A Clock That Plots Time

[Johannes] just sent us a tip about his small plotter that plots out the current time.

[Johannes] small clock plotter uses a dry wipe pen to write out the time on a small piece of dry erase board. The design is Made of three small 9g servos, with one to lift the pen off the writing surface and the other two to control a pair of connected jointed arms for the x and y-axis.

The little robot painstakingly wipes away the previous time before scrawling the current time in its place (with minute accuracy).

[Johannes] had hackability in mind when creating this project, making sure to keep to standard parts and making the code and design files available. The hardware for the build can be laser cut or 3D printed. The Arduino sketch can be found on GitHub and the design files can be found on Thingiverse. There are more detailed build instructions on Nuremberg’s FabLab page (translated). 

56 thoughts on “A Clock That Plots Time

  1. Haha awesome!

    Reminds me of the useless inventions for some reason ;-)

    Is it just me or does that plotter have an attitude? The movements seem to suggest a though process of “ugh, now I gotta erase it and do it again!”

    1. If we mount the whole device on a screw rod with some suction cups on either end we could have it writing sentences on any white board. Add the bobble head as suggested in the comments and you might even keep students or colleagues attention.

    1. I second this idea, just update the digits that need replacing, would require an extra offset for the eraser thickness of course.

      The eraser is already on the right side to make this happen also.

  2. Ha, love it! The movements are great, it looks like a little guy writing with a huge pen! I can see two changes for this, 1, replace the dry erase board and pen with sand, no drying out of the pen so can run forever and 2, use it with a paper roller to write out a twitter feed. Oh thought of a third one, put a little costume on it to actually make it look like a little guy writing! Keep up the good work.

  3. Brilliant! I especially like the fact that the same mechanics are used to erase the board.

    I must say it somehow struck me as a bit depressing, because it just keeps doing to same mundane task over and over again, every time obliterating the result of the previous time. Funny how your mind (or mine, at least) can trick you into feeling sorry for a device made of plastic and some electronics.

    Maybe the eraser cup can prevent the marker from drying out while it’s waiting for the rest of the minute to pass. Either the cup could be placed such that the mechanism doesn’t obstruct the view of the time, or simply fetch the eraser after writing and them move the whole thing out of the way.

    Also, the ink has to go somewhere; I’d think it wouldn’t take long for the eraser to be saturated and start making smears on the board. I don’t have any idea how this could be prevented, but just erasing the digits that need to be changed would delay the need to clean or replace the eraser pad.

    It would be really cool to build one that can be clamped onto the corner of an existing whiteboard in the office, although the sound would probably become annoying really soon. I think using stepper motors instead of servos would significantly reduce the sound, but without microstepping it would probably still be significant, especially if mounted on a large whiteboard.

    I’m not quite sure what the usable range of the mechanism is, but I’d think you could also make it draw an analog clock face, instead of a digital one, or make it draw or write other things depending on the time or other events, like “LUNCH” around lunchtime, “BYE” when the workday is over, or “WEEKEND” on Friday afternoon.

    1. That was my immediate thought. Of all the x-y devices I’ve seen, this is the first time I’ve seen a pantograph type armature used in an automaton. I wonder why we haven’t seen this used in mills or even 3d printers. Maybe it doesn’t scale well?

      1. It’s basically a SCARA (Selective Compliance Articulated Robot Arm) design; these could be used for engraving or 3D printing, but the accuracy and stiffness varies greatly within the usable area. Also, You’d need rather expensive gearboxes to drive a bigger SCARA robot, and fairly big and strong bearings that need to be pre-tentioned to get the stiffness and play within acceptable limits, which probably offsets the cost of linear guides and leadscrews or toothed belts.

        Unfortunately, such a design would not be as simple or cheap as it may seem, but it’s certainly possible.

    1. Your’s writes horribly, jerks around like it’s having a seizure, and is just ugly. This one is a cup of finesse and two cups of cute, blended well and baked on awesome for half an hour.

      How could you possible compare the two?

      1. No need to insult… they both are arduino drawing clocks with servos that clear the time after it has been written. I can definitly see how one could think I built upon that concept, although i first saw it in the posts here.

  4. I appreciate the simplicity of th mechanical design. And it it fast at writing. Replacing the marker by a pencil engraver it could be used to make simple PCB. Should be tested for that purpose.

    1. Unless the time is being read from a global variable that never gets pushed into a temporary variable inside the drawing functions, bad thing’s I’d assume. But anyone with a grasp of why not to use global variables in this scope won’t do that in the first place.

      It is however very possible that if each digit drawn is a recurring function that adds an offset, by the time it got to the next digit it would increment and do something silly.

      1:49 might turn into 1:40 if the change happens right as the 4 is drawn out.

  5. A very fun project and I love it
    I have the plot Clock with my Prusa Mentel and everything works, just not as it should
    As far as I wipe the plotter up instead of down and write he does all left
    What am I doing wrong??
    Can you help me
    Servo1 = lift
    Servo2 = left
    Servo3 = right
    And what do the LCD in the program and what’s the program on the analog input, use a value of the analog input??
    In any case, I’m happy with that small plotter

  6. Hi. I’m Vietnamese. My English is very poor :( .Can you give me the code for this. I really want to make it with AVR. This is a very fun project and i love it!!
    Thank you!!!

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