3-D Printed Gun's First Shot Has Big Implications

A mostly 3D-printed gun represents an imperfect weapon with big implications

3 min read
3-D Printed Gun's First Shot Has Big Implications

The world's first gun made mostly from 3-D printed parts won't beat the power of standard firearms or become the latest item in every U.S. household anytime soon. But the gun's first successful firing test raises new uncertainties about everything from existing gun laws to the future of 3D printing.

A remote firing test of the "Liberator" gun took place in central Texas on 1 May, as witnessed by a reporter from Forbes. The gun's design is based on a digital blueprint by Defense Distributed—a group founded by Cody Wilson with the goal of creating fully 3-D printable guns and making their digital blueprints freely available online. Defense Distributed produced the gun parts by using an $8,000, second-hand 3D printer originally made by Stratasys

Wilson followed up the first firing test by personally hand-firing another Liberator gun on 4 May. He told the BBC that his efforts were "about liberty."

I'm seeing a world where technology says you can pretty much be able to have whatever you want. It's not up to the political players any more

The idea of 3D-printed guns becoming available to anyone with a 3D printer has alarmed U.S. lawmakers already engaged in the political battles over gun control. Senator Charles Schumer of New York described the new 3D-printable gun as having "stomach-churning" implications.

Now anyone—a terrorist, someone who is mentally ill, a spousal abuser, a felon—can essentially open a gun factory in their garage. It must be stopped.

The reality of 3-D printable gun technology still falls short of both Wilson's optimistic view and Schumer's alarm. The Liberator gun remains a single-shot weapon that only fires handgun rounds—hardly a match for any gun produced by standard methods and more comparable to homemade zip guns from the 1950s. When Defense Distributed tried to fire the gun with a higher-charge rifle cartridge, the gun's ABS plastic parts exploded.

Such 3-D printable guns also remain out of reach for the vast majority of people because of legal complications and the difficulty in accessing 3D printers. A writer for the Atlantic Wire was able to download the weapon's digital blueprints easily enough (instructions available in both English and Chinese), but ran into three challenges that prevented him from actually printing out the gun:

The first question is whether or not the firearm is a legal weapon. The second is whether or not I could legally own it. The third is whether or not someone could make the parts for me.

Defense Distributed carried out its test legally by obtaining a federal license for manufacturing firearms. The group then put a hefty slug of steel inside the gun to meet the requirements of the Undetectable Firearms Act that looks to metal detectors as the primary screening technology for guns. (The only necessary non-printable part of the Liberator is its metal firing pin.)

But Defense Distributed also put out warnings for potential gun-makers despite making the blueprint available online for download. Wilson posted a disclaimer online that discourages anyone from following suit by printing the gun for themselves unless they meet the legal requirements.

Making the parts proved toughest of all for the Atlantic Wire writer—especially given the relatively low levels of 3-D printer ownership and the reluctance of 3-D printing companies to get involved in the gun-making business. He ran into stiff resistance from 3-D printing companies that did not want to have any part in printing out a gun—although he received at least one $1,500 price quote that was higher than the cost of a new AR-15 assault rifle.

3-D printable guns remain imperfect weapons at best, but their existence has already led to questions about whether the legal system can effectively limit uses of the technology in the future. Congressman Steve Israel (D-Huntington) of New York quickly renewed his call for overhauling the Undetectable Firearms Act to cover homemade, plastic high-capacity magazines and receivers as individual parts not already covered under the existing law.

The debate over 3-D printable guns could even lead to collateral damage by casting a chill over 3D printing technology overall, according to the Washington Post. The paper warned that the current political mood seems to be focused on shutting down 3-D printing technology related to making guns rather than shutting down the guns themselves.

The current legal framework feels clunky and inefficient, woefully unprepared for responding to rapid technological change. And, in the end, that system may end up hurting 3D printing companies, rather than hurting the actual bad guys

Photos: Defense Distributed

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
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A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay
Blue

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.

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