QEV vs homemade piston valve

[tater slayer]

Helo, Spudfiles!
I'm about to begin my 3rd air cannon build, and this time, I plan to make a smaller air cannon(1/2 inch barrel) working off of a quick exhaust valve. However, Since this is my first cannon that won't be utilizing a ball valve, I thought I'd ask you guys: does a homemade piston valve have any advantage over a store-bought QEV (ie. parker or deltrol)? I know that I could add a spring behind a homemade piston valve, but is this really worth the hassle and the cost of the build?
Thanks in advance!
tater slayer

[jrrdw]

For a 1/2" bore a QEV is a more cost effective way to go.

Welcome to Spudfiles!

[tater slayer]

Cool, Thanks for the help!

[lockmanslammin]

For a 1/2" bore a QEV is a more cost effective way to go.

Welcome to Spudfiles!

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

[jrrdw]

Buying a ready made valve of the size pretty much equals the cost of driving to the hardware store, then buying the parts, the drive home, trial and error, back to the hardware store etc... etc... Then there's the cost of time and aggravation of getting it to work reliably.

tater slayer has only built ball valve cannons and if you've never built a piston valve before, the 1st one is always tricky. :bigsmurf:

[tater slayer]

I've seen some used QEVs listed on eBay for as low as $10. My previous attempt at building a QEV (which I rushed) cost upwards of $15-20.

[lockmanslammin]

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 after I finished it that I didn't really use it a whole lot. I'm sure tater slayer will enjoy the performance gains over a ball valve with either choice.
Thanx for the explanation jrrdw, and good luck on the 1/2" cannon tater.

Chris

[mobile chernobyl]

Like others have said before - after 3/4" - the QEV is going to be more expensive for sure!

It's not always the case that you get a adequately sealing and robust piston valve constructed on your first try. I had a coaxial 2" cannon fracture (explode pretty much) from inadequate design earlier on in my spudding career. The end result was a fractured wrist on the person who was holding it. Never would have expected it to fail like that - but it was certainly a defining point in my transition from "hand held" to "cart mounted" spud cannon design. I also adapted remote firing capabilities to pretty much every cannon after that. The plus side to this was that size and portability no longer were an issue and I was able to make cannons as big as I could transport!

[tater slayer]

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 after I finished it that I didn't really use it a whole lot. I'm sure tater slayer will enjoy the performance gains over a ball valve with either choice.
Thanx for the explanation jrrdw, and good luck on the 1/2" cannon tater.

Chris

Thanks, Chris!

[tater slayer]

Also, I apologize for my inexperience, do you guys have a preferred type of QEV? I mean, between the rectangular block style, the spherical builds, and the heavy duty Parkers/Deltrols, which valve would provide me with the safest (200psi max) and best performing cannon?
Thanks in advance!

[Ianbuckwell]

In my opinion branded ones!!! I boiught a black box Chinese version advertised as 0.5 or 0.75" and it was utter dog do, the actual outlet was far smaller maybe they measure them before they put the gold color red part on, who knows?. I now have a Parker QEV and couldn't be happier, its taken serious abuse and is showing no sign of deterioration.

Saw a second on Ebay and thought to myself has anyone run two in parallel? Not because it needs it (the flow of them is great) but just for the hell of it but that's another story and will have to wait as currently working on a cannon

[Gippeto]

Still have a preference for home built....you LEARN by building and trouble shooting....you learn next to NOTHING by threading pre-built stuff together.

Mistakes cost a lot less when you're building a small valve than when building a large valve, and they WILL be made...all part of the learning process.

JMHO