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Fully adjustable piston valve.

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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Fully adjustable piston valve.

Unread postAuthor: Procyon » Tue Nov 10, 2009 12:44 pm

What started out to be a simple tool to measure the depth from port to the back of the valve assembly ended up being a fully adjustable piston valve. The pics below show it with a metal rod but I intend on replacing it with nylon before placing it in the gun for trials. The valve is 1" with a 3/4" port. The back of the piston seals against a washer in the back of the valve assembly.

The pistons are made from plastic deck lumber cut out with a 1 3/8" hole saw the sanded on a poor mans lathe. There are 2 ports drilled thru the aft piston, one for fill the other for equalization. On the front of the aft piston is a 1 way valve for the fill. It is adjustable from 0 to 3/16" by rotating the cut washer. This port remains open in the back of the piston and allows for a faster fill time plus gives me an adjustment so I don't shock the cylinder advance piston. On the back of the aft piston is another cut washer that allows for adjustment of the equalization port from 0 to 1/8". By loosening the 2 nylon lock nuts, the aft piston can be adjusted for travel by spinning the piston up and down the rod. Both pistons are threaded on their interior. With having these 2 ports cut into the piston I was able to install o-rings on the exterior of the piston. Again on a poor mans lathe.

The fore piston rest entirely in the cavity of a 1" copper T. A slight chamfer allows it to side effortlessly through the pipe. This leaves a larger face of contact from the aft piston when the valve is opened. It is already noticeably lighter then a smaller 3/4" piston I made with epoxy for the last gun and will even be lighter once the steel rod is replaced with nylon.

Again I would to thank the producers of this site and all the contributors who's information and creativity has inspired this hobby.
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Valve Fore.jpg
Front of piston
Valve Aft.jpg
Back of piston

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