SpudFiles

For my next multishot QEV project i have decided im not going to use a blowgun as a pilot valve like the one below:

i have used these in my other 2 guns and they work well but i have many problems sealing the thread as it is soft metal and im not sure how well they rate at higher pressures. Any suggestions for other types of pilot valves?

pressure washer trigger, slide valves and ball valves are all good.

For something a bit smaller and more concealable, you could use a presta valve. Then you would have your trigger attached to the rod of the shrader. This would offer plenty of flow for most of the smaller qevs.

jmez1996 wrote: i have used these in my other 2 guns and they work well but i have many problems sealing the thread as it is soft metal and im not sure how well they rate at higher pressures. Any suggestions for other types of pilot valves?

If they leak where the metal plate presses the valve down to release pressure, just grab a crescent wrench and tighten it down until it stops. Other wise grab teflon tape.

I would say a slide valve. However, I think I read somewheres that you can modify the blowgun in question. Take a look around the forums.

Modifying it doesn't make it stronger, if anything, weaker. You modify it for flow. I believe the good quality ones don't leak until 500 psi.

As pointed out in the other thread, it's not a bad pilot that's your problem but a poor piston configuration.

I just want to add that all blow guns are not equal. The ones $2.99 ones from Harbor Freight are pretty much worthless. Not only is the flow low, but they tend to fail to work at all after a while. The $4.98 Kobalt one that I picked up at Lowes isn't great but is much better.

After messing with these I have to wonder if I wouldn't be better off to build a pilot valve. Any suggested designs for that? I have been using an Orbit 1" jar top triggered with a blow gun as a pilot for a variety of sizes of home made valves. It would be nice if I found a blow gun that worked well enough to serve as a pilot without the Orbit.

With a well made piston setup - ie tight fitting piston and minimum dead space - the size of the pilot is not that important.

This used a schrader valve to pilot a 1" piston and it worked great: http://www.spudfiles.com/forums/3-4-exh ... t7173.html

I had blowguns leak at the brass insert threads, teflon tape fixed it

How about a homemade hammervalve?

I use them all the time.

Just a bolt with a small O-ring under the head, push it through a small fitting, add a spring on the opposite side and turn on a nut...basically.

You might have to superglue the O-ring to the head to prevent it being blown out...that or cut a groove for it to sit in....and you 'll probably have to file away the unused threads for better flow...

I'll have to tinker with some hammer valves. I could go a bit more elaborate as an excuse to play with my new lathe

Brian the brain wrote:How about a homemade hammervalve?

I use them all the time.

Just a bolt with a small O-ring under the head, push it through a small fitting, add a spring on the opposite side and turn on a nut...basically.

You might have to superglue the O-ring to the head to prevent it being blown out...that or cut a groove for it to sit in....and you 'll probably have to file away the unused threads for better flow...

Yes of course, hammer valve, I love hammer valve, I made a simple and cheap one like this for my gun...

If you used a hammer valve to pilot a QEV would it empty the entire chamber of air, or would it be possible to set up so the piston re seats itself fast enough so it only empties part of it?

on the contrary, you can use hammer valve to pilot for multiply shoot, you just need to add spring behind the piston valve and you can fill the air (if you want it) from the chamber side. The hammer valve will close when the pilot area pressurized..
I add picture for mine, I use one spring that used by the piston and the hammer valve, I don't know if this is OK, its work on mine though.