Homemade projects to begin

C-A_99 · Post by **C-A_99** » Sun May 20, 2007 11:35 pm

Nevermind, the valve (that was just depicted) is very leaky, I'll have to buy another one anyways. Or maybe I'll have a look at the pull valve since it provides better flow and opens fast at the same time. However, it seems like both valves have reliability issues, though the pull valve would probably have less once the seal is done just right. Then again, the solenoid should work fine for a while too since it's not being used a lot. A pull valve seems like it'd be cheaper though.

For now I'll look into the pull valves, but I've heard some people having problems getting them to work. (finding O-rings that seal, etc.)

Silence · Post by **Silence** » Mon May 21, 2007 4:02 am

Yep, once you get the seal well enough with the pull valve, you should have an effective, cheap valve that has a trigger. The caveat, of course, is getting the seal. The best way to approach the seal, in my opinion, is to treat the plunger like the plunger on a pump.

Scavenger · Post by **Scavenger** » Tue May 22, 2007 2:46 am

Yes, the pull valve I built has pretty good flow, and I could've made it larger if I wanted (make the slots in the pipe wider). The seal is the tricky part, though. Maybe I never got it right to begin with. I've been through 3 homemades and 5 different sets/styles of o-rings, and they all leaked. I hope you have better luck.

Silence · Post by **Silence** » Tue May 22, 2007 8:51 pm

Creating seals appears to be the toughest part of building homemades. Scavenger, I presume you've tried Ben's 3/8" rod and 3/8"-5/8" O-ring combo? What about DX's 1/2" wood dowel with a groove for the O-ring?

DX · Post by DX » Tue May 22, 2007 11:20 pm

Speaking of, the wooden dowel with a cut groove works really, really well. You cut it so that the O-ring is just a bit loose in the pipe, for when the dowel gets wet, it expands and creates a sweet seal. Of course you've got to figure out exactly how deep the groove has to be, otherwise the seal won't work. Too shallow and the O-ring will get stuck; too deep and it won't draw water.

Drenchenator created an interesting seal using CPVC to hold the O-ring in place, don't know where that topic is at the moment.

joannaardway · Post by **joannaardway** » Wed May 23, 2007 11:53 am

SilentGuy wrote:Assuming it's for the WBL, then no, as all solenoids restrict flow. Still, with the possible exception of quick exhaust valves that are impossible to find in the US, sprinkler valves the best solution unless you're willing to build a valve on your own.

I have to correct you on that. QEV's are easily found in the US.

Go to Mcmaster and search "Quick Exhaust Valve", or just head straight for page 941. It's the second product up from the bottom of the page.

Odds on, for a good launcher you really want the 3/4" right angle version, and you will need a piloting valve (a blowgun would be more than sufficent). Of course, you do have to fill from the pilot port, but that's not really a problem. No modification needed and not overly expensive, after it's fitted, it'll work flawlessly straight out of the box (if you fit it right of course).

A good QEV will allow a smaller, and more efficent launcher for the same power level. Seriously, don't even consider a manually operated valve (I can also see some risk and potential injury from trying to use a pull valve like I think you're talking about for compressed air)

My brother's latest (and horrifically powerful) 20.3mm bore launcher has easily over triple the power of a similarly sized spring loaded ballvalve cannon.

Silence · Post by **Silence** » Wed May 23, 2007 9:01 pm

Jo: Good to see you're still alive!

I still have my doubts regarding quick exhaust valve availability in the US. I'm talking about local hardware stores - McMaster-Carr doesn't count. Just look at their first page to see all the stuff they carry but that others don't. Next time I go to each of the local hardware stores, I'll ask the people there if they even know what QEVs are.

Also, QEV configuration is different when compared to sprinkler valves, ball valves, etc. The air inlet is in one leg of the tee, the PC is in the middle, and the air outlet is in the other leg of the tee.

Granted, if you can get a QEV, then by all means do so. As Jo has said, they're the best for launchers. Of course, it's harder to get large QEVs for more flow, but any QEV should be sufficient for a WBL. Much better than a sprinkler valve.

DX: Sounds good. I'll try cutting a groove for my next pump. I had been apprehensive because I'm not too confident in my abilities in cutting a decent groove...but the results should still be good enough. Thanks for the inspiration!

Scavenger · Post by **Scavenger** » Wed May 23, 2007 10:23 pm

I found Drenchenator's pump.
http://waterwarfare.com/forums/index.ph ... post&p=709

As for my seals, after looking at my most recent set of o-rings, and then looking at the container they came in, the OD of the rings were 1/16 too small. It makes sense now, the first set didn't work because the cpvc came off (Drenchenator's style). The second set didn't work because I used a grommet, which doesn't seal on the inside, and the third set was too small. The only bad part is that I am using a 3/8" rod, and I didn't see any larger sizes of o-rings at the store.

C-A_99 · Post by **C-A_99** » Fri May 25, 2007 7:45 pm

Hmm... Got a very annoying problem right now, there is leaking all over my backpack's threads and through where the tubing goes in. Should I add duct tape to the sides and by the hole in the cap to seal it? Also, I need to do the same thing for the ball valve (duct tape around it) but that's a given. First I tried a small bottle with a 1" cap, then a large bottle from a peanut can container. Neither bottle leaks at all when I do light test, where I test only the top of the bottle/container and the tubing hole for leaks. No leaks at all for both bottles, but when I put in a trash bag to either one, both the tubing hole and the threads leak for some reason. (I can see why the threads would leak but not the tubing connection) Had a read on that article again and the procedure is just the same. Maybe I ought to find a large container and use that if there's too much trouble with this, but it's hard to find a container that's actually large, and there may be a bit trouble getting the ball valve on.

joannaardway · Post by **joannaardway** » Fri May 25, 2007 10:23 pm

Haven't died yet. I've just been busy.

You're not going to find a QEV in any normal hardware store - they're a specialist component for use with pneumatic cylinders (but some types are also used in paintball guns). Unless the place supplies those as well, you're going to be hard pressed to find one there.
They're mostly internet exclusive items, unless you're talking the paintball variant, and I'm not sure that you'll be able to fit one of those.

The elbow configuration of a QEV can actually help - it makes under/over construction easier (IMHO, then any launcher should be under/over except in rare cases - the reduction in length is massive.)

Go with the size of QEV you want - I'd suggest 3/4, for the extra power, but if the lower cost of 1/2" appeals, go with that.
Going below 1/2" won't be great though - the air flow is proportional to the square of the diameter, so the flow is heavily choked by a small valve.

Of course, 1.5" valves are sometimes up for sale on eBay for not a huge amount. I sometimes scour eBay US to find out if any sellers will ship to the UK. I can see uses for a valve that big - other than deafening myself.

C-A_99 · Post by **C-A_99** » Sat May 26, 2007 1:57 pm

Well, this is getting pretty annoying, can't find any 2 gallon's around the house, and have no solution for the backpack. I'm either reading the instructions wrong, my trashbag's opening is way too big, and/or I need to tighten the threads even more...