SpudFiles

Hey guys, in light of my new project..

I need a rather gigantic valve, I won't settle for anything smaller than 3" really. I'm just wondering whether it would be worth it waiting for something to float by on Ebay, make a 4" Burst Disc or a Large (140mm) piston for a Coaxial.
If anyone happened to see anything interesting at all, I'd be over it like a fly.

I'm quite stumped really, any feedback?

By 3" you mean at least 3" of full porting, correct?

Burst disks are possible for any size, but I'm going to take a departure from my normal position and advise that you build a piston valve. With some 4" steel tube, 1/2" plate, and a friendly welder, it could easily be done for under $100.

The best part is, the steel tube and plate, unlike PVC pipe and fittings, are ubiquitous; you can find them equally easily, in exactly the same form, anywhere in the world.

So what is it that you're building?

I would say burst disk but I doubt anyone else would.
but the coaxial idea would work well also.
Or you could do a tee valve because that doesnt waste the volume in the chamber

Here is a three inch piston. This is posted somewhere on this site, but I don't know who did it or where it is. I just happen to have a picture of it:

That looks like a 4" piston to me

Specifically, it looks like the piston for a 4" housing, 3" barrel porting valve.

A burst disk for this size wouldn't be incredibly practical - the material consumption would be enormous. that isn't to say I'm not doing it myself

Ahh, perfect timing

This pertains to my 4 inch piston valve i am almost done with (well not really but i have all the parts, gluing is easy, i already drilled a hole for my universal pilot setup, so really i just have to assemble, which doesnt take long).

It is a 3 inch porting, 10', 4" chamber, barrel is 3", as mentioned.

Piston is a 3 inch endcap which fits just perfectly, with some easy sanding it will be perfect. But my problem now is the support for my sealing face. Im getting neoprene from mcmaster, but what i need is the 3.5 inch washer, which will support my sealing face.

So, where can i get a 3.5 inch washer? Will homedepot have it? If not easily available, or not at homedepot, what are alternatives?

If you know respond as soon as you can because i am going to homedepot tomorrow so i need to know ASAP.

you could use a disk grinder disk, those are about that big i think, could be a bit pricey though, just an option if you can't find a washer that size

@MaxuS... Piston valve, 4" Tee, 3in. porting. Start with pvc, its cheap, easy to learn with, then jump up to steel.

@LikimysCrotchus5... What about gluing the neoprene to the piston face? I had problems with neoprene with my 3" tee, 2" ported valve. The only thing I could figure out was there was so much pressure on the neoprene that it was starting to tear after only a dozen shots. I ended up using a 6" x 6" x 1/8" Rubber Packing Sheet I picked up at Lowe's. I used 3 to 4 layers of this and got rid of the large washer.

One question though, if you are porting at 3", wouldn't the washer need to be less than that?

http://www.spudfiles.com/forums/75mm-pi ... 11388.html
I already made that, but it was a bit of a git to get working. I'm reluctant to use that because it's seated on something else at the moment.

I was hoping more for a 3" Solenoid Valve to mod. A coaxial would be awesome, with a 1" Sprinkler to vent the pilot, how the hell would i make a 140mm piston though..That's massive.

I would go with a Piston Valve, but for a 4" tee and 3" porting I could have bought a 3" Sprinkler Valve.


..Going for the Coaxial option, although it won't be able to have interchangeable barrels..Should I go for Tennis Ball size or Golf Ball sized barrels?

DYI wrote:So what is it that you're building?

Well, a short while ago I bought a 1m length of 140mm pipe. I wanted it to be the combustion chamber for a very large combustion, but I then had a change of heart about what to do with it after looking at the cost of creating an advanced combustion launcher with it. So pneumatic it is.

how in the hell do you fit a 3.5" washer in a 3" coupler?????

ispudder wrote:how in the hell do you fit a 3.5" washer in a 3" coupler?????

lol, just noticed that. so what is up with that anyway?

@MaxuS

I would go with a Piston Valve, but for a 4" tee and 3" porting I could have bought a 3" Sprinkler Valve.

When you can find a 3" valve for less than the price of a 4" tee and 3" porting, I'll take 20 of them... The last 3" sprinkler valve I priced was well over $270.. Not my idea of keeping it cheap. $30 on a piston valve of that size, and that's with sch.80 bushings.

Thx Eddbot thats what i think i ended up using, its a cutting wheel which is almost the same, but ne way, it fits in sch 40, 4 inch pipe.

Ispudder if you are talking to me, i am using a 4 inch tee and 4 inch pipe as a housing for the piston 3.5 inch fits in 4 inch pipe.

Fireman565 it is better to bolt the sealing face rather than glue it. I am getting neoprene from mcmaster carr, 9013K823 thats the neoprene i am getting, it should work well.

LikimysCrotchus5 wrote:Fireman565 it is better to bolt the sealing face rather than glue it. I am getting neoprene from mcmaster carr, 9013K823 thats the neoprene i am getting, it should work well.

I agree. I had run into a problem with my latest cannon where anything I did, my neoprene seals were being sucked right off of my pistons!.. Even with washers over the neoprene. So, in a rage, I superglued the seals on both pistons (duel piston valve gun). To my amazement, they both stayed. It was the only way I could keep some sort of rubber seal on the pistons. But bolting them on IS the best way so you can 'maintain' the piston.

EDIT: Oops... In my head I crossed your post with MaxuS' post. I thought MaxuS was looking for a 3.5' washer for his 3" piston, not you Liki. Just bare with me I confuse my four children every minute of the day

I'm going with a 140mm Coaxial design. Wood will be goof enough for that.