Part 2 – Keycaps

What we need to know about keycaps is that they have different lengths – 1U is the regular “square” keycap, e.g. Q; 2U is double this and here as an example we have the standard Backspace. Due to the way the keycaps are scattered upon the keyboard we also encounter different length keycaps like Tab (1.5U), ANSI Left Shift or Enter (2.25U), ANSI Right Shift (2.75U), and a plethora of 1.25U keycaps which in addition to the 6.25U spacebar constitute what we like to call the standard bottom row (1.25U-1.25U-1.25U-6.25U-1.25U-1.25U-1.25U-1.25U). The is also a 7U bottom row which includes a 7U spacebar, four 1.5U keycaps (ctrl and alt), and two 1U keycaps (Win/sys keys) (1.5U-1U-1.5U-7U-1.5U-1U-1.5U).

There are also other bottom row layouts such as the non-standard found on most Razer keyboards or the winkeyless (WKL) layouts which can be found on older vintage boards or select new custom keyboards. The WKL layout does not have a Win/SYS key which is replaced instead with a blocker integrated in the keyboard case.

Another physical characteristic is of particular interest is the keycap profile. The keycap profile can be defined as the style the keycaps are sculpted (or not). There are sculpted profiles (like Cherry, OEM, SA) and uniform profiles (like SA). Xah Lee pieced together an image that is worth a thousand words when it comes to different keycap profiles encountered in the wild:

Besides the keycap profile what matters is the keycap material as well as its thickness. And last but not least the technological process of obtaining these keycaps matters. That is why there are ABS and PBT keycaps of various quality.

A lot of people are wary of ABS and tend to take a step back when they hear about the price of a GMK keycap set. But not all ABS keycaps are created equal. Keycaps on cheap keyboards are made of thin ABS (sometimes as thin as 0.75mm) and are coated with a coloured material in which the keycap legends are then etched in. The issues are multiple – the coating material is not oleophobic at all and thus retains the fat from our fingers regardless of how often we wash our hands, it can chip and peel off, and the acoustics are unsatisfying due to the insufficient thickness.

By contrast an ABS GMK keycap set is first of all double shot which means that the legends are injected in a mould and then placed in another machine where the second colour is injected. This will give the keycap its final shape. As a result these legends will never wipe or peel off and the increased 1.5mm thickness gives these keycaps a pleasant and specific sound signature.

And whilst with ABS the main issues stem from the material thickness and the technological process which drives the colour consistency and sound signature in the case of PBT the situation is more complicated.

High quality PBT sets are few (e.g. CRP from Hammerworks). And the issues with PBT are not with the 1U keycaps but with the ones longer than 2U – especially the spacebar – be it 6.25U or 7U. Cheap PBT sets suffer with long keycap warping which means the keycap is rotated around the long axis and because of this it will strain the stabilisers and keep the switch underneath in tension. In the best of cases functionality will not be affected and the keyboard will just look odd under certain angles however in the worst cases the keys’ movement will be slowed or even stopped which is unacceptable.

We have to remember that the function of a keyboard is to interface man and machine and has to fulfill this function without any issues.