A combo-based layout for Ergonomic Mechanical Keyboards, implemented in QMK.
View on keyboard-layout-editor.com
- Combo based Symbols layer, including ' " ? : < > and double symbols () [] {} <> '' "" ``
- Backspace next to right pinky
- Nav Layer (Arrow Keys, Home/End)
- Shifts, Space, and Enter on home position thumb keys
- Page Up/Dn, Undo/Redo on Rotary Encoders
- Colemak DHm
- Mod locations are not symmetric
- Learning it makes typing on "normal" keyboards feel slow
- Software Development in Vim using a tiling window manager
- Large hands with strong middle and ring fingers
- Preference for same hand mod/layer activation
- The alternative is opposite hand activation like miryoku
Keep it simple. Keep it ergo. Test everything!
Remember: Optimal Layout is specific to an individual's biomechanics, keyboard hardware, and use case.
- Combos are incredibly fast
- Combos are easy to remember
- Commonly shifted symbols like : and are " are faster (and more ergo) as combos
- Moving ' and " to combos frees up a great key for backspace
- Symbols are typically pressed and released, which is ideal for combos
- Held keys like arrow keys are tiring as combos because they require you to hold two keys
- Double symbols like <>, "" make great combos
- A left arrow is added to position the cursor in between
- They work in every application and website
- Having all symbols on the base layer and combos is easy to remember
- Compare with the common practice of: some on the base layer, some on the shift layer, and some on a "symbols" layer
1 Finger vs 2 Finger Combos
Vertical Combos (like @#$%) and Horizontal Index Finger Combos (+|) use 1 finger to activate
- You can think of these combos as another key in the space between two keys
- These combos are fast and ergonomic because they are close to the home row
- Accidental activation of 1 finger combos is rare
All other Combos use 2 fingers to activate
- Press both keys together, like stenography/plover
- Accidental activation of 2 finger combos may occur at high typing speeds
- Reducing COMBO_TERM helps to minimize accidental activations
- Set COMBO_TERM as low as possible while still allowing consistent activation of combos
- A per-combo COMBO_TERM setting would be ideal, but QMK does not yet support it :(
- If accidental activation still occurs, remove the offending combos from your layout
- Reducing COMBO_TERM helps to minimize accidental activations
QMK Combo Limitations
Combos are amazing, but they are half baked in QMK.
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At the time I wrote my layout, combos required massive boilerplate with silly things like counting and defining the total number of combos
- I used a C preprocessor file from the community to make it tractable
- If that file's functionality was incorporated into QMK, combos would be easier to use
- I used a C preprocessor file from the community to make it tractable
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Combos didn't work with home row mods, record macro keycodes, or tap dance keys, and this was not well documented
- A possible workaround from precondition
- Once QMK allows home row mods and combos on the same key, I will likely update my mod locations
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There is only one global COMBO_TERM setting
- A specific COMBO_TERM for each combo would be ideal
Features tested and NOT used
- Symbols on a layer
- Symbols on combos tested more ergonomic, faster, and more enjoyable
- Arrow keys on mnei and neio (qwerty hjkl and jkl;)
- As a long time vim user I was expecting to prefer mnei
- Testing revealed neiu (jkli) to be most ergo because it put the the more frequent keys (down and right) on my strongest two fingers (middle and ring)
- Numbers on the home row, numbers on the top row
- The numpad tested fastest and most usable, which I also did not expect
- F keys on the top row, and F keys on the numpad
- F keys on the home row tested best, because of the frequency of pressing F1-F5
- Home Row Mods for all mods
- Having mods on the index fingers tested poorly because they locked out 6 alpha keys per side
- Shift on home thumb keys tested better, which I was not expecting
- Home row mods tested poorly with Colemak DHm because the high speed rolls caused accidental triggering
- Backspace on a home thumb key
- I thought backspace would be best on a home thumb because it is often pressed and held
- Testing revealed that timing of the release was actually most important, and the pinky was more precise than the thumb
- If I were using qwerty I would test backspace on the ; key
- Other combo locations
