Fully adjustable piston valve.
Posted: 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.
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.