Ok, I'm confused too, maybe shuttle qev, is just a different way of saying piston qev.

Hopefully someone else will answer and clear the confusion.

Chris

I might be able to help if I can understand how this is intended to work. Is it supposed to momentarily open similar to a hammer valve? Is the yellow part just there to guide the right piston, and has holes all oround the perimeter for air to go through? I'm assuming you have an actual valve that yo...

I'm guessing it isn't to difficult to know what thread I'm really talking about that I'm currently helping some on out in. I just worry too much I guess. It's just that no one else has commented on the thread at all. It made me feel like I was the guys only source of info on how not to injure himsel...

A shuttle valve is not the same thing as a qev. I suppose you might be able to use it, but it would require a lot of extra parts and strange routing to get it to do the same job. Look up shuttle valve on Google, and you will see what I mean. It is designed to have two different pressure supplies to ...

I was just wondering if anyone else worries about the liability involved personally, when giving people advice on how to build a good cannon? I have been trying to give someone advice recently (on the forum) and although I feel that I have plainly stated the safety issues I see, at the same time I g...

A little update on the variable volume chamber plug. I don't quite know why , but I think I might have been over tightening it when I put it in the chamber. I never made any sort of a leverage handle on the wrench tube, but I guess I got too good of a grip on the wrench tube anyhow. Both the bushing...

That pump will work, but I think you will be suprised by how many pumps it will take to get the pressure up very high. What is the length of your pressure chamber? I suppose the risk you are willing to accept is up to you as far as pressure and pvc go. I would still do an over pressure test with a g...

I hear ya. The first one especially like you say. I have went the diy route on my few projects I guess without considering cost. I was more interests in the build process than anything else, more " I want to see if I can do this" than, "I want a cannon". Of course performance was a goal but I found ...

I'm glad it worked out for you. You should post some pics of it and give some performance details. Pvc is rated for water pressure, not necessarily air pressure. Water isn't compressable like air, so if pvc fails with water it just cracks and the water runs out. With air, it explodes and can send sh...

For a 1/2" bore a QEV is a more cost effective way to go. Welcome to Spudfiles! :mrgreen: I'm wondering how it is more cost effective jrrdw? Easier for sure, but how does a ready made, purchased valve cost less than a diy piston? I'm not trying to be argumentative , I'm honestly just curious. Chris

I think lubing the barrel would reverse the "ammo to barrel friction" improvement gained by double beveling the barrel, and decrease performance. If it were a pneumatic cannon, beveling the barrel might help because the pressure is already at max so a sealed and slippery projectile is what your aimi...

A couple of things I have been pondering on this project. #1: if I were to cut the end of the barrel off at an angle where the top of the barrel would be longer than the bottom would that impart a kind of hop up spin to the marshmallow? I'm thinking the air rushing out under the shmallow first as it...

I went with it for maybe 1/3rd looks and 2/3 function. I was thinking of possibly making some sort of a sliding breech loading barrel, so I needed that support up front, and I liked that location of the gauge so it would double as a cheek rest for the scope. I feel my chamber volume is to big though...

Totally digging up an old post here but I couldn't help it...

Great minds think alike?

http://www.spudfiles.com/pneumatic-cann ... 13286.html

Alright, more work done. I really just didn't want to use band clamps on this one, so had to figure something else out. Had some oak pallet scrap laying around so I slapped this together today. Still needs some counresinking done, some grinding on the t-nuts and general smoothing and shaping but it ...