Keyboard Builders' Digest
Save 5% at Loobed Switches! Code: KBDNEWS
Keyboard Builders' Digest / Inspiration

Mikefive, a Kailh PG1316S keyboard

Mike Hölscher aka dynam1keNL presents you the unibody split mikefive, this work-in-progress super-thin keyboard built around Kailh's PG1316S notebook switches.

Mike Hölscher
Published May 6, 2024
Creators! Feel free to tip me off about your keyboard related projects to bring them to 100K readers.

I present you my second keyboard project and my first full custom project: the mikefive. If you like, read below how it came to be and more details about the build.

The first keyboard project was a typeractive wireless Corne which I built about a year ago. After typing 6-finger-qwerty for my whole 38-year life, I switched to ortho, split, colemak-dh, blank keycaps, learned to touch type, and never looked back. However, I found that I was always orienting the Corne halves the same way and started thinking about an unibody.

A friend from work liked my 'alternative' keyboard and wanted to build something too. I showed him the rabbit hole including switch options and also showed him the Kailh X (PG1425) switches. These, and especially the keycaps, were hard to come by but we liked the idea of a slim keyboard, so we decided to email Kailh directly. To our surprise, we could order X switches and caps directly from them, although there was a somewhat high MOQ (minimum order quantity). So, him, me and my friends’ housemate decided to order together.

But Kailh suddenly said: “Are you also interested in these PG1316 switches?”

I never heard of those, but the spec sheet they sent looked interesting: tactile, even lower than the X switches, and completely surface mounted on PCB. Officially, these are laptop switches. But hey, potentially this could become something really slim. So we decided to order a sample batch of these too.

My friend continued his design for the X switches and Chocs (PG1350), but when the Kailh box arrived, and I saw and felt the PG1316Ss, I knew I wanted to build a keeb with those. I learned to make PCBs with help from Joe Scotto's YouTube video and KiCad library, and the same friend who happens to be a mechatronic engineer. I am an industrial product design engineer, so I know my way around 3D CAD and product design.

And, here we are. The mikefive, which gets its name from, well.. me, and its complete thickness of 5mm.

Including the keycap, the switch stands 4.2mm tall and is mounted on a 0.8mm thick PCB, making a total of 5mm. The switch has a travel of 1.8mm, and magically disappears completely inside the keycap volume when pressed. In the picture below you can see how thin it is, compared to my Corne with Chocs.

Pic:

Because the switch is surface mounted, there are no solder pins sticking through the PCB and the PCB can be safely used as a bottom plate without exposing any contacts.

Kailh was nice enough to send the 3D CAD files of the switch and cap so I could use it for checking the fit in KiCad as well as make some nice renders to make design choices a bit easier. Here is a render of the final design before I ordered. Note how I made the bottom edge of the housing near the thumb clusters a little lower then the other edges so the user thumbs will not interfere with the edge there.

Pic:

I chose a 17x17mm spacing, sometimes referred to as CFX spacing. This is 1mm narrower than the 18x17mm Choc spacing I was used too. The choice was primarily based on the square PG1316 keycaps, because I dislike unequal spacing between keycaps. I 3D printed a mock-up and the CFX spacing felt very workable, so I went with it. The PCBs and the CNCed aluminum housing are both from JLC. I did some splatter artwork on the back of the PCB including an isolated solder pad in the shape of the logo.

Pic:

Soldering was done all using a Miniware hotplate and solderpaste we have at work. It is impossible to solder the PG1316S switches by iron, because the contacts are located underneath the switch. Four larger contacts on the corners of the switch lock the switch its ‘frame’ to the PCB by solder. I placed vias in these corner pads for a more secure connection to the PCB. Because the hotplate is small, it took some time to solder everything, but is was easy and I enjoyed getting closer to testing it.

Pic:

Despite being the thinnest switches I have seen, there is space underneath the switch for a backlight LED, which I did not place. Instead, I used this space for the 1N4148W diodes in SOD-123 package. Soldering with a hotplate is easy and magical as the tiny components magically align by themselves.

