Keyboard

articulation70

The articulation70 keyboard is a successor to the articulation80, with LEDs and a more personalised layout.

It features:

• Variable pinky stagger, supporting ±1 mm vertically offsetted soldering configurations.
• 3 × 6 main body, 3 thumb switches, 2 corner switches and 3 × 4 numpad layout.
• Kailh Choc V1 hot-swap support.
• A breakaway-able number pad.
• Serial or I2C connection between halves.
• Pro Micro-compatible controller support, however a micro-controller. with more pins are required to operate LEDs 2 and 3.
• 3 LEDs
• Reversible PCB to reduce manufacturing costs for hobby usage.

KiCad plugins

This repo comes included with two plugins. To install these plugins, copy the directories in plugins into your Plugins Directory, which is found by Tools → External Plugins → Open Plugins Directory in the PCB Editor.

Split intersecting traces

When joining traces from rotated switches, it can be difficult to connect traces from two angles to form a aesthetic curve. This plugins splits two selected intersecting traces into four traces.

An example of use:

Total trace length

Why not?

Build Instructions

This build is very similar to many hobby keyboards. Please refer to the instructions for articulation80. You will need a soldering iron.

Which jumpers do I need to solder?

If using serial, then solder J1, and J4. If using I2C, then solder J2, J3 and J4. Solder on the back of each respective half.

Build Parts

I would recommend substituting for cheaper or easier to source components when possible.

*Adjust for number of keys desired.

**Adjust for number of numpads.

How to order PCBs and plates

I ordered from JLCPCB, however there are many other manufacturers. Take a look at PCBShopper.

For the PCBs, I used:

• Base material: FR-4
• PCB thickness: 1.6 mm
• PCB colour: black
• Surface finish: LeadFree HASL
• Remove order number: Yes

For the switch plates, I used:

• Base material: FR-4
• PCB thickness: 1.2 mm
• PCB colour: black
• Surface finish: HASL (with lead) because the unleaded option greatly increases cost and the plates do not have any pads.
• Remove order number: Yes

For the controller plates, I used:

• Base material: FR-4
• PCB thickness: 1.2 mm
• PCB colour: black
• Surface finish: HASL (with lead)
• Remove order number: Yes

How to adjust the layout

This was tested on installation of FreeCad 0.20.2, Python 3.11.6 and KiCad 7.0.6.

1. First, open layout.FCStd with FreeCad and open Constants under the model tree view. You should see a spreadsheet of parameters.

2. Change values as necessary. If the values change too much from their intended range, then the sketch (as shown in the next step) may become broken.
3. Click on one of the sketches in the model tree view. Verify the layout shown is correct.

4. Export the layout to a file by coping the contents of scripts/export_geometry.py into FreeCad's Python console. The console is accessible by View → Panel → Python console. If you get a permission error, change geometry.txt to an absolute path within the repo. You should get a number, which reports the bytes written to geometry.txt.

5. Update the PCB by running the following scripts:

python scripts/update_geometry.py pcb/keyboard.kicad_pcb geometry.txt
python scripts/update_geometry.py left_plate/plate.kicad_pcb geometry.txt
python scripts/update_geometry.py right_plate/plate.kicad_pcb geometry.txt

For now, I will run the first script. Update the PCB files for the plates if desired.

6. Clean-up residual graphic objects on the Edge.Cuts layer. The script deletes all previous edges and plots edges in the Edge and EdgeNumpad sketch, which includes construction lines that should not be included in the Edge.Cuts layer. The script also positions footprints according to the Components sketch. The script will output some text because some components' positions are not specified by the layout, such as the resistors.

7. Update traces and refill copper zones. Unfortunately this step takes the longest. Make sure to thoroughly check PCB.

The PCB is ready!

Firmware

I used QMK program the controllers. To use the same setup as me, copy the contents of qmk directory into your installation of qmk_firmware/keyboards. Flash the left and right controllers with the respective commands:

qmk flash -kb articulation70 -km default -bl dfu-split-left
qmk flash -kb articulation70 -km default -bl dfu-split-right

These commands assume the usage of Elite-C's.

If you want to upgrade the toolchain, you can do so at your own risk:

pacboy update avr-gcc:x

Additional documentation

scripts/corner_switch_pad_geometry.py
scripts/curved_switch_pad_geometry.py

These switches generate the geometry for curved pads featured in the switch footprints. The curved shape comes from the rectangular pad subtracted by the clearance of the centre switch drill hole. KiCad supports polygons in pads, but it is not very easy to use. These scripts makes the design of these footprints a bit easier.

Gallery

More images can be found here.

Future Considerations

There are a few improvements that can be made:

• Adding a pattern to improve aesthetics on the plates.
• Adding solder mask expansion on pads and pins.
• Re-route ROW4 trace.
• Support LED placement in top-right.
• Improve LED brightness as they are too dim.
• Support both micro-controllers mounted face down.
• Strive to continually improve layout. The key columns are perpendicular to the fingers. This does not effectively utilise the flexibility of the hand.

Credit

Thanks to:

• KBD.news for inspiration.
• sevmyer for the open-source KiCad teardrop plugin which was very helpful given many KiCad teardrop plugins were for Kicad 6.
• The QMK community on Discord for their helpful explanations.
• Various open source keyboards for guidance, but not limited to: KLOTZ, Corne and Breeze.