Gunsmith Uses 3D Printer To Make A Rifle • Hacker News Board

Re: Gunsmith Uses 3D Printer To Make A Rifle

#11

Post by cubicle » Thu, Jul 26, 2012, 6:28 PM UTC

1.) Blogspam. OP is http://www.webpronews.com/gunsmith-uses-3d-printer-to-make-a...

Does HN have any mods?

2.) Have blue has a blog, he's written two posts about this: http://haveblue.org/?p=1041 http://haveblue.org/?p=1321 It appears to be down right now, though. Cache links: https://webcache.googleusercontent.com/search?q=cache:DlBe32... https://webcache.googleusercontent.com/search?q=cache:Z_5bOF...

3.) He printed a AR-15 lower receiver, which is the part, under US law, considered a "firearm". The high pressure components (barrel, bolt) are all made from conventional manufacturing processes, using steel.

Lowers are typically made out of aluminum, but they don't really experience any great stresses, so it's perfectly possible to make them out of plastic. (There's a number of commercial lowers made out of fiberglass: http://www.mdshooters.com/showthread.php?t=65134 (I'd link directly to the manufacturer's site, but it seems they're better at making guns than they are at securing web servers)) As he notes, people have even carved them from wood.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#12

Post by Kallikrates » Thu, Jul 26, 2012, 6:28 PM UTC

jff wrote: post #5

I might be reading it wrong, but it looks to me like he printed a receiver and placed all the moving parts and the barrel etc. in it. See "I printed a modified version of the lower from cncguns.com"

The receiver is the only part of the rifle that is controlled. Everything other than the receiver can be bought on the internet without background checks or registering of serial numbers.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#13

Post by cmelbye » Thu, Jul 26, 2012, 6:28 PM UTC

Strallus wrote: post #7

Seriously, what happened to real journalism? Articles are now being written based on a handful of unverified forum posts. Really?

Not to mention the gratuitous editorializing by the author throughout the article.

Are there any technology news sites that are truly journalistic these days? (serious question)

Re: Gunsmith Uses 3D Printer To Make A Rifle

#14

Post by ChuckMcM » Thu, Jul 26, 2012, 6:29 PM UTC

Doesn't pass the sniff test.

Chamber pressure in a .22 cal pistol is on the order of 20,000 PSI [1] The tensile strength of thermoplastic at standard temperatures is 1/2 that [2] and it goes down as the temperature goes up (its a thermoplastic for a reason). Firing a .22 caliber round using gunpowder would destroy the barrel on the first firing.

Now I could believe you built the receiver and triggering mechanism on a thermoplastic printer, but not the actual firing chamber.

[1] http://www.lasc.us/SAAMIMaxPressure.htm [2] http://www.engineeringtoolbox.com/physical-properties-thermo...

Re: Gunsmith Uses 3D Printer To Make A Rifle

#15

Post by ktizo » Thu, Jul 26, 2012, 6:31 PM UTC

jff wrote: post #8

jakeonthemove wrote: post #4

Well, it's definitely possible to print a silencer, a pistol shouldn't be that much harder. I'm afraid that this would make the governments impose stricter laws on 3D printers, which is not a good thing...

A suppressor has no moving parts and serves only to baffle the expanding gas and reduce noise. It experiences relatively low heat and gas pressure. The components of a firearm have far tighter tolerances and must withstand significantly higher levels of pressure and heat. It's not even close to the same thing.

This technology is used to print engine parts for F1 car racing - http://www.eos.info/en/products/systems-equipment/metal-lase...

