You would have to rebuild the valve to make this idea work. Spring hooks would have to be added, tension would have to be adjusted, tension adjusters would have to be added. The tee would need to be acomendateing to the springs. There's probly more I'm missing but thats just off the top of my head.spudfarm wrote:mabe you can use some springs that pulls the piston back like 1/100" and then the pressure can work on the whole sealing face
Sticky Piston
- jrrdw
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Actually I have 1.5" porting and a 2" piston. My problem is what brogdenlaxmiddie said, and that is that my sealing face is being pushed into the barrel since there is no washer behind it. I'm putting in an order to McMaster soon and I added some 2" washers and o-rings for the new piston.psycix wrote:Ahh I see!
You are trying to seal a 1,5" porting with an 1,5" piston?
That means youve got NO frontal area for the pressure to work out force on.
I think adding a spring behind the piston will just make it harder to seal.
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Ok, here's the diagram of the new piston I'm going to be making. Anyone see any problems with it? Its basically the same as the previous one, with the addition of o-rings and a washer behind the sealing face.
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- daberno123
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Good idea elitesniper, just added one to my McMaster order.
Part #7768K26
Edit: I'm also changing the servicability of the back from bolts to a threaded reducing bushing. Hopefully it will make it alot easier (and faster) to take apart. The bolts always leaked anyways. Has anyone had any trouble with threaded pvc parts not sealing? They never seem to screw in all the way.
Part #7768K26
Edit: I'm also changing the servicability of the back from bolts to a threaded reducing bushing. Hopefully it will make it alot easier (and faster) to take apart. The bolts always leaked anyways. Has anyone had any trouble with threaded pvc parts not sealing? They never seem to screw in all the way.
Drilling a small hole under the flap of your sealing face can act as a check valve.
It just flaps open to let air pass into the chamber, but when pillotted, the flap is sucked against the hole and seals it.
It just flaps open to let air pass into the chamber, but when pillotted, the flap is sucked against the hole and seals it.
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So I would have to drill through the washer and the cap behind the sealing face?
I was going to install one from McMaster inside the piston but this method seems much easier. As long as I can drill through the washer...
EDIT: OK, I'm pretty sure I'll be able to find a drill bit to drill through metal. Where will the holes in the washer need to be? Where it presses up against the walls of the 1.5" porting? Or inside the porting?
I was going to install one from McMaster inside the piston but this method seems much easier. As long as I can drill through the washer...
EDIT: OK, I'm pretty sure I'll be able to find a drill bit to drill through metal. Where will the holes in the washer need to be? Where it presses up against the walls of the 1.5" porting? Or inside the porting?
Last edited by daberno123 on Sun May 18, 2008 7:12 pm, edited 1 time in total.
- daberno123
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Wow jrrdw, you seem to read minds.
I don't think I'll be able to drill outside the walls of the porting, there will only be about .05" around there. If I drill a little further in, like right where the washer presses against the wall, will I still be okay?
Otherwise I could add the check from Mcmaster inside the valve and drill holes around the circumference of the piston before the first o-ring groove. It would work in the same basic way, except it would be heavier.
I don't think I'll be able to drill outside the walls of the porting, there will only be about .05" around there. If I drill a little further in, like right where the washer presses against the wall, will I still be okay?
Otherwise I could add the check from Mcmaster inside the valve and drill holes around the circumference of the piston before the first o-ring groove. It would work in the same basic way, except it would be heavier.
You will have to.
If you are drilling it on the walls of the porting (or even worse, inside the porting), the chance exists that it will not be able to let air pass onto the chamber since the piston presses the flap against the hole.
When its outside of the porting, the sealing face can flap open somewhat.
It doesnt need to be a large hole
If you had a larger one (say, 2,5"), you would not only be able to install the check valve hole easier, but it would also perform better.
You COULD make the porting pipe have tapered edges (like a spud-cutter, but then not sharp) this makes not only the sealing face seal better, it also improves flow AND because the porting walls that press against the sealing face are thinner it will be easier to install a check valve-hole.
It also increases initial frontal area somewhat, and since yours is small, it is relatively a large difference.
If you are drilling it on the walls of the porting (or even worse, inside the porting), the chance exists that it will not be able to let air pass onto the chamber since the piston presses the flap against the hole.
When its outside of the porting, the sealing face can flap open somewhat.
It doesnt need to be a large hole
In that case, your piston may still be too small for the porting.I don't think I'll be able to drill outside the walls of the porting, there will only be about .05" around there.
If you had a larger one (say, 2,5"), you would not only be able to install the check valve hole easier, but it would also perform better.
You COULD make the porting pipe have tapered edges (like a spud-cutter, but then not sharp) this makes not only the sealing face seal better, it also improves flow AND because the porting walls that press against the sealing face are thinner it will be easier to install a check valve-hole.
It also increases initial frontal area somewhat, and since yours is small, it is relatively a large difference.