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Buckling Spring: The Origin of Mechanical Keyboards

Buckling spring mechanism being actuated.Click to enlarge and see animated, Source: Wikipedia

The buckling spring keyboard was invented by Richard Hunter Harris and later patented in 1977 by IBM. Its name actually derives from how the physical mechanism works when actuating a key, with a spring being put under pressure and “buckling” between the keycap and a pivoting hammer, creating a distinct mechanical auditory feedback.

The buckling spring switch design has undergone several revisions to reach its current form. Initially, it was hard to predict the direction the spring would bend in as it’s attached to the key at only two points of contact. If the spring were to bend in the wrong direction no contact would be made and the circuit wouldn’t complete.

Harris solved this issue by introducing a pivoting hammer underneath the spring that moves it into the correct orientation after each key press. In addition, the spring is held tense and slightly curved in the right direction by the keycap. One important aspect of this design is that the spring no longer made contact with the plate (later membrane). As the spring buckles it pushes the hammer down onto it when the key is pressed. After the key is released, the spring unbuckles and allows the hammer to lift, which in turn pushes the key back up.

IBM Model M: A Star Is Born

One of the earliest and most well known keyboards to make use of the buckling spring switch mechanism was the IBM Model M in 1984. The Model M is now considered timeless by many keyboard aficionados. The keyboard is praised for its durability, premium build quality, and versatility.

While the rest of the computing world advanced at lightspeed in the 1980s, the Model M design has seen little variation, with consumers appreciating its unique feel and sound. Due to its more refined touch, many typists believe that it enables them to type faster and more accurately as each key has a distinct weight to it which makes it easy to gauge the exact pressure you need to apply before moving on to the next key. Typists can use just the right amount of force for each key stroke, never more or less which makes the Model M highly efficient.

When compared to the cheaper dome and membrane type keyboards, many users feel more comfortable with the distinct sound of the buckling spring design. Along with being more user friendly, proponents also enjoy the added benefit of it being less susceptible to dirt and wear. Its functionality, long lasting nature (some owners have been using the same Model M keyboard for 25+ years) and its vintage aesthetics make it a perennial favorite for typing purists and keyboard enthusiasts who find it a real pleasure to own and use.

The IBM Model M was originally conceived as a more consumer friendly and cheaper to manufacture version of another IBM keyboard, the Model F (which also made use of buckling springs). Model M keyboards were produced all over the world, coming out of IBM plants in both Scotland and Mexico. The most common version of the keyboard implements the US ANSI layout; a layout that is practically the same as modern boards, minus the Windows keys.

Between 1985 and 1993 the Model M used a detachable coiled cable. The design shifted to a flat, non-detachable cable in 1994, after IBM’s keyboard manufacturing operations were sold to Lexmark, in an effort to reduce manufacturing costs. During Lexmark’s time as manufacturer they made a few changes in the manufacturing process and build materials in an effort to reduce cost of the keyboard. This included using a single color for the key legends and a lighter plastic shell, but the venerable buckling spring was thankfully left intact.

Modern Buckling Spring Keyboards

Manufacturing was taken over in 1996 by Unicomp, a Kentucky-based company, after Lexmark’s contract with IBM expired. With the beginning of Unicomp’s production of the Model M came new unique designs. Updated key layouts were introduced, and the classic buckling spring keyboard was optimized for different operating systems. Users can now choose between Unix, OSX, and Windows.

Modern Unicomp buckling spring keyboard.Modern Unicomp produced Model M with buckling spring, Source: Unicomp

Their EnduraPro line of keyboards includes the Trackpoint integrated pointing stick mouse. Another interesting design modification is the inclusion of a trackball in the Classic Trackball model. If you’re not interested in Unicomp’s new unique designs, rest assured they also manufacture a “Classic” model based on the Model M using the same equipment and molds acquired from Lexmark.

Unicomp also sells a variety of customizations for Model M bucking spring keyboards. So nowadays you can combine the efficacy of the buckle spring design, its durability, loud audible feedback, and generally satisfying typing feel with the innovations in customization available with modern mechanical keyboards. Best of both worlds!