3D printed ergonomic split keyboard
Introducing an ergonomic split keyboard inspired by Dactyl and Corne.
Specs
- Split
- Tilt/Tent - minimal
- Concave - minimal
- Column Staggered
- Thumb Clusters - 3 or 4 buttons
- Hot Swap Switches
- Hand-wired
Motivation
Many traditional ergonomic keyboards feature a highly concave surface, implying that keys are pressed with the fingertip, almost like a doorbell. However, I prefer pressing keys with the pads of my fingers, akin to playing a piano. I experimented with some Dactyl-ManuForm derivatives including the Charybdis Mini Kit and aimed to create a more compact version with less pronounced curvature.
In feel, the it resembles more of a flat keyboard with an angled stand than a classic ergonomic keyboard.
Design
I wanted to create a keyboard that was not only comfortable but also compact and looks nice. Unlike many other ergonomic keyboards, it is almost invisible behind the keycaps.
It was clear from the start that the keyboard would not be based on a PCB. Boards are flat and ergonomic keyboards are not. I had seen projects using custom semi-flexible boards, but I decided that approach was too labor-intensive and would slow down prototyping. I chose to print everything possible on my home 3D printer.
Before designing this keyboard, I looked at some solutions where wires were soldered directly to the switches. I didn’t want to solder the switches, as I was still searching for the perfect ones.
There are hot-swap sockets designed to be 3D-printed. It turned out that manufacturing them is possible, but the process is labor-intensive and not very reliable: wires oxidize over time, and contacts can loosen. I decided to use factory hot-swap sockets to simplify the assembly and improve the reliability.
The hot-swap socket clicks into a designated space under the switch socket. After a year of use, there have been no issues. Switches can be inserted and removed many times without damaging the printed parts.
I based the design on my previous flat split keyboard (it was Corne). I extended its geometry into the third dimension so that the keys would be positioned optimally. It worked! After a couple of prototypes, I achieved a compact and comfortable version.
Initially, the microcontroller simply lay between the flat base and the curved key plate. Throughout the process, ideas evolved. At one point, I felt that the abundance of wires and the exposed controller detracted from the elegant form, so I decided to conceal the controller within the plastic base.
Printing
It turned out to be quite difficult to print such intricate parts on a home FDM printer. The support structures left marks, and small details either broke off or came out at the wrong size.
To ensure a high-quality surface, I developed an additional support with hidden attachment points that left no visible marks on the exterior parts. The regular support settings were tuned to be as disconnected from the printing parts as possible, so they could be removed easily.
Wiring
The wires were so thick that they did not touch each other, so insulation was not needed. However, wiring it this way was time-consuming. In the next version, I used insulated wire with a smaller conductor diameter.
The design allows for some degree of customization, with options to update the main plate, thumb plate, or base with the controller, without altering other components. However, wire soldering is required for full assembly, so it is not entirely modular yet.
The first version was build around WaveShare RP2040 MCU. It has two buttons and an RGB LED. I made the LED visible and used it to indicate selected layer. Later I chose a different controller and use a small LED in visible location.
Updated version
Since its initial printing in 2024, the keyboard design has undergone several changes. I relocated the indicator LED to a more visible spot. The split connection now uses a USB-C cable to prevent damage to the controller from misconnected TRRS pins. I printed the keyboard with carbon fiber reinforced PLA for improved structural rigidity.
