10 replies to this topic

[boltsniper]

My next homemade is planned to be air powered so valves pop up as hurdles in the design. I valve would be hard to fabricate out of PVC but not impossible. I took advantage of my access to rapid prototyping equipment and built a valve I drew in CAD.

Here is the valve:





The valve is a basic self sealing valve. Same type found in Nerf air guns. The air enters behind the seal and applies pressure to the seal making it tighter. The higher the presure the tighter the seal. When the shaft is depresed the seal is broken and the air rushes around the seal and to the outlet.










I built the 3 pieces this morning in about 3 hours and assembled it this afternoon.
I did some pressure testing to see how it performed. Initially I jsut put 20psi into to check functionality. The valve works very well and the activation force is much less than I anticipated. It's very on-off which is good. I then ran it up to almost 100 psi to make sure it woud not fail (ie explode). It didn't. Finally I put 60 psi behind it and left it for an hour. After the hour the pressure didn`t drop at all.

It is a bit large and may be difficult to incorporate into a pistol grip nicely. I may trim it down some and build another.

I decided for this homemade to tackle the hard stuff first instead of the other way around.

[ompa]

You have no idea how much I envy your access to that sort of equipment and CAD.

That's incredible; I only hope the college I go to has that kind of equipment. I will also make it my first priority if I have such access to learn how to use CAD.

~ompa

[boltsniper]

You have no idea how much I envy your access to that sort of equipment and CAD.

That's incredible; I only hope the college I go to has that kind of equipment. I will also make it my first priority if I have such access to learn how to use CAD.

~ompa

If you are going into any kind of engineering you should learn CAD. Less so if you are computer or electrical but even though guys use a lot of circuit design programs and such.

There are a number of free CAD packages out there that you can use to learn the basics. Once you learn one it's just a metter of learning different interfaces when you switch packages.

Alibre Design has a free fully functional trial of their solid modelling package.

[foamsmith]

Nice Bolt. Two quick questions. what size of O-ring is that? Where'd you get that long skinny plastic piece (the piece you push in to release the valve)?

[boltsniper]

The O-ring is 1/2" DIA and 0.14" thick. It was in an assortment pack of O-rings and I matched it up with the beveled seal.

The shaft was built with SLA along with the valve body and the end cap.

[WratH]

How's this going bolt? I'm interested to see how it will work out.

[The Inventor Guy]

Erm, mate, he's already built the valve: he's displaying the creation.

-Tidge.

[flamebo388]

I think wrath was asking about the gun tidge. I've been speaking with bolt recently, I believe he said he was gonna run a few parts through the sla machine this week, or maybe it was next week.

[Osiris]

Boltsniper I love that valve could you give me a list of materials you used please? I think I might make one. A homemade rifle with one of those would be a pretty cool idea.

Edited by Osiris, 20 November 2005 - 08:41 AM.

[boltsniper]

Aside from the O-rings and spring, it was all built with the rapid prototyper. This would be tough to make out of PVC and other materials, although probably not impossible.

I plan to use this valve in my next homemade. Some other projects popped up that peaked my interest so the rifle is onthe back burner right now. But I will get back to it.

[Ronster]

Bolt,
Do you possibly think you could give us a concept design of what the new homemade might look like. If not, thats fine.
Your valve looks awsome... Very, very nice.