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Posted: Tue Mar 18, 2008 3:53 pm
by Sticky_Tape
Doesnt the pop off close at a certain low pressure?

Posted: Tue Mar 18, 2008 4:28 pm
by Brian the brain
It does but the pressure is constantly running, so it never again reaches that low point.And that's your problem in a nutshell.

You'd think a gaint pop-off would empty the pilot faster, but a GIANT pop-off also had a much larger surface area,wich needs less pressure to stay open, so no...that doesn't work either.

Maybe a pop-off activating a QEV-wich in turn activates another QEV would work, but that would waste SO much gas, you're no better off with than with a cloud.

Posted: Tue Mar 18, 2008 4:37 pm
by Sticky_Tape
BTB did you look at the diagram I made it has restricted flow into the pilot chamber and if the pop off has greater flow than the fill pipe than the pressure will get low enough for it to close.

Posted: Tue Mar 18, 2008 4:48 pm
by Brian the brain
You posted it like three times already.
I could not have missed it if I wanted to

Okay.. :cry: .Fine...go ahead...make it work

I've wasted three months on the idea.
Get ready for some mayor frustration like me and JSR...

Either you'll solve it or give up on it like I have eventually.
Best of luck :wink:

Posted: Tue Mar 18, 2008 4:50 pm
by Sticky_Tape
Thanks just as a reference have you tried using restricted flow?

Posted: Tue Mar 18, 2008 4:57 pm
by Brian the brain
Yep
It took 2 seconds to fill the reservoir...pssssshhhhhhhhooop
The Snapvalve ( as I called it) dumped the pressure in a split second and that was still not fast enough.


Not really "full auto" if you restict it any more than that now is it.

Posted: Tue Mar 18, 2008 5:15 pm
by Sticky_Tape
did you try useing a larger pilot volume?

Posted: Tue Mar 18, 2008 9:17 pm
by VH_man
If you look at the design posted, i think it would be impossible for this piston system to fail.

if you look at the bottom where the Air cylinder/loader/valve is pushed upwards, you can see its a "tapered" variety.

this means that the little rod will SHOOT upwards once a certain pressure is reached, therefore making it impossible to "fart".

JSR? is your Reciporicating Piston done yet?

Posted: Wed Mar 19, 2008 3:39 am
by jackssmirkingrevenge
VH_man wrote:JSR? is your Reciporicating Piston done yet?
Which one?

The unfortunate problem with all these designs is that nature tends towards a state of equilibrium, hence the flatulence that everyone who has dabbled with these designs has experienced. It's not impossible to achieve, but very, very hard to get the right balance of friction, pressure and spring power.

I still think the future lies with preloaded cartridges, that or high pressure hammer designs like the Caselman or externally powered designs like the ones I detailed in this thread.

Posted: Wed Mar 19, 2008 8:10 am
by Skywalker
Jack, it souds like the problem with your gun was that not all the air left the chamber when it fired, so it took a while for the bolt to close as air leaked around it. Is that right? Or did it 'hang' right at the bottom of the stroke b/c of air coming in from the schrader?

I think we could still make this work if we used the initial version of Jack's concept with the slide style valve instead of the schrader/poppet for the fill valve, and if a different mechanism were found to operate the breach. I've got an idea, let me go draw it up.

Posted: Wed Mar 19, 2008 8:34 am
by VH_man
I actually have an idea now loosely based off of a Paintball Autococker......

it uses electronics. Ill draw up plans as well.

Posted: Wed Mar 19, 2008 10:37 am
by SPG
I'm now confused about whose designs we're critiquing. Are we still on mine, or have we moved on, if we've moved on where have we moved on to.

Mind you, I realised mine will make a fine little self-loading semi-auto, even if it won't go fully. All I'd need to do is take the spring off. Fill with pressurised air and it'll open no problem, then push the slide back by hand and start again.

Of course, pop a solenoid in there with a timing circuit and voila semi/fully auto electro-pneumatic.