Android controlled monitor stand uses marbles as ball bearings

[mobile_earth_explorer] sent in an Instructable he put together documenting an Android-controlled rotating monitor stand he built.

The stand itself is three disks turned on a lathe out of a 18mm thick board. After turning these disks, [mobile_earth_explorer] hopped over to his bench grinder and made a semicircular tool to carve out the track for the ball bearings.

Once the disks could rotate freely on each other, the only thing left was to carve out a space for the servo, Arduino, a pair of pots, and the wiring. The pots control the maximum speed of the monitor stand as well as provide a manual rotation control for when your phone is across the room.

[mobile_earth_explorer] wrote the Android app so up to five of these swiveling monitors can be controlled by just one Arduino; yes, that might be overkill for home or office use, but we’re sure it would be highly useful for some sort of presentation.

You can check out a few videos going over the conception and construction of [mobile_earth_explorer]’s monitor stands after the break.

20 thoughts on “Android controlled monitor stand uses marbles as ball bearings

    1. Officially yes, and you certainly wouldn’t want to try it in a professional shop, but for a medium-precision home shop it’s not so bad.

      The main problem is that it takes forever to clean the sawdust out of the lathe. Sawdust absorbs liquids, so it pulls water vapor out of the air (which can promote rust) and sucks up your lubricants (turning them into gunk).

      If you clean the lathe reasonably well after turning wood, it shouldn’t cause any problems. If you don’t clean your lathe at all, that’s a bigger no-no than turning wood.

      1. Right. There’s a problem if you use wood on a machine that’s getting maintained as if it were a metal-only machine. A standard engine lathe makes a wonderful wood lathe if it’s kept up.

    2. Minor design point: the grooves that carry the balls look pretty deep. You might find it useful to widen the top one.

      Ideally, you want two points of contact between the bearing and the races. To get that, you use a slot with a larger radius than the bearings themselves, so the gap between the races is lens-shaped. The bearings will naturally float to the widest part of the lens.

      If you have more than two points of contact, you have a bearing grinder. At least one point of contact will always have to slip, so you get scraping contact between the ball and the race. Throw in a little abrasive and you have exactly the kind of machine that grinds ball bearings to size.

  1. Why does someone do something somewhat cool, and you definitely want to see it, and maybe even do it yourself— but they then subject you to such a repetitive song that is so annoying you just don’t care about the hack any more?

    1. YouTube has a volume slider that goes down to “Mute” and so does your computer, pick one and use it.

      1. Thank you Captain Obvious, but we all know how to adjust volume.

        I listened to the annoying music anyway, only because I hoped that at some point during the video, the author would actually let us hear the *stand* in operation; and see whether the marble bearings make any grinding or clicking noises.

        Which he did not. So even with personal tastes in music aside, I agree the music is detrimental to the video.

  2. So it’s a Lazy Susan with a servo… would make more sense if it was able to track your movement and move accordingly. The stand itself is probably the best part of the build. Beyond that, it’s mostly just a because I can hack.

  3. What would be cool (something I have been meaning to build) is have a sensor that when you tilt your screens vertically, the resolution/orientation automatically changes. Having motors do this, and also position your screens correctly (so they are side by side) would be really cool.

    Even better would be have this happen when you load up your dev env or make emacs full screen (that might get annoying though…)

    1. I mounted my 22″ monitor on a lazy susan to swap between landscape and portrait just like that. Currently I’ve got a hotkey bound to rotate the desktop, but it would be really trivial to implement a hardware switch.

      Unfortunately my computer desk puts my monitor up way too high for portrait mode to be comfortable (best practise is to put the top of the monitor at the same height as your eyes; mine is already a bit higher when in landscape) so I don’t really use it much anymore.

  4. Wonder what the maximum load of a pile of marbles is, and what the maximum pressure that wood will take is because I feel this form of swivel would be very appropriate for an office chair with a fixed position.

    It’s a slightly unrealistic dream but I did plan on having a central chair with a circular desk around it and a ton of monitors. Perhaps the monitors could all be hooked up to different machines/VMs and the chair would swivel to that machine when it triggers a notification. Just a thought.

    1. A standard router with a straight edged bit on pivoting arm could make the circles, and a rounded bit could then be used to do the raceways for the marbles, if a lathe is unavailable. Arguably quicker, simpler, and less messy, but as this is Hackaday, extra kudos for literally reinventing the wheel!!

  5. A more interesting version would be one that would use a $10 universal remote control from Walmart for control, rather than a phone that costs 20 times that. Not to be critical of those who use what they have in their design, because we are all free to modify anything to fit our needs, generally.

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