Mechanical Keyboard Primer

I’ve been using “fancy” keyboards for my whole professional career.¹ I’ve managed to get one family member hooked so far, and another has some questions, so: here’s some of what I know about mechanical keyboards.

I’ve received no money or goods for anything in this post. There are no affiliate links. If you want actual experts, Keyboard University looks to have some okay primers; note they are trying to sell you something.

What’s mechanical about it?

Non-mechanical keyboards use rubber or metal domes as springs, and some additional material (usually plastic) to stabilize the vertical motion. This page has some good pictures and prose about domes. This page describes the “scissor” and “butterfly” mechanisms common for stabilizing low-profile keys.

Mechanical keyboards have more moving parts for each key, typically encapsulated in a keyswitch. There’s a distinct housing, stem, spring, and contacts, each of which affects the feel, sound, and weight.

US Patent 4467160 figure 1: an exploded view of a mechanical keyswitch, showing a two-part housing, stem, stabilizer, spring, electrical contact mechanisms, and various other parts. — The parts of a keyswitch, according a patent from Cherry Corporation. As far as I can tell this is still how Cherry switches are constructed.From US Patent 4467160

Keyswitch coloring

Keyswitch manufacturers offer several different interchangeable models with different properties (discussed below). Most manufacturers use a color – the same color – to refer to a combination of feel, sound, and weight. “Red”, “brown”, and “blue” are typical options, with offsets from those representing variations.

There’s no “best” for these; it’s all up to your preferences. I typically use a red-like switch, though I’m looking at brown-ish options for the future.

Feel (force curve)

The springs of a mechanical keyswitch can be configured to have different resistances at different points. This gives a different feel to the switch.

Linear: Travel is directly proportionate to force.
Tactile: There’s a “bump” when pressing. Press a little, it goes down, then resists more; overcome that resistance, and it becomes easier again.
Clicky: Like tactile, but also makes an audible click when actuated.

This page from Kailh, a keyswitch manufacturer, has diagrams of the force curves: how much the key depresses for a given force. These diagrams combine feel and weight. You can see the three typical colors:

Red: Linear, quiet, ~45g
Brown: Tactile, quiet, ~45g
Blue: Tactile, clicky, ~45g

Sound

Some switches are specifically engineered to be quieter, or louder, when pressed. A “clicky” profile intentionally makes a sound; some “silent” switches are quieter. There are some modifications that can dampen the sound, with some change to feel.

I’ve been using silent red MX keyswitches and Ambients Choc keyswitches. There’s a noticeable difference in my office volume!

Weight / actuation force

Some switches are lighter (less resistance) and some are heavier, while retaining the same general feel (linear/tactile/clicky).

Weight can be a significant comfort factor, in either direction. A reviewer of this article mentioned she had RSI flare-ups when using heavier switches; I’ve felt some strain after switching to lighter swtiches, trying to keep from accidentally pushing them.

Companies offer key-switch testers to let you try the feel – including weight – of different keys. These can be useful for finding what the best setup is for you.

Customizing keyboards

Lots of mechanical keyboards can be customized by replacing the keyswitches, replacing the keycaps, or performing other modifications.

Compatibility

…but there are some limitations – not all keyswitches or keycaps are compatible with each other. They can differ in:

Footprint: Keyswitches electrically and physically connect to a printed circuit board (PCB), and often physically connect to a stabilizing switch-plate. This repository has some nice screenshots in its README.
Stem: Keycaps physically connect to the stem of the keyswitch.
Spacing: How far apart the switches are spaced determines what size of keycaps can fit.

A keyswitch or a keyboard can mix-and-match compatibility between these, to some extent. For example:²

Cherry MX-compatible switches use the MX footprint,³ stem, and spacing. (Kailh Box switches are MX-compatible.)
Kailh Choc V1⁴ switches use a Choc footprint, but use a different stem. A keyboard with Choc keyswitches may lay them out in an MX spacing or in a tighter Choc spacing, as this post shows. In the tighter spacing, MX-sized keycaps won’t fit.

