Are you dead set on pnuematics? You could set an Arduino to rotate a stepper or servo X number of degrees Y number of milliseconds after firing. Would only be a few more steps to make it continuous fire after that...

Why not just measure the correct amount of fuel with the syringe, and squirt that into the chamber? Would of course have to find a syringe of appropriate size for your fuel density (ie tiny fractions of an mL for liquids, something larger for gases)

I don't there is much of a consensus of one specific pump being the cat's meow. Pumps are pretty much a commodity - some are built a little better, or may last longer, but it basically is a game of 'you get what you pay for'

Probably. But maybe not. Depends on what sort of risks you like to take.

I assume the pneumatic piston on the right side will cycle the bolt automatically?

Holy cow!! SO many animations! You guys are not helping me avoid buying a lathe.

You might do some searching on burst disk pressure. Back in the day, I know that there was some testing done when layered tin foil disks were the cats meow. But basically what was discovered is that if the opening pressure is too high, the pressure spike would already be starting to diminish before ...

Still trying to make heads or tails of that first drawing... Where is the chamber? Is it that little area behind the arrow? Or does it not technically have a chamber, and instead the valve is essentially dumping just the air in the line between the tank and valve? And then your 'barrel' actually ...

Has anyone ever built a piston valve with an off-center valve seat? I am going for a twin barrel configuration, and I want them as close together as possible. But i don't want to use elbows, as that will increase dead volume, and introduce turbulence to the flow.

My gut says this should be a non ...

There's no doubt that I can build the valves, but time is such a limited resource.

I'm looking for a pair of 3/4" or 1" (20-25mm) QEV valves for a double barrel build. Everything I see that can handle ~200 PSI is over $100 per valve. I was hoping to spend more like $75-100 for the pair. Is this possible? Or am I better off just building some nice pistons?

Oh duh

Well I'll be. I had no idea. But it doesn't have any energy output - just distance/height. Although... I could probably work out the final velocity from distance/time. While I was hoping for something much more automated, that may have to do.

I did see that NASA page before, and frankly I am too ...

GGDT/HGDT have made the calculations up to the point of leaving the barrel a dream. But what about after? High school physics was a loooonggg time ago. I found this write up http://www.dummies.com/how-to/content/calculate-the-range-of-a-projectile-fired-at-an-an.html , but it appears to be rather ...

Due to life being life, I have found myself with too much free time, and need to fill it with something productive. I want more practice in my new 3D modeling program (Fusion360 - its awesome so far), as well as tweaking my CNC workflow. My machine can handle parts up to 30" x 18", with a Z travel ...