r/Trackballs

Any ideas or pointers are appreciated, thank you

Gotta use it more before I can give more thoughts but pretty stoked to get it going!

There have been keyboards that are portable and there have been keyboards that have integrated pointing devices, but to date there haven't been any keyboards that combine both features. With this new design I intend to change that.

I'm reaching the end of the design phase on my new keyboard, Androphage. It's a folding unibody split keyboard with 44 keys and a finger trackball in the center. When the keyboard is closed, all the more delicate components --- switches, keycaps, screen --- are protected inside the rugged SLS nylon case. Additionally the trackball is secured in-place by the folding base of the keyboard.

Additional Renders

• Front View

• Top View

• Key Layout

Highlights:

• Unibody with fixed 15° split angle* and 10° tent angle.

• 44 keys: 3x5, plus 4 thumb keys, row 5** middle and ring finger keys, and key that can either be a very tucked thumb key or a row 5 index finger key.

• Rugged SLS nylon case.

• NRF52850 microcontroller and ZMK firmware for Bluetooth, dongle, or wired connectivity.

• Dual-sensor 34mm trackball is capable of 3-axis control, i.e. twist-to-scroll à la Kensington SlimBlade.

• Trackball uses ball transfer units (BTUs) as bearings for maximum smoothness.

• Nice!View or similar screen for layer, pairing, and charging status.

• Low power consumption microcontroller and trackball sensors (PMW3610) paired with a 300 mAh LiPo battery for days or weeks of battery life.

• USB-C charging and connectivity.

• Compatible with Kailh Choc V1, Kailh Choc V2, and Gateron Low Profile (KS-33) switches.

• Designed for Chicago Steno or KLP Lamé keycaps but can potentially be adapted for other low-to-mid-profile keycaps.

• The custom hinges are SLM stainless steel for maximum durability.

• There is space inside the base for storing the charging cable.

• Unfolded dimensions: 290 x 135 x 62 mm

• Folded dimensions: 148 x 135 x 45 mm

* Measured between the centerline of the keyboard and the axis of the index finger key column.

** That is, two rows below the home row, equivalent to the modifier row on an ANSI/ISO keyboard.

Interest Check

I'm getting ready to start building a short run of prototypes. To defray some of the cost of prototyping I'm looking to sell some of them at cost --- I'd roughly estimate $300. It will probably take 3-4 months for me to source all the components, assemble, test, debug, etc. before I'm ready to ship. I'm not taking orders or payments at this time, just checking whether there's interest.

Your feedback is appreciated if you have any suggestions for improvements to the design.

Open Source

This project is licensed under the CERN Open Hardware License, Strongly Reciprocal 2.0. The source code is available at https://github.com/Silcantar/androphage.

The left video shows a roller-bearing trackball, while the right video shows a static ruby-bearing trackball.

In the left video, the Z-axis spin is mostly suppressed, so the ball tends to roll more cleanly in the intended up/down direction. You can see this because the marker stays relatively parallel while moving up and down.

In the right video, the ball rotates not only in the up/down direction, but also around the Z axis. In other words, it twists. You can see this from the way the marker itself rotates/skews during the motion.

I think this difference is not just about friction or smoothness. It also affects how the finger motion on the surface of the ball gets projected onto 2D cursor movement.

With roller bearings, even when you operate the ball away from the “sweet spot” and closer to the edge, you can expect more consistent motion. The roller bearings mechanically resist unwanted Z-axis spin, so more of the motion remains useful for X/Y pointing.

With static bearings, as you move closer to the edge of the ball, the motion can start to feel “duller” or less responsive. That is because part of the finger motion turns into Z-axis spin, and a normal X/Y sensor does not use that spin for cursor movement. In practice, some of the motion is lost.

I am not saying one design is always better than the other. A well-made static bearing trackball can feel extremely smooth and effortless. Roller-bearing designs, on the other hand, usually have some amount of friction, mechanical feel, and noise.

But if someone is used to one type and is thinking about switching to the other, I think this is a useful difference to understand.

P.S. I would expect BTU-style designs, using ball transfer units, to behave more like the static-bearing example, since they allow the ball to spin freely in multiple directions instead of mechanically suppressing Z-axis twist.

Hello folks,

out of curiosity, I unpacked the brand new TB675 thinking I would swap the stock bearings to G5 silicon nitride ones. Hovewer, before that I plugged it once more just to test the movement on stock bearing once more, lo and behold - if you use the rightside portion of the ball for any rotation, then that movement is almost dead, like the cursor wont move as it should, it moves in erratic way and in very small direction, no matter how you would try to spin the ball on that rightside of the ball - it is completely random movement in small directions. If you put the thumb on exact top center of the ball, or on its left side, then the cursor moves as it should.

I suspect it is because the dreaded offset of its sensor, very close to the side , next to the one of its bearings. In comparision, Elecom IST PRO has its sensor on exact bottom center and the bearings are aligned precisely as on the perimiter of the ball. Plus no matter where your thumb is, the cursor moves exactly as it should. So, stay away from TB675 if you move your thumb to the right side of the ball often (I do.) It is damn shame, that Kensington cant put their bussiness in order - for such a mark, I would not expect **mediocre** flawed hardware, just to be put in one of the best ergonomic shaped trackball casing.

Included phots for reference of the dead rightside.

...I don’t think so.

I’ve been refining my setup over the last few months/years and it’s finally started to stabilise after getting stuck in a loop of continuous tweaks.

I put together a write-up covering where things ended up, including my current Adept + Corne keymaps, and some early thoughts on the Endgame trackball.

Curious if anyone else has ended up with a “final” setup that didn’t stay final for long.

Ergonomics: Are We There Yet?

First impressions, this thing is tiny. I like it. Bearings are ruby but I don't plan on changing them unless I need to. Gonna use it when I work out of coffee shops. It's a cute device

I ordered this on Mercari Japan through zenmarket.

I'm going to be using this for digital art and as an occasional companion when I'm doing some design work on my computer.

Highlight for me is the fact that it's programmable like a keyboard and has onboard memory. It's mainly going to be used on my iPad Pro as a companion to procreate and clip studio paint. Also the ball (or is it bearings??) feels really smooooooth.

I plan to mod it; spray paint, add a mini pool ball (it's the perfect size 25mm) as the trackball and finally change those silent switches to something more clicky ( although this may take longer, I'll have to solder 🤢).