together. I like this style of valve since it will not misfire if a leak occurs in the launcher as I have had happen with exhaust pistons. Using some form of rubber stopper would be another way of sealing the valve instead of the o-ring. You just need to make sure that the surface area of the rear piston is greater than the surface on the front stopper or o-ring piston for the piston to shift and open the valve.
It is a three ported trigger valve. The third port is the hole in the pushbutton stem. You can see it in the first picture of my first post. The volume chamber supply is not cut off, it is tapped. The piston shifts once the pressures are equal. Both the tap for the trigger and the tap for your air source are normally in the manifold attached below. I also use a tap for a small air pressure gauge.
The manifold also contains the guard for the cam drive.
Last edited by Solar on Mon Dec 17, 2007 9:33 pm, edited 1 time in total.
Here's a picture that shows the main air supply tap on the side.
The main air supply is connected with a steel tube that doubles as the spindle for the receiver. The caps for the air supply also fit directly on the end of the valve and have different size threaded ports to use for whatever you like.
In this picture you can also see how I made one of the main valves using an oem piston, rated at only 250 psi.
