Amateur gunsmiths have made lower receivers for years, in metal, although the process requires a certain level of machining expertise. Inexpensive 3-D printers have grown in popularity — their rise has been compared with that of personal computers in the 1980s — in part because they are easy to use. It is not even necessary to know how to create the design files that instruct the device to print bit after bit of plastic to build the object, as there are files for tens of thousands of objects available on the Internet, created by other users and freely shared.
Still, some tinkering is usually required. Guslick, who works in information technology and describes himself as a hobbyist gunsmith, printed his receiver on a machine he bought online through Craigslist. He used a file and abrasive paper to make the piece fit properly, but overall the project was not much of a technical challenge.
Only Wilson, a law student who prints his receivers on friends' machines, had overtly political motives, wanting to demonstrate what he called the absurdity of gun-control laws. He took his efforts even further, printing high-capacity magazines like those that would be banned under recommendations proposed by President Barack Obama and successfully testing them earlier this month on a firing range south of Austin. He has posted the drawing files at his website, defcad.org, so that others can print the magazine.
Wilson also has a project to develop a fully printable one-shot weapon, although he has not made much progress. He is seeking a firearms manufacturer's license, which he would need to even make prototypes of a complete weapon.
He gets advice and technical help from a loose network of about 15 collaborators around the world and has posted other printer files at his site, including Guslick's file for a lower receiver.
Baetzel posted his files on his own blog, Ambulatory Armament Depot, after a printer file-sharing site, Thingiverse, forced him to remove them in December. A spokeswoman for MakerBot, a 3-D printer manufacturer that sponsors Thingiverse, pointed out that the site's terms of service prohibit content that "contributes to the creation of weapons."
Guslick, who is machining a couple of metal lower receivers, said 3-D printers were far from the best tool for gun-making, an opinion shared by Neil Gershenfeld, a professor at MIT and director of the school's Center for Bits and Atoms.
"A well-equipped machine shop for a long time has been able to make gun parts," Gershenfeld said. "Three-D printers make not very good ones."
The types of computer-controlled tools found in a machine shop — primarily laser cutters and milling machines — are expensive. But smaller and cheaper versions are now available to dedicated hobbyists, although they do not yet have quite the mass appeal of 3-D printers.
Yet the printers have other drawbacks besides the use of plastic. They are slow, often taking hours to build an object, and the results, while impressive to the eye, can be too crude for extremely closefitting parts.
And as Guslick pointed out, anyone who is desperate for a weapon "has the ability to assemble a zip gun from parts bought in a hardware store for $15."
The National Rifle Association did not respond to messages requesting the group's position on 3-D manufacturing. But for gun-control advocates, the real worry regarding 3-D printers and other machines is what the future might bring in the way of technological advances.
"Down the road it's going to be a big concern," said Josh Horwitz, executive director of the Coalition to Stop Gun Violence. "We don't know how that's going to come about and don't know what technology."
Baetzel, for one, said he did not worry about what other people might do with the technology. "I follow the laws," he said. "I personally think everyone else should follow them." He said he did not post his designs hoping that someone would use them illegally.
沒有留言:
張貼留言