21 replies to this topic

[Zorns Lemma]

Materials:
2 lengths of 1/8"x1/4" tubing
1 length of 1/4"x3/8" tubing
1 ball bearing (7/36" or 3/16")
1 spring

Directions:
1) Glue spring to ball bearing
2) Shove small tubing into large tubing from one side
3) Drop in spring/ball combo
4) Shove in tubing from other side
5) Expand outer tubing to allow for superglue application
6) Add goop

Notes:
- Use a spring that won't fall into the smaller tubing (OD > 1/8")
- Press inner tubing together enough to compress the spring and apply pre-load
- Airflow in direction of arrow (from ball bearing side to spring rest side)
- Your mileage may vary

And a video demonstrating the check valve in action:

You may have to turn up the volume to hear the 2 air releases (the 2nd one being louder than the first).

Edited by Zorn's Lemma, 05 April 2009 - 12:26 AM.

[Ice Nine]

It's worth mentioning here that these are extremely simple and easy to make and less than one-third the price of McMaster check valves, excluding shipping.

Thanks for the work on this Zorn, you're decreased my reliability on McMaster and thus decreased the amount I'll be bothering you.

[Gazoo]

Very nice! Thank you these will come in handy

[cheesypiza001]

Could someone please create a slightly more detailed writeup or a quick drawing in Paint (application)? Thanks so much in advance. Sorry, I'm having a hard time understanding some things about the check valve, specifically how the spring/ball combo stays in place and which tubing it is located in. Thanks again, and great creation!

[wingd man]

Nice and cheap. This brings me to a different subject: you know how radio shack sells their LEDs for like 1.50? I may be saying something obvious, but LEDs cost like a cent to make.

[hereticorp]

Could someone please create a slightly more detailed writeup or a quick drawing in Paint (application)? Thanks so much in advance. Sorry, I'm having a hard time understanding some things about the check valve, specifically how the spring/ball combo stays in place and which tubing it is located in. Thanks again, and great creation!

2 lengths of 1/8"x1/4" tubing
1 length of 1/4"x3/8" tubing
1 ball bearing (7/36" or 3/16")
1 spring

Spring + Ball Bearing goes in the 1/4"x3/8" tubing

1/8"x1/4" tubing gets glued on each end of the 1/4"x3/8" tubing.

How can you not get that from the picture? I mean seriously kid.

[cheesypiza001]

Could someone please create a slightly more detailed writeup or a quick drawing in Paint (application)? Thanks so much in advance. Sorry, I'm having a hard time understanding some things about the check valve, specifically how the spring/ball combo stays in place and which tubing it is located in. Thanks again, and great creation!

2 lengths of 1/8"x1/4" tubing
1 length of 1/4"x3/8" tubing
1 ball bearing (7/36" or 3/16")
1 spring

Spring + Ball Bearing goes in the 1/4"x3/8" tubing

1/8"x1/4" tubing gets glued on each end of the 1/4"x3/8" tubing.

How can you not get that from the picture? I mean seriously kid.

Sorry, I guess I mixed up the two different tubing sizes. In the picture it looks kind of like the smaller tubing is going completely through the larger tubing and that the spring/ball bearing is inside of the smaller tubing. Thanks for the explanation.

[Magic]

Thanks Zorn. I never exactly new how a check valve worked, just new they held air. Does it matter how strong the spring is? Would you recommend using one from a pen clicker?

[TantumBull]

Thanks Zorn. I never exactly new how a check valve worked, just new they held air. Does it matter how strong the spring is? Would you recommend using one from a pen clicker?

Not really. This may even work without a spring, because the pressure may push the bearing against the sealing side. You'd just have to make sure that the side you don't want sealed can't be sealed by the ball.

[venom213]

Very nice. I will definatley be using these in the future. It will make many of my projects affordable and practical. I attempted to make one a while ago for a homemade pump by modifying the design of Ice Nine's homemade blast button. Here is what I did:

I ran a piece of brass through a CPVC endcap, which also acted as a stabalizer for the spring.



I took your suggestion of putting a rubber washer at top of the inside of the cap.



I then assembled it like this:



I'm still not sure why it failed. I think the spring might have been too strong (Ace #3), or there was too much dead space in the valve itself.

Edited by venom213, 05 April 2009 - 01:03 PM.

[Carbon]

Very nice!

For those desiring a bit more information, Nerfturtle had additional information and diagrams in his writeup for his homemade check valve.

[Zorns Lemma]

More general notes:
1) A spring is required for consistency. It could work with just the ball bearing, but the setup would be very finicky.
2) The stronger the spring (and the more you pre-load it) the higher the cracking pressure will be. Cracking pressure the the pressure required between the pump/check valve to open the check valve and let air through.
3) On the other hand, a higher cracking pressure also relates to a higher maximum pressure. This homemade check valve starts to fail at 9-10 pumps of an At2k pump into a single BS tank. By "fail" I mean that if the pump is disconnected, air will slowly leak back (but won't fire anything, just slowly leak) until it stabilizes at the maximum pressure. For homemade pumps, this could be a problem. For use in multiple-tanks on one pump/multiple-trigger setups, you should be fine.

@Magic: A pen click spring will most likely be too thin to work, as it will fall into the 1/8x1/4" tubing
@venom: Which direction is air flowing in? Your pictures show what it is, but not how it's intended to work. However, my first guess would be that you have something backwards.

[venom213]

On mine, the air comes in through the end where the rubber stopper seals against the subber washer, and the air exits through thr brass tube. I've been thinking about it quite a bit, and I'm pretty sure it didn't work beacuse the spring was too strong, or there was too much dead space, or even there ws bad seal at the spot where the air came in.

[Zorns Lemma]

See if you can rig an At2k pump up to it and keep pumping. If it is a spring problem, eventually it will crack (the At2k pump can hit pretty high pressures). In the homemade check valve, the spring is a "meh" spring compressed a bit. Cracking pressure is At2k pump pumped at any decent speed. I have access to a bike pump with a pressure gauge, so I might try to get a more accurate reading of the cracking pressure.

[BlackFox]

Does the valve leak at all? I did something similar to this last summer (albeit without the spring) and it had to be held upright for it to hold any pressure at all.

As CaptainSlug pointed out, I was using a hard plastic piece on one end instead of vinyl tubing and there wasn't a good enough seal. I should have just thought simpler.

Nice work.

[Zorns Lemma]

As I've said before, if the other side gets to too high of a pressure, it will start leaking backwards. I don't see this being a restriction on most guns though, as 1) in integrations, there's still the check valve at the pump 2) the tanks I've been single-shot testing have gotten to "good enough" pressures before leaking; e.g. a difference between 100 and maybe 105 ft for a BS tank.

[venom213]

So this won't work well with homemade pumps? If true, I'd be very dissapointed, because that's one of the main reasons I've been wanting a homemade check valve. Do you think that using two of these valves with weaker springs or something would allow a homemade pump to function?

[Zorns Lemma]

Depends on the pump you're building. This will work fine for high-volume medium-pressure pumps. You could also stick a stronger spring in for a higher pressure.

[roboman]

This would also work well for lower pressure applications.

[Zorns Lemma]

That's both more expensive that this design, and probably doesn't hold up to as high a pressure.

[k9turrent]

I'm not sure if this has made up here yet, I found it in the homemade directory
http://nerfhaven.com...?showtopic=9161

[Zorns Lemma]

Very nice!

For those desiring a bit more information, Nerfturtle had additional information and diagrams in his writeup for his homemade check valve.

I'm not sure if this has made up here yet, I found it in the homemade directory
http://nerfhaven.com...?showtopic=9161