Small Keyboard Guide

Why use small keyboards?

Keyboards come in different sizes. When you talk about keyboard sizes you talk about the number of keys. Most normal consumer keyboards are 104% (104 keys, it is common to add the %). Choosing another uncommon Keyboard size and customizing it to your needs can be great. A curated list for switching to a small keyboard:

• thekeeblog.com
• Introduction to Small Keyboards - Keeb Supply Docs
• λ ryan
• rob.rho.org.uk
• andy.teknostatik.co.uk
• franknoirot.co

If you are interested to try small keyboards.
If you are sold to get a small keyboard you might beg the question "But how can I get a small keyboard if only common sizes are being sold?". This Guide explains how to build one yourself without a lot of cost.

Table of contents

What keyboard sizes are there and how to choose the 'correct' size? In the end there is no correct size and you just have to try and choose.

Parts

Keycaps

The keycaps are maybe the most important part. They contribute a lot for the look and feel of a keyboard. Here are some keycaps I've tried.

MBK

These keycaps are my favorite uniform keycaps for the choc v1. They feel great and come in different colors. They are PBT and they have a textured top so they're rather grippy. They are also not too expensive with ~4.5€/10PCS (blank white). They also come with legends if you prefer this. Oddly the keycaps cannot be sourced via Aliexpress or similar but they are available in several sources (fkcaps.com/). They also have homing keys (these are keys with little dots on the center so one knows where the keys for the index fingers should rest). On the right we can see the "violet" purple and "lavender" purple colored MBK keycaps on one keyboard.
The Colored one might be a tad more expensive (6.9€/10Pcs).
There are also crystal reflective one that are a eyecatcher but they feel glossy and slippery (available on keycapsss.com/ 9€/10Pcs).

Chicago Steno

These are probably my most favorite keycaps. I'm talking about the Chicago Steno by pseudoku. Each Keycap is in effect hugging the finger. The homerow keys (that are the keys where the resting finger lay) are horizontally/vertically symmetric, they have vertical grooves in them which make the fingers feel securely in them.
The bottom and the top row keycaps are similar to the homerow keys. They however are slanted to be more perpendicular to the fingers when trying to press them. This makes everything seem fitting.

The thumbs are also very interesting.
There are different keycaps pseudoku designed for the thumb cluster. In the picture above of the purple keyboard we can see two thumb keycaps that are convex. I actually prefer that they are sculpted in such a way that they make a large indentation that is 2u long, so the right keycap is resembling a right halfpipe, while the left is resembling a left. Due to the fact that the purple/red artisan keycap is only available in this convex form factor I had to make consequences.
Regarding on this note it would also maybe would've been better to adjust the innermost column where the center key is not part of the homerow to some degree to easy the effort of overcoming the hill between the innermost and second innermost column.
Some words about the texture and color:
elaborate on fdm and pla/pbt. and artisan.

Switches

The switches to actually actuate the keypress are usually mechanical, this means they have a spring in them which gets compressed before the key bottoms out. The springs have different strength and they are three main types of switches that categorize the feel of the switch. There are Blue switches that are clicking and are noisy. The forces that have to be applied to steadily press them down is not linear due to the mechanical guiding system of the switch. The "Red" switches are linear actuators, that mean they linearly require some force dependent on the distance traveled. They don't provide any visual/auditoral feedback when they actuate. The Brown switch is a tactile switch. Meaning it is not linear and the force of triggering a press is higher right before the press. After the actuation point the force/distance required to bottom out is decreasing again.

Kailh Choc V1

Kaihl Choc V1 switches are also known as PG1350.

These switches are known for their slim design, making them ideal for portable wireless keyboards. They come in different variants. A list of the variants can be seen here. Because of their limited height they inherently provide less travel and some may say a worse feeling.
The switches can be taken apart and lubed with dedicated keyboard lube. They also can be tape modded. They are fairly cheap and can be sourced form Aliexpress or similar. If we zoom into the switch we can see that it is a blue switch and that a piece of metal gets flug if we overcome the point of actuation.
Personally I do like the red switches but everyone has to decide for themselves.

The way the switches are mounted is rather traditional. The switches don't have the same spacing that the MX switches use (cherry standard is 19.05 mm in the vertical and horizontal). The Choc spacing is 18mm in the horizontal and 17mm in the vertical. This means that the keycaps have to occupy the same spacing to remove any gaps. This in turn means the keycaps cannot be rotational symmetric unlike the cherry ones. They stem is slow slits where the keycap slides in rather nice.
In the following model a choc v1 switch mounted on a PCB is displayed. It can be noted that the two pins on the top side of the switch belong to a led that can be put inside of the switch.

PCB

Every Keyboard has a PCB which is a green slab of silicon that has traces of copper to connect the components of a keyboard to allow functionality. Most of the time it is green rigid (not for a Dactyl Manuform type keyboard) with a thickness of 1.6mm. Some curated list of open source keyboards:

• golem.hu
• awesome-mechanical-keyboard
• kbd.news
• mechanical-keyboard

Nevertheless to really discover the keyboards one has to lurk in discord or visit the sub of r/ergomechboards or similar to really get inspired. Also talking to people and going to meetups helps a lot.

My absolute favorite for the past couple of year is the Sweep. It is a 34 key split keyboard with no features really. Simplicity. Almost all keyboards also provide their source so you can just open the project with the proper app (here KiCad) and modify it if needed. Sometimes (like here with the sweep) they also include the compiled gerber files (files that you can give the manufacturer to produce the PCB) in the release page.
Why would I need to modify the PCB.