There is also a popular MSK12C02 power switch to disconnect the battery. The diodes, switch and controller were ordered from splitkb, which is in my tiny country. Bedankt voor de stroopwafeltjes Thomas 😉

Pic:

Next to the extremely low profile switches I also needed to fit a controller and battery. Luckily, my typeractive Corne already showed me the right parts with the super thin nice!nanoV2 and the 301230 battery that both max out below 3mm. I never saw a through-hole controller mounted flush like this but using the hotplate the soldering was a breeze. I made some small additional pads next to the controller pads (you can see them on the picture above) to check if all the individual pads were connected well using a multimeter.

To my surprise, my first time designing a PCB, first time hotplate soldering, first time making a custom shield in ZMK, everything worked! It was a question whether there would still be a good Bluetooth connection with the metal housing covering the whole center controller, but everything just works perfectly. During PCB design, I removed the ground planes on the PCB locally where the Bluetooth antenna of the nice!nano is, and the controller being so close to the bottom probably helps for getting out the radio waves through the bottom.

Pic:

I wanted the case to add as minimal as possible to the keyboard. I primarily wanted the case to stiffen up the relatively thin PCB and protect the surface mounted switches from side impact, when for example dropping it into my bag. That is also why the ‘holes’ are in the keeb, to make the contour smooth for easy into-backpack-sliding. Each half is at 15 degrees, so 30 degrees total between halves. I experimented with this angle using my Corne and liked it this way. The center piece is as small as it can be for housing of the controller and battery.

Pic:

The Kailh-provided keycaps are transparent, and have the letters A, B, C and D on them from the inside. Probably mold marking from production. I guess these would be painted when used in laptops, and transparent to the light passes through. I decided on the white PCB color and natural aluminum housing to match the current switch appearance a bit.

Pic:

There is one slight flaw, and that is that the PCB slightly warped during all of the hotplate soldering from one side. Therefore you can see it lifts slightly out of the housing at the bottom edge. Unfortunately, I did not put a screw there to hold it in place, like I did on each corner and in the middle using countersunk M2x3 torx screws.

Yes, I did some manual countersinking using a countersinking drill bit in a 0.8mm PCB to make the bottom fully flat.

I made sure to have no copper ground planes around the PCB holes to make countersinking easy, and it was.


So, how does it type? Well, the first thing I noticed, coming from Choc Red (linear 50g), is that PG1316Ss are very tactile and very strong. I also have all the tactile Chocs sampled here, but nothing comes close the tactile bump in these. The spec sheet says 60g tactile force and 32g operation force, but actually I question those values. I am getting more used to it as I work with it more, but I think it is still a bit heavy for my taste. I emailed Kailh about my experience, so I am curious what they will say.

But then, the height. It is so comfortable, its incredible. Even with the low profile Chocs I had some strain during longer sessions. But this is incredible. No strain at all. It is like tapping the table surface.

And then there is the portability. This thing is slimmer than your phone or tablet. It slides into you backpack tablet compartment with ease. It is also very light. The case is aluminum, but is all very thin so it weighs nothing.

I am excited about it, and will keep you updated on revisions and such. I can share Gerbers and stuff if people want it. Let me know in the comments or send me a message.

Resources

Do you like this post? Share, donate, subscribe, tip me off!

Published on Mon 6th May 2024. Featured in KBD #164.


Related

The btrfld

u/SolidusHal's btrfld is a quite unique foldable, low profile, tenting keyboard.

enigma36

Enigma36 - A handwired unibody keyboard with underglow and trackpoint by sadekbaroudi.

Reviung_ish

Frederik's keyboard dubbed the Reviung_ish extends the distinctive Reviung layout with a number row.

Crowboard

The open-source monoblock Crowboard by KeyboardDweebs has been around for half a year now. Better late than never.

Rattlemebonez32

Chris Lo's rattlemebonez32 is a 32-key unibody pocket keyboard with minimal Choc spacing, CH552 MCU and FAK firmware.

UnSplit

The UnSplit is a monoblock Kyria layout with modified thumb clusters. Built by dnlnrdn, designed by crunchyavocados (git).

×
top