And it is only going to get cheaper - http://reprap.org/wiki/MetalicaRap

Re: Gunsmith Uses 3D Printer To Make A Rifle

#16

Post by kwantam » Thu, Jul 26, 2012, 6:32 PM UTC

ChuckMcM wrote: post #14

Doesn't pass the sniff test. Chamber pressure in a .22 cal pistol is on the order of 20,000 PSI [1] The tensile strength of thermoplastic at standard temperatures is 1/2 that [2] and it goes down as the temperature goes up (its a thermo plastic for a reason). Firing a .22 caliber round using gunpowder would destroy the barrel on the first firing. Now I could believe you built the receiver and triggering mechanism on…

The part that's 3d printed is the lower receiver. In an AR-15 style design, the lower receiver doesn't handle any pressure at all, it just houses the magazine and hammer/trigger/sear/safety, and connects to the upper receiver/barrel assembly and the buttstock/buffer tube assembly.

People have made lower receivers out of aluminum basically forever. Aluminum could maybe be made to handle .22lr type pressures, but certainly not .223rem or bigger. A plastic lower is completely believable.

EDIT: to clarify, I meant if you wanted to make the whole gun out of aluminum you might be able to get away with it for a .22lr. Aluminum for a lower receiver is absolutely no problem at all. Apologies for not being clear.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#17

Post by jff » Thu, Jul 26, 2012, 6:33 PM UTC

Kallikrates wrote: post #12

jff wrote: post #5

I might be reading it wrong, but it looks to me like he printed a receiver and placed all the moving parts and the barrel etc. in it. See "I printed a modified version of the lower from cncguns.com"

The receiver is the only part of the rifle that is controlled. Everything other than the receiver can be bought on the internet without background checks or registering of serial numbers.

Yes, I know that part, I was simply pointing out that he did not necessarily print out a barrel or trigger pin or any of the other many parts needed to make a whole pistol.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#18

Post by duaneb » Thu, Jul 26, 2012, 6:33 PM UTC

jakeonthemove wrote: post #4

Well, it's definitely possible to print a silencer, a pistol shouldn't be that much harder. I'm afraid that this would make the governments impose stricter laws on 3D printers, which is not a good thing...

I'd be more scared if they could successfully manufacture lethal ammunition.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#19

Post by pyre » Thu, Jul 26, 2012, 6:35 PM UTC

simcop2387 wrote: post #9

sp332 wrote: post #3

Man, they didn't show you that in Star Trek... edit: to be specific, they glossed over it instead of confronting a scenario where an enemy hijacked a replicator to make whatever physical or chemical weapons they wanted at a moment's notice.

Actually it was touched on in a number of episodes (which i don't feel like digging up) but in more than once instance they mentioned that the replicators had safety systems that prevented unauthorized creation of at least some dangerous materials, (from what i recall, poisons were mentioned in one, weapons themselves i'm not sure).

True, but what could be poisonous to one species, could be nutritious to another. The idea that 'poisons' are easily identifiable is pure fantasy.

Re: Gunsmith Uses 3D Printer To Make A Rifle

#20

Post by cubicle » Thu, Jul 26, 2012, 6:36 PM UTC

kwantam wrote: post #16

ChuckMcM wrote: post #14

Doesn't pass the sniff test. Chamber pressure in a .22 cal pistol is on the order of 20,000 PSI [1] The tensile strength of thermoplastic at standard temperatures is 1/2 that [2] and it goes down as the temperature goes up (its a thermo plastic for a reason). Firing a .22 caliber round using gunpowder would destroy the barrel on the first firing. Now I could believe you built the receiver and triggering mechanism on…

The part that's 3d printed is the lower receiver. In an AR-15 style design, the lower receiver doesn't handle any pressure at all, it just houses the magazine and hammer/trigger/sear/safety, and connects to the upper receiver/barrel assembly and the buttstock/buffer tube assembly. People have made lower receivers out of aluminum basically forever. Aluminum could maybe be made to handle .22lr type pressures, but certa…

  Aluminum could maybe be made to handle .22lr type 
  pressures, but certainly not .223rem or bigger.

?

The Alexander Arms .50 Beowolf lower is made out of aluminum. http://www.gunblast.com/50Beowulf.htm

You can also buy single-shot .50 BMG uppers that bolt right onto regular aluminum AR-15 lowers, though of course you can't feed .50 BMG through a 5.56 magazine well.