Demko Locks: The Endless Pursuit of Performance

Shark-Lock®

RhinoLock®

Scorpion Lock

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Shark-Lock®

THE TRIFECTA OF STRENGTH, SAFETY, AND EASE
Designed in 2016 by renowned knifemaker and designer, Andrew Demko, the patented Demko Knives Shark-Lock® officially appeared on the scene in 2020 and fundamentally changed the way that folding knives are created. The Shark-Lock® allows for a combination of industry-leading strength, ease of use, and safety that isn’t found in other locking mechanisms.

MECHANICS
The Shark-Lock® is unique within the knife industry for many reasons, one being that it is a “stand alone” locking system, meaning that its ability to function is not inherently tied to its attachment to other parts of the knife handle. The Shark-Lock® is a sliding locking mechanism that sits in line with the knife spine, sandwiched between the scales of the knife handle. The Shark-Lock® rests above the blade tang, working in tandem with its forward stop pin and its captured drive spring to keep a folding blade securely locked in place.

The user disengages the lock of the knife by sliding the lock’s “fin”, its dorsal-fin-shaped tab, in a rearward-and-upward motion. Once the lock bar is in the rearward and lifted position, the blade of the knife is free to swing open. With the blade opened, the user releases the lock bar and it returns back into a forward and locked position via the in-line coil drive spring.

The Shark-Lock® is a self-adjusting mechanism, using intentional design geometry to keep the lock bar under constant spring tension. Most knife locks gain play in their components’ tolerances over time due to material wear on the interfacing surfaces. When this happens, the lockup becomes less secure and the knife potentially less safe. The Shark-Lock® design solves that problem because it allows for integrated self-adjustment of the lock bar, which automatically compensates for any material wear or change in the interfacing surfaces. The result is a consistently secure lockup for the entire life of the knife.

While many traditional lock mechanisms rely on a detent mechanism (a mechanical component that applies pressure perpendicular to the side of a closed folding blade to prevent it from falling open), the Shark-Lock® bypasses the need for a detent mechanism because the interplay between the blade tang and lock bar serves to prevent accidental deployment.

COMPOSITION
The Shark-Lock® is made from high tensile strength stainless steel that is heat treated to increase hardness. Because the lock’s tolerances are very strict, the Shark-Lock® is precision cut on a wire EDM machine. Hardness and toughness are both critical for folding knife locking mechanisms. Because the steel lock bar engages with, and moves across, the hardened steel blade tang, the lock must be similarly hardened to reduce asymmetric wear on the moving parts.

Demko Knives’ Taiwan-made knives, such as the AD20.5, Shark-Cub®, and Nano-Shark®, have Shark-Lock® mechanisms that are Metal Injection Molded (MIM), which is a relatively new process used to create parts with tight tolerances. These steel parts are similarly treated to increase hardness.

PURPOSEFUL ENGINEERING
The Shark-Lock® mechanism is one of the strongest folding knife locks in the industry. As with all knife design properties, designing a great lock is about finding compromise between contrasting ideals. A folding knife lock can be so strong that the knife becomes too unwieldy or the lock becomes too difficult to disengage. Inversely, a knife lock can be so lightweight and easy to manipulate that it is not robust enough to withstand hard use.

Because efficacy and efficiency are often at odds in engineering, and because making locks that are both strong and easy to use is critical, Andrew Demko must deliberately optimize these parameters. He treats both of these ideals as variables in a mathematical equation. The Shark-Lock® geometry is a testament to carefully-engineered design, having a unique ability to “hack” the conventional math equation. The Shark-Lock® equation assumes ease of use (efficiency) as a constant, but leaves lock strength (efficacy) as a manipulable variable. This means that the Shark-Lock® is user-friendly and easy to disengage, no matter the lock or knife size. The strength component of the lock is then only limited by Demko’s choice of steel type, thickness, and mass. Adjusting the steel type, thickness, and mass of the Shark-Lock® means that the capabilities of this easy-to-use lock can be employed in near-limitless knife applications while remaining unyielding to its core Performance First™ identity.

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RhinoLock®

FROM HISTORY TO MODERN MECHANICS
The Demko RhinoLock® may look like a normal lockback on the outside; it is even actuated conventionally, using a depressed rocker arm and spring. However, the similarities end there. The RhinoLock’s® Performance First™ methodology means that it is a complete departure from the common lockback knife blueprint.