- I tried over 100 combo pairs and only used the most ergonomic
- The runners up are in the layout image as 'ghosted' keys, and can be used if needed
- Opposite hand mod/layer activation (like miryoku)
- Same hand mod/layer activation tested faster and more natural for my brain
- Tap Dances (like CCCACV and dotSpaceShift)
- Testing revealed them to be too slow compared to combos
- Common words as plover combos across both hands
- For example, "the" as combo(t, e)
- Extensive testing revealed they didn't save enough key presses to be worth the mental overhead and accidental triggering
Hardware
| Price | Part |
|---|---|
| $34 | Kyria Rev 1.2 PCB kit w/ LEDs |
| $8 | Low profile Mill Max sockets |
| $39 | Elite-C 3.1 microcontrollers |
| $72 | 62g Zilents v2 "silent tactile blue" switches |
| $10 | Rotary encoders & knobs |
| $41 | Splitkb Clear Low Profile Plate Case |
| $84 | PMK Keycaps: Standard DSA & Flat |
| $6 | TTRS Cable |
| $15 | GRIFITI Fat Wrist Pads (cut & grinded to size) |
| (Had) | USB-C cable |
| (Had) | Bumpers for tenting |
Total: $309
- Tilting and tenting
- Split
- Rotary Encoders
- Kyria columnar stagger
- Kyria thumb arc position and radius
- Lower profile thumb keycaps
- DSA keycaps for combos
- Plate case required heavy modification (see below)
- TTRS & USB cables are awkward
- Lack of dedicated number row for occasional use (numpad layer is tedious for mixed numbers and alphas)
- Flat thumb keycaps are a great height but have no sculpting
- Pressing two 62g zilents with one finger (e.g. for combos) is a little heavy
- Upper thumb keys are not ergo enough to be useful
- The 1u solder pads under the 2u thumb keys are rotated 90 degrees
- This messes up the uniformity of the thumb arc and prevents non 4-way symmetric stems (like Choch low pro)
- Wrist rests required heavy modification (cutting and grinding)
- Cherry Profile keycaps
- Combos were harder on cherry profile keycaps because of the row height differences and tall height
- Uniform height flater DSA profile keycaps tested much better for combos
- 2u thumb keys
- Even with lube and high quality stabs, the 2u keys took too much effort to press and were less comfortable than the other 1u thumb keys
- It was hard to get 2u keycaps, especially low profile
- I deconstructed my board and re-built it with all 1u keys and was much happier (keep it simple)
Splitkb Plate Case Modifications
- The pcb was just floating between the two acrylic layers, so removing keycaps pulls directly on the solder connections and moves the pcb up and down
- I put bumpers between the top plate and pcb to fix this
- The case resting flat on the desk was uncomfortable, and needed tilting and tenting to be usable
- I tried Lego tenting but it was difficult to construct the right angles with Legos
- When I finally got it, it made the board uncomfortably high off the desk
- I ended up ditching the legos and using stick on bumpers to get the perfect tilt & tent
- This was time consuming because each corner needed a different height, and they had to be perfectly balanced or the keyboard would wobble
- I tried Lego tenting but it was difficult to construct the right angles with Legos
- With any tilting and tenting the plate case becomes quite high off the table, but it's only because of the acrylic on the bottom outside corner
- I ended up grinding away the acrylic and a bit of the pcb on the bottom outside corners
- This made it lower profile, and was worth the effort, but created refraction problems with the corner RGBs shining into the grinded edge
- I regrinded a notch around the LEDs and put electrical tape over the sides so the light couldn't shine in
- This made it lower profile, and was worth the effort, but created refraction problems with the corner RGBs shining into the grinded edge
- I ended up grinding away the acrylic and a bit of the pcb on the bottom outside corners
Final thoughts
Custom keyboards are a fun hobby, but a large investment of time and money. It took months of researching, ordering, waiting, building, and tweaking to get useable hardware. Then months of designing, programming, testing, and debugging to get a comfortable layout.
In time vendors will hopefully make this process cheaper and easier.
I created wonderful hardware, but it's not perfect. A better keyboard would be:
- Full wireless
- Lower profile
- Lighter weight
- More portable
- More durable
and have:
- Easily adjustable tent & tilt
- Integrated wrist rests
Something like a cross between a Kyria/Elora and a GergoPlex Heavy. I also like the corne design
The real innovation is in the layout I created. I love using it, and hope it will inspire you when you design your own layout.