SpudFiles

Hello,I will be leaving for my family cabin in Montana this Friday instead of being cooped up in darn ol' london, so I will have plenty of space and time to build a more powerful air gun. The following drawing is my first attempt at creating a piston valve air gun. Please add constructive criticism, tell me if it would work. Basically its a piston valve actuated by a burst disk. Hope my drawings clear enough! lol.

ummm yeah but you have to know a little about both valves before you try it first of all shrapnel from your burst disk can be very dangerous at close range sometimes they will imbed themselves in a target(so towards your face or body isn't a good idea). but if you really want to have a hammer actuate it i would make a push button valve put it in place of the burst disk. what i would do is get rid of the spring and make one that uses a normal pilot but thats just me ps: there is no need for the equalization port

thanks but my mechanism to actuate it is a little different now. you have a threaded endcap filled with dried glue. you pull back the hammer behind it, pull the trigger, and the needle on the hammer puntures a small hole in the cap. This releases a small stream of air, not to explode the cap. When shot, unscrew cap, screw in new one etc.

If you're going to go to the trouble of using individual burst disks for each round then why not use a burst disk as a main valve?

Porting a piston with a burst disk will give no performance increase compared to say a QEV.

Edit: By the way, the scale of your gun is massively out of whack.

I know its unscaled.

But Im building this for power AND looks, so I want it looking like a real fire arm.

Exactly. A hammer valve to port it will work just as well depending on size.

As a note for the scale, the barrel needs to extend well over the chamber port.

dilweed wrote:I know its unscaled.

But Im building this for power AND looks, so I want it looking like a real fire arm.

well what kind of ammo do you plan on shooting if it's small you could just make a hammer valve and if its large you could just go with a burst disk for the main valve like inonickname suggested it wouldn't be that hard to make it look like a real firearm if you used a hammer valve it would be more difficult but still possible with a burst disk so i don't see the problem

Im planing on making it 30 - 40 cal, use 180 or more psi and want at least 50 ft/lbs from it. I also plan on shooting it up to 25 yards and want it to be capable of shooting into plywood.

dilweed wrote:Im planing on making it 30 - 40 cal, use 180 or more psi and want at least 50 ft/lbs from it. I also plan on shooting it up to 25 yards and want it to be capable of shooting into plywood.

using 20mm chamber 25cm long and a 10mm barrel 120cm long and this valve http://www.spudfiles.com/forums/self-cl ... 17609.html at 180psi ggdt predicts 71ft pounds and 500fps with an 8g projectile more than enought to accomplish what you want

Thankyou very much.