SpudFiles

I need to build a few candy launchers, which will use a sabot (plastic cup) and be fired veriically to avoid any gobstopper projectile injuries, or the occasional 500 fps jelly belly punching holes in the neighbors kids, however much I may want to.

basic mechanism with be a commercial or home built QEV (I have a 3d printer I'm dying to use to make parts), but I'm having trouble finding a really simple way to to pilot the thing without using a slide valve, just because it's awkward to fire and not very high tech. Any suggestions on trigger or push button (sprinkler solenoid) pilot mechanisms to recharge the firing chamber after it empties during a shot?

I know with the slide valve and a spring in the QEV the basic cycle is

move slide valve to open pilot to atmosphere
qev opens dicharging the dump chamber
reduced pressure in the barrel (qev outlet or R) closes the QEV due to spring presurre
closing the slide valves rechanges the dump chamber, ready to fire again.

any help will be greatly appreciated

Any three-way valve will work here. In one position, it connects your line to the pilot of the QEV, in the other, it vents the pilot to the atmosphere. A three-way solenoid would allow any number of electrical options for firing, down to using a microcontroller or monostable multivibrator to pulse the trigger allowing firing without completely exhausting the chamber to save on air and bring the power down a tad.

I'd like something a little cooler than a slide valve, and I'd rather build than buy, I;m thinking about making a solenoid activated spool valve with two ports. I know, that is a 3/2 DCV almost. I can't find any examples of anything but commercial DCVs or Slide Valves

There is an example of a hybrid using homemade solenoid valves for fueling but they're not three ways. I suppose it wouldn't be too difficult to roll your own three-way solenoid valves but that depends on your facilities or creativity.

EDIT: link