To better understand where the RhinoLock® fits into knife history, one must have a brief look at lockback-style folding knives throughout history. Folding knives with locks located on the back, or top spine, have a long history. They are most commonly understood to originate in Europe around the 17th-century. In Spain, for example, government restrictions on swords and other weapons in the 1600s necessitated citizens to carry only folding blades. However, traditional folding knives would not suffice in defensive and protective usage because they did not lock open. Cue the Spanish navaja, a large folding knife that featured an early back lock mechanism. While their lock type and integration were very different from modern designs, the Spanish navaja is commonly regarded as a forefather to lockback mechanisms of the later centuries.

Rocker-style lockback knives, using a pivoting steel rocker arm under spring tension, became commonly used in European and American pocket knives in the 19th century. Along with slip joint folders, these 19th century lock back knives comprise the quintessential “traditional pocket knife” patterns of the industrial age through the mid-20th century. However, Al Buck, of Buck Knives, permanently solidified the rocker-style lock back folding knife as a modern everyman’s tool with the creation of the Buck 110 Folding Hunter in 1964. This knife pattern, lock included, defined a generation of pocket knife owners from the 1960s through the 1990s. This design was the reliable companion of your father and his father before him.

While the general principle of modern lock back mechanisms is particularly robust when compared to the locking mechanisms that came before, Andrew Demko’s Performance First™ criteria stirred a desire for a mechanism that offered performance solutions unavailable to these existing lock mechanisms. Notably, Andrew needed a much stronger, safer, and longer-lasting folding knife lock than anyone had created before.

DEMKO KNIVES ENTERS THE KNIFE LOCK SCENE
While traditional rocker arm lockbacks were adequate for most daily tasks, Andrew needed a knife that could perform any task. Andrew wanted to create a lock that didn’t simply seem strong when compared to traditional folding knives, but one that gave the user utmost confidence in its strength and safety based on objective performance testing. Andrew needed a rocker-arm-based lock that stood alone. He also needed a design that did not wear out or deteriorate over time, as conventional back lock mechanisms can. With strength, safety, and longevity in mind, Andrew started drafting blueprints for an all-new lock that would reshape the way people view folding knives. 

The first iteration of a Demko lockback mechanism was Andrew’s patented Tri-Ad® lock, which introduced a stop pin into the lockback sequence between the rocker arm and the blade. When released, it was the knife industry’s strongest rocker arm lockback mechanism to date. At the time of its creation, Andrew Demko allowed the knife company Cold Steel, of which he was a designer and collaborator, the rights to this new standard-setting locking mechanism. Through the marketing efforts of Cold Steel, and backed by rigorous laboratory testing, the Tri-Ad® lock became an industry darling. Never before had a folding knife lock been so secure, strong, and safe to use.

Until now.

CHASING PERFECTION: THE RHINOLOCK® IS BORN
The Demko RhinoLock® is what happens when you give an engineering-minded perfectionist more than a decade to think, test, and improve upon his most compelling ideas. Andrew was not satisfied with simply holding strength and safety records, he desired to break them. The result of all this thinking, tinkering, and perfecting is the RhinoLock®, the new pinnacle of rocker arm lockback mechanisms.

Two keys to the RhinoLock’s performance are its specific locking geometry and its ability to self-adjust. Combining these key factors means that a RhinoLock-equipped knife can be passed down for generations and every owner can experience the highest standards of strength and safety in folding knives.

GEOMETRY
With Andrew’s previous lockback designs, the rocker arm butted up against a cylindrical stop pin. Even though this geometry created industry-leading strength, Andrew wasn’t satisfied and knew it could be stronger. The theoretical engineering, hypotheses, problems and solutions that preoccupied his mind for years needed to be tested. Andrew Demko’s goal was not simply performance under human conditions. He needed his engineering to perform under super-human stresses in the laboratory. Only if locking mechanisms can pass these unrealistically high standards, would he allow them to be implemented into knives that people rely upon every day.

Building on his earlier engineering principles that introduced a stop pin in sequence with a rocker-arm, Andrew sought to increase lock strength by changing the stop pin’s cross section from circular to lunate (modified crescent shape). Under the cylindrical stop pin method, the two components (stop pin and rocker arm) interface within a very small mating surface area. The RhinoLock’s® new stop pin engineering means that the rocker arm works against the stop pin with a much larger mating surface, substantially increasing the strength of that junction. This new interface, among other new Performance First™ engineering principles, puts the RhinoLock® at the top of its class in strength, safety, and dependability.

