Diaphragm vs. Piston

[noname]

Yeah, pretty much. That diagram is a tiny bit misleading though, let me edit it so if you build one, the diaphragm will work....

Argh.
I edited the diagram and somehow deleted it. Just make sure that the diaphragm is about 1 1/8 the size of the pipe ID. For example, use a 2.5" diameter diaphragm if you're using 2" PVC as a chamber.

[Pyro Ninja]

got cha.. .....I might make a air rifle pellet gun.....I feel so noobish

[schismatized]

to clarify, i will be using a 3" pvc schedule 40 endcap. If i cut say, 1 inch, off the opening to cut weight, will that help any?

[hi]

thats a piston, but yea it will reduce weight.

[schismatized]

any other tips to get a little better performance out of that style of piston? i plan on using a 1 inch sprinkler valve with it.

[hi]

lube it up really well and have a really good bumper.

[noname]

Fill it with foam or something to reduce pilot volume without increasing piston weight.

[schismatized]

good ideas. keep em coming! im wondering what would be a decent bumper for 4"? i dont want anything ghetto like hose lol

[hi]

hose wouldnt work any way, you need to find something that will absorb all the energy from it though.

[chaos]

what about those flotation pool noodle thingies? they might be 3" tho

[spud yeti]

I have decided to start building a coaxial diaphram valve cannon since I have just finished my small piston cannon. I have never built a diaphram before so I have a question: How many layers of inner bike tube do you need for the diaphram? I am building 2" diameter.

[noname]

Don't use a bike inner tube. They are much too thin for this application. You need some tough 1/8" thick rubber sheet.

[spud yeti]

OK thanks. Cant you just use 2 or 3 layers though??

[noname]

You can, but either it'll pop, get sucked into the barrel, or only one layer will get sucked back into the pilot area.

[spud yeti]

OK cool, I think I will just go look for some rubber at the store thanks for the help though.