SpudFiles

ok, ive designed this a copper cannon, but seeing as this will be my first piston gun i would like some input. ive uploaded the images for the layout of the valve, and the layout of my two piston designs(the second one was a bit rushed)







any suggestions would be appreciated, and thanks to BLB for helping out already.

anyone?

Damn you - I've been sigged!

It could work - it depends on exactly where your sealing face is though.

I'll talk to my brother about advanced piston designs - he's somewhat of a guru when it comes to small piston valves (he's built 8 valves around this size)

wow, does he have aim or something. it might be easier. if he does you could PM it to me for privacy. if he doesnt, feel free to leave a comment here.

and it would be nice for a relatively speedy reply due to the fat that i will be leaving monday and gone for a week. so i would like to build it this weekend.

Thanks,
Bryce.

I would use a smaller T or reduce the piston section down to 3/4 copper for the sole reason that 5/8 tap washers are a virtually perfect fit inside 3/4 inch copper. Then you can just stack four washers and a neoprene face together for the piston.
Presumably you have it set up with metal washers which aren't the best sliding surface on copper.
You can also set up a more complicated stacked washer piston with an o-ring one way seal, but start with a simple one first. Just cut a thin groove down the side for air to leak past and fill the chamber.

yes, im planning to make one simple piston, and get the supplies for more and more complicated pistons. i think i will make 2 pistons first, and then thru trial and error improve them. i hope to succesfully make one that uses BTB's design that reduces/eliminates backflow.

That's what my o-ring design does in a simpler fashion.

ya, pretty much.

i think im going to go with the 3/4 valve, or maybe the 1". im going to have a1.5" chamber, and some sort of stock. and ill hopefully find some ball bearings that will fit a 1/2" copper barrel with minumum wadding.

Ok, the offical words from my brother are:

-You really need some sort of bumper for that, as pistons come back quite hard.
-The sealing face should be almost at the front of the branch of the tee.
-Any anti-back flow idea is good.
- Your second piston design is better (you really need at least three washers - allegedly), but make it shorter.

He's apparently also working on a new "ultra piston valve" idea, but he's staying quite quiet about that.

If that helps, then good. If not, I'll go kick him for you.

i have used 2 washers and it worked fine but im working on this really kool new piston as well its one piece done on a lathe.

joannaardway wrote:Ok, the offical words from my brother are:

-You really need some sort of bumper for that, as pistons come back quite hard.
-The sealing face should be almost at the front of the branch of the tee.
-Any anti-back flow idea is good.
- Your second piston design is better (you really need at least three washers - allegedly), but make it shorter.

He's apparently also working on a new "ultra piston valve" idea, but he's staying quite quiet about that.

If that helps, then good. If not, I'll go kick him for you.

that helped alot, and i forgot to include a bumper in the drawing .
any input on the specific design of the piston, other than atleast 3 washers, would be greatly appreciated. and any tips on the anti back-flow design would be appreciated.

sorry for any hassles.

Put up the design I drew for you , A-98. Maybe they can improve it

Edit: Ahh, I'll put it up.

Edit: Ok, heres the design of piston I made for A-98, you have to download the picture and zoom in on it to see it well.



Oops, looks like I forgot the nut behind the washer on the sealing face.


off topic - Would it be safe to make a 600 psi 3/4 porting copper piston valve? Or put 600 psi in 1.5" or 2" galvanized steel pipe? thanks

You might want to make one that operates at 200-350, shoot it, and then decide if you need to double your psi.
I guess more complicated heavier pistons are preferred judging by the posted diagrams. Not sure why though.

I just want a ridiculously powerful gun, thats all. But I don't know if I should order the pressure rated fittings on mcmaster, or just use the galvanized steel parts at my hardware store.
PM me if instead of posting here, I dont want this topic to be off topic and all the mods be mad at me.

Back on topic: A-98, I'll draw you some more piston designs if you want, we could talk on aim about it too. It would help if I got pictures of your parts too.

Anti backflow eh?

What you can see here is the piston my brother currently uses.

The rubber washer on the left of the image acts as a check valve, allowing flow from left to right, but not vice versa.