Blue Line


January 1, 2013  By Tom Rataj

1185 words pics – rataj folder_

“Print” you own guns

by Tom Rataj

In the wake of yet another mass-shooting at a US school, there is news of a do it yourself gun. The Defense Distributed project, led by 24-year old University of Texas law student Cody Wilson, aims to “produce and publish a file for a completely printable gun.”


Wilson claims to have already test-fired a printed replica of a Bushmaster AR-15, apparently the prime weapon used in the Newtown school massacre.

The printed replica weapon was apparently fired six times before it failed. While there are still a lot of technical challenges to overcome before a reliable firearm of this type could be produced, the test product shows that it can be done.

{3D printing}

What makes all this and much more possible is a technology commonly known as “3D Printing” or “Rapid Prototyping,” but more correctly as “Additive Manufacturing.”

In simple terms it begins with a three-dimensional Computer Aided Design (CAD) or modelling software model of a physical item and ends by printing an actual 3D item.

A 3D printer can precisely move a print-head on three axis; x, y and z (left, right and up and down) to print very fine layers of material one on top of another.

Most printers use one of several types of plastic to print an item. It is typically fed in from a spool and melted into a liquid state in the print-head before being ending up on the printer’s production platform.

This technology has a number of similarities to an inkjet printer, where the print-head assembly moves back and forth across a page to output text or images.

The plastic formulation used and the thinness of the printed layers causes the plastic to harden almost immediately upon being printed.

While this is all quite complicated, the technologies involved — computer, software and even the printers — make it all quite affordable. The 3D printer is the most expensive part, since computers and software are cheap and many of the CAD files of objects can be had for free from a variety of Internet sites.


Although the Defense Distributed project is relatively new, 3D printing began in the early 1980’s with a couple of different technologies that achieved the same basic result; the ability to print objects.

The attraction is the ability to quickly, easily and most importantly cheaply produce product prototypes. Numerous slightly different prototypes can easily be printed to fine-tune a final design.

Mass produced commercial products are often quite cheap to manufacture but their final retail price is largely set by the manufacturer at a level which recoups research and development costs. Reducing these costs helps to reduce the final retail price and shorten the product development life-cycle, which in turn allows manufacturers to produce new products or updates to existing products more cheaply and quickly.

Since its introduction the technology has progressed to the point where all the requisite components are much more precise and inexpensive, allowing manufacturers to produce very small run finished products (not just prototypes) that ordinarily might not have been economically viable using conventional methods.

Last year at this time I wrote about the Mobile Innovations and the Chatham-Kent Police Service pilot project using the BlackBerry PlayBook tablet in police vehicles. Because it was a pilot, the hardware mounting solution developed by D and R Electronics included several 3D printed parts in the tablet mount.

The prototypes were contracted out to a subcontractor and were quick and easy to design and manufacture. The final commercial versions of the parts will likely be made using conventional injection-molding technology.

Using conventional product development and production methods would have made the mount much more expensive and time consuming to produce.

{Technical stuff}

The electronic file of an item is created in a Stereo-lithography or Standard Tessellation Language (STL) file format in CAD software developed by 3D Systems Inc. It is supported by many other software products and widely used for 3D printing, rapid prototyping and manufacturing.

The STL file describes the surface geometry of an object without any other attributes such as colour and texture. The item can be created directly in the software package or imported by laser scanning an existing item.

The 3D printer typically outputs layers that are only 100 micrometers (0.1mm) thick, although some higher-end printers can produce layers only 16 micrometers (0.016mm) thick. The actual print resolution is roughly equivalent to a laser printer output in terms of dots-per-inch, commonly 1,200 x 1,200 dpi.

Depending on the size and complexity of the item being printed and the type of material it is manufactured from, it will take from several hours to several days to print. If the printer resolution cannot match the demands of the finished product, it can be printed slightly larger and then machined down to its final precise dimensions and finish.

There are a number of 3D printing technologies that use different material and techniques to arrive at the same end result.

The most common system is Fused Deposition Modeling (FDM), which uses a plastic filament or metal wire. The filament is typically ABS plastic (the same type used in black plumbing pipes) and polycarbonate (the hard clear plastic used in plastic water-bottles and car headlights).

Other systems include Granular Material Binding, which uses selective laser sintering to produce plastic and metal items, and Electron Beam Melting (EBM), used for products made of metal alloys. Photo-polymerization uses a liquid polymer (plastic) that is manipulated with a Digital Light Processing (DLP) projector.

On the novelty end of the scale there is also the CandyFab machine, which uses hot air and granulated sugar to print food grade art objects.

For advanced hobbyists there is the Replicating Rapid Prototyper (RepRap) machine — an open-source software based 3D printer that can print most of its own components. Kits to build these types of printers are down to around the $500 level.

The Internet propels the business and hobbyist sides of this technology. Web sites such as share digital designs for 3D printers.

{The future}

This technology can be used to design and make almost any object, allowing for the creation of complex products without the expensive industrial infrastructure and scientific equipment normally required. It undermines economies of scale and many other established business models and practices by making it easy for anyone to produce simple items almost anywhere, including at home.

Items can also be printed by contract manufacturers, which would have much higher-end printers available than a home user. Send the STL file to them over the Internet and they produce the part and ship it back.

Biotechnology firms and academics are also studying the possibilities this technology offers for body tissues, organs and body part production. Custom made replacement parts such as artificial hips and other joints could conceivably be quickly and cheaply produced.

While there are still many limits to what can be printed there is a lot of research into printing far more complex items such as functioning circuit boards.

The ramifications are wide reaching and, in the wrong hands, downright scary.

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