loading

Using a small solenoid to trigger a co2 hammer valve

Hello, I have a question that is integral to the design of a project i'm making.

I am trying to make an airsoft gun. For a power source, I am using a 12 gram co2 powerlet. My main problem is the trigger mechanism. Since I want the design to be semiautomatic with no blowback, I decided on an electric trigger to avoid the long trigger pull associated with mechanical triggers. My valve is taken from an airsoft pistol magazine and is pretty small. It is operated by having the rear "button" of the valve hit with a simple hammer, which moves the valve pin and releases gas into the barrel. I want to use a small solenoid in place of the mechanical hammer. When activated, the solenoid's push end would snap forward and hit the valves "button."

I was wondering if this is possible on any kind of smaller power supply? It doesn't seem like the valve button needs much more than a tap to dump a good amount of gas. All the projects i have seen like this are fairly large scale, for larger airguns, and they had to use large unreliable power supplies. I would like to keep this whole thing as lightweight as possible. 

I was thinking that i could use a simple switch or circuit that would just dump some voltage into the solenoid for just a fraction of a second, to fire one shot for each trigger pull.

Would this solenoid work? http://www.adafruit.com/products/413

Also, the valve I am using is tiny, about an inch long. The "button" that needs to be tapped to release gas is about 6 mm in diameter. 
Is there any way to calculate the exact amount of force needed to trigger the valve? 

Does anyone have any advice for me? 

I have done a lot of paintball games in my young years and we all modified our guns one way or the other.

At some stage I experimented with an electrical trigger for a semi automatic rilfe I had.

Biggest problem was to find a reliable solenoid with enough force and only after a lot of trials I found out that a push type with a weight attached to it was the only thing producing the right impulse and power.

Downside was that the speed as there is only a spring getting the solenoid back in starting position.

It was simply impossible to get the speeds you reach when just your finger for each shot.

In the end I bit the bullet and used a trigger mechanism that works just with the gas pressure by a moving pin with two valve holes.

One to get it moving on the trigger, the other to get it back fast.

Used a bit more gas but was the most reliable thing ever.

If you can store a good 12V battery you can try to use a solenoid valve like used on LPD tanks in the car (cheap at the wreckers).

Not 100% if they get the usualy icing problem after heavy use but would be your best option as I doubt you can find a proper way to operate a manual trigger with small sized solenoids.

Kiteman2 years ago

I don't know about the solenoid, but you could measure the required force by bracing the "button" vertically, then piling weights on it until gas is released. 100g mass weighs roughly 1N.