You don't but you can. There are some advantages.

• personal silkscreen (colorful pictures or popart)
• some keyboards are designed to have trrs wires in between them. If you know you'll use bluetooth you can remove unneeded parts
• removing of mounting if no tenting/mounting is intended
• you can make a new keyboard but base it on the project

Price of Manufacture

The price of manufacturers differs depending on the size and requirements of the PCB. So far I would say that you cannot go wrong with JLCPCB.
You want to have some number: The price for 5Pcbs is round 20-30€ but keep in mind this is for a small keyboard.

Case

People would say that a case is mandatory for a keyboard. I disagree. As you've seen earlier in section MKB you can build keyboards without a case. The structural integrity of the PCB is more than enough that the keyboard feels and is sturdy. In all those years nothing every happened to the keyboards except some switches breaking when the keyboard falls on the ground. But a case can contribute to the look and feel of the keyboard. For example the background image of this page is my self made 5column Corne with an cast acrylic case. Next to it is a 2% milk (just a milk carton with two buttons). The acrylic sandwich is the eye-catcher of this corner, even though it also has really nice switches.
In the keyboard community it important to have a nice case. CNCed metal with a nice engraving in the back is highly regarded one of the best cases.

Pin Headers/ Pin Sockets

For the pins headers we can repurpose LED strip pin headers. They have the correct size and don't cost anything. I used to buy specialized keyboard pin headers but they don't bring any benefit.

Why do we want pin pin sockets? Why don't we just solder the pins to the controller and into the PCB?
Sure we could do that but we have the space (the battery is usually under the MCU) to make the decision to use pins and sockets to later allow the controller to be hot swappable. In case the controller breaks we can solder pins to a new one and plug it in. The sockets and pins don't add a lot to the cost. The sockets are spring loaded that means no screwing and just placing it in there once.

Battery

If the keyboard is intended to be used wirelessly then a battery is mandatory. Usually the battery is under the MCU and has the following dimensions. 32mm x 12mm x 4mm. The model of such batteries are 301230 and they often have a capacity of 80-110mAh. The battery life of wireless keyboard running zmk is usually several months. There are also coin battery, solar and AAAA battery powered keyboard but they are rare because 3.7v lipo batteries are so good and they prove easier to charge. Virtually all wireless keyboard controllers have a lipo battery charger integrated.

For a rough estimate on Battery life with ZMK see Battery Profiler and choose nice!nanov2.
Where to source lipo batteries?
Batteries can be bought from Aliexpress. The shipping is horrendous expensive and takes a long time. I would recommend buying several batteries. Maybe 5€/Battery can be calculated. The Capacity of the batteries cannot be trusted. There is just no other choice.

Software

The software (firmware in the case of keyboards) is very important for customizing the keymap. There are many different keyboard firmwares available. A list can be seen here. The takeaway should be if you go with a wireless keyboard go for ZMK. If you go wired you can also go for QMK.

ZMK

Keymap

Alt Layouts

As an example of a keymap I'd recommend visiting KeymapDB to get inspired from. But in the end it is a process that takes to grow your keymap naturally. I'm currently using  Colemake DH. But there are so much more better ones than QWERTY so please consider switching. A list to some: kinesis-ergo (mainstream alt layouts), list alt laytous on getreuer.info, His Guide Is Very Good.

cyanophage.github.io is sooo good to compare layouts! For example in the source of getreuer.info we can see that apparently Focal does very good and has little SFB (same finger biagram (two consecutive presses with the same finger)) and thus is seems very good. If we use the comparison tool and compare colemake dh (Effort 535.05) to Focal (Effort 537.85) we can see the effort is the same. Always use different compare tools and adjust the effort per key with personal tendencies in mind. In the end it does not really matter compared to QWERTY which has a huge effort (1258.34) and is inferior to almost all other keymaps. I personally use the popular Colemake DH (2014).
If you really want to dive deep in to the rabbit hole look at stenography.

My layout

This is my personal opinion. I don't think the keyboard layout matters too much. I would not put letters on the thumb, I'm file with space and shift on the thumb that's already enough for me. In fact I only use one of the right thumb keys.

If you are interested you can look at the image on the right to see my personal keymap (see XML drawio graphics,code for Keymap on Github). I only type English but it can be useful to be able to type on other peoples devices with other input methods. This requires some configuring which I did. 

I recommend to go with US International as a input method. Dead keys or no dead keys does not matter as long as we define the macros for the keycodes properly. Example for ' (Single Quote/Apostrophe) I use a macro that types Single Quote plus space afterwards. Ä is " double quotes plus A and so on. If you want it simple just stick with US layout.

Some Recommendations:
Break free of the shifted symbols. If you have a dedicated key to do the parenthesis you don't need Shift(9) to produce (. My Shift(9) produces ? instead and Shift(8) is #. My Shift(3) is not # but it generates '.

Cost

Some people might not care too much about the cost of their keyboard. It'll be around for years and important especially if you work in an office. I'll provide a real world example of a keyboard and the price to build it.
Economical tip: Look on Aliexpress first before sourcing from local shops.

Assuming you have some soldering hardware you can expect to build a keyboard for less than 100€. Some prices change. The controllers used to be 30€ each now they are actually less than 5€ per MCU. MBK keycaps are manufractured less and prices have risen. This table is just giving a rough estimate and it is not timeless so take it with a grain of salt and just do your own research. Leave an anonymous comment and let me know your thoughts.