Tyndmyr wrote:I hope to god they take proper safety precautions when testing. IE, remotely triggered, not held in hand, LOTS of safety gear. I've got a flak vest for this very purpose. You don't want a gun to kaboom when you're holding it.
, which is kind of good since the gun did end up in several pieces when they tried firing a 5.7mm round through it.
It held up to .380 ACP, though (the barrel lasted for 10 shots). But it's still quite unreliable- sometimes the firing pin doesn't hit the right part of the cartridge...
Not surprised...that said, 10 rounds of .380 is still better than I expected for a first time. Firing pins tend to be kind of fiddly bits, so yeah, that's gonna happen when you're using a springless design. Easily solvable by going to a more conventional spring-fed design to get more power on the pin, and springs are sufficient available that I don't see that being any more of a roadblock than the inclusion of the nail.
Also, regarding tracking and the like- governments were pretty worried when laser printers became widespread and inexpensive, due to how easy they made counterfeiting. Laser printers now encode information about the printer serial number and time of printing in a pattern of barely-visible dots on each page they print. I wonder if governments will try to persuade major 3-D printer manufacturers to do something similar- and how easy it would be to remove the tracking.
Extremely easy. Might happen accidentally. Even if we ignore current resolution limitations, it's gonna be very common to have at least minor post-print finishing. Removing support materials, sanding down any rough areas/expansion, gluing other things to it and what not.
Plus, rather a lot of 3d printers are in the hobbyist camp atm. People rolling their own.
Plus, pages have a standard location for the dots. Objects, by virtue of their diversity, do not. There's rather a lot of problems facing anyone who wants to limit this technically.
The barrel of the gun was printed from a $8000 printer and then chemically treated to improve the strength of the plastic.
But one important trick may be the group’s added step of treating the gun’s barrel in a jar of acetone vaporized with a pan of water and a camp stove, a process that chemically melts its surface slightly and smooths the bore to avoid friction. The Dimension printer Defense Distributed used also keeps its print chamber heated to 167 degrees Fahrenheit, a method patented by Stratasys that improves the parts’ resiliency.
Huh, I heard Acetone helps with ABS, and have already tried washing it with that as a solvent...didn't do jack for me. Let the piece in there overnight just for fun, and it didn't care. Vaporization shouldn't matter...that should only be to limit the exposure.
Heated print chamber is something I've considered(didn't realize it was patented, seemed obvious), but I haven't gotten around to building one yet.
Moving on to nastier solvents, I suppose.
And if the process is done wrong... have they created a grenade? What insures that you've treated the plastic barrel correctly?
Yeah, that's pretty much always what happens when a gun kabooms. You really don't want that happening in your hands, since a round is basically a small explosive. Commercial guns tend to err WELL on the side of safety here.
Now, you can get by with using weaker materials in greater quantities...but as you go to extremes(like say, marshmallows), even if a vast quantity of them would contain the blast, it doesn't really direct the blast the way you need to for the bullet to travel. I'm curious what sort of speed they're seeing on the .380 round...and conversely, how much the gun is getting damaged in each shot.
Edit: Well, got the plans downloaded, cookin' on the printer now...looks like I can do it all in four batches over a day in a half, and, as it happens, Ive got about a hundred rounds of .380 sitting in my closet for no reason. I'm thinking that *should* be enough to destruction test it. If it doesn't fail immediately, I'm gonna kick out another barrel for sleeving(I've got a .22 sleeve on hand for exactly this reason, and at 4 inches of sleeve per handgun, that's only a coupla bucks per). If, and this is a big if, everything is still functioning decently at that point, I'm gonna go crazy and adapt a .410 barrel for it to become a shotty pistol. I fully expect that this'll shatter the springs at minimum, but what the hell, plastic is cheap.