Concentric Rings Keep This Calendar Perpetually Up To Date

The variety of ways that people find to show the passage of time never ceases to amaze us. Just when you think you’ve seen them all, someone comes up with something new and unusual, like the concentric rings of this automated perpetual calendar.

What we really like about the design that [tomatoskins] came up with is both its simplicity and its mystery. By hiding the mechanism, which is just a 3D-printed internal ring gear attached to the back of each ring, it invites people in to check it out closely and discover more. Doing so reveals that each ring is hanging from a pinion gear on a small stepper motor, which rotates it to the right point once a day or once a month. Most of the clock is made from wood, with the rings themselves made using the same technique that woodturners use to create blanks for turning bowls — or a Death Star. We love the look the method yields, although it could be even cooler with contrasting colors and grains for each segment. And there’s nothing stopping someone from reproducing this with laser-cut parts, or adding rings to display the time too.

Another nice tip in this write up is the trick [tomatoskins] used to label the rings, by transferring laser-printed characters from paper to wood using nothing but water-based polyurethane wood finish. That’s one to file away for another day.

7 thoughts on “Concentric Rings Keep This Calendar Perpetually Up To Date

    1. A basic version of this is done with mechanical watches for the day/date of the month. The price starts to (very, very, quickly) go up once you turn it into a perpetual calendar that accounts for 28/30/31 days, and even moreso with leap years.

      This is all to say that a mechanical version which accounts for proper calendars would be incredibly complicated, and unlikely to fit in as nice of a footprint as this version.

    2. That becomes a balancing act between multiple springs engaging the time train under load. Not as simple as you think, especially in true perpetual form. I should know- working on just that sort of thing for a wristwatch.

      Should be much easier to do with a weekly wound wall clock however. If you’re really into this sort of thing, a copy of the book “Modern Calender Watches” by Bernard Humbert will help you make much more sense of how such things, including perpetual calenders, are designed. Lots of large clear line mechanical drawings explaining just how they work. You could then adapt them for clock use.

      1. Apparently akismet hates b l o g s p o t links, so I can’t show you a mechanical perpetual calendar made out of wood, but you can easily DDG it by “Wooden Clock Spot” and “perpetual calendar”

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