Diaphram material

[ralphd]

What have you sucessfully used as the diaphram in a valve. I was thinking of using neoprene from a truck tire or from the hardware store but these are aproxamatly 1/8 or 3/16 inch thick. Spud wiki says to use a Tupperware lid but I feel that it is too stiff. Any opinions?

[Technician1002]

What have you sucessfully used as the diaphram in a valve. I was thinking of using neoprene from a truck tire or from the hardware store but these are aproxamatly 1/8 or 3/16 inch thick. Spud wiki says to use a Tupperware lid but I feel that it is too stiff. Any opinions?

An option is to use the thin stuff as the flex portion and use something stiff in the middle like a flat washer sandwich to prevent excessive bow in the middle, but still providing good movement like many sprinkler valves.

[THUNDERLORD]

...Any opinions?

IMO a few of the Kevlar layers bullet-resistant vests etc. are made from, could be used with vulcanized rubber...and maybe work BETTER than a pistoned QEV...!!!

My HD MC has a kevlar belt...got me to thinking is all. 8)

[thedeathofall]

IMO a few of the Kevlar layers bullet-resistant vests etc. are made from, could be used with vulcanized rubber...and maybe work BETTER than a pistoned QEV...!!!

My HD MC has a kevlar belt...got me to thinking is all.

Haha ya lets go cut up a few $1000 vests to see if they can be used for spudcannons That was priceless man, I cant stop laughing...

I think tech could be onto something. I don't really know much about diaphrams, as pistons are just as inexpesive and easier (for me) to build, but it sounds like it should work.

[Technician1002]

I got the idea from common sprinkler valve diaphragms. None of them that I am aware of is just a sheet of rubber. They all have a stiff center section of one kind or another either molded in or bolted on.

[THUNDERLORD]

IMO a few of the Kevlar layers bullet-resistant vests etc. are made from, could be used with vulcanized rubber...and maybe work BETTER than a pistoned QEV...!!!

My HD MC has a kevlar belt...got me to thinking is all.

Haha ya lets go cut up a few $1000 vests to see if they can be used for spudcannons That was priceless man, I cant stop laughing...

I think tech could be onto something. I don't really know much about diaphrams, as pistons are just as inexpesive and easier (for me) to build, but it sounds like it should work.

A Kevlar/ rubber drive belt costs around $160 USD.
Kevlar vests have several layers.
Even MANY more than needed to stop a single bullet.
And with enough surface area to make more than a ton of diaphrams.
And then suply and demand kicks in lowering the price.
"Priceless"???
I Consider your "Priceless" "HAHA" ,"till you can't stop" the laugh of a monkey.
Nothing funny there IMO.

EDIT: Excuse me Tech, we posted about the same time.

@thedeathofall:To add though, "$1000 for spud cannon"...You sound like a cheap petty style no-class spudder, it's showing.
Tell me will it really be the death of all with such petty mentality???
Man, you need higher standards, or re-evauluate spudding IMO!

[inonickname]

I have some thin kevlar sheet if anyone really wants to try.

Use a thin, flexible airtight sheet for the outer part, and for the inner part use a metal washer or plate and a sheet of neoprene rubber to seal the barrel.


WOOO 1.1k posts..

[PVC Arsenal 17]

Funny this topic came up. I was almost about to post a thread asking why you don't see many diaphragm guns these days. I guess too many good ideas for piston making came about and diaphragms became obsolete. I used to make them all the time.

Look in your local harware store for a rubber pipe cap. They're made from thick black rubber and come with a hose clamp to secure them to the end of a pipe. I always used a 4" cap, and then made a simple gasket punch (sharpened copper coupling) to punch out whatever size diaphragm I needed.

[THUNDERLORD]

@inonickname:
Any idea where one can get individual sheets???(Haven't searched yet).
Is it woven or solid (the stuff you have)?
Seems like maybe a potential burst-disc if it's not woven fiber stuff.

The metal washer combination mentioned, seems to defeat the purpose of a large diameter flexible, light weight sheet, moving with no need for a bumper or much pilot volume....(?)

BTW, I like your new avatar. 8)
EDIT, I imagine the good stuff would dull a bandsaw blade quick(?).

[inonickname]

@inonickname:
Any idea where one can get individual sheets???(Haven't searched yet).
Is it woven or solid (the stuff you have)?
Seems like maybe a potential burst-disc if it's not woven fiber stuff.
BTW, I like your new avatar. 8)

Pedobear is dissapoint.

It's woven fibers in a semi flexible epoxy. Probably not ideal for a burst disk.

Mine is just sheet stock I believe..as to where you can get it, no clue.

[ralphd]

I am planning on using two washers for the diaphram; a small one to fit inside the pipe and a larger one to seal on the face of the pipe. I thought about using a diaphram from a sprinkler valve but I feel the material is too thin. I used sprinkler valves on open loop geothermal air conditioning systems. It was always the weakest link. Although kevlar is very durable I can't justify the cost.

Look in your local harware store for a rubber pipe cap. They're made from thick black rubber and come with a hose clamp to secure them to the end of a pipe.

I have seen these caps but never gave them a second thought, I'll pick one up today to check it over...thanks.

[inonickname]

You're in the US aren't you? If you're in Aus I'll happily post you some to try if you really wanted.

I've had too many similar things confiscated going through customs to post internationally.

[noob of noobs]

Funny this topic came up. I was almost about to post a thread asking why you don't see many diaphragm guns these days.

Way ahead of ya!
http://www.spudfiles.com/forums/homemad ... 18496.html

I've been using a bike tube with a washer bolted on the center so it holds up to pressure (the tube fails at 60psi against a 1/2" copper lip). It's been working pretty well, when piloted by a unmodified blowgun.