Author Topic: [IC] Plus12 Split Keyboard  (Read 4252 times)

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Offline Dotdash32

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  • Posts: 55
  • Location: Bay Area, CA
[IC] Plus12 Split Keyboard
« on: Tue, 17 July 2018, 16:57:25 »


Have you ever wanted a keyboard that was as flexible as a gymnast?
Always thought that if you could get one more thumb key, it would make it so much easier to type?

The plus12 sets out to be a unified buy for over 20 different keyboard combinations.
The Mainland body of the keyboard functions with either 5 or 6 columns,
and is wired for a replaceable connection to any of the thumb fans.

One buy, 20 Options

The Mainland is the home controller of the board, it houses the controller, TRRS interconnect, and the main body of keys.
It also has a ribbon cable connector for any of the three thumb key layouts. 
In this manner, the two can be connected and a wide variety of combination layouts are possible.

The silkscreened lines on the PCBs indicate where they can be cut off to create smaller version. 
Thus, the Mainland can have five or six columns, the most common sizes for very small keyboards (one pinky row or an extra one, like shift/tab/return).
The thumb islands are adjustable from six down to three keys in both an arc and straight line, like the Planck.


Right now, I've prototyped each of the boards on an Othermill, and am looking for which ones will be most popular to move to PCB production prototyping from a full fab house.
In addition, the most popular ones will get case designs, either as double plates (switch and bottom plate) or CNC'd cases, depending on interest.  CNC materials would likely be Aluminum and HDPE.

There is also a possibility of including Holtites as an addon, and formatting the PCBs to accept them for hotswapping. 

I2C is not currently supported, but it would be a possible option if people really want it.  Instead, there is an "Extra Data" pin hooked up to run across the TRRS jack so that an RGB strip can be synced.

There is also a possiblity of creating a double row thumb key, since the ribbon cable can carry up to two thumb key rows.
It would be modelled after the Mitosis, but I don't want to make it unless there is an interest in it.
By a similar token, if there is a specific thumb pattern you want, let me know and we can try to include it. 


QMK supports "folders" inside keyboard projects, so right now each common Mainland column number and thumb key combination have separate folders and build paths. 
This lets you create a keymap unique to the number of keys you want, and not deal with extraneous entries in the keymap.c file.
However, this means each keymap must be matched exactly to a configuration, and the "default" ones must have several options to fit within this scheme.

Another option is to just configure the board to have one large configuration, and just use KC_NO in the keymap.
I personally like the matched config and keymap system better, because it is easier to see how many keys you have and where everything fits together.


The plus12 is the spiritual successor of the Lil' 38, my earlier split keyboard prototype.
It's primary goal was to take the staggered rows of a normal keyboard and transform them into something more ergonomic.
Here, I'm definig ergonomic as making the keys easier to reach from the natrual hand position, and requiring the hand to move less over the entire range of the keyboard.
This manifests itself in staggered column format that follows the way fingers move and stretch, along the axis of the hand, while also splitting the keyboard into two so that a proper wrist angle can be achieved.
It features a stagger much more aggressive than the ErgoDox (and most of it's descendents), and an improved set of thumb keys.
In my research, I found that the thumb moves basically in an arc, and the easiest keys to hit would lay on that arc.
Thus, the "thumb fan" was born, several thumb keys placed along the path your thumb would travel.

As I've been prototyping the Lil' 38 for about 3 years, the constant feedback is that a sixth column would be incredibly useful.
My own philosophy is to move every modifier key that would be hit with the pinky to the thumbs, thus reducing finger straing, but adding more keys also allows for many more combinations and possibilities. 
So I tried to figure out how to include both the staunch minimalism that I desired and the expansive possibilites that were so popular.

Another concern was how to fit the range of thumb keys that other have wanted.
I think only four are truly needed, but for some, the fifth or sixth is a livesaver.
Plus, many keyboards only have 3.
I tried to figure out how to fit so many options into a group buy, because having so many different PCBs would be impossible to hit MOQ for anyone.

The answer came in a roundabout way.
This summer, I've been prototyping PCBs on an Othermill, which has a really small bed compared to the standard keyboard or even PCB.
What I then realized was that if I separated the controller and "main matrix" of the keyboard from the thumb keys, they could be easily interchanged and customized. 
In the end, the idea is to produce the largest PCB, and then cut it down to the prefered size. 
This reduces MOQs, while greatly increasing the options for customization.

There are so few keys, how do I type numbers?

The second part of the Ergonomic keyboard philosophy is reduction of the number of keys. 
It is much easier by definition to reach the QWERTY row than it is to reach the number row, so removing the last row reduces finger strain.
But the constant problem for 40% keyboards is how to fit more characters than there are keys.
This where the idea of layers comes in.
I would argue that layers are easier when there are more thumb keys, because the thumb can trigger a layer while the other fingers continue to type like normal.
Instead of devoting a pinky to shift, a thumb holds it and there is no more swapping hands when you have to type a letter on the other side of the keyboard.

In addition, moving the numbers to underneath home row means that there they maintain their same relative position to their normal locations, but are simpler to type.
Thumb shifting and chording is simple, since the two thumbs can work in tandem to hit most generic combinations for typing characters, and clever side-by-side placement lets one thumb press two keys if the need arises.

Offline LastBrat

  • Posts: 55
Re: [IC] Plus12 Split Keyboard
« Reply #1 on: Wed, 18 July 2018, 16:02:28 »
Please, add an option for Kailh low profile switches, and I'm definitely interested!  :thumb:

Offline nilpt

  • Posts: 74
  • Location: Portugal
Re: [IC] Plus12 Split Keyboard
« Reply #2 on: Wed, 18 July 2018, 16:15:04 »
Would like to see renders of the complete keyboard (all the combinations imaginable...) before commiting.
It looks promising, thanks.
IBM 1391410 / Qume terminal keyboard (teensy 2++)

Offline kimusan

  • Posts: 13
  • Location: Gistrup, Denmark
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Re: [IC] Plus12 Split Keyboard
« Reply #3 on: Thu, 02 August 2018, 04:13:42 »
looks great. I would love to build me one of these with an alu casing.

Offline rumlyne

  • Posts: 31
  • Location: Vienna, Austria
  • ortho, ergo, ertho?!
Re: [IC] Plus12 Split Keyboard
« Reply #4 on: Tue, 23 October 2018, 03:17:15 »
This i gonna be my new gamepad.

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