Keycaps, since the invention of the keyboard, have been the second face of keyboards apart from their housing. If we were to compare them to bespoke suits, the keyboard housing would be like the cut and tailoring of the suit, while keycaps would be akin to collars and cuffs. Carefully selected keycaps can elevate a keyboard to new heights, while neglecting them can instantly lower its quality.
This article aims to delve into the world of keycaps. With a plethora of themed keycap sets flooding the market and new group buys launching almost daily, it's essential to understand that beyond colors, the shape and material of keycaps significantly influence typing sound, no less than the switches themselves. However, I won't dive into every color and theme available, as that would require countless articles. Therefore, this article will focus on keycap shapes, materials, and manufacturing.
Keycap Shapes
In the world of custom keyboards, the shape of keycaps is referred to as "profile." This term, akin to a user's profile information, describes the overall shape of the keycap. It's important to note that even within the same "profile," the shape of each key may vary. Therefore, a "profile" refers to a set of keycap shape parameters.
Here are some common profiles:
Cherry Profile
The Cherry profile, also known as the OEM profile, is undoubtedly the most famous profile. The German company Cherry popularized this square and angular keycap design as early as the 1980s with the G80 and G81 keyboards. Today, keycap manufacturers like GMK and ePBT, known as the "golden keycap factories," also use Cherry profile molds. The image below showcases the classic ePBT 9009 keycap set.
OEM Profile
The OEM (Original Equipment Manufacturer) profile closely resembles the Cherry profile but is slightly taller overall. This adjustment was likely made by manufacturers to avoid infringing on Cherry's patents while imitating their design. Many mass-produced keyboards from brands like Dell, Razer, Logitech G, and others utilize OEM profile keycaps. Additionally, most of the keycaps available on shopping websites are OEM profile.
SA Profile
The SA (Spherical All) profile, characterized by its spherical shape, is another common profile in the keyboard community. It gained popularity through IBM's Selectric typewriters. Recently, keyboard designer Matt3o introduced a variant called MT3, addressing some issues like overly concave keycaps and sharp edges. MT3 keycaps are primarily available on Drop.com. SA keycaps are known for their unique homing key design, which features deep recesses instead of Cherry's underline. Additionally, a new variant called OSA profile has emerged, reducing the height of SA keycaps for easier typing and adding underlines to homing keys.
KAT Profile
The KAT (Keyreative All Touch) profile, designed by Keyreative, falls between Cherry and SA profiles in terms of height. An example is the KAT KATHA keycap set.
DSA and XDA Profiles
These profiles are grouped together because they are similar, featuring spherical and uniform heights across all keys. DSA is slightly shorter than XDA. DSA (DIN-compliant Spherical and same profile across All rows) was designed by Signature Plastics, while XDA, inspired by Cherry M8 keycaps, is less common.
Chiclet Profile
The Chiclet profile refers to a series of keycaps characterized by uniform low-height square shapes, akin to the keys on Apple's Magic Keyboard. These keycaps are commonly found on membrane keyboards like those from Apple. While not prevalent in the custom keyboard community before the rise of low-profile switches, they are gaining attention.
Some interesting new profiles (feel free to add):
KATE/CAPS Profile
Designed by RAMA.WORKS studio, this profile was initially named KATE but later renamed CAPS due to circumstances involving RAMA. It's still in production, and reviews are eagerly anticipated.
Keycap Materials and Manufacturing
Materials: The two main materials used for keycaps are ABS and PBT, both engineering plastics.
In terms of performance, PBT is considered superior. However, due to factors like cost, processing difficulty, and aesthetics, ABS is more popular. Additionally, some artisan keycaps are made from resin or metal, offering unique characteristics.
Legend Production: To address wear over time, manufacturers use various techniques for legends (the letters or symbols on keycaps) to ensure durability.
Three main techniques include double-shot molding, dye-sublimation, and pad printing. Laser printing is also becoming popular, especially for backlit keycaps commonly found on gaming keyboards.
Surface Treatment: Surface treatment is crucial for keycap feel. Techniques like electrical discharge machining (EDM) and texturing are used to smoothen the surface of injection-molded plastics. Sandblasting is another treatment method, primarily used for refinishing worn keycaps.