Lots of mechanical keyboards come with hot-swap sockets, which allow replacing keyswitches without soldering. Having hot-swap sockets on my keyboads has been very useful in letting me replace “stock” keyswitches with silent ones.

Three mechanical keyswitches: Ambients Silent Choc Twilight, Kailh Box Red, and Cherry MX Silent Red. Shown head-on, highlighting the differences in their stems. — From left to right: Ambients Silent Choc (V1) Twilight; Kailh Box Red; Cherry MX Silent Red. The Box and MX switches are compatible with the same keycaps. The Choc V1 requires a different shape of keycap.

Choc switches (left) are designed for low-profile keyboards. Choc switches are less than half the height of MX-compatible switches (right).

Two mechanical keyswitches: Ambients Silent Choc Twilight and Kailh Box Red. The bottoms are shown, highlighting the difference in pin layout and the extra stabilizers of the Choc. — The Choc switch (left) has additional stabilizing pins and a slightly different pinout from an MX-compatible switch (right). The keyboard’s PCB and other hardware need to be compatible with the switch form-factor.

Keycaps

Keycaps attach to the top of the keyswitches; the thing you touch is the keycap. Since the keycap is a separate part, it can be replaced for aesthetics or to change the texture of your keyboard.

Keycaps can be flat, with all rows the same height; or sculpted, so the home row is lower than neighbors. This page has some nice cross-sections.

This Ergodox keyboard has DCM-profile keycaps, scuplted to be lower near the home row.

This Atreus keyboard has flat-profile keycaps, all of the same height.

An Atreus keyboard shown head-on, highlighting different styles of keycaps: some have Linear A characters on them, one has a cat's paw, and another is red and says 'PANIC'. — This Atreus keyboard mixes keycaps from different sets. Most from a set of Linear A keycaps, but the cat’s paw and PANIC buttons add some more personality.

Grommets

You can fit rubber grommets around some MX keycap stems to quiet keypresses. It’s a pretty simple way to cut down on noise, without changing out keyswitches.

An Ergodox keyboard with one key removed, showing a rubber grommet on the keycap's stem. — The small white ring around the stem of this keycap is a rubber grommet, which helps reduce noise from keypresses.

Custom programming

All modern keyboards have some sort of microcontroller in them, to check for keypresses and report to the computer. Many use open source, customizable firmware, like QMK or ZMK.

These firmware stacks can provide some neat features. For instance, keys can be configured to have different hold and tap behaviors: hold for a “shift” key, tap for an “enter” key.

You don’t have to write any software to use these features! Most firmware stacks have a graphical configurator that let you click-and-select key behaviors; QMK’s, ZSA’s, or another depending on the keyboard.

Layouts

The only thing you can’t really change about a mechanical keyboard is its layout: where the physical keys are. The typical US keyboard has an ANSI layout, while a European keyboard probably uses the ISO layout (see here).

But keyboard enthusiasts have made some Very Interesting choices in layout.

Reduced layouts

A not-too-tricky variation is an “X%” layout, providing a subset of the ANSI keys without really moving those that are kept. This page lists some typical variations:

Full-size (ANSI): A normal keyboard
Ten-key-less (TKL): …without a numpad
Compact / 60%: …and without arrow keys, function keys, or the home/end/etc cluster
40%: …and without a number row.

The removed keys are usually replaced by “layers” in the keyboard firmware.

You can think of layers like the Fn key on a laptop: an additional set of modifiers that change the meaning of some keys. For instance, on a 40% layout, you might press “layer raise + W” to get a “2” key, instead of having a dedicated number row.

Split

A split keyboard has a gap between the left and right-hand sides.

Some split keyboards come as a single piece, but angle the keys to orient your wrists straight forward from your forearms. Among others, the Atreus and Microsoft Ergonomic 4000 keyboards take this approach.

There’s also two-piece split keyboards, where the left-hand and right-hand halves are physically separate (though typically joined by an electrical cable). Moving the two halves further apart allows your shoulders to open up, as well as keeping your wrists aligned with your arms.

Posture when using a split keyboard with a gap. Wrists are aligned with lower arms, but the elbows and/or shoulders are angled in. — Switching from a laptop keyboard to a single-piece split keyboard alleviated my wrist pain.

