SpudFiles

I have consturucted a new cannon for use with my shock pump, and i have been trying for days to make a good sealing face. im asking the people who have sucessfully consructed a high-pressure piston valve what they used as a sealing face?

BTW my piston diameter is 3/4 inch and the barrel is 1/2 inch.

Thanks in Advance im pulling my hair out on this one. ill presusrize it to 200 psi and then ill hear a "pop" followed by a fssssssssttttttt which gets annoying after youve spent 30 minutes on the shock pump to get there.....

mabey teflon or viton?

some people have used a solid peice of rubber, just go to a craft store and get a small cylindrical peice of rubber the same size as your chamber(if its a coaxail), and just use that as your piston. If not, I have used a cut peice of basketball(works great), other than that, truck tire>

they sell cylindrical peices of rubber at miachels? whooooo...... missed that one.

ill have to look into that along with a wooden piston.

I used a rubber gasket and glued it with neoprene glue which was actually meant for bonding a rubber 'toe guard' to my cricket bat.

Wow! Blowing out at only 200psi?

When you take it apart to repair the seal, what are you finding? ie. How exactly is it failing?

I've been using a single layer of neoprene gasket material. 1/16" thickness simply bolted on. (copper gun) Working trouble free at 400psi.

The co-ax uses teflon.

And by the way,...30 minutes to get to that 200psi? How big is your chamber?

VH_man wrote:cylindrical peices of rubber

rubber bung/rubber cork, you may find them in a boating stall.
Just machine it down to the right size.
One rubber cork = piston, sealing face(perfect seal) and bumper.

-edit- -may not have big enough corks for what you want-

the best thing i have ever used is the diphram found in argon regulators, i have fired uncountable shots with it and yesterday it finally gave way.

I just use a 3/4" tap washer - they're made of tougher rubber, because they're designed to be clamped down hard onto that kind of surface.

Truck tire inner tube, never failed me

Or just the good old bike tire inner tube
But neoprene would certainly be the best.

Did you bolt on your sealing face correctly? Glueing is not recommended, use a bolt and washer.

im using 3 layers of bike inner tube and it simply pops at 200 PSI

and if i use a bolt and a washer it makes that "cone" shape and at 50 PSI the face gets sucked into the barrel.

I need a new piston also, im going to be using a dowel machined down to the proper size. I will try the "tap washers" first, because i have a few of those laying around. if i cant get anything to work i will use a solid rubber rod from McMaster......

And BTW, it takes about 15 minutes..... my pump bore is 1/2 inch copper and my chamber is 5 feet of 3/4 inch pipe, not including the tee valve.

EDIT: WOHOOOOOOOO i got it to seal at 200 PSI. DAMN its loud..... and powerful...... but then on the next shot the sealing face popped again.....

You need a bigger washer to keep the sealing face down, also glue the back of it to the piston. I had similar issues.

Damn i feel lucky not to have these apparently very normal problems.. i use two layers of bike innertube and it works flawlessly for me at 500psi also i dont use any kind of bumper and i have no problems at all

EDIT: picture of my piston, back side up (if its to any help)

Probably the best piston I've come up with was a rubber stopper that I got from a place called "Clark Rubber". They specialise in rubber products but they also deal in pools and what not. I just lathed it down on a timber lathe. You can't go wrong. No sealing face to blow out when you're using one big sealing face .