Tuesday, May 14, 2013

Printing the Liberator

My Experiences Printing 'The Liberator'.

Recently ( DefCad released the STL model files for 'The Liberator', the first completely printed 3D gun. Even more recently, the U.S. Government claimed ownership of these files and had DefCad remove them( Almost immediately, the files appeared on torrent sites. I was lucky enough to have downloaded the files while there were still being hosted, although I'm sure that I would have had no trouble finding a torrent of them if I had been too late.
The parts I've printed so far


First, let me say that I'm not a lawyer, nor should you just 'take my word' on any legal claims here. A quick Google search on 'homemade guns' would seem to indicate that many people have been building guns at home for a very significant time. A few more quick searches about the legality of doing this seems to indicate that it is allowed by the United States Federal Government, provided that no existing federal laws are violated. Hurray 2nd Amendment rights!
An inventoried list of said parts

More disclaimer:

Although I'm documenting the process of printing and assembling 'The Liberator', I'd like to make it clear that I'm not a gun nut, nor have I ever owned a firearm (Actually, I have an antique Civil War flintlock somewhere in storage I got as a gift from my Grandpa). I remember firing a 22 rifle in boy scouts at 15ish or so.
     My plan is to add the steel slug weight to make the gun detectable by metal detectors to comply with federal law. Additionally, my plan is to print the -Frame, Grip, & Barrel as 0-20% fill. I think this should made it clear this gun is being produced for display/research purposes only. Any attempt to fire a pistol at this low infill would probably be suicidal. I am also going to not install a firing pin for safety reasons. I think at the end of this all, I'll probably build a display case for this in my office as a conversation piece.

I had trouble printing the grip, so I split it into two halves

Examining the files:

After examining the files, I noticed the objects needed to be scaled by 25.4 to convert them into mm. Most of the parts seemed simple enough to print, others had significant overhangs the required building the models with exterior/full supports. I'm still in the process of printing all the parts on my Makerbot. Most of the parts printed without fault, however, the -Frame.stl file was too large for the Makerbot TOM build plate, so the model needs to be split for printing and joined together with acetone after printing. As of today(5/14/13), the only thing left to print is the Frame. Additionally, I had issues with printing the Grip.stl file, so I split the model along with Y axis and created my own GripLeft and GripRight stl files.

Durability of printed parts:

This is a big issue that cannot be ignored. While it may be convenient  ABS or PLA printed 3D parts do not have the durability of machined steel commonly used in gun production. Others have quickly noted that this is not a safe gun ( Other materials can be used to print the parts. Hopefully in later blog installments, I'll go through the process of printing some Liberator parts in UV resin. ABS plastic can be re-enforced a bit by using an acetone vapor smoothing process ( This will fuse together the exterior of the parts, lessening the chance that a part may split along an axis.

Nylon would be a better choice for printing some of the parts, namely the barrel. Nylon is far more durable of a material, however printing nylon from a FDM printer at home is challenging, namely because of part warpage and shrinking. A heated bed and chamber may be necessary to proper print nylon without warpage.

Casting the parts for mass-production:

Another option for part durability and repeatability is to cast the finished printed parts in metal such as aluminum. This process has been described before by several other 3d printer users ( .

I'm fairly certain that creating a 2-part reusable mold may be possibly either directly created by a mill, or from the castings of these 3d printed parts and is practicle for making multiple copies. This would yield far faster, more economical, and more durable parts than printing all the parts in plastic.

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