LONGEVITY
While conventional lockback mechanisms have rocker arms that are pinned in place with a fixed arc of movement, Andrew Demko first introduced the idea of a rocker arm that swings with a variable arc of movement many years ago when the Tri-Ad® Lock allowed for movement on the rocker arm’s X-axis. The RhinoLock® expounds on Andrew’s earlier design ideas and introduces yet another axis of movement. The RhinoLock® rocker arm, in addition to rotating around its pivot pin on the B-axis, can also move on the X- and Z-axes. This combination of free movement in three axes means the rocker arm mechanism can self-adjust its position and angle in relation to the stop pin and blade tang, ensuring proper security over time. 

Its self-adjustment ability allows the RhinoLock® to compensate for the inevitable wear of interfacing components that is present in all locking mechanisms. Mechanisms that do not self-adjust ultimately wear out, allowing looser tolerances, weaker lockup, and less safe usage over the lifetime of the knife. Examples of locking mechanisms with the security of built-in self-adjustment are Demko Knives’ RhinoLock®, Shark-Lock®, and Scorpion Lock. These mechanisms are built to last the lifetime of the product and are the perfect mechanisms for performance-oriented users who demand heirloom-quality folding knives.

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Scorpion Lock

THE FRAMEWORK FOR LOCK DESIGN
Andrew Demko’s fascination with locking mechanisms is deeply rooted and began early. He views the world through an inherent engineering lens. Even since his early days as a teenager forging steel in his parent’s garage, Andrew focused on making his tools better, stronger, or more efficient. He was never satisfied with substandard quality or poor performance. When you combine this mindset with a love of knifemaking and design, you get a lifetime of dreaming, tinkering, blueprinting, and pushing the envelope of performance engineering.

The Scorpion Lock’s conception is a case in point of Andrew’s dedication to his craft. The Scorpion Lock arrived on the scene shortly after Andrew woke up from a restless night’s sleep and found a sketch in his bedside notebook. In a period of sleeplessness, he sketched a concept for a new locking mechanism – a sketch he didn’t realize he made until he woke up the next morning. These types of revelations aren’t random; they are always the result of spending endless hours fully immersed in a problem.

WHY THE SCORPION LOCK?
The Scorpion Lock is the result of Andrew’s desire to make a simpler, more quickly manipulated lockback mechanism. His goal was to streamline the engineering and production of a lockback mechanism by reducing the amount of interfacing surfaces and angles in its components. Arriving on the heels of his previous creation, the patented Tri-Ad® Lock, the Scorpion Lock allowed for more efficient manufacturing and easier usability. Instead of a rocker arm that is made to simultaneously interact with the knife blade tang and stop pin (meaning engineering four separate interfaces), the Scorpion Lock interacts with the blade tang solely through a cylindrical pin held between a spring-driven yoke. The strength and simplicity of a round lock pin in a rounded slot in the blade tang proved to be an ingenious concept.

THE DESIGN
By definition, the Scorpion Lock is a type of lockback mechanism because the lock is located and manipulated on the spine of the knife. However, the Scorpion Lock departs significantly from a typical rocker-arm-style lockback. 

A knife that integrates a Scorpion Lock has a divided chassis comprised of two separate components: a lower grip assembly and an upper grip assembly, called the yoke. The entire yoke, or upper assembly, is held under spring tension, acting as a pivoting locking arm in addition to being part of the handle. The actual locking interface is a hardened steel pin inside the yoke that is oriented perpendicular to a slot the blade. The lock is released by lifting the yoke assembly away from the lower grip. The lock’s pin is thereby lifted out of the blade tang’s slot and the blade is free to open or close. When the yoke is released, spring tension causes the yoke to return to the locked position, dropping the lock pin into a slot in the blade tang. 

BETTER IN USE
Andrew Demko is known for his Performance First™ lock designs. This means that strength and safety are paramount. Andrew’s use of a large cylindrical hardened steel pin was deliberate because of the inherent strength of the form’s geometry. Additionally, with this lockup design, the interfacing surface area of the locking components is maximized, a critical aspect of a strong knife lock.

However, the strength of the Scorpion Lock is only part of the equation. Increased safety measures are built into the Scorpion Lock’s engineering. Because the yoke is integrated into the handle of the knife, the lock’s security is reinforced when gripped. The lock's spring keeps the yoke in place but, unique in the knife industry, gripping the knife plays an active role in the security of the lock; the user’s input forces work in tandem with the spring force to make the knife more secure while in use.

The Scorpion Lock’s pivoting yoke assembly comes with an additional feature – it is safely operated one-handed, keeping the user's fingers away from the blade path. This ability, along with the lock’s high strength, allows knives equipped with the Scorpion Lock to be a great choice for the jobsite, when tasks require safe, one-handed knife operation. Its ease of use also means the Scorpion Lock plays well in fidgety everyday carry knives.