Jun 5, 2015 | By Simon

Ever since they launched in July of 2012, open source firearm - or “wiki-weapon” - organization Defense Distributed have been fueling both sides of the gun control debate while simultaneously breaking down barriers to reveal what the future of manufacturing might look like for other, non-firearm industries.

The organization has already had success with creating 3D printed firearm components that are otherwise regulated, and has openly shared them with the worldwide community of 3D printing enthusiasts and gun lovers alike.  More recently though, the organization has looked other ways of fabricating their gun parts - particularly the lower receiver of an AR-15 assault rifle - while utilizing the same digital file that they were able to use for 3D printing.   

Their latest development comes in the form of the Ghost Gunner; a general purpose CNC mill that was built upon a large body of open source work and includes gshield 3 axis motion hardware, the grbl g-code parser and motion controller and popular microcontrollers.  The Ghost Gunner allows users to create the exact same AR-15 receiver that was 3D printed, however instead of plastic, the CNC capabilities allow users to create the receiver in solid aluminum - which is clearly a much more durable material for a firearm.  

To test out the difference between the 3D printing method and the Ghost Gunner method, Wired senior writer Andy Greenberg recently created the untraceable “ghost gun” firearm using both methods and documented both the final costs as well as his build process - which occurred in the back of Wired’s offices in downtown San Francisco rather than a presumed industrial workshop.  

“I did this mostly alone. I have virtually no technical understanding of firearms and a Cro-Magnon man’s mastery of power tools,” says Greenberg.

“Still, I made a fully metal, functional, and accurate AR-15. To be specific, I made the rifle’s lower receiver; that’s the body of the gun, the only part that US law defines and regulates as a “firearm.” All I needed for my entirely legal DIY gunsmithing project was about six hours, a 12-year-old’s understanding of computer software, an $80 chunk of aluminum.”

While existing desktop 3D printers can easily cost over $2,000, the Ghost Gunner CNC mill is just $1,500 and is capable of creating more durable metal parts through a material extraction method rather than an additive method - however they both utilize the same 3D CAD model types to produce a finished, physical object.  

Over the course of a few weeks, Greenberg produced the firearm design using three different manufacturing methods: 3D printing, the Ghost Gunner CNC Mill and the more traditional drill press.  

While the drill press has been used for generations to mill out metal for the creation of firearm parts, Greenberg admits that due to his lack of fabrication skills, this proved to be a disastrous method and became more of a burden than a means of producing.  

“That’s when I gave up,” said Greenberg. “I had nothing to show for my labor but a sad metal block scarred by a maze of crooked channels. Well, that and a left hand bristling with tiny aluminum shards where my latex glove had split.”

Next up was 3D printing, which was performed using the commonly-used MakerBot Replicator 2 fused deposition modeling (FDM) desktop 3D printer.

After finding a file for the AR-15 lower receiver on The Pirate Bay, it took just minutes for Greenberg to extract the file and import it into MakerBot’s software and be prepared for the 3D printing process.  Over the remainder of the day, Greenberg watched the physical object be created in front of him - however at the end of the day (six hours into a nine-hour print job) he started running into problems.     

“As science-fictional as that process felt, the results were flawed,” admits Greenberg.

“When I pried the finished lower receiver off the print bed, one side was covered in support material meant to prevent the hot plastic structures from collapsing before they solidified. Snapping and scraping off that matrix of plastic was a long, messy process. I tried using a knife, cut my thumb, and bled all over one side of the rifle body. And the same support materials also filled tiny holes in the piece, in some cases choking the delicate threads meant to accept metal screws.

Although he understands that the process of creating a 3D printed AR-15 lower receiver is certainly possible, Greenberg’s own experience with the process left him with much to be desired.   

With both the drill press and 3D printing methods under his belt, Greenberg then moved onto creating the lower receiver using Defense Distributed’s own Ghost Gunner CNC mill.

According to Greenberg, after his first moments of using the machine it was clear that “this was the machine for making a gun”.

Over the course of a few hours, Greenberg watched the aluminum block get shaved down into a lower receiver based off of the same file that he previously used for attempting to create a 3D printed version.  Once the part was finished, he was able to finally assemble the firearm using the freshly-produced part and test-fire it.

Ultimately, Greenberg sacrificed the gun parts to a local San Francisco police department but was left with the conclusion that although a drill press and a 3D printer can certainly be used to create a lower receiver for the AR-15 assault rifle, the Ghost Gunner is certainly a revolutionary product that, firearm or no firearm, is a powerful tool for Makers.  

You can read Greenberg’s build process in-full over on Wired.  

 

 

Posted in 3D Printing Applications

 

 

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Tom wrote at 7/18/2015 5:13:37 PM:

So, what is the point - if you had some brains left, you would have went to a local store and bought one for $40. Or to a local flea market, or the next gun show... It does not get much more pointless than this post. Besides understanding that the author has two left hands and no clue what he was doing or how a gun functions, there was nothing to be learned here.

jotux wrote at 6/9/2015 2:18:04 AM:

Wearing gloves and long sleeves while trying to use a drill-press as a milling machine...

guns-europe wrote at 6/8/2015 2:11:29 AM:

Hooray, now we only need trigger group, bolt carrier group, barrel and it's extension, upper receiver, gas system and buttstock with all its parts, a bunch of magazines - and oh, don't forget the ammunition. Please come back when you have any real news, like printing a bolt head or a barrel with functioning chamber, rifling and locking lugs. Like they did with 1911 a while ago.

ConcernedCitizen wrote at 6/6/2015 1:47:32 AM:

So, you can spend $1500, to complete an already 80% completed receiver, and make it functional (with the addition of another $3-500 worth of other parts including barrel, trigger kit, etc). Oh my god, all the criminals will surely stop spending $300 on a stolen AR's and become closet gunsmiths now! Lead raining from the sky! Our children, and our children's children, and our childrens childrens puppies will lie bleeding in the streets due to the release of this CNC mill!

ThatGuy wrote at 6/5/2015 9:24:55 PM:

Soooo, a you can use a CNC machine to make a fairly simple part... amazing. An $80 block of aluminium? On sale you can get a finished lower for less... But iis the argument is that a bad guy is going to buy a $1500 machine to instead of just buying a stolen gun?

Curious wrote at 6/5/2015 3:25:41 PM:

I wonder why he chose to print the lower on it's side, instead of standing up.



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