aball - A Buttonless trackball for all
I like keyboards, and my workflow is defintely keyboard first. Tiling window manager, VIM, bash... pretty
much all the keyboard I can get. Yet, however hard I try, there is always some need for a pointing device.
So this is my stab at a trackball for keyboard first workflows.
Why not a mouse? Well, space... trackballs take up less space. Which got me thinking, what is the minimum footprint for a usable trackball? I managed to get it down to 60x80mm... you could go even smaller, but I wanted some sort of case on it and this particular size sits nicely next to my daily driver, the Kyria.
In the quest to reduce size, I did away with any buttons. I have plenty of buttons on my keyboard, and my left hand is capable of pressing them when I'm using the aball with my right hand. Via a layer, I've mapped buttons on the home row to:
- F: Left Click
- D: Middle Click
- S: Right Click
- G: Scroll Up
- B: Scroll Down
Scroll up and down are not really needed, but they are pretty handy, even when not using the trackball.
Aside from having no buttons and being as small as practical, I wanted the aball to be pretty easy to build and potentially serve as a jumping off point for other designs. So I kept these things in mind:
- Readily available parts
- Low cost
- Simple to assemble
- Majority 3d printed if desired
- Supports 38 and 34 mm balls
The design is pretty stripped back, here is a shot of the guts which are self supporting and can be used just as is:
The ball sits on a 3d printed frame which holds three roller bearings, and a microcontroller. The ball moves on top of an optical mouse sensor which is connected to the microcontroller. To make the whole thing as close as possible to the desktop, the mouse sensor sticks out of the bottom of the case, but only a bit and is off the desk due to the rubber feet on the bottom.
If you have not used a trackball with roller bearings before, I think you are in for a treat. It takes a day or two of good use to break them in, but I find them much smoother and more enjoyable than static dot type bearings. You can go cheap here, spending less than a dollar for all three of them and they will still be pretty good. However, a nice set of high quality bearings for RC use are not that much more expensive and the quality is definitely higher.
The microcontroller runs firmware based on QMK (Quantum Mechanical Keyboard). QMK is a fantastic open source project for keyboard firmware, but it also includes pointing device support. You can find the firmware source for the aball here: https://github.com/brickbots/qmk_firmware/tree/aball/keyboards/handwired/aball
The minimal implementation is pretty much what you see above and it can be put together for well under $40 if you already have a 3d printer. From there you can either 3d print an enclosure, or use the files here to get some acrylic and metal laser cut for a different look. I hope that other folks will adapt these guts and come up with new and clever case options. Maybe even add buttons on-board :-)
You can build one yourself! This repo contains design files, build guides, and a parts list so you can build your own aball if you so choose. If you do, please drop me a note at rich@brickbots.com. All information here is provided as-is for your personal use and is released under a specific Creative Common license which lets you use them for non-commercial use. Please see the included LICENSE file for details.
If you are ready to learn more, or even get started on your own aball, click below to keep exploring
Thanks and email with any questions to suggestions!