Posture when using a split keyboard with two halves. Wrists, elbows, and shoulders are aligned forward from the body. — Spacing my arms further apart opens my shoulders and chest, which is more comfortable for long periods.

Columnar and ortholinear

Typical keyboard layouts (ANSI, ISO, etc.) are row-aligned: keys are arranged in rows, and the rows are offset from each other.

A columnar keyboard arranges keys into columns, and offsets the columns. This layout means that your fingers curl and uncurl, but don’t usually have to splay in or out.⁵ These are often split, since there’s a natural / smooth column break.

An ortholinear keyboard arranges keys in rows and columns, i.e. on a grid. These can be split (for example, Kinesis Advantage) or single-piece (for example, OLKB Planck).

Diagrams of row-oriented, columnar, and ortholinear layouts. In the row layout, keys aligned in rows but not in columns. In the columnar layout, keys are aligned in columns but not in rows. In the ortholinear layout, keys are in a grid. — Columnar layouts are designed on the idea that fingers curl in and out, but aren’t all the same length.

Topography

There’s several ways the topography (height) of keyboards can deviate from “flat”.

Risers can change the forward/backward angle of a keyboard. Some keyboards angle the top edge up to present the keys closer to face-on to… uh, your face. Others tilt the keyboard on a downward slant, like the riser for the Microsoft Ergonomic 4000.

Split keyboards often can be tented, tilting downwards from the gap between the halves. This puts the wrists and forearms in a supinated position, which can be more comfortable.

Some keyboards have finger wells. Instead of putting keycaps at different heights, they put the keyswitches at different heights, curved to approximate the reach of each finger. This post describes a particularly scuplted design based on the Dactyl Manuform; Kinesis offer commercial models with substantial wells.

The case of this Ristretto keyboard is made of multiple layers of plexiglass, but not all layers span the full depth of the keyboard. As a result, the keyboard is tilted towards the typist.

Voyager keyboards come with optional risers for the inner edge, providing a mild tent.

Thumb clusters

Most thumbs are underserved by having one key for two thumbs. Especially in split keyboards,⁶ keyboard designers add additional keys in reach of the thumb; the thumb can curl around and hit several different keys.

Thumb clusters are especially useful for avoiding the splay mentioned in this footnote.⁵ Putting shift, enter, and other modifiers on the thumb cluster allows you to tap them without splaying fingers.

Thumb cluster size varies, and what size and shape work best depend on your hands. Some of my keyboards have a thumb cluster that’s too big for me to use, others have too few keys.

Thumb clusters of a Voyager keyboard (two buttons, 1u and 1.5u) and an Ergodox keyboard (6 keys, two of which are 2u). My hands rest on the outermost key of each cluster, close to my hands. — The Voyager keyboard (left) has two thumb buttons; I use hold-and-tap to get more mileage out of both. The Ergodox (right) has six, but most of them are too hard for me to reach effectively. Your hands may be in a different resting position than mine on the same keyboard!

A Model01 keyboard. My hand comfortably touches one of the four keys in the thumb arc, and rests against the palm button. — A Model01 keyboard has an arc of four thumb buttons on each hand, plus – unusually – an additional palm button, typically configured as a layer switch.

Other thoughts

Wired and wireless

Most mechanical keyboards are wired.⁷ A USB cable connects to the computer: for two-piece split keyboards, another cable connects the two halves.

Wireless designs are becoming more common; the nice!nano controller, launched a couple years ago, is designed to ease converting wired keyboards to wireless. But unless it says “wireless”, expect a wired keyboard.

Why get a mechanical keyboard?

There are a lot of reasons to get into mechanical keyboards, some good (ergonomics, fun, repairability) and some bad (conspicuous consumption, intentional annoyance of coworkers).

If you have a dome or laptop keyboard that you’re happy with, great! Use it! If you want to try something else, great! There are lots of options!

I have my preferences in keyboards, but they’re not normative; I recommend exploring your network⁸ and trying out different options, to see what you like or don’t.

If you have questions, corrections, or comments, let me know!

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