A Trackball So Good You Can’t Buy It

The projects we feature on Hackaday are built to all standards, and we’d have to admit that things have left our own benches as bundles of wire and tape. Sometimes we see projects built to such a high standard that we’re shocked that they aren’t a high-end manufactured product, such as [jfedor2]’s two-ball trackball project. It combines a pair of billiard balls and a couple of buttons with a beautifully-designed 3D-printed case that looks for all the world as though it came from a premium peripheral brand.

Inside are a pair of PMW3360 optical sensors on PCBs mounted with a view into the billiard ball sockets, and for which the brains come courtesy of an RP2040 microcontroller. There are five PCBs in all, each having a set of purpose-built stand-offs to hold it. The result appears to be about as good a trackball as you’d hope to buy, except of course that you can’t. All the files to make your own are in the GitHub repository though, so all is not lost.

Over the years we’ve brought you a variety of trackball designs, including at least one other build using a billiard ball.

21 thoughts on “A Trackball So Good You Can’t Buy It

  1. As a trackball lover I’m looking at this with some dubious feelings as to how it will be to use, it looks superb, but I’m not sure on the ergonomics at all.

    Interesting one though, certainly going on my list of ideas its worth replicating or at least mocking up when I get the chance. I just don’t see the two trackballs being easy to operate, seems from the pictures like you would forever be bumping the one you were not actively trying to move, or contorting you hand uncomfortably to reach it… Might well be great if you hands are exactly the size of the original designer, and could be much better than I think in use – I can see the layout and logic but some things you just have to have in hand to know they feel right/wrong.

    Also I like the idea of the USB socket for swappable cable – if a device is going to be wired and a HID it really should let you plug whatever length of wire into you need, there is nothing more annoying than having a mouse cable too short to reach the computer so you have the whole cable from the USB hub on the desk, or so long that the weight of the cable (and all the others its got tangled with) off the back of the desk is pulling it around too… So putting wires the length you like neatly tied up at each station and being able to just plug in your preferred HID is great. With a trackball where the device shouldn’t move its less trouble, but still a good idea IMO.

    1. I’m in team “leave” on dual trackballs as well. I like to scroll either up/down or right/left. Not both at the same time. I remember how cool the little IBM mouse with the nipple instead of a wheel seemed, but in practice I hated it.

      I’m a recent trackball convert, but have been smitten by the sexy scroll wheel on the Logitech MX3 and have been using it for months. The thumb scroll on it is nice, but I wish it was clicky.

      I think my biggest complaint with this mouse is that I feel like buttons were sacrificed for the scrollball. I love the thumb cluster in the Elecom huge – 4 buttons plus a scroll wheel right there! Though I had to replace the 140gf tact switch (which is even stronger thanks to the pressure point being halfway between the fulcrum and the switch) in the scroll wheel clicker for a 55gf one.

      1. > Not both at the same time.

        I’m thinking more like independently, not having to press a button or key. That’s why mice have scroll wheels (and some tilt sideways for horizontal) despite middle-click being available.

        That said, maybe the scroll-ball could be smaller. Personally I think it’s too further back (my thumb hurts when I use the back/forward buttons on my mouse a lot).

        1. Now that I think about it, scrolling could be constrained to one axis or another depending on how you start the scroll. The 3DConnexion Spacemouse has an option for this that works very well. Being open source, I’d bet someone much more intelligent than I could code this in. I’d still rather have two independent scroll wheels, each of which could give me an extra button. Being open source, I suppose I could make this happen myself if I put a fraction of the time or thought into it as the maker did this mouse – after all, he/she made it for themselves, not for me :)

  2. What is the purpose?

    The only thing I can think of is to rotate 3D object in 2 different planes at the same time, but you’d really have difficulty coordinating your finger & thumb.

  3. “Color matching”, apparently a type of sub-preist in the video production industry, uses a triple trackball setup somehow. NFI how that works.

    I take every opportunity to recommend the “Elecom M-HT1UR” trackball, like this one; because they’re the closest match to the old MS Trackball Explorer that’s out there; and they’re pretty good.

