Q+A: Cody Wilson Of The Wiki Weapon Project On The 3-D Printed Future of Firearms

popsci.com ^ | 21 December, 2012 | Clay Dillow

[archy]

3-D printer ping

I'll be mightily impressed when I can print springs.

[null and void]

You can now.

[archy]

You can now.

Some possibilities exist using designs engineered for these new methods and processes. Using them to build replacement springs for equipment based on preexisting technologies may be another matter.

*example*

We shall see. But things are advancing nicely.

[null and void]

Yes. CURRENT available materials include: Ti and Ti alloys, Stainless Steel, Cobalt, Cobalt Chrome, Tool Steel, Nickel, Nickel Super alloys, 316 Stainless Steel/Bronze, 420 Stainless Steel/Bronze (Annealed & Non-Annealed), Bronze, maraging steels, dental alloys, Al and AlSiMg, 18kt gold, silver.

I've seen shape memory alloys mentioned in the past day or so but can't find the source off hand.

[null and void]

Shove a pellet into the front end of a cylinder, meter acetylene into the center of that cylinder at 10 psi, then abruptly slam a piston into the back end...

[Gandalf_The_Gray]

Shove a pellet into the front end of a cylinder, meter acetylene into the center of that cylinder at 10 psi, then abruptly slam a piston into the back end...

Sounds promising, you'd probably need cast iron piston rings to contain the gas pressure and a spring mechanism like the single shot spring/piston air guns at least for "proof of concept". It might be possible to let the spring piston rebound, cocking it for another shot. Full auto may even be possible. The characteristics of acetylene are such that you don't need air or oxygen if you can get it to detonate reliably from heat of compression it makes for a much simpler mechanism.

I remember a long time back the old Science and Mechanics magazine had a cover story about a rocket powered go cart. The exhaust gas from a single cylinder two piston engine was ported through a nozzle along with steam from the engine cooling jacket. The two pistons were not connected to any output mechanism. They ran a two cycle porting with bounce chambers to return them to top dead center. It ran on acetylene and reached something like 20,000 cycles per second. The inventor called it "loud mouth". Hmmm

Regards,
GtG

[null and void]

Yes. I’m thinking a structural plastic frame and piston with a steel spring, brass (or steel?) tube sleeve and cap on the piston.

[Gandalf_The_Gray]

It was really late (early?) when I wrote this so:
"20,000 cycles per second" should be "20,000 cycles per minute"

Regards,
GtG

[Gandalf_The_Gray]

I’m thinking a structural plastic frame and piston with a steel spring, brass (or steel?) tube sleeve and cap on the piston.

You are entering entirely new territory here so remember to stay on the safe side. Do not hold your little monster in your hand when test firing as one handed typing would slow down future posts. It's better to make haste slowly.

Myself, I'd go with steel frame and piston until I could debug the mechanism and make sure everything works before lightening things up. Acetylene Is unpredictable and without knowing peak pressures (we are talking detonation not ordinary combustion) it's better to make your prototype as robust as possible then carve away until something blows up. Stay safe!

Regards,
GtG

[null and void]

Purely a speculative exercise. I know the limits of my skills.