Bolt/Washer Piston

Cannons powered by pneumatic pressure (compressed gas) using a valve or other release.
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Mr.Tallahassee
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I finally said screw it and went to Ace Hardware and bought a stainless steel rod and some washers and nuts. I put them together and all I need is an O-ring to fit 1.5'' PVC pipe. Comments? Suggestions?
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Bolt and washer Piston valve 003.jpg
Bolt and washer Piston valve 002.jpg
The Sealing face is hose splicing tape. It works surprisingly well as long as the surface on the end of the PVC is polished smooth.
The Sealing face is hose splicing tape. It works surprisingly well as long as the surface on the end of the PVC is polished smooth.
Bolt and washer Piston valve.jpg
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Crna Legija
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I would put the two O-ring groves further apart to stop it twisting and then cutting into the weak PVC.
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Mr.Tallahassee
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I will do that. Finding O-rings is my main concern at the moment. Other than that, all I need is the tee, two bushings, an adapter, and a short section of pipe. Where can I find 1.5'' O-rings?

EDIT: I found 1.5'' O-rings at Lowe's. Are these suitable?
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Crna Legija
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Mr.Tallahassee wrote:I will do that. Finding O-rings is my main concern at the moment. Other than that, all I need is the tee, two bushings, an adapter, and a short section of pipe. Where can I find 1.5'' O-rings?

EDIT: I found 1.5'' O-rings at Lowe's. Are these suitable?
If they fit yes, but you can buy O-ring stock or a really big O-ring and cut to size and use super glue to hold the joint.

also you can try make a floting O-ring that makes your piston a oneway.

hears a great vid made by Technician1002

[youtube][/youtube][/youtube]
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Gun Freak
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1. Spread the grooves apart more so it is more stable.
2. Put a washer in front of the sealing face that is smaller than the seat ID to prevent blowouts.
3. Use floating o-rings and cut a groove in the washers in front of each o-ring to create a check valve effect.
4. Go to a hardware store for o-rings. I have got some big enough for 2" PVC at my local ace hardware.
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Technician1002
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My local Parkrose Hardware store has O rings in bulk bins sorted by size. They recently added metric o rings. The free air compressor I got was leaking air out the back plate of the pressure regulator so I took it apart and located the replacements by matching the size. I got the round ones to replace the flattened ones the regulator had. If anyone is interested the common pressure regulator used on small compressors use a 20mm o ring with the 3mm cross section. It uses two. one on the bottom and one on the top. For less then 3 bucks it eliminated the need to buy a new regulator.

My regulator is the small square body one similar to this one.
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Mr.Tallahassee
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Gunfreak: Thanks for the info. I looked in my local Ace Hardware but couldn't find them. I'll look again soon.

Technician: Thanks for the hijacking! :lol: That might actually come in pretty handy as my little 8 gallon compressor runs a lot because of my higher volume chambers. Three shots drops the tank to under 100PSI and sets off the pump. I'm sure something HAS to pop up sometime soon. :smilebox:
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Mr.Tallahassee
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For the Benefit of anyone who needs an idea on an easy bolt and washer piston valve. Here is a diagram
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My airgun valve.JPG
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Gun Freak
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Very nice diagram, easy to read, but the piston shouldn't reallly be that long. The valve can be more compact too.
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Mr.Tallahassee
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I had fit issues with the washers. Having it longer minimized the side to side shaking. It prevents the nut on the sealing face from jamming into the edge of the barrel. I just didn't have the hardware in any of the stores nearby.
MRR
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I think that this design is way to complicated and heavier than it has to be. Get rid of two washers and add a rubber disk (with a trapeze shape) in front of the first washer.

Have a look at the shape of the rubber disk on this piston. Works like a charm.
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Mr.Tallahassee
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That's not a bad idea. I'll work with that later on. This one's too much fun! :D
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sorry for hijacking this topic but here is something you might find interesting

a QDV valve and a breech load in one

this one is for a hybrid, that's why the piston is unbalanced - of course there is no need to do that in a pneumatic
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I think that this design is way to complicated and heavier than it has to be. Get rid of two washers and add a rubber disk (with a trapeze shape) in front of the first washer.
+1 on the design. A beveled edge performs very, very well.

2 and 3 inch pistons. (Before barrels were welded on)

Image

Long chamber 2 inch piston for another 81mm replica. (I just never have time to complete)

Image

///ed///
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