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Is 3D-printing the key to unlocking a safer future?

5 June 2017

Christopher Barrow of London’s Metropolitan Safe Deposits looks at the history of lock designs and identifies a revolutionary new mechanical key.

After many years of hype, the 3D printing industry has reached a tipping point where many industry specialists believe that it is set to become a real alternative to traditional manufacturing processes. It is predicted that many multinationals will be using 3D printing for mass manufacturing in the next 3-5 years. An industrial revolution using new, smart technologies will transform the global manufacturing landscape. These changes will affect not only industrial sectors (factories and warehouses), but also what goes on in our homes. A good example is the recent launch of a 3D-printed cylinder lock and key, which can be used for doors and padlocks, with unscannable security features.

The history of locks and keys normally goes back to the ancient Egyptians whose oldest preserved door locks date back to 2000 BC. These were made entirely out of wood and were called wooden pin locks, which comprised a bolt, door fixture and key. Then came all-metal locks, such as the warded lock, which were much in evidence in the Middle Ages in China and Europe, especially Rome. A warded lock uses a set of obstructions to prevent the lock from opening unless the correct key is inserted, and can still be seen today mounted to old wooden doors.

These types of locks are now only used in low security applications since a well-designed skeleton key can be made to bypass the obstructions (or wards). Another issue with the warded lock is that there is a relatively limited number of unique keys that can be created, so many keys are able to open locks that they were not designed to open.

The invention of the lever tumbler lock was designed to solve this problem as each lever is required to be lifted to a certain height in order to operate the locking mechanism. Lifting the tumbler above a certain height allows the bolt to slide past. This type of lock, for example the well-known 5-lever mortice lock, is still used today, mostly on doors, and can also be found on safes and gun cabinets.

In recent years, these locks have declined in popularity as pin tumbler locks have become cheaper. Another reason for the decline in lever tumbler locks is that they can be picked with a tool called a curtain pick, which is inserted into the keyway of the lock, and a force is applied to the locking bolt. The pick is then used to lift each lever inside the lock to the correct height in order for the locking bolt to pass.

The pin tumbler lock, or Yale lock, is a lock mechanism that uses pins of varying lengths to prevent the lock from opening without the correct key. These pin tumblers are commonly used in cylinder locks where an outer casing has a cylindrical hole in which the plug is housed. To open the lock, the plug must rotate. The basic pin tumbler lock alone is vulnerable to several lock picking methods and attacks, the most common being lock bumping and snap guns. To combat this, many higher security cylinders incorporate the use of specialised pins known as security pins, which are designed to catch in the lock cylinder if a snap gun or bump key is used.

Lock picking is the art of unlocking a lock by manipulating the components of the lock device without the original key. The most common tools, as described above, have been the skeleton key (used to open warded locks and padlocks), the curtain picks (for the lever tumbler lock) and various wrenches and picks used to open pin tumbler locks. These include the torsion wrench, ball pick, half-diamond pick, hook pick, rake pick and bump key.

The battle continues between lock pickers and lock inventors. Lock designers develop an array of anti-picking methods, for example by using side wards to obstruct the keyway. Another method (as mentioned above) is to use security pins, which are shaped like a spool, mushroom or barrel and have the effect of feeling as though they have set when in fact they have not.

The lock and key device has not actually changed that much. The key remains, to a large extent, a piece of metal with a series of grooves, teeth and indentations which, when inserted into a keyway, line up to move the pins and levers in order to lock or unlock a mechanism. Keys are manufactured using conventional techniques, typically cutting and stamping. Despite improvements in key design, the majority of locks today are still variants of previous designs. Just as the Roman iron lock was an improvement on the wooden Egyptian model, the modern lock is essentially a more developed version of those invented by the likes of Chubb and Yale in the 19th century.

Various new products have been developed in recent times in order to improve security, increase applications and add to customer experience. Some important examples include the magnetic keyed lock, the digital key-card such as the RFID proximity card, and the smart key that facilitates an electronic access and authorisation system.

The latest new product to emerge involves the reinvention of the mechanical key using a radically different manufacturing process. A Swiss company called UrbanAlps has developed the world’s first 3D printed metallic key, which hides most of its mechanical security features internally. The company has launched a range of cylinder locks and an unscannable key called a Stealth Key. Thanks to 3D metal printing, they have literally turned the common house key inside out. A 3D printer works by melting together layers of material that are added successively to the object being created. It can therefore make a product from the inside out.

In the case of the Stealth Key, this 3D technology is able to print intricate internal features, including coding, and then cover them with a solid layer. The key features are shielded from view and are therefore extremely difficult to copy or indeed reproduce by using normal machine tools. The Stealth Key is printed in titanium and its teeth are hidden under a pair of ledges, which, they claim, makes it unscannable. When the key is inserted into the lock, the teeth can operate the mechanism.

One potential issue at the moment is cost. The 3D printer uses a laser to fuse the layers of metallic powder to make the Stealth Key, which is currently a slow process and therefore relatively expensive ($200 for each cylinder with two keys). In the short term, it is likely that this exciting new product will attract specialist customers protecting high-value goods, such as ATM machines and safe deposit boxes, and perhaps the top end of the retail market in the shape of high-security door locks and padlocks. If UrbanAlps can mass-produce their locks and keys at an affordable price, as well as provide a secure local locksmith solution in the event that you lose your keys, this could be a very important development in the history of lock security.