Piston Help

[Sergeant Dotson]

How small should the holes be? Also considering that I'm using felt, couldn't the air pass through the felt?

[jrrdw]

I drill mine 1/32nds". Why felt, sounds like it will wear easy, most builders use duct tape and lube it up.

[Sergeant Dotson]

Actually, I've seen some on other sites like YouTube that have some with felt that hold up quite nice.

P.S.
Since my piston is smaller than most of yours, how big should it be?

[jrrdw]

The piston and cylinder it slides in should be matched. It don't matter if it's .50" or 10". As long as it don't tilt/jam or fit so tight it wont slide. It should have a slight drag when you push it with your hand.

[SpudFarm]

not much to say the diagram says it all.

ask if you don't understand (Crowley did not understand)

[Sergeant Dotson]

Crowley did confuse me,lol. But I still don't get it, why none of them I make work. I just wish I could know what I was doing wrong.

BTW
Sorry, but I don't get the diagram.........

[jrrdw]

When you slide your piston with your hand, what does it feel like? Is it real easy to move, or is it hard to move?

[Sergeant Dotson]

Well, it's relatively easy.

[jrrdw]

Air should pass by it then. I'd like to see some pics of the piston and inside the cylinder and end cap. It would make it easier to help you.

[Sergeant Dotson]

Here she blows.... sorry for the bad picture quality, I'll turn off flash next time.

[jrrdw]

Looks like it's got some rough edges, how about the cylinder it slides in.

[MrCrowley]

not much to say the diagram says it all.

ask if you don't understand (Crowley did not understand)

What the hell is your problem dude? I didn't understand my ass, i've probably had more piston experience then you. Members even recommend me as a good guy to talk to for building a first piston.

Oh and I do understand, more then you. You don't understand many things, refer to the bottom of this post.

You just wanted a damn sticky and had no clue what to do to get one. Anyone can make a diagram of a piston, that does not mean it should be a sticky.

MrCrowley, there is actually not a seam on the inside of my pipe and there is also not a lip on the inside. Not trying to put you on the spot, but just stating what is there.

Don't worry about it, we're progressing here

So just want to get a few things straight...

1) The piston housing, i.e where the piston travels, is the 1" metal chamber?

2)If you answered 'yes' to the above, It definitely has no lip or seam? Is the inside of the pipe rough?


Personally I highly recommend you sleeve the pipe, it will cost you piss-all and make things a helluva lot easier and probably will increase performance from the smoothness of the PVC pipe compared to the roughness of the metal.

All you have to do is cut a length of PVC that will reach to the barrel inside the chamber. Then find some doweling that fits, if not sand some that will. Doweling sands very easily, it'll only take a few minutes.

Then glue a neoprene sealing face onto the front of the piston, either attach a bumper or make on to suppress the impact once it opens. Lube the piston up (you are using lube right?) and then stick it inside and I see no reason why it shouldn't work.

Some trouble shooting tips:

1) Have you used a lubricant?

2) How well is the fit? Can it be pushed forward and back with your finger?
If you turn the chamber upside down with the piston inside... Does much light escape around the sides of the piston?

3) Is the seat (barrel) perfectly flat?

4) Is there area of the sealing face unexposed to the barrel when it seals?

5) Are you using enough initial pressure with enough flow to get it to seal? Mine seals with 10psi from a compressor, but my previous one only sealed at 60psi+

6) Is the sealing face clean and even? Is it made from a non-porus and suitable material?

7) Do you have minimal pilot volume?

8) Is your pilot valve adequate? Technically you could exhaust it with a schrader, but that requires some skill.

9) Do you have o-rings? If yes, do you have a very very small equalization hole?

It took two o-rings to get my piston to seal and require a equalization hole. O-ring grooves are incredibly easy to make when using wooden dowel as a piston.

Any questions, feel free to ask.


Also, spudfarm looks like he didn't understand your diagram.

You still don't get it, everyone knows how to make a piston, but in reality there are some difficulties. A diagram does not work.

Anyone can name the key components of a piston and put one together. But you can't have ONE diagram for ALL pistons. You simply don't understand, I don't know why.

Pistons are very different from one another, that's why one piston doesn't work for every piston.

Also it'd be very hard getting a disk designed piston to work in a co-axial without some support.

[Sergeant Dotson]

I'm sure spudfarm did not mean to offend you. And here are some pics of my NEW piston. It is made of wood, felt, a rubber washer and a rubber piece I found. I also pust some silicone around it to help the seal.

[Blitz]

Cool, it kinda resembles a pill bottle in that last photo. What kind of wood did you use for the piston material?

[Sergeant Dotson]

I used dowel rod, its about 3/4 inch.