    I’m on my second one now, the first lasted at least 4 years under my hands, which is about as long as I get out of anything. My model M keyboards last 6yr, tops. *Heavy* usage and psoriasis on hands.

  4. I am not all thumbs but just 2. They’re good for grabbing things but not controlling unless against fingers ie. a pen or pencil. They have one of these at work and the click buttons are hard to see over the hill on the far side, as I have to use my fingers on the front mounted thumb ball. Yuck. I have two gyro touch tuning wheels from an old tuner that would make a great X or Y mouse that I’d like to make. I have an old USB ball mouse to hack it to, but not the time. I’ve spent less than 2 minutes trying to play a video game with that left thumb “+” control.

    1. You can make great use of a thumb for control – dexterity and sensitivity wise they are right up there with fingers – the real thing with any change of HID device is getting used to the new one, the more different it is from what you know the more it feels bad to start with. Though it can also just be worse ergonomically for you there is nothing inherently wrong with trackballs for the thumb.

    1. There’s a .step file available for your convenience. The designer was kind enough to make this available for free and open source. They could be keeping it all for themselves, unmodifiable by anybody who mouses differently.

  5. Custom trackballs interest me. I use a Logitech M575 trackball. I upgraded from an M570 in late 2020 before the notorious switches in the M570 failed. Introduced in October 2020 supposedly the M575 has much improved switches – time will tell. With the advent of affordable 3D printers building custom mice and trackballs became a real thing. Also surface motion sensors became good enough to track resin snooker balls. Here [1] is a whole page on mouse and trackball sensors.

    Snooker balls are used instead of billiard balls because they are one solid color. I’m not sure if that’s a requirement for tracking or that solid colors are simply preferred for the aesthetics. Mini snooker and billiard balls for kiddy tables usually come in 25, 32, & 38 mm diameters.[2] 32 mm snooker balls are most commonly used in bespoke trackballs. For comparison purposes, at 52.5 mm in diameter standard snooker balls [3] are too large for trackballs used by Humans.

    BTW if you are wondering, I read somewhere that you cannot just drop a 32 mm mini snooker ball into your Logitech M570/M575 trackball. Evidently the Logitech ball is 34 mm in diameter, not 32 mm like a mini snooker ball, so the 32 mm snooker ball rattles around a bit in the M570/M575 socket and will fall out if the trackball is inverted.

    1. Mouse Guide – Sensors


    2. 25MM/32MM/38MM Billiard Ball Set Resin $14.55 – $30.19


    3. Billiard Ball – Snooker


    1. There are trackballs out there that are great to use with balls even bigger than 52mm, and the one on my desk now is something around that size. Smaller ones do clearly have some advantages – like building into smaller packages, being simpler to make than the hollow balls you require as you get bigger – you can use a bowling ball size as a trackball quite comfortably if its built in to the surface, but the balls mass would really be fatiguing to use so you need a nice smooth even hollow sphere to get bigger at some point eventually.

      1. @Foldi-One said: “There are trackballs out there that are great to use with balls even bigger than 52mm, and the one on my desk now is something around that size.”

        I said: “…at 52.5 mm in diameter standard snooker balls [3] are too large for trackballs used by Humans.” That’s my opinion. I have used large direct contact trackballs on commercial and military equipment before. In all cases I found the balls to cause finger and wrist fatigue because they were too big and heavy and therefore easily build up angular momentum (p = mass x velocity).

        1. I’ve used a few very large ones, and with hollow sphere balls they are not that bad – also once you get big enough you stop using fingers in favour of palms I would suggest – as a kid I had a giant trackball (think I’ve still got it somewhere awaiting transformation from a useless serial device) and it was great to use, even as a rather smaller person with a ball something near bowling ball in scale (smaller than most but the best comparison I can think of – way bigger than any of the other common enough balls)

          I do agree though if you don’t make the ball much lighter for its size than the smaller trackball its going to be horrible to use – with a smaller trackball you pretty much want a heavy ball so it will keep rolling a little with its inertia – so you can cross the larger screen area with a flick while still having the sensitivity sane enough you can hit the target you want to.

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