10 replies to this topic

[TheRedRanger]

I have designed an automatic system as a homemade alternative to the MS valve. I am planning on using it with a relatively low air pressure system (30-40 psi); however, I do not have a lot of experience with airgun systems, so I was wondering if the mechanism would work at this pressure.

The Basic Design

I got the inspiration for this while looking at Boltsniper's semi-auto prototype. I did not notice until after the fact that it works similarly to a paintball marker.

*These rather shabby paint diagrams represent the cross-section of tubes. Lighter shades represent holes in the wall of the tube. Black lines represent o-rings.


1.) The trigger holds the piston in a partially forward position. The airtank at the back is sealed off by a small valve.


2.) The trigger is depressed, allowing the piston to be propelled backwards by a spring. The piston hits the valve, forcing it open.


3.) Air is released from inside the tank, forcing the piston forward. The piston seals with the air outlet (barrel) and also opens vents, which allow air to flow past the first o-ring, into the piston, and through the outlet. After the air is released, the piston is pushed backwards by the spring, where it is either stopped by the trigger or continues to cycle.

[Jewstein]

Yeah it could work, but don't expect godly ranges out of it, regardless of the the spring you put in it, because there will always be the pressure of the spring in the front resisting against the plunger itself.

[LotusNerf]

When you said you were wondering if the mechanism would work at that pressure, 30-40 psi, I hope you were wondering if that relatively low pressure could handle it. There are two factors that I can think of right now in which it wouldn't. One, you use a mighty spring onto the piston so the pressure can't push it far enough because of all the force. And two, there is way too much friction for the pressure to push. Other than that, it should be fine.

Good luck on building this. I hope you've got a good system to feed darts. I would recommend either a hopper clip or simple breech that works with the piston to feed the darts.

-Lotus

[meatballica]

I could see this working but I see a few problems.

1. Range is more than likely terrible but hell if it works then you have built something that someone else could improve on.

2. I see a couple of leak points diminishing the range of the gun it self.

3. Something about the trigger design itself just does not sit right with me.

Also I like atleast you put some serious thought to this.

[zaphodB]

If you build that, it has a 50/50 chance of breaking every time you let go of the trigger. There's nothing to stop the trigger from catching behind the plunger and totally fucking everything up.

There's a bunch of other problems too, probably, but none that would totally prevent this from working as much as your trigger design.

[cheyner]

If you build that, it has a 50/50 chance of breaking every time you let go of the trigger. There's nothing to stop the trigger from catching behind the plunger and totally fucking everything up.

There's a bunch of other problems too, probably, but none that would totally prevent this from working as much as your trigger design.

The trigger problem would be easily solved just by cutting the back of the trigger into a slant. That way if it does go "behind" the plunger, it will simply slide over and catch the right way.

[meatballica]

If you build that, it has a 50/50 chance of breaking every time you let go of the trigger. There's nothing to stop the trigger from catching behind the plunger and totally fucking everything up.

There's a bunch of other problems too, probably, but none that would totally prevent this from working as much as your trigger design.

The trigger problem would be easily solved just by cutting the back of the trigger into a slant. That way if it does go "behind" the plunger, it will simply slide over and catch the right way.

Now that I think about it. I think a wall at the top of the T-part on the Plunger thing that would go over the trigger while it was back might be a good idea too. That way It would also help with the seal with the trigger.

[TantumBull]

You say you need a homemade replacement for the MS valve... Why not just emulate the function of an actual MS valve. It would be a lot easier/simpler than this set-up.

[TheRedRanger]

Just a few more details that I probably should've mentioned earlier. First of all, the diagrams are not to scale, and I also simplified some things in them; they are only designed to demonstrate the basic function of the valve. For example, the trigger. The catch design I am planning on using is similar to the one used in most nerf guns (and also Boltsniper, again... ). The full piston travel will be about an inch, and the piston tube has a 3/4" i.d.

-Just Some Bob: please elaborate?

-Out of curiousity, what if I used a 50-60 psi air source? I am experimenting with pvc tanks right now, but am trying to stick to lower pressures because of the dangers of pvc and air pressure.

Thanks for all of your help,
RR

Edit: posted at the same time as TantumBull. Tantum- This mechanism is designed to be easier to fabricate than a MS-type valve, while mantaining a small profile and cost(cheaper than buying a magstrike).

Edited by TheRedRanger, 07 April 2010 - 06:46 PM.

[LotusNerf]

Before everyone comments more, I would like to say that his main question was "Will this work?" We have concluded that it would but has flaws and whatnot, but that really doesn't matter until he shows us what he has made. So why don't we save what we have to say until he creates his product and then we can criticize and compliment the goods and bads of the design, before we clearly know how well this design may work.

And that is why I look downwardly upon design threads. (Not the design, just the comments and ideas that are left afterwards).

-Lotus

[CaptainSlug]

No design threads.
Build a prototype, then post about it. We're not your R&D sounding board.