johnny_7713 wrote:Tyndmyr wrote:
Unfortunately, it looks like they're focusing on plastic because they're targeting the type of 3d printers people actually own. Plastic's burst strength is not traditionally great. You also have to worry about layer separation from the 3d printing process. In addition, the burst strength of plastic normally decreases sharply if you heat it(especially suddenly). These are not at all good properties for a firearm. Sure, there are specific parts where plastic can be used with little risk. Grips, for instance. AR lowers(as has already been done elsewhere). But 100% plastic is going to fail very, very quickly. Just getting it to make it through one round without failing in a way that injures the user is non-trivial.
Many good points. I do feel compelled to point out that 'plastic' can mean any of a very broad variety of materials, with very different properties. The sub-set of those that are suitable for 3D-printing is probably much smaller however (I'm not sure what the requirements for 3D printing are).
Most home printers are doing PLA, ABS, or some variation thereof. These are not bad plastics...Lego is made from a type of ABS, for instance. However, I wouldn't trust a gun made out of Legos.
Ormurinn wrote:They're using ABS - with regards to making a gun, it could be better, could be worse, as polymers go. The really interesting developments are going to come in 3d printing when you can reliably print multiple materials in a single job.
Tyndmyr, (welsh name?) in your experiments with home firearms, have you come across any particular configuration that's worked well whilst incorporating printed parts?
Random internet name born of frustration at everything being taken, actually. =) My experimenting has been rather minor so far. I did print an AR mag, but experienced problems with expansion based on the models freely downloadable from thingiverse. I rather suspect they were originally CNC models that were not tested heavily on printers. So, I twerked 'em a bit to get them to work, and added a crude spring(their model didn't have this essential part). I'm not 100% satisfied with the spring yet, and metal is probably still a lot better, but you can indeed print a functional mag if you're willing to twerk it a bit. I've also done some basic trigger mechanisms, primarily styled on crossbow rotary styles. This seems to work pretty well, but I'm still trying to work out how to get enough springiness from the plastic to slam a firing pin fast enough without taking ludicrous space. And also for the firing pin to not just fail.
There's a lot of parts on existing guns that can indeed be replaced by plastics, though. Usually, barrel, chamber, firing pin are the toughest parts. They're exposed to the highest forces. That said, from a strictly "making a gun practically" standpoint, two of those three are mostly just pipe, and the last is a metal pin. They're not that hard to machine(though rifling does raise the difficulty a notch).
omgryebread wrote:If you're sane and responsible enough to have a gun, you should be able to get one without overwhelming obstacles without printing it. If you're not, it should be as hard as we can reasonably make it to get one.
I admit, the image of crooks trying to learn materials science and 3d modeling skills does amuse me. The idea of making self-education a necessary obstacle on the path to obtaining a firearm does have a certain oddball appeal to it. It's probably unlikely to ever happen...anyone with a coupla grand to get a printer and stuff for it is gonna just be able to buy a gun with that money, but the idea of a desire for crime motivating people to better themselves is kind of ironic.
BlackSails wrote:I cant wait for 3d printer technology to advance to the point where the RIAA commercials on "you wouldnt download a car" can be answered with "I can and I have"
Oh, I'd download a model for a car in a heartbeat. Also, I'd need to order more plastic. Again, like with guns, there are some serious obstacles to printing entire vehicles, of course...but there are in fact many minor parts that can be printed. Break a stupid mounting bracket that the company will charge you a ton for? Print a new one.
some_dude wrote:If you don't like the current gun control laws, the correct response is to try to influence politicians to change the laws; not to abuse a new technology to circumvent them. That you don't agree with a law doesn't give you the right to break it.
While I would generally encourage political means first, in extreme cases, people may indeed be morally justified in breaking an immoral law.
Red Hal wrote:3D Printing is the first step of many along the road to a post-scarcity society. Such a society would be a very hostile environment for traditional capitalist organisations. No wonder they want to shut it down.
One fine day, I hope the Culture exists, and it is us.